In the paper by Sakakibara et al (this volune, pp 600–606),1 the differences in findings of investigations of bladder function between patients with Parkinson's disease and multiple system atrophy are reported. The authors' new findings focus on the urethral sphincter mechanism, examining this functionally (using some of the newer urodynamic indices) and fluoroscopically. But the paper also provides a useful summary, reviewing as it does, previous work in this area, which has so far been mainly published in the urological literature. Although urinary symptoms can be troublesome in advanced Parkinson's disease they do not have the same prominence and severity as those seen in early multiple system atrophy, probably due to the multiple defects of neurological control of the bladder and sphincter function that develop in the initial stages of multiple system atrophy. Abnormalities of urethral sphincter innervation, both the external (striated) and intrinsic (bladder neck) are marked as a feature of multiple system atrophy but not Parkinson's disease, as has been shown in this study.

There has been a tendency up to now to include bladder symptoms as part of the “autonomic failure” which characterises multiple system atrophy, but the growing realisation that the entire system of neurological control of the bladder is selectively involved in its early stages, may lead to a new approach in understanding the evolution of this progressive and fatal neurodegenerative disease.