OBJECTIVETo study the display of different types injuries of recurrent laryngeal nerve (RLN) in laryngeal electromyography (LEMG).

METHODSLEMGs of one hundred and forty-seven patients (147 sides) with traumatic unilateral vocal cord paralysis (UVCP) were studied. After LEMGs, the RLNs exploration operations were performed. The condition of RLNs injury and laryngeal muscles was observed and recorded during the operation.

RESULTSThe severe injuries of RLNs were found during operation. The types of injuries were listed as ligation (58 cases), adhesion (28 cases) and cut (61 cases). The waveform morphology of LEMG was recorded less in the patients with the RLNs cut than that in the patients with the RLN ligation or adhesion, respectively. 75.4% RLNs cut showed spontaneous waveform while 96.4% RLNs adhesion and 94.8% RLNs ligation. When the RLN was cut off, single pattern was showed oftener. When the RLN was adhered or ligated, mixed pattern was showed oftener. 92.9% RLN adhesion showed misdirect-regeneration-potentials while 70.7% RLN ligation and 24.6% RLN cut. There were significant difference between two types, but the compound muscular active potential (CMAP) amplitude wasn't significantly different. Evoked amplitude could be recorded in 91.4% patients with ligation and its amplitude was (23.6 +/- 8.1)%, in 85.7% patients with adhesion and its amplitude (16.3 +/- 5.2)%, in 29.5% patients with cut and its amplitude (2.6 +/- 4.2)%.

CONCLUSIONSThe display of different injuries of RLN in LEMG presents significant difference. If RLN was cut off, the CMAP might be recorded in most cases. The clinical injury of RLN often is followed by sub-clinic reinnervation.