Urinary dysfunction and orthostatic hypotension in multiple system atrophy: which is the more common and earlier manifestation?

OBJECTIVES Urinary dysfunction and orthostatic hypotension are the prominent autonomic features in multiple system atrophy (MSA). A detailed questionnaire was given and autonomic function tests were performed in 121 patients with MSA concerning both urinary and cardiovascular systems. METHODS Replies to the questionnaire on autonomic symptoms were obtained from 121 patients including three clinical variants; olivopontocerebellar atrophy (OPCA) type in 48, striatonigral degeneration (SND) type in 17, and Shy-Drager type in 56. Urodynamic studies comprised measurement of postmicturition residuals, EMG cystometry, and bethanechol injection. Cardiovascular tests included head up tilt test, measurement of supine plasma noradrenaline (norepinephrine,NA), measurement of R-R variability (CV R-R), and intravenous infusions of NA and isoproterenol. RESULTS Urinary symptoms (96%) were found to be more common than orthostatic symptoms (43%) (p<0.01) in patients with MSA, particularly with OPCA (p<0.01) and SND (p<0.01) types. In 53 patients with both urinary and orthostatic symptoms, patients who had urinary symptoms first (48%) were more common than those who had orthostatic symptoms first (29%), and there were patients who developed both symptoms simultaneously (23%). Post-micturition residuals were noted in 74% of the patients. EMG cystometry showed detrusor hyperreflexia in 56%, low compliance in 31%, atonic curve in 5%, detrusor-sphincter dyssynergia in 45%, and neurogenic sphincter EMG in 74%. The cystometric curve tended to change from hyperreflexia to low compliance, then atonic curve in repeated tests. Bethanechol injection showed denervation supersensitivity of the bladder in 19%. Cardiovascular tests showed orthostatic hypotension below -30 mm Hg in 41%, low CV R-R below 1.5 in 57%, supine plasma NA below 100 pg/ml in 28%, and denervation supersensitivity of the vessels (alpha in 73%; beta2 in 60%) and of the heart (beta1 in 62%). CONCLUSION It is likely that urinary dysfunction is more common and often an earlier manifestation than orthostatic hypotension in patients with MSA, although subclinical cardiovascular abnormalities appear in the early stage of the disease. The responsible sites seem to be central and peripheral for both dysfunctions.