multiple system atrophy vs parkinsons

multiple system atrophy - group of three overlapping neurodegenerative disorders

striatonigral degeneration - predominant parkinsonism

autonomic dysfunction (shy drager)

olivopontocereballar degeneration - predominant cerebellar ataxia

now categorized

MSA - P - predominant parkinson's - brady, rigid, post instability, tremor (can also get dystonia)

MSA - C - predominant cerebellar - nystagmus, dysarthria, impaired smooth pursuit,

dysphagia, increased urinary frequency, urgency, incomplete emptying

sleeping and breathing disorders (involuntary sighs/gasps)

cognitive function - typically spared

Raynaud's

Imaging - atrophy of putamen, pons, cerebellar peduncle (middle), "hot cross bun" sign -T2 hyperintense signal within pons (degeneration of transverse pontocerebellar fibers)

pathology - intracytoplasmic inclusions of alpha-synuclein, tau, ubiquitin

autonomic symptoms come from loss of neurons in the intermediolateral cell column or catechol C1 neurons of ventral lateral medulla

urinary symptoms can be result of loss of inhibitory pontine micturition neurons or Onuf's sacral nucleus (cause of erectile dysfunction in men)

KEY DIFFERENTIAL FOR MSA VS. IDIOPATHIC PARKINSON'S

response to L-dopa - MSA does not have sustained responses to L-dopa

MSA - C secondary to cerebellar, inf. olivary neucleus, basis pontins, pontine nuclei

Diagnosis is clinical. Levodopa dx MSA from idiopathic Parkinson's (above),

-must use HIGH dose to avoid false negative (lack of response)

-L-dopa can create false positive if trial doesn't last long enough (MSA can manifests after brief period of L-dopa responsiveness) trial period is 3 months

- use Ldopa w/carbidopa (peripheral decarboxylase inhbitor)

+ response is >30% increase in UPDRS score (unified parkinson disease rating scale

unilateral facial dystonias after L-dopa treatment suggest MSA over idiopathic parkinson