principles of deglutition || progressive neurologic disease and dysphagia (including parkinson’s...

395R. Shaker et al. (eds.), Principles of Deglutition: A Multidisciplinary Text for Swallowing and its Disorders, DOI 10.1007/978-1-4614-3794-9_27, © Springer Science+Business Media New York 2013

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Approximately 600 neurologic syndromes have been identi fi ed. Oropharyngeal dysphagia may result from any neurologic disease affecting neu-ral networks. It is dif fi cult in a chapter-length

discussion to select the disorders to incorporate and with what detail they should be addressed. A second, and overlapping, challenge is to avoid a simple encyclopedic listing of disease. Categorizing neurologic disease is challenging. Grouping by neuroanatomical site of lesion is dif fi cult because the majority of neurologic dis-eases involve multiple system impairment (e.g., Parkinson’s disease, multiple sclerosis, multisys-tem atrophy). Ordering by underlying pathophys-iology such as rigidity, spasticity, weakness, or dyscoordination is also unsatisfactory because as diseases develop, multiple symptoms may become affected. Limited data make organization

Progressive Neurologic Disease and Dysphagia (Including Parkinson’s Disease, Multiple Sclerosis, Amyotrophic Lateral Sclerosis, Myasthenia Gravis, Post-Polio Syndrome)

John C. Rosenbek and Michelle S. Troche

J. C. Rosenbek , PhD University of Florida, Speech, Language Hearing Sciences , 101 S. Newell, Rm 2128 , Gainesville , FL 32610-0174 , USA

M. S. Troche , PhD (�) Department of Speech, Language, and Hearing Sciences , University of Florida , PO Box 117420 , Gainesville , FL 32611 , USA e-mail: [email protected] fl .edu

Abstract

This chapter’s purposes are to provide a compact review of eleven progressive neurologic conditions’ effects on swallowing dysfunction and to brie fl y discuss management options speci fi c to each. They were selected because dysphagia, with subsequent in fl uences on health and quality of life, is nearly inevitable during the course of each. The conditions include eight syndromes, among them Parkinson’s disease, amyotrophic lateral sclero-sis, and multiple sclerosis and three movement abnormalities-ataxia, dys-tonia, and chorea. Each syndrome or movement abnormality is de fi ned, then prevalence/incidence, pathophysiology, evaluation, complications such as aspiration pneumonia, and team management are described. The emphasis is on focused evaluation and rehabilitation of the dysphagia.

Keywords

Progressive neurologic disease • Dysphagia • Parkinson’s disease • Multiple sclerosis • Amyotrophic lateral sclerosis • Myasthenia gravis • Post-polio syndrome • Introduction

396 J.C. Rosenbek and M.S. Troche

based on neuropathology such as abnormalities of the tau protein untenable, and the neuropathol-ogy data available in some instances are incom-patible with traditional clinical diagnosis as when progressive supranuclear palsy (PSP) de fi ned pathophysiologically is diagnosed clinically as PD. Consensus conferences [ 1 ] have improved the correlation of clinical and pathophysiological diagnosis but have left some clinicians (and neu-ropathologists) unsure about traditional clinical syndromes. What remains is a traditional hybrid approach to the ordering of the disease content mixing clinical diagnoses such as PD and Parkinson plus syndromes with sections based on the primary pathophysiology such as dystonia and ataxia. This approach affords the most com-mon progressive neurologic diseases supple-mented by brief, presentation of rarer conditions such as Wilson’s disease, Guillan–Barre, and post-polio syndrome. The purpose of this chapter is to provide a comprehensive review of the effect of progressive neurologic disease on swallowing dysfunction and brie fl y discuss management options.

Parkinson’s Disease

De fi nition Parkinson’s disease (PD) has long been considered an illness caused by dopamine depletion in the substantia nigra that affects only motor function, but the current conceptualization of PD acknowl-edges that it affects distributed neuroanatomical regions, disrupting multiple motor and non-motor systems [ 2 ] . The cardinal symptoms include bradykinesia, rigidity, resting tremor, and postural instability. In addition to basal ganglia-speci fi c changes, it is now recognized that the PD process begins in the dorsal motor nucleus of the vagal nerve and, from there, proceeds upward until it arrives at the cerebral cortex [ 2 ] .

Prevalence/Incidence of Swallowing Dysfunction The incidence of dysphagia in persons with PD established by careful clinical and instrumental examination has been reported to be between

18.5% and 100% [ 3– 6 ] with silent aspiration occurring in at least one-third of patients [ 7 ] . Not surprisingly, many PD patients report no swal-lowing impairment presumably due to their frequent lack of insight about their neurologic changes [ 8 ] .

