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NeurocysticercosisOscar H. Del Brutto, MD, FAAN

ABSTRACTPurpose of Review: Neurocysticercosis occurs when humans become intermediatehosts in the life cycle of Taenia solium by ingesting its eggs directly from a taeniacarrier or, less often, by contaminated food. Within the nervous system, cysticerci maylodge in the brain parenchyma, subarachnoid space, ventricular system, or spinal cord,causing a number of pathologic changes that are responsible for the pleomorphism ofneurocysticercosis. This article discusses the clinical manifestations, diagnosis, and treat-ment of neurocysticercosis.Recent Findings: Formerly endemic in the developing world, mass immigration ofpeople from disease-endemic to nonendemic areas has caused a recent increase in theprevalence of neurocysticercosis in developed countries, where this condition should nolonger be considered exotic. Recent advances in neuroimaging and immune diagnosticmethods, and the introduction of a set of diagnostic criteria, have enhanced thediagnostic accuracy for neurocysticercosis. Likewise, introduction of potent cysticidaldrugs has radically changed its prognosis.Summary: Neurocysticercosis is the most common helminthic infection of the CNS andamajor cause of acquired epilepsy worldwide. Diagnosis of neurocysticercosis is possibleafter interpretation of clinical data together with findings of neuroimaging studies andresults of immunologic tests in a proper epidemiologic context. The use of cysticidal drugsreduces the burden of infection in the brain and improves the clinical course of mostpatients. Further efforts must be directed to eradicate the disease through the imple-mentation of control programs against all interrelated steps in the life cycle of T. solium,including human carriers of the adult tapeworm, infected pigs, and eggs in the environment.

Continuum Lifelong Learning Neurol 2012;18(6):1392–1416.

INTRODUCTIONNeurocysticercosis, defined as infectionof the CNS by the larval stage of the porktapeworm Taenia solium, is currentlyconsidered the most common helmin-thic disease of the CNS in humans anda major public health challenge formost of the developing world. In ruralareas of endemic countries, almost allconditions favoring the transmissionof the disease, including warm climate,poverty, and illiteracy, are combined.The complex and unpredictablenature of the immunologic reactionof the host against cysticerci, as well asthe myriad pathologic lesions thatparasites may induce in the CNS, makeneurocysticercosis a fascinating dis-ease. Basic and clinical aspects of neuro-

cysticercosis with emphasis on recentadvances on diagnosis and therapy willbe discussed in this review.

EPIDEMIOLOGYThe exact prevalence of neurocysticer-cosis is unknown; however, it is esti-mated that millions of people living inthe developing world are infected bythe larval form of T. solium, and thatmany of them will experience the clin-ical consequences of this infection atany point of their lives.1 In broad terms,neurocysticercosis is endemic in mostLatin American countries, sub-SaharanAfrica, and some regions of Asia, includ-ing the Indian subcontinent, Indonesia,Vietnam, Korea, and China. Cysticerco-sis is rare in Northern Europe, Canada,

Address correspondence toDr Oscar H. Del Brutto, AirCenter 3542, PO Box 522970,Miami, FL 33152-2970,[email protected].

Relationship Disclosure:Dr Del Brutto has receivedtravel expenses for servingon the Safe Implementationof Treatment of Strokesteering committee.

Unlabeled Use ofProducts/Investigational

Use Disclosure: Dr Del Bruttoreports no disclosure.

* 2012, American Academyof Neurology.

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Review Article

Copyright @ American Academy of Neurology. Unauthorized reproduction of this article is prohibited.

Australia, Japan, and New Zealand,except among immigrants, and is onlyoccasionally reported from Israel andMuslim countries of Africa and Asia(Figure 8-1). Neurocysticercosis wasrare in the United States and WesternEuropean countries up to 30 years ago.With the growing number of immigrantsfrom endemic areas, an increased num-ber of patients in these countries areestimated to have neurocysticercosis.These outbreaks, followed by an endemicnature of cysticercosis in the affectedregion, together with the appearanceof indigenous cases, are examples ofthe difficulties that exist to control azoonotic disease once it has been estab-lished. In the United States, most caseshave been reported from the south-western states, where more than 20 mil-lion Mexican Americans live. Almost90% of patients with neurocysticercosisdiagnosed in the United States are immi-grants from Mexico or South America.2,3

A similar scenario has been observed inSpain, where mass immigration of peo-ple from South America has caused arecent increase in the prevalence ofthis parasitic disease.4 These and othermajor cysticercosis outbreaks have re-sulted from mass movement of people(or infected swine) from endemic to non-endemic areas (Figure 8-2).

While neurocysticercosis is still animportant cause of admission to neuro-logic hospitals and a major cause of ac-quired epilepsy, some recent evidencesuggests that its prevalence is decreas-ing in developing countries, not onlyin urban centers but also at the rurallevel. It has been considered that wide-spread use of cysticidal drugs, im-proved sanitation, and increasedpublic awareness of the disease maybe responsible for the recently recog-nized drop in the number of patientswithsymptomatic neurocysticercosis inendemic areas.5,6

KEY POINTS

h In broad terms,neurocysticercosis isendemic in most LatinAmerican countries,sub-Saharan Africa,and some regionsof Asia, including theIndian subcontinent,Indonesia, Vietnam,Korea, and China.

h In the United States,most cases ofneurocysticercosis havebeen reported fromthe southwesternstates, where morethan 20 million MexicanAmericans live. Almost90% of patients withneurocysticercosisdiagnosed in theUnited States areimmigrants from Mexicoor South America.

FIGURE 8-1 World map showing regions where neurocysticercosis is endemic.

1393Continuum Lifelong Learning Neurol 2012;18(6):1392–1416 www.aan.com/continuum


ETIOPATHOGENESISLife Cycle of Taenia SoliumThe life cycle of T. solium involves twohosts: humans and pigs. Humans are

the only definitive hosts for the adult ces-tode, whereas both pigs and humansmayact as intermediate hosts for the larvalform called cysticercus (Figure 8-3).

KEY POINT

h The life cycle of Taeniasolium involves twohosts: humans and pigs.Humans are the onlydefinitive hosts for theadult cestode, whereasboth pigs and humansmay act as intermediatehosts for the larval formcalled cysticercus.

FIGURE 8-2 World map showing major outbreaks of human cysticercosis related to massmovement of people or infected swine from endemic to nonendemic areas. (1)Return of British soldiers from India to England; (2) gift of infected swine from

Bali to Irian Jaya; (3) mass return of Portuguese living in African colonies after wars in Angolaand Mozambique; (4) migratory movements of people from Mexico and South America to theUnited States (mainly to the southwestern and the New York City areas); (5) mass migration ofpeople from Ecuador, Peru, and Bolivia to Spain; (6) migration of people from India to countriesof the Arabian Peninsula (mainly Kuwait, Saudi Arabia, and Qatar).

FIGURE 8-3 Diagram of major steps in the life cycle of Taenia solium.


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The head (scolex) of the adultT. solium consists of four suckers anda double crown of hooks, a narrowneck, and a body formed by hundredsof proglottids. The adult parasite isattached to the intestinal wall by itspotent suckers and hooks. Every fewdays, some gravid proglottids aredetached from the distal end of theworm and passed with the feces. Eachproglottid liberates thousands of fertileeggs that are resistant to the environ-ment. In places with deficient disposalof human feces, free-roaming pigs haveaccess to human feces containing T.solium eggs (Figure 8-4). Once in theintestinal tract of the pig, the eggsliberate embryos (oncospheres), whichcross the intestinal wall, enter thebloodstream, and are carried to thetissues, where they evolve to formmetacestodes, which, in turn, evolveinto larvae (cysticerci). The larvae aresmall vesicles that consist of two parts,the vesicular wall and the scolex.7

Under these circumstances, pigsdevelop cysticercosis and becomeintermediate hosts in the life cycle ofT. solium. The normal life cycle of T.

solium is completed when humansconsume improperly stored andcooked pork meat infected with cys-ticerci (Figure 8-5). This process resultsin release of cysticerci in the small in-testine where, by the action of digestiveenzymes, scolices evaginate and attachto the intestinal wall, and proglottids

FIGURE 8-4 Pigs roaming free in rural villages ofdeveloping countries. In this way, pigs haveaccess to human feces, become infected withTaenia solium eggs, and develop cysticercosis.

