CNS INFECTIONCNS INFECTION

• Definitions:Definitions:• MeningitisMeningitis ::infection predominantly involved infection predominantly involved

subarachniod space.subarachniod space.

• EncephalitisEncephalitis ::infection predominately involved brain infection predominately involved brain tissues.tissues.

• Brain abscessBrain abscess : :is afocal suppurative infection within is afocal suppurative infection within the brain parenchyma typically surrounded by a the brain parenchyma typically surrounded by a vascularized capsule.vascularized capsule.

• Acute bacterial meningitisAcute bacterial meningitis : :--Definition.Definition.

-Epidemiology-Epidemiology:: -it is the most common form of suppurative CNS infection.-it is the most common form of suppurative CNS infection.-annual incidence in the united states of >2.5 cases /100,000 -annual incidence in the united states of >2.5 cases /100,000

population.population.-dramatic decline in the incidence of meningitis due to H. inf. -dramatic decline in the incidence of meningitis due to H. inf.

& smaller decline due to N. men.& smaller decline due to N. men.-community acquired bacterial meningitis .-community acquired bacterial meningitis . -strep. Pnue. -N. men. -group B S. -L. mono.-strep. Pnue. -N. men. -group B S. -L. mono. -H. inf.-H. inf.

-S. pneumonia : is the most common cause of meningitis in -S. pneumonia : is the most common cause of meningitis in adults >20 years.adults >20 years.

-N. men. 60 % of cases in children & young adults bet. 2-20 -N. men. 60 % of cases in children & young adults bet. 2-20 years.years.

-group B strp. & S. agalactiae are mostly in neonates.-group B strp. & S. agalactiae are mostly in neonates.-L. mono. Mostly in pregnant neonates & >60 years.-L. mono. Mostly in pregnant neonates & >60 years.-Staphylococcus predominantly in neurosurgical head trauma.-Staphylococcus predominantly in neurosurgical head trauma.

Risk factors:Risk factors:--pneumococcal pneumonia. -acute & chronic pneumococcal pneumonia. -acute & chronic

sinusitis.sinusitis.-alcoholism. -otitis media.-alcoholism. -otitis media.-D.M. -splenectomy.-D.M. -splenectomy.-hypogamaglobulinemia. -complement deficiency.-hypogamaglobulinemia. -complement deficiency.-head trauma. -cirrhosis.-head trauma. -cirrhosis.-Chronic UTI. -immunecompromise def. -Chronic UTI. -immunecompromise def.

• Clinical presentation:Clinical presentation:-present either acute or subacute onset.-present either acute or subacute onset.-the classic clinical triad >90%.-the classic clinical triad >90%.-alteration in mental state vary from lethargy to coma.-alteration in mental state vary from lethargy to coma.-seizures.-seizures.-nausea, vomiting , photophobia are common.-nausea, vomiting , photophobia are common.-sings of increase ICP.-sings of increase ICP.-petechial or purpuric skin lesions.-petechial or purpuric skin lesions.-cranial N. palsy.-cranial N. palsy.

• Diagnosis:Diagnosis:-1- History & exa. :-1- History & exa. : --neck stiffness -kernigs sing. -Brudziaski neck stiffness -kernigs sing. -Brudziaski

sing.sing.-2- Blood culture.-2- Blood culture.-3- neuroimaging : -3- neuroimaging : all patient should undergo to CT or all patient should undergo to CT or

MRI prior to LP.MRI prior to LP.-4- CSF exa: classic finding .-4- CSF exa: classic finding . -pressure.-pressure. -WBC.-WBC. -RBC.-RBC. -Glucose.-Glucose. -Protein.-Protein. - Gram stian.- Gram stian. -Culture.-Culture. -5- PCR :-5- PCR :

• DDx:DDx:

1- viral meningoencephalitis &HSV encephalitis.1- viral meningoencephalitis &HSV encephalitis.2-Rickteshial disease.2-Rickteshial disease.3-focal suppurative CNs infection.3-focal suppurative CNs infection.4-chemical meningitis .4-chemical meningitis .5-drug induced meningitis.5-drug induced meningitis.6-carcinomatous & lymphomatous M. 6-carcinomatous & lymphomatous M. 7-inflammatory disorders.7-inflammatory disorders.8-subacute meningitis.8-subacute meningitis.