Pathophysiology The etiology of swallowing dysfunction in per-sons with PD has not been well de fi ned. Changes have been attributed to the cardinal symptoms of PD from dopaminergic pathway abnormality: rigidity, hypokinesia, and tremor [ 9 ] . Rigidity and bradykinesia have been implicated speci fi cally as responsible for dif fi culty chewing and drool-ing. Eadie and Tyrer [ 10 ] and Ertekin et al. [ 11 ] hypothesized that the hypokinetic, reduced rate of spontaneous swallowing movements, and the “slowness of segmented but coordinated sequen-tial movements” (p 948), may be the most signi fi cant cause of swallowing dysfunction in PD. Lastly, swallowing dysfunction in PD has also been attributed to the involvement of the dor-sal motor nucleus of the vagus nerve and of “Lewy bodies in the myenteric plexus of the esophagus” [ 12 ] (p 730).

Diagnosis Widespread impairment in PD results in swal-lowing de fi cits of every stage of swallowing, and therefore, in addition to a complete history, video fl uoroscopy seems to be the best method for assessing both motor and sensory involve-ment of the entirety of the swallowing mecha-nism. Dysfunction is commonly seen in oral manipulation of the bolus including lingual pumping, labial bolus leakage, lingual tremor, slowed or limited mandibular function, piece-meal deglutition, pre-swallow spill, delayed swallow triggering, and post-swallow residue [ 4, 11, 13– 20 ] . Changes to the pharyngeal phase of swallow include slow pharyngeal transit, abnormal/delayed contraction of the pharyngeal wall, coating of the pharyngeal walls with bolus material, de fi cient epiglottic positioning, decreased epiglottic range of motion, stasis in the vallecula and pyriform sinuses, slow laryngeal elevation and excursion, penetration, aspiration,

39727 Progressive Neurologic Disease and Dysphagia...

and upper esophageal sphincter (UES) discoordi-nation [ 4, 8, 13– 21 ] . Other associated impair-ments include vocal fold bowing, drooling, and dif fi culty swallowing saliva in up to 78% of per-sons with PD, and de fi cits in swallow–respiratory relationships as evidenced by more swallowing during inhalation and swallowing at low tidal volume [ 22– 24 ] . Further complicating the man-agement of persons with PD and dysphagia are the associated gastrointestinal symptoms which often accompany PD [ 25 ] . These in conjunction with oropharyngeal dysphagia can result in reduced oral intake.

Complications The risk of death secondary to pneumonia in PD is six times greater than in those without PD [ 26 ] , with aspiration pneumonia being the leading cause of death [ 27– 31 ] . This risk is probably a consequence of chronic immobilization and swallowing impairment, particularly in later stages of the disease [ 32 ] .

Management Levodopa ( l -Dopa), the gold standard for the treatment of PD related symptoms, has not been found to be ef fi cacious for the treatment of dys-phagia in PD [ 5, 15, 16, 33 ] , nor does l -Dopa improve/in fl uence respiratory–swallow relation-ships [ 23 ] . A study testing the effects of various compensatory strategies (i.e., chin tuck, nectar and honey-thickened liquids) on occurrence of pneu-monia in persons with dementia and PD found signi fi cantly higher incidence of pneumonia in persons given honey-thickened liquids versus nectar-thickened liquids [ 34 ] . Additionally, a recent randomized clinical trial found 4 weeks of treatment with an expiratory muscle training device resulted in signi fi cantly improved swal-lowing safety (i.e., reductions in penetration/aspi-ration) and improved cough effectiveness [ 35 ] . Other smaller scale non-randomized studies have identi fi ed LSVT [ 36 ] , verbal cueing [ 24 ] , tradi-tional swallowing exercises (e.g., Mendelsohn, range of motion) [ 37 ] , and bolus modi fi cation [ 38 ] as possible treatment modalities for dys-phagia in PD. Surgical management with cri-copharyngeal sphincterotomy and myotomy for

cricopharyngeal dysfunction have been discussed in the literature with good results on selected patients [ 15, 39 ] .

Parkinsonian Syndromes

De fi nition Depending on the source, 12 or more conditions are included among the parkinsonian syndromes [ 40 ] . Multiple system atrophy (MSA) and pro-gressive supranuclear palsy (PSP) are discussed in this section. Gilman and colleagues [ 41 ] de fi ne MSA as a “progressive neurodegenerative disease of unknown etiology. The disease occurs sporadi-cally and causes parkinsonism with cerebellar, autonomic, urinary and pyramidal dysfunction in many combinations” [ 41 ] . Three syndromes are traditionally identi fi ed: (1) MSA-P (also called striatonigral degeneration or SND) in which parkinsonian features predominate, (2) MSA-C (also called OPCA) in which cerebellar features predominate, and (3) MSA-A (called Shy–Drager syndrome, an increasingly infrequent label) in which autonomic features predominate. Signs of all three types appear in more than 25% of patients with disease progression. See Higo [ 42 ] for more details. PSP, also called Richardson’s disease, is a progressive neurologic disorder of middle age often beginning with gait abnormality and frequent falls. Litvan and colleagues [ 43 ] outline criteria for diagnosis.