FIGURE 8-5 Consumption of undercooked pork meatunder poor sanitary conditions is a threat to

thousands of people living in rural villages of developingcountries.



begin to multiply and become matureapproximately 4 months after theinfection.

Humans can also act as intermediatehosts for T. solium after ingesting itseggs, thereby allowing human cysticer-cosis to develop. The mechanisms bywhich eggs cross the intestinal wall andlodge in human tissues are the same asthose described in the pig. Humansmost often acquire cysticercosis by thefecal-oral route from a close contact har-boring the adult parasite in the intestine.Recent epidemiologic data showingclustering of people with cysticercosisaroundtaeniasic individualshavechangedprevious concepts crediting the environ-ment as the main source of human con-tamination with T. solium eggs.8 Humancysticercosis should now be consideredas a disease mostly transmitted fromperson to person; the role of infectedpigs is to perpetuate the infection.

Morphology and Stagesof Involution of CysticerciAfter entering the CNS, cysticerci are ina vesicular (viable) stage in which theparasites have a transparentmembrane,a clear vesicular fluid, and a normal in-vaginated scolex (Figure 8-6A). Cysti-cerci may remain viable for years or, asthe result of the host’s immunologic attack,enter into a process of degenerationthat ends with their transformation intoinert nodules. It is also possible that theimmune attack can occur even beforethe transformation of metacestodes intovesicular cysticerci. Independently, if themetacestode or the vesicular cystundergoes the immunologic attackfrom the host, the first stage of involu-tion of cysticerci is the colloidal stage, inwhich the vesicular fluid becomes tur-bid and the scolex shows signs ofhyaline degeneration. Thereafter, thewall of the cyst thickens and the scolexis transformed into mineralized gran-ules; this stage, in which the cysticercusis no longer viable, is called the granularstage. Finally, the parasite remnantsappear as a calcified nodule. It is com-mon to find cysticerci in differentinvolutive stages in the same individual.It is unknown whether this representscysts of different ages from recurrentinfections or a single infection in whichonly some parasites have been attackedby the host’s immune system.

In some cysticercus, the scolex can-not be identified. These parasites arecomposed of several membranes at-tached to each other that tend to groupin clusters resembling a bunch of grapes.This form is called the racemose form ofcysticerci, and is usually observed in par-asites located within the CSF cisterns atthe base of the brain, where they mayattain a large size.9 While the mecha-nisms responsible for the transformationof cysticerci from single vesicles to theracemose form are not totally under-stood, it is likely that scolices disappear

KEY POINTS

h Human cysticercosisshould now beconsidered as a diseasemostly transmitted fromperson to person; therole of infected pigs isto perpetuate theinfection.

h It is common to findcysticerci in differentinvolutive stages in thesame person. It isunknown whether thisrepresents cysts ofdifferent ages fromrecurrent infectionsor a single infectionin which only someparasites have beenattacked by the host’simmune system.

FIGURE 8-6 Anatomopathologic findings inneurocysticercosis. A, Vesicular cysts in brainparenchyma. B, Subarachnoid parasitic

membranes surrounded by dense mononuclear inflammatoryreaction. C, Dense exudate surrounding the brainstem andthe engulfing basilar artery.


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and parasites grow as the result of a de-generative process called hydropic de-generation, caused by the continuousentrance of CSF into the vesicles.

Tissue ReactionAround CysticerciParenchymal brain cysticerci in thevesicular stage elicit a scarce perile-sional inflammatory reaction that ismainly composed of plasma cells, lym-phocytes, and eosinophils. Colloidal cys-ticerci are surrounded by a thick collagencapsule and a mononuclear inflamma-tory reaction that usually includes theparasite itself. The surrounding brainparenchyma shows an astrocytic gliosisassociated with microglial proliferation,edema, neuronal degenerative changes,and perivascular cuffing of lymphocytes.When parasites enter into the granularand calcified stages, the edema subsidesbut the astrocytic changes in the vicinityof the lesions may become more in-tense, and epithelioid cells appear and

coalesce to form multinucleated giantcells (Table 8-1).

Meningeal cysticerci usually elicit asevere inflammatory reaction in the sub-arachnoid space with formation of anexudate composed of collagen fibers,lymphocytes, multinucleated giant cells,eosinophils, andhyalinizedparasiticmem-branes leading to abnormal thickeningof the leptomeninges (Figure 8-6B).This inflammation may be dissemi-nated, inducing damage in structuresdistant to the site where the parasiteslodge. The optic chiasm and cranialnerves arising from the brainstem areencased in this leptomeningeal thick-ening. The foramina of Luschka andMagendie may also be occluded by thethickened leptomeninges and parasiticmembranes, with the subsequent de-velopment of obstructive hydrocephalus.Intracranial vessels may also beaffected by the subarachnoid inflam-matory reaction (Figure 8-6C) and causeocclusion of the lumen of the vessel

TABLE 8-1 Correlation Between Appearance of Parasites andPathologic Changes in CNS According to Stage ofInvolution of Parenchymal Brain Cysticerci

Stage ofInvolution Appearance of the Parasite

Pathologic Changes inthe Brain Parenchyma

Vesicularstage

Translucent vesicular wall

Transparent vesicular fluid

Viable invaginated scolex

Scarce inflammatory reaction

Formation of a thin collagencapsule around the parasite

Colloidalstage

Thick vesicular wall

Turbid vesicular fluid

Scolex showing signs ofhyaline degeneration

Intense inflammatory reactionthat includes the parasite

Thick collagen capsule aroundthe parasite

Granularstage

Thick vesicular wall

Degenerated scolex

Astrocytic gliosis around the cyst

Microglial proliferation

Calcifiedstage

Transformation of the parasitein coarse calcified nodules

Intense gliosis

Multinucleated giant cells



with the subsequent development of acerebral infarction.10

Ventricular cysticerci may also elicitan inflammatory reaction if they areattached to the choroid plexus or to theventricular wall. The ependymal liningis disrupted, and proliferating subepen-dymal glial cells protrude toward theventricular cavities, blocking the transitof CSF, particularly when the site ofprotrusion is at or near the foramina ofMonro or the cerebral aqueduct.9

Immune ResponseAgainst CysticerciSome cysticercal antigens play a role inthe evasion of the immune surveillanceagainst the parasite. One of them, an-tigen B, is a paramyosin with affinity forcollagen that may bind to C1q, inhibit-ing the classic pathway of complementactivation. Since destruction of cysticerciseems to be mediated by activation ofthe complement cascade, antigen Bcould play a role in the protection ofcysticerci against the host’s immuno-logic attack. Host immunoglobulins havebeen found around living intracranialcysts, suggesting that cysticerci use thesemolecules as a screen to avoid recogni-tion from the immune system.

Some reports suggest the occur-rence of cellular immune dysfunctionin patients with neurocysticercosis. Thisimpairment results from an increase inthe subpopulations of CD8 T lympho-cytes, impaired proliferation of lympho-cytes, and abnormal concentration ofcytokines. The depressed cellular immu-nity may be responsible for the associa-tion of neurocysticercosis with conditionsresulting from immunodeficiency statesand glial tumors. In the latter, the in-tense glial proliferation around the para-sites, along with the suppression of thecellular immune responses, may causeinhibition of the immunologic surveil-lance against cancer, leading to malig-nant transformation of astrocytes.11

CLINICAL MANIFESTATIONSNeurocysticercosis may produce noclinical manifestations at all or may besevere enough to cause the death of thepatient. This pleomorphism is relatedto individual differences in the num-ber and location of the lesions as wellas in the severity of the host’s immuneresponse to the parasite. Therefore, defin-ing a typical syndrome of neurocysticer-cosis is unrealistic. In endemic areas thisparasitic diseasehas traditionally been con-sidered the ‘‘great imitator,’’ as it maymimic almost any neurologic disorder.12

A recent systematic review showed thatrecurrent seizures occur in approximately80% of symptomatic neurocysticercosiscases, confirming previous findings thatepilepsy is themost commonclinicalman-ifestation of the disease.13 Other man-ifestations of neurocysticercosis includefocal neurologic deficits (16%), increasedintracranial pressure (12%), and cognitivedecline (5%). Cysticercosis outside theCNS is not associated with clinical man-ifestations, with the exception of ocularcysticercosis and some cases with mas-sive muscular involvement.12

Cysticercosis affectsmales and femalesequally from infancy to old age, with apeak incidence among middle-agedadults. The course of the disease is some-what different in infants and childrencompared to adults, and neurocysticerco-sis tends to be more severe in women.The reasons for these findings are incom-pletely understood; however, it is possi-ble that the interaction of several factors,including increased reactivity of theimmune system in children and women,could be responsible for the age- andgender-related observed differences inthe pattern of disease expression.

