[Shy-Drager syndrome and multiple system atrophy].

Shy-Drager syndrome (SDS) is a subtype of multiple system atrophy (MSA) with the clinical predominance of autonomic failure. The differential diagnosis between SDS and Parkinson's disease (PD) can sometimes be difficult clinically. The features favoring a clinical diagnosis of SDS are marked orthostatic hypotension, erectile impotence in males, urinary symptoms, nocturnal stridor, rigidity and akinesia without tremors, levodopa unresponsiveness, cerebellar signs, cerebellar atrophy on brain CT scans and MRI.