Prevalence and Incidence The estimated prevalence for MSA, without regard for subtypes, is 4.0 per 100,000 people [ 44 ] . Ben-Shlomo et al. [ 45 ] report onset at an average age of 54 years and a median survival of 6.2 years. Dysphagia occurs earlier and with greater severity in MSA than in Parkinson’s disease. Shulman et al. [ 46 ] call dysphagia a “pervasive” sign. Using video fl uoroscopy, Higo and colleagues [ 47 ] identi fi ed at least one sign of dysphagia in approximately 75% of patients with MSA referred for swallowing evaluation. Prevalence of PSP is estimated at 3.9 per 100,000 persons in the United States [ 48 ] . Onset usually occurs between ages of 55 and 70 and death for


most occurs 5–7 years after diagnosis. Litvan et al. [ 49 ] reported a variety of oral and pharyn-geal stage symptoms in 26 of 27 patients with PSP, including coughing and choking and signs on video fl uoroscopic swallowing examination including delayed swallow initiation.

Pathophysiology Pathophysiology is complex in MSA. Delayed initiation of movement, slowed movement, and rigidity are the most frequent parkinsonian signs. Hypotonicity and dyscoordination are likely with cerebellar involvement. Hypertonicity and affective disorders and additional cognitive changes impacting swallowing can also occur. Rigidity, bradykinesia, spasticity, and dystonia are common features of PSP and are often accom-panied by general cognitive slowness and behav-ioral abnormalities [ 43 ] .

Diagnosis The de fi nitive diagnosis of MSA requires autopsy. The clinical diagnosis of PSP requires the presence of gait instability, early falls, rigid-ity, bradykinesia, vertical gaze abnormality, spastic dysarthria, profound dysphagia, and frontal lobe abnormalities [ 49 ] . The swallowing clinician is often working with a tentative diag-nosis. The swallowing evaluation can accom-plish the following: (1) establish the signs of dysphagia and its severity, (2) support hypothe-ses about the usually complex underlying pathophysiology as a focus of treatment, (3) determine the probable quality of life and health impact of the dysphagia, (4) identify potential affective and cognitive in fl uences on the swal-lowing and on treatment, (5) attend carefully to laryngeal stridor secondary to vocal fold immo-bility which may be more common in MSA than in other neurodegenerative diseases, and (6) contribute to differential diagnosis by identify-ing the onset and features of the dysphagia. Both oral and pharyngeal de fi cits are often observed. According to Higo and colleagues [ 47 ] the most common signs are delayed initiation of the swal-low, reduced posterior tongue movement, and “disturbance of bolus holding” (p 632). Residuals in the pyriform sinuses and valleculae

and reduced opening of the UES are among the most frequent pharyngeal signs [ 50, 51 ] .

Complications Higo’s group [ 52 ] says dysphagia “is the most critical complication of MSA” (p 647). Muller et al. [ 53 ] report an average duration of 15 months from a patient’s recognizing swallowing changes to death. Twenty-four percent of Higo et al.’s [ 47 ] patients had a history of aspiration pneumonia. Muller and colleagues [ 53 ] identify dysphagia as a bad prognostic sign in PSP. Aspiration, dehy-dration, malnutrition, and prolonged eating with attendant caregiver stress are among the complications.

Management Because medical and surgical management of parkinsonian syndromes is often of limited use-fulness for all but general symptom reduction, dysphagia management is especially critical. If the underlying pathophysiology is assumed to be rigidity, hypotonia, and/or weakness then a variety of the strengthening techniques may be appropriate. If dyscoordination, delayed initi-ation, or slow movement predominates, the skill building techniques may be appropriate. Combinations will likely be necessary as will be a concerted behavioral effort to improve cogni-tive de fi cits that include attention and general responsiveness. While these efforts are ongoing, compensations will also be useful.

Multiple Sclerosis

De fi nition Multiple sclerosis (MS) is an in fl ammatory pro-cess in which the myelin surrounding the axons of the brain and spinal cord is damaged leading to demyelinating and lesions throughout the neuroaxis [ 54 ] . There are four main types of MS: (1) relapsing/remitting, (2) secondary progres-sive, (3) primary progressive, and (4) progressive relapsing. Relapsing/remitting, the most preva-lent of the subtypes, is characterized by acute attacks of MS followed by periods of remission. This is in contrast to secondary progressive MS


that also involves acute attacks, but in these cases there is a progression of disease between attacks as well. Those with primary progressive MS have a steady decline of symptoms from onset of disease and those with progressive relapsing experience a steady decline of disease, but with superimposed attacks throughout the disease process [ 55 ] .

Prevalence/Incidence of Dysphagia The prevalence of dysphagia in MS is estimated between 30% and 43% [ 56, 57 ] , although some have suggested that this fi gure is likely underesti-mated [ 57 ] . The incidence of dysphagia in MS increases to 65% in those most severely disabled (as measured by the Expanded Disability Status Scale (EDSS)). It is important to note, though, that 17% of patients with low disability will also have dysphagia [ 56 ] .

