Evaluation of the surgical efficacy of the anterior cervical fusion and internal fixation for Hirayama disease using electrophysiological techniques

English Keywords:Electrophysiological examination  Hirayama disease  Anterior cervical fusion and internal fixation

English Abstract:

  【Abstract】 Objectives: To evaluate the neurological function of patients with Hirayama disease before and after anterior cervical fusion and internal fixation surgery using nerve conduction study and electromyography (EMG), in order to investigate the effects of surgical intervention on the recovery of neurological function in such patients. Methods: This study enrolled 43 patients with Hirayama disease who underwent anterior cervical fusion and internal fixation in the Department of Orthopedics of Huashan Hospital from January 2016 to July 2017(41 males and 2 females, averaged 18.2±2.8 years old, ranging from 14 to 26 years. The average course of disease was 22.3±20.1 months, ranging from 6 to 84 months. The average follow-up duration was 7.2±4.4 months, ranging from 3 to 18 months). All patients underwent nerve conduction examination and electromyography of the upper limbs before operation and during follow-up, and completed DASH scale at the same time. Bilateral electrophysiological results before and after operation were compared separately. In addition, paired-sample t test was used to compare CMAP amplitude; Pearson chi-square test was used to compare the muscle spontaneous potential, motor potential morphology and, muscle recruitment. DASH score before and after operation was also compared using paired-sample t test. Results: The amplitude of median nerve and ulnar nerve in severe side was significantly lower than that in the other side before operation(P<0.05). Bilateral neurogenic damage could be detected in more than half of the patients in electromyography. The results of nerve conduction examination showed that the mean CMAP amplitude of the median nerve in severe side was 9.79±4.63mV before operation and 11.04±4.43mV after operation, with the difference being statistically significant(P<0.05). The mean CMAP amplitude of the ulnar nerve in severe side was 4.04±3.25mV before operation and 6.19±4.30mV after operation, with the difference being statistically significant(P<0.001). The CMAP amplitude of the medial nerve and ulnar nerve of the mild side was also increased, but the difference was not statistically significant. The results of needle electromyography showed that the decrease of the proportion of spontaneous potential and prolonged MUAP duration in the severe side of the patients was not statistically significant(P>0.05); muscle recruitment in some of the muscles were significantly improved. Among them, 42 patients had decreased muscle recruitment in flexor carpi radialis(42/43, 97.7%) before operation, while only 32 patients had decreased muscle recruitment in the same muscle(32/38, 84.2%), and the difference was statistically significant(P<0.05). The DASH score showed that the average preoperative DASH score was 7.04±7.63, and postoperative one was 6.89±7.47. The difference was not statistically significant(P>0.05). Conclusions: The CMAP amplitude of the upper limbs increased and the muscle recruitment improved in patients with Hirayama disease after anterior cervical fusion and internal fixation. This procedure has a positive effect on controlling the progression of the disease and improving the nerve function.