Geographic differences in the clinicalspectrum of the disease have also beennoted. For unclear reasons, subcutaneousand muscular cysticercosis is observedfar more frequently in Asia and Africathan in the Americas. Moreover, almost

KEY POINT

h Defining a typicalsyndrome ofneurocysticercosis isunrealistic. In endemicareas this parasiticdisease has traditionallybeen considered the‘‘great imitator,’’ as itmay mimic almost anyneurologic disorder.


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all reported patients with massive andsymptomatic infection of skeletal mus-cles came from China and the Indiansubcontinent.14 Such geographic dif-ferences have led to the suggestion ofpossible strain differences of cysticerci;however, other factors such as a moresevere burden of infection due to en-vironmental, cultural, dietary, and nutri-tional differences, as well as geneticvariations between populations, couldmore suitably explain clinical differencesamong African, Asian, and American pa-tients with the disease.

Seizures/EpilepsyRecurrent seizures usually representthe primary or sole manifestation ofparenchymal brain cysticercosis.1,15 Neu-rocysticercosis is a leading cause ofacquired epilepsy in endemic areas andpartly responsible for the increasedprevalence of epilepsy in the devel-oping world.16Y18 While some serieshave shown that most patients withneurocysticercosis-related epilepsyhave generalized seizures, it is mostlikely that those patients actually hadpartial seizures with rapid secondarygeneralization. Epileptogenesis inneurocysticercosis has been a subjectof debate. While it has been suggestedthat seizures occur when the parasitesbegin to degenerate, large series haveshown that seizures may also occur inpatients who only have vesicular (viable)cysts at the time of diagnosis.15 Therehas also been debate about the risk ofrecurrent seizures in patients with calci-fied parenchymal brain cysticerci.19 Whilecalcifications have been considered inertlesions, recent data suggest that calcifiedcysticerci may cause recurrent seizureswhen parasitic antigens trapped in thecalcium matrix are exposed to the hostimmune system because of a processof calcification remodeling, inducing in-flammatory changes in the brain paren-chyma.20,21 Recurrent seizures may

also be the cause of hippocampalsclerosis, thus perpetuating the risk ofseizures.22

Focal Neurologic DeficitsNeurocysticercosis has been associatedwith almost any known focal deficit ofcentral origin, including motor and sen-sory deficits, language disturbances, invol-untarymovements, parkinsonian rigidity,gait disturbances, incoordination, andsigns of brainstem dysfunction.13 Suchdeficits may be related to strategicallylocated parenchymal brain cysts or, mostoften, to compressive effects of large sub-arachnoid cysticerci. Other patients pres-ent with focal signs of acute onset relatedto the occurrence of a cerebral infarctdue to cysticercotic angiitis. Ischemic ce-rebrovascular complications of neuro-cysticercosis include lacunar infarcts andlarge cerebral infarcts. Lacunar infarctsoccur as the result of inflammatory oc-clusion of small perforating arteries atthe base of the brain and may be lo-cated at the posterior limb of the inter-nal capsule, the corona radiata, or thebrainstem; they produce typical lacu-nar syndromes, clinically indistinguish-able from those caused by hypertensivearteriolopathy. Large cerebral infarctsmay be caused by occlusion of majorintracranial arteries; patients presentwith profound focal neurologic deficitssecondary to an infarct involving basalganglia and cerebral cortex, or may de-velop subacute dementia when bothanterior cerebral arteries are occluded.10

Cysticercotic arachnoiditis may also causeentrapment of cranial nerves arising fromthe ventral aspect of the brainstem. Thismay cause extraocular muscle paralysisdue to damage of oculomotor nerves,as well as sensorineural hearing loss,facial palsy, or even trigeminal neuralgiadue to involvement of lower cranialnerves. Neurocysticercosis of the spinalcanal also occurs with focal neurologicsigns, including weakness and sensory

KEY POINTS

h Neurocysticercosis isa leading cause ofacquired epilepsy inendemic areas and ispartly responsible forthe increasedprevalence of epilepsyin the developing world.

h While calcifications havebeen considered inertlesions, recent datasuggest that calcifiedcysticerci may causerecurrent seizureswhen parasitic antigenstrapped in the calciummatrix are exposed tothe host immune systembecause of a process ofcalcification remodeling,inducing inflammatorychanges in the brainparenchyma.



disturbances below the level of thelesion that may be associated withradicular pain when cysts are locatedin the spinal subarachnoid space.23

Intracranial HypertensionVarious mechanisms explain the occur-rence of increased intracranial pressurein patients with neurocysticercosis.The most common is hydrocephalus,which, in turn, is most often related toinflammatory occlusion of the Luschkaand Magendie foramina, although somepatients develop hydrocephalus be-cause of blockage of CSF circulation byventricular cysts or ependymitis occlud-ing Monro foramina or the cerebralaqueduct.24 The clinical course of in-creased intracranial hypertension inpatients with hydrocephalus due tobasal arachnoiditis is subacute orchronic, while that of patients withhydrocephalus related to fourth ven-tricle cysts may be punctuated byepisodes of sudden loss of conscious-ness related to movements of the head(Bruns syndrome), and that of cerebralaqueduct stenosis may be associatedwith paroxysmal headache and Pari-naud syndrome (Case 8-1).

Irrespective of their pathogeneticmechanism, hydrocephalus is an omi-nous sign associated with highmortalityrates.

Intracranial hypertension may alsobe related to the occurrence of the so-called cysticercotic encephalitis, whichis a severe form of parenchymal neuro-cysticercosis that usually affects childrenand young women (Case 8-2). Patientswith cysticercotic encephalitis presentwith cloudiness of consciousness of acuteor subacute onset associated with sei-zures, decreased visual acuity, headache,vomiting, and papilledema.12

Cognitive DeclineCognitive decline, ranging from poorperformance on neuropsychological

testing to severe dementia, may occurin some patients with neurocysticercosis,particularly in those with chronic normalpressure hydrocephalus.12 Before theintroduction of CT, these patients wereadmitted to psychiatric hospitals foryears until the correct diagnosis wassuspected because of the occurrenceof seizures or focal neurologic signs.Some patients with parenchymal brainlesions develop psychotic episodes char-acterized by confusion, paranoid idea-tion, psychomotor agitation, violentbehavior, and visual hallucinations;some of these episodes could repre-sent attacks of psychomotor epilepsyor postictal psychosis.

DIAGNOSISPeripheral eosinophilia is a common,albeit nonspecific, hematologic abnor-mality in patients with neurocysticerco-sis. The frequency of positive stoolexaminations for T. solium eggs amongthese patients has varied from oneseries to another and seems to be re-lated to the severity of infection. Pa-tients with heavy infections have agreater chance of also having taenia-sis.25,26 Recognition of Taenia eggs isnot easy, and many patients may es-cape detection when coproparasitologicstudies are performed. Specific coproan-tigen detection by ELISA and PCR hasimproved the screening for T. soliumcarriers.27

Nonspecific abnormalities in thecytochemical composition of CSF arecommon in patients with neurocysti-cercosis. These abnormalities directlycorrelate with the activity of the diseaseand with whether or not the parasitesare located in the subarachnoid space.The most common finding is a moder-ate mononuclear pleocytosis, with cellcounts rarely exceeding 300/2L. Mildincrease in CSF protein counts, usuallyin the range of 50 mg/dL to 300 mg/dL,is also common. CSF glucose levels are

KEY POINT

h The frequency ofpositive stoolexaminations forT. solium eggs hasvaried from one seriesto another and seemsto be related to theseverity of infection.Patients with heavyinfections have agreater chance of alsohaving taeniasis.