Pathophysiology The in fl ammatory processes involved in MS affect a variety of areas of the central nervous system, thus making the pathophysiology of dysphagia in MS variable from patient to patient [ 58 ] . Longer disease duration in addition to involvement of cerebellar, brainstem, and cognitive regions has been found to better predict the presence of dysphagia in MS [ 56 ] . Therefore, it can be postulated that dyscoordination of the swallowing mechanism secondary to cerebellar lesions, weakness of the swallowing mechanism from brainstem involvement, and/or disruption of the swallowing mechanism secondary to dimin-ished cognitive resources during swallowing most often characterize the pathophysiology underlying dysphagia in MS.

Diagnosis As described above, dysphagia in persons with MS varies greatly in its presentation depending on the areas of the neuroaxis which have been most affected by the disease. Therefore, a com-plete history identifying speci fi c swallowing changes in conjunction with instrumental assess-ment of swallowing with video fl uoroscopy is rec-ommended. This will help identify loci of

dysfunction and any sensory changes as well. In general, all phases of swallowing are affected with the greatest percentage of patients with dysphagia and MS, demonstrating pharyngeal phase disorders (28.7%), oral stage disorders in 5% of patients, and aspiration in 6.9% [ 57 ] . There also appears to be particular cricopharyn-geal dysfunction in persons with MS and dys-phagia. A study by Abraham and Yun [ 59 ] found impairment of the UES in 100% of a small group of persons with MS with moderate impairment as measured by the EDSS.

Complications In addition to reductions in quality of life, dys-phagia in MS has been linked with enhanced risk for dehydration and aspiration pneumonia [ 60, 61 ] . These complications result in enhanced morbidity and ultimately death in late stages of MS [ 60– 63 ] .

Management There are no pharmacologic treatments found to be ef fi cacious for the treatment of dysphagia in persons with MS. Surgical myotomy has been used to treat UES hyperactivity [ 64– 66 ] and a recent study found that botulinum neurotoxin type A injection of the CP is also effective for the treatment of oropharyngeal symptoms in select persons with MS [ 58 ] . It has been demonstrated that given the very low referral rates, only 2% of patients with MS and dysphagia receive behav-ioral treatment [ 67 ] . This is further complicated by a complete paucity of literature on the ef fi cacy and effectiveness of swallowing rehabilitation in MS. It is considered that in milder cases of dysphagia, the treatment should focus on improvement of oral bolus control with later therapy focused on improved function of the pharyngeal mechanism [ 68 ] . A study investi-gating the effects of neuromuscular electrostimu-lation (NMES) on swallowing dysfunction in patients with MS demonstrated improvements in swallowing function. Following NMES these participants were found to have signi fi cantly less pooling of saliva in the pyriform sinuses and less incidence of aspiration [ 69 ] .


Amyotrophic Lateral Sclerosis and Motor Neuron Disease

De fi nition ALS, the most common of the motor neuron diseases, is a rapidly progressing neurodegenera-tive condition affecting both upper and lower motor neurons [ 70 ] . ALS is fatal and character-ized by progressive muscular paralysis re fl ecting degeneration of motor neurons in the motor cortex, corticospinal tract, brainstem, and spinal cord. The clinical picture most often includes progressive limb weakness, respiratory insuf fi -ciency, spasticity, hyperre fl exia, and bulbar symptoms [ 71 ] . Survival is about 2–5 years after con fi rmatory diagnosis, with death usually resulting from respiratory failure [ 70 ] . Motor neuron disease is sometimes used as a general classi fi cation comprising (1) ALS; (2) primary lateral sclerosis, with deterioration con fi ned at least initially to the upper motor neurons of the spinal, bulbar, or both systems; and (3) lower motor neuron variants called spinal muscular atrophy when the spinal system is exclusively involved and progressive bulbar palsy when the bulbar system is the focus of disease. Life expec-tancy is longest for primary lateral sclerosis with severe dysphagia primarily involving delayed initiation of the pharyngeal swallow. Progressive bulbar palsy can have devastating and early effects on all stages of swallowing. Even when the disease is con fi ned to the spinal system respi-ration can be affected especially in the lower motor neuron variant of the disease resulting in impaired ability to coordinate respiration, swal-lowing, and cough [ 72 ] . This section will focus on ALS, as most literature on dysphagia and motor neuron disease pertains to ALS versus other vari-ations of motor neuron disease.

Prevalence/Incidence of Dysphagia The incidence of ALS is about 2 in 100,000 [ 70 ] . Bulbar dysfunction is the presenting symptom in one-third of cases with ALS, but the incidence is markedly increased in later stages of the disease [ 73, 74 ] . It has been reported that 86% of those with ALS and bulbar involvement have dysphagia [ 75, 76 ] .

Pathophysiology Both upper and lower motor neuron involvement in ALS can result in dysphagic symptoms. Pseudobulbar palsy, or upper motor neuron involvement in ALS, often results in spasticity of the bulbar musculature. Degeneration of cranial nuclei in the brainstem results in fl accid pareses, muscular atrophy, and fasiculations and/or tongue fi brillations. Degeneration of motor neurons in the spinal cord can also result in dysphagic symp-toms secondary to changes in the respiratory–swallow coordination and inef fi ciency of cough function [ 71, 77, 78 ] .

