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Multiple system Atrophy, abbreviated MSA defines a
specific syndrome within the larger less well defined category of multiple system degenerations. The features of the MSA include: parkinsonism, cerebellar or corticospinal signs, orthostatic hypotension,
impotence, and urinary incontinence or retention, usually preceding or within two years after the onset of the motor symptoms. The previous division into Shy Drager Syndrome (SDS), Striato Nigral
Degeneration (SND), and Olivopontocerebellar Atrophy (OPCA) has been dropped. Immunohistochemistry demonstrates that these three disorders share a common pathology.
The latest diagnostic criteria are shown in the table below.
Wenning et. al. determined that the
combination of autonomic insufficiency, speech or bulbar dysfunction, absence of dementia, postural instability with falls, poor response to levodopa, and absence of levodopa-induced confusion gave a
diagnostic sensitivity and specificity greater than 90%.
Median age of onset of MSA is about age 55
years (range of 33 to 76). It affects men slightly more than women. Nearly half of patients are disabled or wheelchair bound within 5 years of the onset of motor symptoms. Mean survival is 6 to 7 years.
80% of MSA patients develop predominant parkinsonism (MSA-P) and 20% develop predominant cerebellar signs (MSA-C). The latter statistics are likely skewed by referral patterns to movement disorder
centers. There is considerable overlap. Cerebellar features are present in over 40% of patients with SND type, and parkinsonism is detectable in 50% of OPCA type patients.
30% and 65% of MSA patients had a good
levodopa response at some stage. Between 13% and 30% maintained some response through the course of the illness. 25% to 50% of those treated with levodopa had dyskinesias (particularly orofacial) and
dystonia, even if they did not experience improvement in motor state.
Autonomic symptoms were the initial
feature in 41% of patients, but ultimately 97% of patients developed some degree of autonomic dysfunction. The most frequent autonomic symptom in men was impotence and in women urinary incontinence.
Orthostatic hypotension occurred in 68%.
A mild restriction of downgaze may develop
in about 10% of MSA cases.. Anterior horn cell loss may occur but is uncommon. Anal sphincter EMG (90% have an abnormality) is a sensitive and specific diagnostic test for MSA. Even less frequently seen
is a mild sensory neuropathy. Classic rest tremor is uncommon (29%).
Cerebellar signs occurred in 54% of patients and upper motor neuron signs in 49% of the cases. MSA-P type generally demonstrates more tremor, pyramidal signs, and myoclonus than MSA-C type. Severe dementia is uncommon
Respiratory stridor (which ultimately
occurs in 1/3 of cases) in combination with parkinsonism is highly suggests MSA until proven otherwise; although stridor can also occur in PD, it is exceptionally rare.
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Multiple System Atrophy: Clinical Diagnostic Criteria
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STRIATONIGRAL DEGENERATION Type
(predominant parkinsonism)
Sporadic adult-onset (age 30 years or above)
Possible
Non/poorly levodopa responsive parkinsonism*
Probable
Above**, plus severe symptomatic autonomic failure*** or cerebellar signs or pyramidal signs or
pathological sphincter EMG
Definite
Post mortem confirmed
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OLIVOPONTOCEREBELLAR Type
(predominantly cerebellar)
Sporadic adult-onset (age 30 years or above)
Possible
Cerebellar syndrome with parkinsonism
Probable
Sporadic adult-onset cerebellar syndrome*
(with or without parkinsonism or pyramidal signs) plus severe symptomatic autonomic failure*** or
pathological sphincter EMG
Definite
Post mortem confirmed
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* Without DSM III dementia, generalized tendon areflexia, down gaze PSNP or other identifiable cause.
** Moderate or good, but often waning, response to levodopa may occur, in which case multiple atypical features need to be present.
*** Postural syncope or presyncope and/or urinary incontinence or retention not due to other causes.
Sporadic: one other case of typical clinical IPD among 1st or 2nd degree relatives allowable.
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Frequency of individual clinical features in 203 cases of MSA
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From Wenning, et al, MSA: A Review of 203 Pathologically proven Cases Movement Disorders Vol 12 No 2 1997 – 133-147
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Autonomic symptoms
Urinary incontinence 55%
Postural faintness 51%
Impotence 47%
Recurrent syncope 18%
Fecal incontince 12%
Parkinsonism
Akinesia 83%
Tremor 67%
Rigidity 63%
Best L-Dopa response
Poor 72%
Good 28%
Last L-Dopa response
Poor 95%
Good 5%
Dyskinesias
Orofacial 15%
Limbs 10%
Fluctuations 24%
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Cerebellar Signs
Gait ataxia 49%
Limb ataxia 47%
Intention Tremor 24%
Nystagmus 23%
Pyramidal signs
Hyperreflexia 46%
Babinski 41%
Spasticity 10%
Other features
Intellectual deterioration
Mild 22%
Moderate 2%
Severe 0.5%
Stridor 13%
Dystonia 12%
Anisocoria 8%
Contractures 7%
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