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Case 8-1A 60-year-old woman was evaluated because of progressive headache andvomiting. She had been admitted 2 months before at another hospitalbecause of hydrocephaluswith asymmetric dilatation of the lateral ventricles,as well as dilatation of the third and fourth ventricles. A right ventricularshunt was placed with isolated reduction in the size of the right lateralventricle, and 15 days later, she underwent the placement of anotherventricular shunt, this time on the left side, with reduction in the size of leftlateral and third ventricles. However, because the fourth ventricle remaineddilated she was transferred to the present institution for further evaluation.On admission, neurologic examination revealed abnormal downward gazeand generalized increased muscle stretch reflexes with bilateral Babinskisigns. CT of the head showed collapse of both lateral ventricles resulting fromshunt placement and an abnormally dilated fourth ventricle (Figure 8-7). MRIshowed no evidence of a cystic lesion in the fourth ventricle. A serumimmunoblot test for the detection of anticysticercal antibodies was positive.She underwent the placement of another shunt device for drainage ofthe fourth ventricle, with progressive clinical improvement and furtherreduction in the size of that ventricle.

Comment. Thiswoman had doublecompartmenthydrocephalusrelated tosimultaneousocclusion of thecerebral aqueductand the Luschka andMagendie foramina.She also hadependymitis at thelevel of the rightMonro foramen,which explains thefact that the firstventricular shunt

only reduced the size of the right lateral ventricle, and it was only afterthe second derivative procedure that the size of the left lateral and thirdventricle returned to normal. Double compartment hydrocephalus inneurocysticercosis may also be related to a fourth ventricle cyst occludingthe CSF transit at both the cerebral aqueduct and the Luschka and Magendieforamina levels. In this patient, the absence of a fourth ventricle cyst onMRI and the finding of an incomplete Parinaud syndrome favored thediagnosis of aqueductal stenosis, since fourth ventricle cysts have rarely, ifever, been associatedwith Parinaud syndrome. Differential diagnosis betweenthese two pathogenetic mechanisms causing an isolated fourth ventricle inpatients with neurocysticercosis is important, as the therapeutic approachesare completely different. For patients with a fourth ventricle cyst, endoscopicresection of the lesion is advised. In contrast, multiple shunts are needed forpatients with segmental occlusion of the CSF transit at different levels becauseof the simultaneous occurrence of ependymitis and basal arachnoiditis.

FIGURE 8-7 CT scans of a patient with doublecompartment hydrocephalus due to

simultaneous occurrence of aqueductal stenosis and occlusionof Luschka and Magendie foramina.



usually normal despite active meningealdisease. Hypoglycorrhachia, observedin a few patients, is associated with apoor prognosis.

Immunologic DiagnosisImmune diagnostic tests have been usedto assess the prevalence of cysticercosisin populations and to exclude or confirm

Case 8-2A 20-year-old woman presented with a 1-week history of progressive headache, vomiting, andsomnolence. On admission, neurologic examination showed obtundation, bilateral papilledema(Figure 8-8), increased muscle stretch reflexes, and bilateral Babinski signs. MRI showed diffuse brainswelling with collapse of the ventricular system, and multiple small cysticerci disseminated through the

brain parenchyma with predominance of the cerebral cortex.Lesions showed a ringlike pattern of enhancement aftercontrast medium administration (Figure 8-9). Serumimmunoblot for the detection of anticysticercal antibodies wasstrongly positive. ELISA and Western blot for the detectionof antibodies against HIV were negative. High doses ofdexamethasone (8 mg IV every 8 hours) and mannitol(100 mL of a 20% solution every 6 hours) were started.Standard doses of sodium phenytoin were also added tothe regimen. The patient improved over the next few days.Mannitol was discontinued after 3 days, and IVdexamethasone was switched to oral prednisone after 1 week.She was discharged asymptomatic 2 weeks after admission.

Comment. This young woman had cysticercotic encephalitis,a severe form of neurocysticercosis related to an intenseinflammatory reaction from the host in response to massivecysticerci infestation of the brain parenchyma. Diagnosis is

suspected on clinical and imaging grounds and must be confirmed by the practice of a serum immunoblottest. It is also prudent to evaluate the HIV status of the patient, since Toxoplasma encephalitis or otherHIV-related opportunistic infections of the nervous system may occur with similar clinical andneuroimagingfindings. Cysticidaldrugs are formallycontraindicatedin patients withcysticercoticencephalitis, astherapy mayexacerbate theinflammatoryreaction within thebrain parenchyma,causing furtherincrease in theintracranial pressureand death. Incontrast, prompt administration of corticosteroid and osmotic diuretics usually result in marked clinicalimprovement. Decompressive craniotomies have been suggested for patients who do not respond to thisinitial therapeutic approach. Patients who survive recover without sequelae, and further neuroimagingstudies from 3 to 6 months after the acute episode usually show complete resolution of lesions.

FIGURE 8-8 Funduscopic examinationshowing papilledema.

FIGURE 8-9 MRI of patient with cysticercotic encephalitis. A, T1-weighted imaging showingdiffuse brain edema with collapse of the ventricular system. B, T2-weighted

imaging showing multiple colloidal parenchymal brain cysts surrounded by edema. C, After contrastadministration, cysticerci appear as ring-enhancing lesions.


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the diagnosis of neurocysticercosis inneurologic patients with inconclusiveneuroimaging findings. The comple-ment fixation test and the serum ELISAare time-honored tests used for deca-des to diagnose cysticercosis. These tests,however, have been faced with prob-lems related to poor sensitivity orspecificity. False-negative results aredue to local production of antibodieswithin the CNS, without a parallelincrease of antibodies in peripheralblood, or to immune tolerance to theparasite without production of anticysti-cercal antibodies at all. False-positiveresults are due to previous contactwith the adult T. solium or to cross-reactivity with other helminths.28

Enzyme-linked immunoelectro-transfer blot assay for detection ofantibodies to T. solium glycoproteinantigen in serum. The only reliableserologic test for the detection of anti-bodies specific for T. solium antigens isthe enzyme-linked immunoelectrotrans-fer blot (EITB) using partially purifiedantigenic extracts. The EITB has been ex-tensively evaluated in different hospital-based and population-based studies. Thisassay has a documented specificity ap-proaching 100% and a sensitivity of upto 98% for patients with two or moreparasites in the nervous system. A majorweakness of the EITB is the high rateof false-negative results (up to 50%) ob-served in patients with a single intra-cranial cysticercus.29 Sensitivity of theEITB is also poor in patients with cal-cified cysticerci. Since antibody assaysreflect cysticercus infection in any tis-sue, not only patients with neurocysti-cercosis but also those with muscularor subcutaneous cysticercosis may testpositive. Consequently, results of theEITB must be evaluated with caution,since extraneural cysticercosis or evenexposure without infection may resultin antibody development. Paradoxically,the sensitivity and specificity of antibody

detection by EITB performed in CSF islower than that performed in serum,even in patients with evidence of CNSinvolvement.

ELISA for detection of anticysticer-cal antibodies or cysticercal antigensin CSF. Detection of anticysticercal anti-bodies by ELISA using CSF is 87% sen-sitive and 95% specific, and remains arelatively useful tool for the diagnosisof neurocysticercosis in areas withlimited access to the EITB assay. ELISAmay be falsely negative in patients withonly parenchymal brain lesions or inthose with inactive disease, and it maybe falsely positive in patients with otherhelminthic infections.28

Detection of cysticercal antigens.Detection of circulating parasitic anti-gens using monoclonal antibodies isanother immune diagnostic techniquethat has been used in some field studies.However, detection of circulating anti-gens is possible only in patients withactive disease. While the sensitivity ofthis test as a screening tool for the di-agnosis of neurocysticercosis is poor,it may be of value to monitor theresponse to cysticidal drug therapy.27

Some studies have also suggested thatthis test may be useful for the demon-stration of excretory-secretory cysticer-cal antigens in CSF, as it has sensitivityranging from 72% to 86%, with false-negative cases restricted to patientswith a single intracranial cysticercusand inactive disease. However, thespecificity of this assay has not beenassessed in patients with other infec-tions of the CNS.