Diagnosis Motor neuron degeneration will result in changes to the spectrum of oropharyngeal swallowing which may begin with dif fi culty in lip control and end with cricopharyngeal dysfunction. A complete history identifying nutritional needs, current feeding strategies, and long-term plans for feeding and respiratory support is important to identify dur-ing the clinical evaluation. Instrumental assessment with video fl uoropscopy seems to be most appro-priate for identi fi cation of possible silent aspiration and involvement of all swallowing phases. With the possibility of reductions in motility, strength, and coordination of orofacial structures come likely impairments of bolus preparation, mastication, and oral transport. The patient with ALS will likely demonstrate dysfunction of the pharyngeal phase of swallowing, speci fi cally poor pharyngeal strip-ping, poor laryngeal elevation, incomplete laryn-geal closure, reduced extent and duration of cricopharyngeal opening, and reduced sensation in the laryngopharynx [ 79– 84 ] , especially if lower motor neuron de fi cits predominate. Reduced cough effectiveness is also likely [ 72 ] .

Complications Malnutrition has been identi fi ed as an indepen-dent risk factor for death in ALS. This, combined with the increased risk for airway obstruction and aspiration, results in markedly reduced life expec-tancy in patients with ALS [ 85, 86 ] . During the course of the disease, these marked changes of swallowing and feeding function adversely affect quality of life [ 87, 88 ] .


Management At all levels of management, care is often proac-tive and palliative in nature, and a multidisci-plinary approach is considered a necessity. Most swallowing management is going to be compen-satory in nature, with changes to position during feeding along with dietary modi fi cations. The speech pathologist will often identify when it is no longer safe for the patient to eat orally, in cases where the patient has decided not to consider non-oral feeding, decisions regarding the safest possi-ble diet should be made. In addition to education regarding proper diet, it is essential that the clini-cian educate the patient and family regarding the bene fi ts of early PEG placement. This is espe-cially salient given the data suggesting that PEG placement once the patient becomes nutrionally compromised may be inappropriate and even unsafe [ 89 ] . The safety and ef fi cacy of behavioral swallowing therapy in ALS has been challenged; however, sensorimotor exercises in ALS have been considered to improve sensory response to the bolus in the oral and pharyngeal cavities [ 71 ] . The utility and safety of other rehabilitative swal-lowing exercises for ALS have not been well stud-ied, but evidence from the training of the limbs in ALS would suggest that modest stretching, gentle strengthening, and even skill training as with a hard swallow may be bene fi cial [ 90 ] .

Ataxia

De fi nition Ataxia is characterized by dyscoordination mani-fest as irregular, erratic, jerky, and incomplete movements. Rate, range, and force of movement across structures such as the tongue, larynx, and velopharynx may be abnormal. These abnormal patterns, leading to over and undershooting of targets, have also been called asynergia or dyssynergia.

Any process damaging the cerebellum or path-ways connecting cerebellum to other portions of the nervous system can cause ataxia. Common in clinical practice are the autosomal-dominant and autosomal-recessive ataxias. The spinocerebellar atrophies are autosomal-dominant. Dysphagia is

especially likely in SCA-1 and SCA-3, also known as Machado–Joseph disease. Friedreich’s ataxia (FRDA) and ataxia telangiectasia (AT) are among the most frequent autosomal-recessive ataxias, and dysphagia is a risk in both.

Prevalence/Incidence of Dysphagia The prevalence of hereditary ataxias is estimated to be 6 per 100,000 [ 44 ] . FRDA is the most com-mon inherited ataxia with an estimated preva-lence of 1 per 30,000–50,000 Europeans [ 91 ] . Jardin and colleagues [ 92 ] report that 30 of 47 patients (64%) with Machado–Joseph disease (SCA-3) had dysphagia. Nagaya and colleagues [ 93 ] report aspiration in 30% of a heterogeneous group of ataxic patients. Twenty-one of 23 patients described in the study by Ramio-Torrenta et al. [ 94 ] complained of swallowing dif fi culty. All 23 had abnormal instrumental examinations.

Pathophysiology Dyscoordination and hypotonia are the major in fl uences on swallowing function in pure ataxia. Because other portions of the nervous system such as the brain stem, cortical, and subcortical struc-tures may also be involved resulting in weakness, spasticity, hypokinesia, and cognitive de fi cits. Cognitive de fi cits including impaired learning ability may further complicate swallowing reha-bilitation and its management. Dyscoordination alone may produce no or only a mild and function-ally insigni fi cant swallowing impairment.

