Objective:  To determine the ability of sphincter electromyography (EMG) and post-void residual urine volume (PVR) during a free-flow study and a pressure-flow study (PFS) for distinguishing multiple system atrophy (MSA) from Parkinson’s disease (PD).

Background: Although it is often difficult to differentiate multiple system atrophy (MSA) from Parkinson’s disease (PD), examining urinary dysfunction might be helpful for diagnosing MSA in cases with more severe urinary voiding dysfunction than in PD. We previously reported that the post-void residual urine volume (PVR) and sphincter electromyography (EMG) might be helpful for differentiating MSA from PD. However, we do not know which modality is more suitable in distinguishing MSA from PD.

Methods: We retrospectively reviewed 241 case records; both urodynamic study and sphincter EMG were performed in patients with MSA (n = 147) and PD (n = 94).

Results: There was a statistically significant difference (p < 0.01) in the mean PVR during the free-flow study (113.1 ± 7.5 mL in MSA and 40.4 ± 3.8 mL in PD), mean PVR during PFS (230.1 ± 12.6 mL in MSA and 71.7 ± 6.6 mL in PD), and mean duration of MUP for sphincter EMG (9.3 ± 0.1 ms in MSA and 7.7 ± 0.1 ms in PD). The area under the curve used for differentiating MSA from PD was 0.79 and 0.73 for PVR during PFS and the free-flow study, respectively. There was a mean duration of 0.69 for the sphincter EMG. (Figure)

Conclusions: The present results suggested that PVR was more appropriate than sphincter EMG for differentiating MSA from PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-utility-of-post-void-residual-volume-versus-sphincter-electromyography-to-distinguish-between-multiple-system-atrophy-and-parkinsons-disease/