NeuroimagingThe advent of modern neuroimagingtechniques has drastically improveddiagnostic accuracy for neurocysticer-cosis. Both CT and MRI provide objec-tive evidence on the topography oflesions, the burden of infection, thestage of involution of cysticerci, and the

KEY POINTS

h The only reliableserologic test for thedetection of antibodiesspecific for T. soliumantigens is theenzyme-linkedimmunoelectrotransferblot using partiallypurified antigenicextracts.

h A major weakness ofthe enzyme-linkedimmunoelectrotransferblot is the high rate offalse-negative results(up to 50%) observed inpatients with a singleintracranial cysticercus.Sensitivity of theenzyme-linkedimmunoelectrotransferblot is also poor inpatients with calcifiedcysticerci.



severity of the host’s inflammatoryreaction against the parasites. WhileMRI is the preferred method for evalu-ating patients with cystic lesions locatedin the ventricular system, the brain-stem, and the subarachnoid space, CTremains the best screening neuroimag-ing procedure for patients with sus-pected neurocysticercosis, since manypatients have parenchymal brain calcifi-cations as the sole evidence of thedisease, and many of these lesionsmay escape detection if only an MRI isperformed.30

Parenchymal neurocysticercosis.The stage of involution of parenchy-mal brain cysticerci determines theirappearance on neuroimaging studies

(Figure 8-10). Vesicular cysticerci ap-pear as small and rounded cystic lesionsthat are well demarcated from the sur-rounding brain parenchyma. Imagingshows little or no perilesional edemaand no abnormal enhancement aftercontrast-medium administration. Manyvesicular cysts have in their interioran eccentric hyperdense nodule repre-senting the scolex, giving the lesionsa pathognomonic ‘‘hole-with-dot’’appearance. When the infection ismassive, as in the so-called heavy non-encephalitic form of neurocysticerco-sis,25 the brain looks like a ‘‘Swisscheese,’’ another imaging finding thatis pathognomonic of neurocysticercosis(Figure 8-11).

KEY POINTS

h CT remains the bestscreening neuroimagingprocedure for patientswith suspectedneurocysticercosis,since many patientshave parenchymalbrain calcifications asthe sole evidence ofthe disease, and manyof these lesions mayescape detection if onlyan MRI is performed.

h Many vesicular cystshave in their interior aneccentric hyperdensenodule representing thescolex, giving the lesionsa pathognomonic‘‘hole-with-dot’’appearance.

FIGURE 8-10 Imaging findings in parenchymal brain cysticercosis. A, T1-weighted MRI ofvesicular cysticerci showing scolices. B, Contrast-enhanced MRI showing singlecolloidal cysticercus. C, Plain CT showing parenchymal brain calcifications.

FIGURE 8-11 A, B, C, Contrast CT of patient with heavy nonencephalitic parenchymal braincysticercosis showing more than 100 vesicular cysts with no evidence ofabnormal enhancement or perilesional edema.


Neurocysticercosis


Colloidal cysticerci appear as ill-defined lesions surrounded by edema,and most of them show an abnor-mal ring pattern of enhancement aftercontrast medium administration. Sincethe scolex is rarely visualized in colloi-dal cysticerci using CT or conventionalMRI sequences, the presence of oneor two ring-enhancing lesions in thebrain parenchyma has generated muchdebate in the literature and may repre-sent a diagnostic challenge, as otherconditionsVtuberculomas, Toxoplasmabrain abscesses, primary or metastaticbrain tumorsVmay course with similarneuroimaging findings.29 In doubtfulcases, the practice of diffusion-weightedimages and apparent diffusion coeffi-cient maps facilitates the diagnosis byallowing the recognition of the scolex(Figure 8-12).31 Another particularneuroimaging pattern of parenchymalneurocysticercosis in the colloidalstage is observed in patients withcysticercotic encephalitis (Case 8-2).In this severe form of the disease, bothCT and MRI show diffuse or multifocalbrain edema and collapse of the ven-tricular system without midline shift.After contrast administration, multi-ple small nodular or ring-enhancinglesions appear disseminated throughthe brain parenchyma.

Parenchymal brain cysticerci mayalso appear on CT as discretely hyper-dense nodular-enhancing lesions sur-rounded or not by edema. This patterncorresponds to the granular stage ofcysticerci, which on MRI are often vi-sualized as areas of signal void on bothT1- and T2-weighted images, surroundedby hyperintense rims representing gli-osis. Calcified cysticerci appear on CTas small, hyperdense nodules withoutperilesional edemaor abnormal enhance-ment after contrast-medium administra-tion. As noted before, the sensitivity ofconventional MRI sequences for the de-tection of calcified lesions is poor. Recentevidence, however, suggests that theuse of susceptibility-weighted imagesmay enhance the identification of cal-cifications by MRI.32

Subarachnoid neurocysticercosis.Subarachnoid cysts are most oftensmall when located within cortical sulciand may present with similar neuro-imaging findings to those described forparenchymal brain cysts, ie, cystic lesionsshowing the scolex, ring-enhancing le-sions, or calcifications. On the otherhand, cystic lesions located within thesylvian fissures or at the CSF cisterns atthe base of the brain usually attaina large size and have a multilobulatedappearance (the racemose form of

FIGURE 8-12 A, Contrast-enhanced imaging; B, diffusion-weighted imaging; andC, apparent diffusion coefficient map of patient with colloidal parenchymalcysticerci. Scolices are visualized only on the last two sequences.



neurocysticercosis), displacing neigh-boring structures and behaving as space-occupying mass lesions (Figure 8-13).Another common finding in patientswith subarachnoid neurocysticercosis ishydrocephalus caused by inflammatoryocclusion of the Luschka and Magen-die foramina. The fibrous arachnoidi-tis responsible for the development ofhydrocephalus is seen on CT or MRI asareas of abnormal leptomeningeal en-hancement at the base of the brain.24,30

Cerebrovascular complications of neu-rocysticercosis are well visualized withCT or MRI. In patients with cysticercosis-

related infarcts, the association of sub-arachnoid cystic lesions (particularly atthe suprasellar cistern) or abnormal en-hancement of basal leptomeninges sug-gests the correct diagnosis.10 Angiographicfindings in subarachnoid neurocysticerco-sis include segmental narrowing or oc-clusion of the major intracranial arteriesin patients with infarcts (Figure 8-14)or even in those lacking clinical or neu-roimaging evidence of a cerebral infarct.Magnetic resonance angiography is avaluable noninvasive imaging modalityto demonstrate narrowing or occlusionof intracranial arteries in patients withsubarachnoid neurocysticercosis.

Ventricular neurocysticercosis. Ven-tricular cysticerci appear on CT ashypodense lesions that distort the ven-tricular system, causing asymmetric ob-structive hydrocephalus. Ventricularcysts are isodense with CSF; there-fore, they cannot be directly visual-ized (Figure 8-15). In contrast, mostventricular cysts are readily visualizedon MRI because the signal propertiesof the cystic fluid or the scolex dif-fer from those of the CSF.30 Cyst mo-bility within the ventricular cavities inresponse to movements of the head,the ventricular migration sign, facili-tates the diagnosis of ventricular cysti-cercosis in some cases. In other patients,

KEY POINTS

h Cystic lesions locatedwithin the sylvianfissures or at the CSFcisterns at the base ofthe brain usually attaina large size and havea multilobulatedappearance (theracemose form ofneurocysticercosis),displacing neighboringstructures and behavingas space-occupyingmass lesions.

h Cyst mobility withinthe ventricular cavitiesin response tomovements of thehead, the ventricularmigration sign,facilitates the diagnosisof ventricularcysticercosis insome cases.