Diagnosis The medical diagnosis primarily depends on the neurologic examination and special imaging and genetic testing. The swallowing evaluation’s purposes are to (1) establish the presence, signs, and severity of dysphagia, (2) assess the quality of life and health consequences, (3) hypothesize the speci fi c underlying pathophysiology, and (4) determine patient’s motivation, insight, and ability to learn

Complications In a study of SCA-1, pulmonary complications, presumably at least in part resulting from


dysphagia, were the major cause of death [ 95 ] . This and other health and quality of life conse-quences can be expected whenever severe dys-phagia is present especially if mobility and independence are also compromised.

Management Paulson and Ammache [ 96 ] identify speech therapy for dysphagia in ataxic disorders as being “especially helpful” (p 779) in part because medical and surgical treatment options are limited. Skill building treatments will be important because, depending on severity, patients may be able to compensate for their dysfunction by consciously trying to modify their behavior. Accompanying weakness or hypotonia will require simultaneous strengthening approaches. In our experience, intense and lengthy treatment duration is required.

Dystonia

De fi nition Dystonia is a heterogenous pattern of involuntary, sustained, and repetitive muscle contractions resulting in abnormal postures and twisting movements of involved body parts. Dystonia is classi fi ed by age of onset—early versus late; by etiology—primary (idiopathic) or secondary (symptomatic); and by distribution—generalized, multifocal, segmental, or focal [ 97 ] . Regardless of onset, etiology, or distribution, swallowing will be altered if respiratory or bulbar muscula-ture is affected. Among the dystonias of greatest signi fi cance to the swallowing specialist or deglu-tologist are spasmodic torticollis [ 98 ] and the oromandibular dystonias (OMDs) [ 99 ] , including Meige syndrome sometimes called Brueghel’s syndrome [ 100 ] . These distinctions are important because different sites of dystonic involvement may lead to different signs of dysphagia.

Prevalence/Incidence of Dysphagia The prevalence for early onset dystonia ranges from 3 to 50 cases per 1,000,000 [ 97 ] . The range for late onset is 30–7,320 cases per 1,000,000. Focal dystonia is more common than generalized

dystonia and cervical dystonia is the most common of the focal dystonias. The incidence of oromandibular dystonia derived from a popula-tion study in Iceland was 2.8 per 1,000,000 [ 101 ] . Dystonia occurs more often in women than in men and varies by ethnicity. In a typical study, Ertekin and colleagues [ 98 ] report dysphagia in 76% of a mixed group of 25 dystonic patients. Oral abnormalities are more frequent than pha-ryngeal ones.

Pathophysiology The simultaneous co-contraction of agonist and antagonistic muscle groups that de fi nes dystonia disrupts the skilled movements necessary to normal swallowing. The cause may be genetic, sporadic, or secondary to acquired nervous system damage from trauma, disease, toxins, or medica-tions. For a recent summary of the genetics of dystonia see Bruggemann and Klein [ 102 ] . Dystonia can also occur as an accompaniment to a variety of basal ganglia diseases including Parkinson’s disease, Wilson’s disease, cortico-basal degeneration, and progressive supranuclear palsy.

Diagnosis The medical diagnosis rests primarily on a history and neurologic examination supplemented by genetic testing and imaging. The swallowing diagnosis will include history; physical examina-tion of the respiratory and bulbar musculature including non-speech and speech tasks; a clinical swallowing examination; and an instrumented evaluation, in most instances the video fl uoroscopic swallowing examination. Evaluation’s goals are to (1) establish the likelihood that a patient has dystonia alone or in combination with other neurologic abnormalities, (2) de fi ne the dysto-nia’s distribution across the respiratory and swal-lowing structures, and (3) identify the resulting swallowing abnormalities. During the instru-mented examination special attention should be paid to the in fl uence of sensory tricks and posture and to teasing out the in fl uence of dystonia on the interaction of oral and pharyngeal stages. In cervical dystonia, oral stage abnormalities include abnormal bolus preparation [ 103 ] . In Meige


syndrome pre-swallow spill is a common fi nding [ 104 ] . Pharyngeal abnormalities in both cervical and oromandibualr dystonia include post-swallow pharyngeal residue particularly in the vallecula. Asymmetric bolus transport is more likely to occur in cervical dystonia [ 105, 106 ] .

Complications Embarrassment, social isolation, weight loss, and aspiration are possible functional consequences with the psychosocial implications often out-weighing the physical.

Management The primary treatments of dystonia are botulinum toxin injection and deep brain stimulation (DBS) [ 100 ] . DBS’s positive effects for Meige syndrome are reported by Ghang and colleagues [ 107 ] and Lyons et al. [ 108 ] . Transcranial magnetic stimu-lation (TMS) to somatosensory cortex is prom-ising [ 109 ] .

