[The electromyography of rectus abdominis muscle in the diagnosis of polyneuropathy].

To assess the value of electromyography ( EMG) of rectus abdominis muscle in the diagnosis of polyneuropathy.109 patients with polyneuropathy were studied. The routine nerve conduction study was done and standard EMG was recorded from rectus abdominis muscle, first dorsal interosseous muscle and tibialis anterior muscle. The parameters studied included spontaneous activity fibrillation potentials (fib) and positive sharp waves (psw); duration, amplitude and percentage of polyphasic wave of motor unit action potential (MUAP) and pattern of recruitment. A group of controls and patients with amyotrophic lateral sclerosis (ALS) were studied at the same time. EMG parameters of rectus abdominis muscles were compared among patients with polyneuropathy, patients with ALS and the controls.EMG of rectus abdominis muscle in the patients with polyneuropathy showed neurogenic change. The amplitude of motor unit potential in patients with polyneuropathy (451.67 +/- 75.01) microV was higher than that of the controls (373.78 +/- 56.46)microV(t = 2.01, P < 0.04) and lower than that of patients with ALS (537.19 +/- 159.04) microV (t = 2.32, P < 0.03).EMG of rectus abdominis muscle might be used to find the lesion of intercostal nerve in polyneuropathy.