FIGURE 8-13 Imaging findings in subarachnoid cysticercosis. A, Contrast-enhanced CTshowing large cyst in sylvian fissure. B, Contrast-enhanced CT showing

hydrocephalus associated with cysts in CSF cisterns. C, T1-weighted MRI showing huge cystcompressing brainstem.

FIGURE 8-14 Cysticercotic angiitis. A, Plain CT showinginfarct in territory of left anterior cerebralartery. B, Angiogram showing segmentalnarrowing of A1 segment of left anteriorcerebral artery.


Neurocysticercosis


parasitic membranes or ventriculitisocclude the Monro foramina. In suchcases, it is common to observeasymmetric internal hydrocephalus,most often noticed after the placementof a ventricular shunt, as the lateralventricle contralateral to the shuntremains dilated after the derivativeprocedure. A particular finding in ven-tricular cysticercosis is the so-calleddouble compartment hydrocephalus,in which the fourth ventricle is isolatedfrom the rest of ventricular cavitiesbecause of simultaneous occlusion ofthe cerebral aqueduct and the foraminaof Luschka and Magendie (Case 8-1).

Spinal cord neurocysticercosis.While myelography and CT were usedfor years for the diagnosis of spinalcysticercosis, they are now of historicalsignificance since MRI has become theimaging modality of choice for theevaluation of patients with suspectedcysticercosis of the spinal cord or thespinal subarachnoid space. On MRI,intramedullary cysticerci appear asrounded or septated lesions that mayhave an eccentric hyperintense nodulerepresenting the scolex.30 If the scolex

is not identified, however, it may bedifficult to differentiate this condi-tion from spinal tumors. Leptomenin-geal cysts are easily identified with MRI(Figure 8-16). These lesions may befreely mobile within the spinal subar-achnoid space and change their posi-tion during the examination accordingto movements of the patient on theexploration table.

Unification ofDiagnostic CriteriaDespite the introduction of the above-described immune diagnostic tests andneuroimagingmethods, the diagnosis ofneurocysticercosis can still be a challengebecause clinical manifestations are non-specific, neuroimaging findings are oftennot pathognomonic, and immune diag-nostic tests are faced with problemsrelated to poor sensitivity or specificity.Moreover, histologic demonstration ofthe parasite is not possible in most cases.

During the second half of the 20thcentury, it was common in field studiesto diagnose neurocysticercosis in pa-tients presenting with seizures anda positive immunologic test for thedetection of anticysticercal antibodies

FIGURE 8-15 Plain CT showingventricular

cysticercus causing asymmetricdilatation of right lateral ventricle.

FIGURE 8-16 T1-weighted gadoliniumcontrast-enhanced MRIof patient with spinal

cysticercosis showing multiple hypointensecystic lesions in the spinal canal.



in serum. Such practice could haveresulted in the inclusion of many pa-tients who actually had cryptogenicepilepsy and false-positive results onimmunologic testing. On the otherhand, some infected persons escapeddetection just because they had neg-ative immunologic study results. In thehospital setting, diagnosis of neurocys-ticercosis usually rested only on neuro-imaging findings. Using this approach,neurocysticercosis could be overdiag-nosed in endemic areas. In contrast, thisdisease used to be overlooked in otherregions of the world simply because itwas rare. Such diagnostic pitfalls couldlead either to the progression of otherdiseases requiring urgent therapy or tothe practice of unnecessary and inva-sive diagnostic procedures.

In 1996, the first attempt to settle achart of diagnostic criteria for humancysticercosis was published, based onthe objective evaluation of clinical,radiologic, immunologic, and epide-miologic data of patients.33 After someyears of experience, the same group ofinvestigators considered that chart tobe somewhat confusing and complex,since it was developed for the diag-nosis of patients with neurocysticerco-sis as well as those with systemiccysticercosis. With few exceptions, cys-ticercosis outside the CNS is not clinicallyrelevant. Therefore, it was consideredthat a more accurate and stringent set ofdiagnostic criteria exclusively devoted tothe diagnosis of neurocysticercosis wouldbe more comprehensible than thoseinitially identified.34 As in the 1996publication, revised criteria included fourcategoriesVabsolute, major, minor, andepidemiologicVstratified on the basisof their individual diagnostic strength.Absolute criteria allowed unequivocaldiagnosis of neurocysticercosis; majorcriteria strongly suggested the diagno-sis but could not be used alone toconfirm the diagnosis; minor criteria

were frequent but nonspecific manifes-tations of the disease; and epidemio-logic criteria referred to circumstantialevidence favoring the diagnosis. Inter-pretation of these criteria permittedtwo degrees of diagnostic certainty: (1)definitive diagnosis in patients whohad one absolute criterion or in thosewho had two major plus one minorand one epidemiologic criteria; and (2)probable diagnosis in patients whohad one major plus two minor criteria,in those who had one major plus oneminor and one epidemiologic criteria,and in those who had three minor plusone epidemiologic criteria (Table 8-2).34

This set of diagnostic criteria waspromptly adopted by the medical com-munity and is now considered by manyas the gold standard for the diagnosisof neurocysticercosis.

Advances in neuroimaging from thetime of that publication should be incor-porated in the subheading of ‘‘highlysuggestive lesions’’ to enhance the di-agnostic accuracy of MRI. These includethe use of diffusion-weighted imagingto visualize the scolex in doubtful cases,the use of susceptibility-weighted imagesto enhance the identification of calcifica-tions, and the practice of spectroscopy todifferentiate neurocysticercosis fromneurotuberculosis in selected cases.30Y32

THERAPYAccurate characterization of neurocysti-cercosis in terms of viability of cysts,degree of the host’s immune responseto the parasites, and location of thelesions is important for a rational ther-apy.35 Therapeutic approaches mayinclude a combination of symptomatictherapy, cysticidal drugs, surgical resec-tion of lesions, and placement of ven-tricular shunts. General strategies oftherapy described in Table 8-3 mayneed some adjustment in the individualpatient, particularly in those who havemixed forms of the disease.

KEY POINTS

h Revised criteria forthe diagnosis ofneurocysticercosis includefour categoriesVabsolute,major, minor, andepidemiologicVstratifiedon the basis of theirindividual diagnosticstrength. Absolute criteriaallow unequivocaldiagnosis; major criteriastrongly suggest thediagnosis but cannot beused alone to confirm thediagnosis; minor criteriaare frequent butnonspecific manifestationsof the disease; andepidemiologic criteriarefer to circumstantialevidence favoring thediagnosis.

h Accurate characterizationof neurocysticercosis interms of viability of cysts,degree of the host’simmune response to theparasites, and locationof the lesions is importantfor a rational therapy.


Neurocysticercosis


Parenchymal NeurocysticercosisParenchymal brain calcifications. Cal-cifications represent sequelae of previ-

ous infections and should not be treatedwith cysticidal drugs. In cysticercosis-endemic areas, parenchymal brain

TABLE 8-2 Diagnostic Criteria for Neurocysticercosisa

b Diagnostic Criteria

& Absolute Criteria

Histologic demonstration of the parasite from biopsy of a brain or spinalcord lesion

Evidence of cystic lesions showing the scolex on neuroimaging studies

Direct visualization of subretinal parasites by funduscopic examination

& Major Criteria

Evidence of lesions highly suggestive of neurocysticercosis on neuroimaging studies

Positive serum immunoblot for the detection of anticysticercal antibodies

Resolution of intracranial cystic lesions after therapy with albendazole orpraziquantel

Spontaneous resolution of small single-enhancing lesions

& Minor Criteria

Evidence of lesions suggestive of neurocysticercosis on neuroimaging studies

Presence of clinical manifestations suggestive of neurocysticercosis

Positive CSF ELISA for detection of anticysticercal antibodies or cysticercal antigens

Evidence of cysticercosis outside the CNS

& Epidemiologic Criteria

Individuals coming from or living in an area where cysticercosis is endemic

History of frequent travel to disease-endemic areas

Evidence of a household contact with Taenia solium infection

b Degrees of Diagnostic Certainty

& Definitive Diagnosis

Presence of one absolute criterion

Presence of two major plus one minor or one epidemiologic criteria

& Probable Diagnosis

Presence of one major plus two minor criteria

Presence of one major plus one minor and one epidemiologic criteria

Presence of three minor plus one epidemiologic criteria

a Reprinted from Del Brutto OH, et al, Neurology.34 B 2001, with permission from American Academy ofNeurology. www.ncbi.nlm.nih.gov/pmc/articles/PMC2912527/.



calcifications may be an incidentalfinding on neuroimaging studies. Sincethe actual risk of epilepsy in these pa-

tients is unknown, prophylactic anti-epileptic drug (AED) therapy is notjustified in such cases. In contrast,

TABLE 8-3 General Guidelines for Therapy of Neurocysticercosisa

b Parenchymal Neurocysticercosis

& Vesicular Cysts

Single cyst: Use albendazole 15 mg/kg/d for 3 days or praziquantel 30 mg/kg in three divideddoses every 2 hours. Corticosteroids are rarely needed. Use antiepileptic drugs (AEDs) for seizures.