Behavioral therapy for dysphagia secondary to dystonia has been compensatory. Postural stabilization may reduce swallowing symptoms secondary to abnormal posture. In addition, because enhanced sensory input (geste antago-niste) such as touching the cheek, neck, jaw, or other bulbar structures can sometimes reduce dystonia, it behooves the clinician to inquire if a patient has discovered such methods and further-more to evaluate the effects of touching the neck, face, and head. The array of rehabilitation tech-niques can be employed, but recent data on neurorehabilitation and treatments for focal dys-tonia of the hand should motivate new treatments. For example, Candia and colleagues [ 110 ] base a treatment on principles of neural reorganization and functional imaging data of cortical maps in cases of focal hand dystonia. Their method, SMR, involves splinting different combinations of non-dystonic fi ngers and then having the participant use the dystonic fi nger(s) in various skilled move-ments with various combinations of normal fi ngers. The goal is reestablishment of the normal patterns of cortical fi nger representation and an accompanying improvement in dystonic fi nger movement. The hypothesis that dystonia results in part from alterations in what Vitek [ 111 ] calls

somatosensory responsiveness should motivate research into sensory stimulation as part of dys-phagia treatment.

Chorea

De fi nition Chorea is de fi ned as a series of quick, unpredict-able, irregular, jerking movements. Impaired voluntary movements, delayed initiation, and slowness of movement are also features of chorea and may involve one or multiple body parts. Chorea can occur in a number of syndromes such as Wilson’s disease (discussed later in this chapter), but occurs primarily in two conditions—Huntington’s disease (HD) and Sydenham’s chorea (SC). SC is a rare condition that is the result of infection in children and usually resolves spontaneously. HD is an inherited disorder of adults with chorea beginning often in the hands and face and generalizing to other body parts. Behavior change and dementia are also hallmarks of this relentlessly progressive disease that ends in severe dementia, anarthria, and aphagia.

Prevalence/Incidence HD occurs with a prevalence of 2–12 persons per 100,000 [ 44 ] . Klasner [ 112 ] , referencing National Institutes of Health data, says approximately 30,000 new cases of HD are diagnosed in the United States each year. Age of onset is typically between 30 and 45, although earlier or later onset is possible. Disease duration is usually 15–20 years [ 113 ] . Eating and swallowing abnor-malities occur in nearly 100% of patients at some time during the disease’s course. More speci fi cally, Yorkston et al. [ 114 ] describe choreatic involve-ment of the respiratory mechanism in 40%, aspi-ration and aerophagia in 10%, and excessive belching or eructation in 40%.

Pathophysiology Pathophysiology of dysphagia in HD is complex. Patients may be primarily hyperkinetic, hypoki-netic, or both. Dyscoordination may be a major or secondary in fl uence on skilled eating and swallowing movements. Affective disorders,


including apathy, and other cognitive abnormali-ties, including impulsivity, may complicate swallowing signs, evaluation, and treatment.

Diagnosis Aims of diagnosis are the same as for previously discussed conditions. Of special importance in chorea are clinical and eating evaluations. Tachyphagia or fast eating and belching are among the signs that may be missed with an instrumented examination although such an examination may inform the clinician about underlying swallowing physiology. Chorea makes patience and special positioning during instru-mental examination a necessity. Allowing self-administered boluses may inform the clinician about the difference between caregiver and self-administered bolus consumption. A substantial challenge is identifying the focus of abnormality, whether it is respiratory, oral, or pharyngeal involvement alone or in combination.

Complications Common health consequences include aspiration pneumonia, dehydration, malnutrition, and weight loss. The medications utilized to treat chorea may further degrade swallowing [ 115 ] . Tachyphagia, belching, and abnormal movements may lead to social isolation and a host of other psychosocial consequences. The incidence of fatal airway obstruction may be elevated.

Management Bilney, Morris, and Perry [ 116 ] found only “a small amount of evidence to support the use of speech pathology services or that of a swallowing specialist for the management of eating and swal-lowing disorders” in HD (p 12). Nonetheless, treatment can be offered. Kagel and Leopold [ 117 ] support the use of a variety of compensa-tions including the use of a weighted cup and wrist and leg weights. If the patient has a more rigid form of HD, maximum performance and even muscle strengthening exercises may be appropriate. The affective and behavioral abnor-malities make treatment dif fi cult, and the clini-cian must consider the cost–bene fi t ratio of introducing treatment.

Myasthenia Gravis

De fi nition Myasthenia graves (MG) is a rare auto-immune disease affecting the neuromuscular junction. MG can be classi fi ed as either ocular or general-ized. Ocular MG affects extraocular muscles speci fi cally, but can often develop into general-ized MG at which time the oropharygeal musclu-lature may be involved [ 118 ] . Presentation of MG usually occurs with ocular symptoms (60%), but there have been cases of oropharyngeal muscle weakness as the presenting symptom [ 119 ] .

Prevalence/Incidence One in every 5,000 people will develop MG [ 120, 121 ] . Forty percent of persons with MG will develop dysphagia during the course of the disease [ 122 ] . Only 6–15% will present with dysphagia [ 123 ] .