• Treatment: Treatment: -the goal to start Abs. therapy within 60 min. of arrival -the goal to start Abs. therapy within 60 min. of arrival

emergency room.emergency room.-empirical therapy is initiated before CSF result.-empirical therapy is initiated before CSF result.-empirical therapy in children & adults should include.-empirical therapy in children & adults should include.-antibiotic used in empirical meningitis.-antibiotic used in empirical meningitis. 1- preterm infants to infants < 1 month.1- preterm infants to infants < 1 month. 2- infants 1-3 months.2- infants 1-3 months. 3-immunocompetent children > 3mon & adults <55.3-immunocompetent children > 3mon & adults <55. 4-adults >55 & adults of any age with deblitating illness4-adults >55 & adults of any age with deblitating illness 5- hospital acquired meningitis.5- hospital acquired meningitis.-prophylaxis .-prophylaxis .

--Adjuctive therapy:Adjuctive therapy:1- dexamethasone .1- dexamethasone .2-treat raised ICP.2-treat raised ICP.

Prognosis:Prognosis:-mortality rate is 20% for S. pneu.-mortality rate is 20% for S. pneu. 15% for L. mono.15% for L. mono. 3-7% for H.inf., N.men., or group B strep.3-7% for H.inf., N.men., or group B strep.

-Poor prognostic factors:-Poor prognostic factors:-decrease level of consciousness on admission.-decrease level of consciousness on admission.-Seizures within 24 h.-Seizures within 24 h.-sings of increase ICP.-sings of increase ICP.-extreme age. -comorbid condition.-extreme age. -comorbid condition.-delay in the initiated of treatment. -delay in the initiated of treatment. -decrease CSF glucose <40 & increase protein >3g. -decrease CSF glucose <40 & increase protein >3g.

• Complication :Complication :--moderate or severe occurs in 25% of patient.moderate or severe occurs in 25% of patient.-decrease intellectual function.-decrease intellectual function.-memory disorders.-memory disorders.-seizure.-seizure.-cranial N. palsy.-cranial N. palsy.-hemiparesis & hemisonsory loss.-hemiparesis & hemisonsory loss.-dizziness & vertigo.-dizziness & vertigo.-hydrocephalus.-hydrocephalus.-cerebellar ataxia.-cerebellar ataxia.Urine disorders.Urine disorders.

• Acute viral meningitis:Acute viral meningitis:-it is aseptic meningitis present as fever, headache, malaise, -it is aseptic meningitis present as fever, headache, malaise,

myalgia, anorexia, vomiting .myalgia, anorexia, vomiting .-focal neurological deficits, seizures &disturbance level of -focal neurological deficits, seizures &disturbance level of

consciousness are generally absent.consciousness are generally absent.-meningeal irritation are usually absent.-meningeal irritation are usually absent.

Etiology:Etiology:--EnterovirusEnterovirus account for 75-90% of aseptic M., that represent the account for 75-90% of aseptic M., that represent the

commonest one ,typically occurs in summer monthe in children < 15 commonest one ,typically occurs in summer monthe in children < 15 years.years.

--ArbovirusArbovirus, typically occurs in summer months in endemic & epidemic form., typically occurs in summer months in endemic & epidemic form.

--HSV2HSV2, occurs in 25% of women & 11% of men as episode of genital herpes., occurs in 25% of women & 11% of men as episode of genital herpes.

- - mumpsmumps, present in late winter early spring., present in late winter early spring.

• Diagnosis: Diagnosis: 1- CSF examination : typical profile is.1- CSF examination : typical profile is.2-PCR.2-PCR.3-Serological studies:3-Serological studies:-4-Other sources for viral isolation:-4-Other sources for viral isolation:

Treatment:Treatment:-usual case of aseptic M., treatment is symptomatic & -usual case of aseptic M., treatment is symptomatic &

hospitalization is not required.hospitalization is not required.-indication for admission :-indication for admission :-symptomatic T.-symptomatic T.-oral or I.V. acyclovir.-oral or I.V. acyclovir.

