Sphincter EMG in possible multiple system atrophy: to do or not to do?

In multiple system atrophy (MSA) the motor neurons of sphincter muscles (Onuf's nucleus) degenerate earlier than those of limb muscles (Sunget al 1). Such lower motor neuron loss is, in principle, accompanied by muscle pathology, which may be readily assessed by EMG methods, of which there are several. Although there is no doubt that expertise may be accumulated with any of the various methods, data comparing different techniques are only beginning to appear. Giladet al (this issue, pp 596–99) report on results obtained by concentric needle EMG (CNEMG) single fibre EMG (SFEMG), and interference pattern (IP) analysis in a small group of patients with MSA.2 Their findings both confirm and contradict the commonly held views on …