Pathophysiology Weakness and fatiguability of facial, jaw, buccal, lingual, and pharyngeal muscles are thought to contribute to the etiology of swallowing dysfunc-tion in MG. Electrophysiological studies of laryngeal function have demonstrated abnormali-ties suggesting that the neuromuscular junctions of the corticobulbar tract can be affected by MG [ 124 ] . It is considered that antibodies working against the acetylcholine receptors result in de fi cits to neuromuscular transmission [ 125, 126 ] . The relapsing and remitting of swallowing distur-bance in this population is often observed, and relapse usually signals worsening of overall condition.

Diagnosis When gathering the patient history it is important to identify changes in swallowing function that may occur as the day and time spent in eating progress. VFES is the gold standard as changes are evident throughout the swallowing mecha-nism. In some cases dysfunction will be speci fi c to orofacial structures, but the pharyngeal phase of swallowing seems to be the most signi fi cantly impaired in MG with pharyngeal phase delay and particular impairment in laryngeal elevation


and epiglottic inversion [ 127 ] . Abbreviated video fl uoroscopic swallowing examinations before and after tensilon testing may contribute both diagnostic and prognostic information.

Complications Dysphagia with aspiration is often a source of morbidity and mortality in MG [ 119 ] . Additionally, the strain of intermittent and often embarrassing swallow disturbance can be detri-mental to quality of life.

Management MG is a treatable disease, and pharmacological management is the fi rst line of treatment. Treatments, however, are often more effective for corticospinal than corticobulbar symptoms. Both compensatory and restorative swallow-speci fi c treatments can be utilized. Given the worsening of symptoms with continued muscle fatigue, smaller more frequent meals are essential for maintaining swallowing safety and good nutritional state. Exercises aimed at increasing muscle strength of the oropharyngeal mechanism are limited by fatiguing of muscles and in some cases may be inappropriate [ 127 ] . Skill-based treatments may be an alternative to strength-ening but have not been well studied in this population. Compensatory treatments are frequently offered and include diet modi fi cation, postural adjustment, and in severely affected individuals, non-oral feeding. Exacerbations or relapsing of dys-phagia in MG will often result in changes to phar-macological management with increased doses of cholinergic agents, immunomodulatory therapies, and even initiation of plasma exchange.

Rare Disorders

There is a subset of rarer neurodegenerative disorders that may lead to dysphagia and for which we provide a more cursory review below.

Wilson’s Disease

Wilson disease is an autosomal-recessive genetic disorder that can result in neurodegeneration

[ 128 ] . The disease is characterized primarily by a disorder of copper metabolism which can result in a build up of copper in the liver, eyes, and central nervous system at times manifesting as a movement disorder. Unless WD is diagnosed and treated early in the disease’s course, muscular discoordination, tremor, muscle stiffness, behav-ioral changes, and resultant dysarthria and dys-phagia can occur [ 129 ] . Imaging studies have identi fi ed lesions throughout the neuroaxis including cerebral cortex, white matter, cere-bellum, thalamus, and basal ganglia all of which might result in dysphagia [ 130, 131 ] . Swallow-speci fi c symptoms include prolonged oral transit times and greater percentage of oral residue when compared to age-matched healthy individuals [ 132 ] . Additional parkinsonian swallowing de fi cits are also common. Lifelong treatment is required to control the disease, but if identi fi ed promptly and treated appropriately patients can maintain function long term. Therefore, treatment of swallowing dysfunction should have marked impact for health and quality of life.

Post-polio Syndrome

Post-polio syndrome is a neurologic disorder occurring in about 5% of individuals at least 15 years after infection with the polio virus. PPS has been reported to result in weakness, fatigue, and reduced endurance of limbs, trunk, respira-tory, and oropharyngeal musculature [ 133, 134 ] with subsequent muscle atrophy, respiratory insuf fi ciency, dysphonia, and dysphagia [ 135, 136 ] . As in other neurodegenerative diseases, dysphagia in PPS is the result of a slow progres-sive deterioration to bulbar functioning [ 135– 138 ] . The proper management of dysphagia in PPS requires further investigation.

Guillain–Barre Syndrome

Guillain–Barre syndrome (GBS) is an acute, immune-based disorder of the peripheral nervous system usually following an infectious process. GBS results in a paralysis beginning in the lower


extremities which quickly ascends to the upper extremities and bulbar musculature [ 139 ] . Management in the acute phases of the syndrome is centered on sustaining life through control of autonomic dysfunction. Management of insidious swallowing dysfunction is secondary. Following the acute phase of the disease, patients may have mild to severe changes to the swallowing mecha-nism and respiration. The manifestation of swal-lowing dysfunction will depend on the affected cranial and/or spinal nerves involved with impair-ments including dif fi culty with bolus formation and aspiration/penetration. If respiration is also involved, coordination of swallowing and respi-ration may be disrupted. For example the person may have dif fi culty prolonging the apneic period of swallow suf fi ciently to allow safe, adequate oral feeding. Swallowing management may include compensatory or behavioral techniques. Treatment effects must be carefully monitored, as ef fi cacy data is limited.

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principles of deglutition || progressive neurologic disease and dysphagia (including parkinson’s...

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