Shy-Drager syndrome was diagnosed in patients with parkinsonism and prominent autonomic failure. In some cases, the designation MSA alone is used, when the patient does not fit into a clear subtype. Three-fourths of patients develop autonomic symptoms up to four years before the onset of other neurological compromise. Tremor is more common in MSA of SND subtype, though the classic pill-rolling tremor at rest is uncommon. Dysmetria of the upper extremities is less common.
Intellectual impairment is usually mild, corresponding to a mild subcortical dementia.
Emotional lability may be seen in advanced disease. In diagnosing parkinsonian syndromes, one must first attempt to distinguish IPD from other causes. Factors that help make this distinction include symmetry of symptoms, absent or minimal tremor, early autonomic dysfunction, early falling, prominent postural instability, and a poor response to levodopa therapy, with each of these features seen more prominently in non-IPD parkinsonism. Definitive diagnosis of MSA requires autopsy, but clinical criteria for diagnosis of SND and OPCA subtypes have been developed. The diagnosis of possible MSA, SND subtype may be made in any patient with parkinsonism and a poor response to levodopa therapy.