To investigate the efficiency of bisection urine collection to evaluate autonomic dysfunction in multiple system atrophy (MSA).

MSA is an adult-onset progressive neurodegenerative disorder that manifests clinically with autonomic failure, parkinsonism, and ataxia in any combination. Autonomic failure is a mandatory feature in the current consensus criteria. Urinary dysfunction and orthostatic hypotension (OH) are the prominent autonomic features in MSA. Because urinary dysfunction is more common and often an earlier manifestation than OH, we evaluated the nocturnal urinary concentration failure using bisection urine collection.

We reviewed the medical records of consecutive Japanese patients with probable MSA according to Gilman's 2008 consensus criteria. Urinary osmolality were analyzed using urine collection during the daytime (9:00-21:00) and nighttime (21:00-9:00). We defined nocturnal urinary concentration failure as osmolality in the nighttime was lower than that in the daytime. We investigated the presence of urinary concentration failure, age, disease duration, unified multiple system atrophy rating scale (UMSARS), residual urine volume, the coefficient of variation in the R-R intervals, and Schellong test. Moreover, longitudinal changes were also evaluated in the four patients.

We evaluated 74 MSA patients. No significant difference was observed in the disease characteristics between the patients with and without OH. However, the disease duration in the patients with nocturnal urinary concentration failure (N=37) (50.4 ± 25.4 months) was significantly shorter than those without (N=37) (68.8 ± 41.6 months) (P=0.024). The association between the presence of OH and nocturnal urinary concentration failure was absent (P=0.456).Moreover, four patients changed the Gilman criteria for possible to probable MSA longitudinally. Three of four patients revealed nocturnal urinary concentration failure prior to OH.

Some MSA patients developed nocturnal urinary concentration failure prior to OH. Bisection urine collection might be useful to evaluate autonomic dysfunction prior to the presence of OH.