• Viral Encephalitis:Viral Encephalitis:-there are approximately 20,000 cases of -there are approximately 20,000 cases of

encephalitis per year.encephalitis per year.-the most important viruses -the most important viruses causingcausing sporadic cases sporadic cases

in immunocompetent adults are .in immunocompetent adults are .-less commonly enterovirus & others include.-less commonly enterovirus & others include.

Clinical manifestation:Clinical manifestation:--in addition to acute febrile illness with meningitis, patient in addition to acute febrile illness with meningitis, patient

commonly has confusion, behavioral abnormalities.commonly has confusion, behavioral abnormalities.-altered level of consciousness. -seizures.-altered level of consciousness. -seizures. -focal neurological deficits. -cranial N. palsy.-focal neurological deficits. -cranial N. palsy.-involuntary movement. -psychological disorders.-involuntary movement. -psychological disorders.-hypothalamus-pituitary lesion.-hypothalamus-pituitary lesion.

• Laboratory diagnosis:Laboratory diagnosis:

1- CSF examination: csf finding is indistinguishable from viral 1- CSF examination: csf finding is indistinguishable from viral M.M.

2-CSF PCR:2-CSF PCR:3-CSF culture:3-CSF culture:4-serological studies:4-serological studies:5- CT & MRI:5- CT & MRI:6- EEG :6- EEG :7-Brian biopsy:7-Brian biopsy:

• DDx:DDx:-1- Meningitis.-1- Meningitis.-2-Meningoencephalitis.-2-Meningoencephalitis.-3-Brian abscess.-3-Brian abscess.-4Empyema.-4Empyema.-5-Tumors.-5-Tumors.-6-Subdural hematoma.-6-Subdural hematoma.-7-Vasculitis.-7-Vasculitis.-8-Toxic encephalopathy.-8-Toxic encephalopathy.-9-Limbic encephalitis.-9-Limbic encephalitis.-10-ADEM.-10-ADEM.-11-Prion disease.-11-Prion disease.

• Treatment:Treatment:-specific antiviral therapy should be initiated when -specific antiviral therapy should be initiated when

appropriate.appropriate.-monitoring of vital functions.-monitoring of vital functions.-treat raise ICP.-treat raise ICP.-treat seizure.-treat seizure.-prevent & treat of complication.-prevent & treat of complication.-antiviral therapy.-antiviral therapy. -acyclovir.-acyclovir. -ganciclovir & foscarnet.-ganciclovir & foscarnet.

• Subacute meningitis:Subacute meningitis:

-typically have unreleating headache, stiff neck, low grade -typically have unreleating headache, stiff neck, low grade fever, & lethrgy for days.fever, & lethrgy for days.

-cranial N. palsy.-cranial N. palsy.-night sweats may be present.-night sweats may be present.-unsteadiness & ataxia. -unsteadiness & ataxia. -memory impairment.-memory impairment.-mylopathy, radiculopathy & neuropathy.-mylopathy, radiculopathy & neuropathy.-common organisms include.-common organisms include.

• TB. Meningitis :TB. Meningitis :

-M. tuberculosis is acquired by inhalation of aerosolized -M. tuberculosis is acquired by inhalation of aerosolized droplet nuclei.droplet nuclei.

-it is does not develop acutely from hematogenous spread of -it is does not develop acutely from hematogenous spread of bacilli to the meninges.bacilli to the meninges.

-Miliary tubercles form in the parenchyma of the brain during -Miliary tubercles form in the parenchyma of the brain during dissemination of tubercle bacilli in the course of primary dissemination of tubercle bacilli in the course of primary infection.infection.

-The propensity for a caseous lesion to produce meningitis is -The propensity for a caseous lesion to produce meningitis is determined by its proximity to the SAS.determined by its proximity to the SAS.

• Diagnosis :Diagnosis :

1- History & examination :1- History & examination :2- Classic CSF exa.:2- Classic CSF exa.:3-PCR:3-PCR:4-Chest x-ray:4-Chest x-ray:5-ESR.5-ESR.

• Treatment:Treatment:

1- combination of antibiotics.1- combination of antibiotics.2-steriod.2-steriod.