Chaojun Zheng1, Yu Zhu2, Shuo Yang1, Feizhou Lu3, Xiang Jin1, Robert Weber2, Jianyuan Jiang4. 1. Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai 200040, China. 2. Department of Physical Medicine and Rehabilitation, Upstate Medical University, State University of New York at Syracuse, Syracuse, NY 10212, USA. 3. Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai 200040, China; Department of Orthopedics, The Fifth People's Hospital, Fudan University, Shanghai 200240, China. 4. Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai 200040, China. Electronic address: jianyuanjiang05@126.com.
Abstract
OBJECTIVE: The study aimed to analyse changes in the upper limb F-waves during neck flexion in patients with Hirayama disease (HD). MATERIAL AND METHODS: This study included 41 healthy subjects, 38 HD patients and 24 patients with amyotrophic lateral sclerosis (ALS). Bilateral F-waves were consecutively recorded 20 times with the neck both in the standard position and after persistent neck flexion for 30min. The persistence, minimal latencies, chronodispersion, F/M ratios and amplitudes of the F-waves and repeater F-waves were compared between the standard neck and neck flexion positions. RESULTS: During neck flexion, repeater F-waves were found in more HD patients, the percentage of both the ulnar and median repeater F-waves increased significantly, and higher F/M ratios were observed on the symptomatic side (P<0.05). No differences in the F-waves were observed in the healthy subjects or the ALS patients during neck flexion (P>0.05). DISCUSSION: HD might be more likely to present as a position-related dysfunction rather than a spinal cord-intrinsic disease. Thus, HD patients could be counselled to avoid neck flexion for long periods of time to prevent further damage, especially in the progressive stage of the disease.
OBJECTIVE: The study aimed to analyse changes in the upper limb F-waves during neck flexion in patients with Hirayama disease (HD). MATERIAL AND METHODS: This study included 41 healthy subjects, 38 HDpatients and 24 patients with amyotrophic lateral sclerosis (ALS). Bilateral F-waves were consecutively recorded 20 times with the neck both in the standard position and after persistent neck flexion for 30min. The persistence, minimal latencies, chronodispersion, F/M ratios and amplitudes of the F-waves and repeater F-waves were compared between the standard neck and neck flexion positions. RESULTS: During neck flexion, repeater F-waves were found in more HDpatients, the percentage of both the ulnar and median repeater F-waves increased significantly, and higher F/M ratios were observed on the symptomatic side (P<0.05). No differences in the F-waves were observed in the healthy subjects or the ALSpatients during neck flexion (P>0.05). DISCUSSION: HD might be more likely to present as a position-related dysfunction rather than a spinal cord-intrinsic disease. Thus, HDpatients could be counselled to avoid neck flexion for long periods of time to prevent further damage, especially in the progressive stage of the disease.