Mild to moderate infections: Use albendazole 15 mg/kg/d for 1 week or praziquantel50 mg/kg/d for 15 days. Corticosteroids may be used when necessary. Use AEDs for seizures.

Heavy infections: Use albendazole 15 mg/kg/d for 1 week (repeated cycles of albendazole may beneeded). Corticosteroids are mandatory before, during, and after therapy. Use AEDs for seizures.

& Colloidal Cysts

Single cyst: Use albendazole 15 mg/kg/d for 3 days or praziquantel 30 mg/kg in three divided dosesevery 2 hours. Corticosteroids may be used when necessary. Use AEDs for seizures.

Mild to moderate infections: Use albendazole 15 mg/kg/d for 1 week. Corticosteroids are usuallyneeded before and during therapy. Use AEDs for seizures.

Cysticercotic encephalitis: Cysticidal drugs are contraindicated. Use corticosteroids and osmotic diuretics toreduce brain swelling. Use AEDs for seizures. Perform decompressive craniotomies in refractory cases.

& Granular and Calcified Cysticerci

Single or multiple: Cysticidal drug therapy is unnecessary. Use AEDs for seizures. Use corticosteroids inpatients with recurrent seizures and perilesional edema surrounding calcifications.

b Extraparenchymal Neurocysticercosis

& Small Cysts Over Convexity of Cerebral Hemispheres

Single or multiple: Use albendazole 15 mg/kg/d for 1 week. Corticosteroids may be used whennecessary. Use AEDs for seizures.

& Large Cysts in Sylvian Fissures or Basal CSF Cisterns

Racemose cysticercus: Use albendazole 15 mg/kg/d to 30 mg/kg/d for 15 to 30 days (repeated cyclesof albendazole may be needed). Corticosteroids are mandatory before, during, and after therapy.

& Other Forms of Extraparenchymal Neurocysticercosis

Hydrocephalus: Cysticidal drug therapy is unnecessary. Insert a ventricular shunt. Continualcorticosteroid administration (50 mg 3 times a week for up to 2 years) may be needed to reduce therate of shunt dysfunction.

Ventricular cysts: Perform endoscopic resection of cysts. Albendazole may be used only in small lesionslocated in lateral ventricles. Ventricular shunt only needed in patients with associated ependymitis.

Angiitis, chronic arachnoiditis: Cysticidal drug therapy is unnecessary. Corticosteroids are mandatory.

Cysticercosis of the spine: Perform surgical resection of lesions. Anecdotal use of albendazole withgood results has been reported.

a Level 1 evidence favors the use of cysticidal drugs in patients with parenchymal brain vesicular and colloidal cysts. For other formsof the disease, guidelines are based on Level 2 and Level 3 evidence.


Neurocysticercosis


treatment with AEDs is advised whenparenchymal brain calcifications areassociated with seizures. In these cases,the administration of a single AEDusually produces adequate seizure con-trol.15 Length of AED therapy inpatients with epilepsy due to paren-chymal brain calcifications remainsundefined as some studies have shownthat the risk of seizure recurrence afterAED withdrawal is high, even in patientswho had been seizure-free for 2 years.36

Neuroimaging studies performed imme-diately after seizure relapse have shownfocal edema and abnormal contrast en-hancement around previously inert cal-cifications.19,20,36 As previously noted,these observations suggest that paren-chymal brain calcifications representpermanent epileptogenic foci suscep-tible to reactivation when the host im-mune system is exposed to antigenicmaterial located in the interior of thelesion.19 While epilepsy due to paren-chymal brain calcifications is easily con-trolled with AEDs, a seizure-free statewithout medication seems to be diffi-cult to achieve in many patients. Thesepatients should receive corticosteroids torelieve the inflammatory reaction that iscausing recurrent seizures.19

Viable parenchymal brain (vesicular)cysts. Vesicular cysts have reached a stateof immune tolerance with the host andmay remain for years in the brainparenchyma. Therefore, the only way todestroy these cysts is by the use of acysticidal drug (Figure 8-17). Level 1evidence favors the use of cysticidaldrugs in such cases, as this approachprovides clinical improvement and res-olution of lesions in most patients whencompared with placebo or no ther-apy.37,38 Theoptimal therapeutic regimenin such patients, however, is somewhatuncertain.39 Current evidence seemsto favor the use of albendazole overpraziquantel; however, the latter is alsoa potent drug that may be needed in

some cases, particularly in albendazolefailures. The initial regimenof therapy forpatients with parenchyma brain vesicu-lar cysts mainly depends on the burdenof infection. Levels 2 and 3 evidencefavor the use of albendazole for 3 days ora single-day course of praziquantel ther-apy for patients with a single cyst,albendazole for 1 week or praziquan-tel for 15 days for patients with mild tomoderate infections, and albendazolefor 1 week for patients with heavyinfections (Table 8-3). Repeated coursesof therapymay be needed as control neu-roimaging studies, performed 3monthsafter the trial, showed persistence ofsome lesions. In such cases, it is advisedto give a different cysticidal drug thanthe one used in the first attempt.12

During the trial with cysticidal drugs,some patients develop headache, vomit-ing, or seizures. These manifestationsare related to the inflammatory reactiondeveloped by the host in response todestruction of the parasites and maybe anticipated in patients with morethan a few cysts in the brain paren-chyma. Simultaneous use of corticoste-roids usually results in control of theseadverse reactions.35 Likewise, patientswith epilepsy due to vesicular cysts

KEY POINTS

h Calcifications representsequelae of previousinfections and shouldnot be treated withcysticidal drugs.

h While epilepsy due toparenchymal braincalcifications is easilycontrolled withantiepileptic drugs, aseizure-free statewithout medicationseems to be difficultto achieve in manypatients.

h Vesicular cysts havereached a state ofimmune tolerancewith the host andmay remain for yearsin the brain parenchyma.Therefore, the onlyway to destroy thesecysts is by the use of acysticidal drug.

FIGURE 8-17 Contrast-enhanced CT of patient withheavy infection of the brain parenchyma bymultiple vesicular cysticerci, before (A) and

3 months after (B) a trial with albendazole. Note the resolutionof most lesions as a result of therapy.



must be treated with AEDs regardlessof the specific cysticidal drug used. Thelength of AED therapy will depend onwhether the lesions disappear or aretransformed into calcifications as theresult of therapy.36

Dying parenchymal brain (colloidal)cysts. Colloidal cysts are degeneratingparasites that result from the host’s im-munologic attack, so the natural historyof most of these lesions would be tovanish or end up as a calcified nod-ule.29 While some of these lesions maydisappear without therapy, Level 1 evi-dence also favors the use of cysticidaldrugs in these patients.38 According toa number of double-blind trials, the useof albendazole results not only in amore expedited resolution of colloi-dal cysticerci, but also in a reductionof the risk of seizure recurrence inmost patients.40Y42 As described for pa-tients with vesicular cysts, many patientswith colloidal cysts also experience ad-verse reactions during the trial of cystici-dal drugs. In such cases, simultaneousadministration of corticosteroids usu-ally results in prompt relief of symp-toms. The length of AED therapy willalso be related to whether colloidal cystsvanished or were transformed into calci-fied nodules as the result of therapy, as itis generally accepted that in the lattercase, the risk of seizure recurrencesafter AED withdrawal is high.29

Cysticidal drugs must not be used inpatients with cysticercotic encephalitis,since these drugs may exacerbate theinflammatory response within the brainparenchyma that occurs in this severeform of parenchymal neurocysticerco-sis. High doses of corticosteroids andosmotic diuretics are advised as the firsttherapeuticmeasures in order to reducethe severity of brain edema (Case 8-2).This therapeutic approach should beprolonged for 2 to 3 weeks until theedema subsides. Refractory casesshould undergo decompressive cra-

niotomies to avoid the life-threateningrisk of intracranial hypertension.

ExtraparenchymalNeurocysticercosisSubarachnoid cysts. Medical treatmentof small subarachnoid cysts over theconvexity of cerebral hemispheres issimilar to that described for parenchy-mal brain cysts; the only difference isthat albendazole is the preferred drugbecause it penetrates the subarachnoidspace better and reaches higher con-centrations in the CSF than praziquan-tel. Clinical experience with this formof the disease is limited, but Level 2 evi-dence suggests that the percentage ofsmall subarachnoid cysts disappearingafter albendazole treatment is similarto that reported for parenchymal cysts.43

Treatment of giant cysts located in-side CSF cisterns is controversial (Level 3evidence). While some authors recom-mend surgical resection of these le-sions, it has been suggested that medicaltherapy with albendazole may be anequally effective albeit less aggressiveapproach. Higher doses of albenda-zole, more prolonged courses of ther-apy, or even repeated cycles may beneeded for patients with racemosecysticercus (Table 8-3).24,44,45 In addi-tion to the dramatic improvement in-duced by albendazole on neuroimagingstudies, reports have shown markedimprovement in the neurologic mani-festations, mainly in focal neurologicdeficits, after therapy. Because of thevicinity of blood vessels arising fromthe circle of Willis, it is possible that theinflammatory reaction that followsdestruction of the cysts enhances aprocess of endarteritis resulting in acerebral infarct. Routine corticosteroidadministration is mandatory whentreating patients with large subarach-noid cysts with albendazole to avoidthe hazard of a cerebral infarct. Corti-costeroids must be given before the

KEY POINTS

h The use of albendazoleresults not only in amore expeditedresolution of colloidalcysticerci, but also in areduction of the risk ofseizure recurrence inmost patients.

h Cysticidal drugs mustnot be used in patientswith cysticercoticencephalitis, since thesedrugs may exacerbatethe inflammatoryresponse within thebrain parenchyma thatoccurs in this severeform of parenchymalneurocysticercosis.

h Higher doses ofalbendazole, moreprolonged courses oftherapy, or even repeatedcycles may be neededfor patients withracemose cysticercus.

h Routine corticosteroidadministration ismandatory whentreating patients withlarge subarachnoid cystswith albendazole, inorder to avoid thehazard of a cerebralinfarct.


Neurocysticercosis


start of albendazole therapy, and theiruse must be prolonged for several daysafter the trial has been completed.24,44,45

Hydrocephalus. Patients with hydro-cephalus due to cysticercotic arachnoidi-tis require a ventricular shunt before othertherapeutic measures are attempted.35

In contrast, not all patients with hydro-cephalus due to ventricular cysts needa derivative procedure. In the latter, theneed for a ventricular shunt dependson the location of the cyst and the co-existence of granular ependymitis.Patients with hydrocephalus due to cys-ticercotic arachnoiditis usually have aprotracted course and a poor progno-sis. The main problem in these cases isthe high frequency of shunt dysfunc-tion. Mortality, which can be as high as50% at 2 years, has been directly re-lated to the number of surgical interven-tions to change the shunt.24 Continuousadministration of prednisone may re-duce the risk of shunt dysfunction (Level3 evidence).

Ventricular cysts and ependymitis.Depending on its size and location,ventricular cysticercosis may be treatedby surgical resection or by cysticidal

drugs. While some reports suggest thatalbendazole therapy destroys ventricu-lar cysts, consensus guidelines, based onLevel 3 evidence, have favored surgicalresection of most of these lesions, withthe possible exception of small cysts lo-cated in the lateral ventricle (a site wherethe inflammatory reaction secondary todestruction of the cyst is not danger-ous).35 Surgical approaches include directexcision of the cyst or endoscopic aspira-tion using a flexible ventriculoscope.The surgeon must always consider thepossibility of cyst migration within theventricular cavities from the time of di-agnosis to themoment of surgery; there-fore, it must be a routine practice toobtain a control neuroimaging study im-mediately before surgery to avoid an un-necessary surgical procedure.

In patients without associated epen-dymitis, permanent shunting proceduresare unnecessary after the excision of aventricular cyst. In contrast, placementof a ventricular shunt must follow oreven precede excision of the cyst inpatients who also have granular epen-dymitis. Surgical excision of a ventricularcysticercus associated with ependymitis

KEY POINTS

h Patients withhydrocephalus due tocysticercotic arachnoiditisusually have a protractedcourse and a poorprognosis. The mainproblem in these casesis the high frequency ofshunt dysfunction.Mortality, which canbe as high as 50% at2 years, has been directlyrelated to the numberof surgical interventionsto change the shunt.

h The surgeon mustalways consider thepossibility of cystmigration within theventricular cavities fromthe time of diagnosisto the moment ofsurgery.

TABLE 8-4 Strategies for Elimination of Taeniasis and Cysticercosis

b Community Level

Improving living conditions

Health education and awareness of mechanisms of disease acquisition

Mass human chemotherapy (useless without education)

b Infected Pigs

Improved husbandry (pig corralling)

Slaughterhouse control

Control of illegal markets for infected pigs

Freezing of pork meat before human consumption

Mass chemotherapy of pigs

Pig vaccination



is more difficult than excision of a freelyfloating cyst, and it has been suggestedthat the efforts of therapy must beprimarily directed to the resolution ofhydrocephalus by a ventricular shuntand not to cyst removal. A peculiar formof ventricular neurocysticercosis is dou-ble compartment hydrocephalus, causedby the dual effect of granular ependymitisof the cerebral aqueduct and arachnoidi-tis occluding the foramina of Luschkaand Magendie. In these patients, twoindependent shunt devices may beneeded, with one draining the supra-tentorial ventricular system and theother draining the isolated fourthventricle (Case 8-1).

Spinal cysticercosis. Current accep-ted therapy for intramedullary cystsand cysts in the spinal subarachnoidspace is surgical resection of the lesion(Level 3 evidence).12,35 Possible migra-tion of spinal subarachnoid cysts be-tween the time of diagnosis and thelaminectomy must be ruled out by re-peating neuroimaging studies immedi-ately before surgery. The prognosis aftersurgery is usually good unless prolongedcompression of spinal nerve roots oc-curred before diagnosis. Albendazole hasbeen used with good results in anecdotalcases. Further experience with medicaltreatment is needed before a clear rec-ommendation can be made for either asurgical or medical approach to thisform of the disease.

CONTROL MEASURESAs previously noted, neurocysticercosisis common in areas where conditionsfavoring the transmission of T. soliumare found, including warm climate, pov-erty, deficient disposal of human feces,low levels of education, slaughtering ofpigs without veterinary control, andpresence of free-roaming pigs aroundhouseholds. Neurocysticercosis is a po-tentially eradicable disease as was dem-onstrated in European countries by the

end of the 19th century. To be effective,however, eradication programs must bedirected to all the targets for control,particularly human carriers of the adulttapeworm, infected pigs, and eggs in theenvironment (Table 8-4). Since thesetargets represent interrelated steps inthe life cycle of T. solium, inadequatecoverage of one of them may result in arebound in the prevalence of taeniasis/cysticercosis after the program has beencompleted.5,46,47

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KEY POINT

h Neurocysticercosiseradication programsmust be directed to allthe targets for control,particularly humancarriers of the adulttapeworm, infectedpigs, and eggs in theenvironment.


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