Jian Sun1, Sushan Luo1, Jie Song1, Jun Huang2, Shuang Cai1, Wenhua Zhu1, Lei Zhou1, Jianying Xi1, Jie Lin1, Jiahong Lu1, Minjie Xu3, Tonghai Dou3, Chongbo Zhao1,4, Kai Qiao2. 1. Department of Neurology, Huashan Hospital, Fudan University, Shanghai, China. 2. Department of Clinical Electrophysiology, Institute of Neurology, Huashan Hospital, Fudan University, Shanghai, China. 3. Key Laboratory of Contraceptives and Devices, Shanghai Institute of Planned Parenthood Research, Institute of Reproduction and Development, Fudan University, Shanghai, China; and. 4. Department of Neurology, Jing'an District Center Hospital of Shanghai, Shanghai, China.
Abstract
PURPOSE: Hereditary skeletal muscle channelopathies are characterized by muscle stiffness and/or periodic muscle weakness because of different gene mutations. The objective of this study was to investigate the clinical and electromyographic phenotypes in Chinese patients with different skeletal ion channel mutations. METHODS: The electromyographic results of 61 Chinese patients with skeletal muscle channelopathies were retrospectively reviewed and the differential features were characterized. RESULTS: Myotonic discharges were in patients with chloride voltage-gated channel 1 and sodium voltage-gated channel alpha subunit 4 mutations. Subclinical myotonia was identified in four patients with hypokalemic periodic paralysis because of sodium voltage-gated channel alpha subunit 4 mutations. Patients with potassium voltage-gated channel subfamily J member 2 mutations had an early decline after exercise (5.7 ± 4.9 minutes) and patients with calcium voltage-gated channel subunit alpha 1S mutations have a relatively lower baseline amplitude (4.6 ± 2 mV). Specific patterns were characterized in patients with Becker disease and paramyotonia congenital after short exercise. CONCLUSIONS: Myotonic discharges help to discriminate chloride and sodium from other channelopathies. Early decline and low baseline compound motor action potential amplitude in long exercise test are significant in patients with potassium voltage-gated channel subfamily J member 2 and calcium voltage-gated channel subunit alpha 1S mutations, respectively. Electromyographic patterns in the electromyography study and exercise test may help in better providing the comprehensive picture for patients with primary skeletal muscle channelopathies.
PURPOSE:Hereditary skeletal muscle channelopathies are characterized by muscle stiffness and/or periodic muscle weakness because of different gene mutations. The objective of this study was to investigate the clinical and electromyographic phenotypes in Chinese patients with different skeletal ion channel mutations. METHODS: The electromyographic results of 61 Chinese patients with skeletal muscle channelopathies were retrospectively reviewed and the differential features were characterized. RESULTS:Myotonic discharges were in patients with chloride voltage-gated channel 1 and sodium voltage-gated channel alpha subunit 4 mutations. Subclinical myotonia was identified in four patients with hypokalemic periodic paralysis because of sodium voltage-gated channel alpha subunit 4 mutations. Patients with potassium voltage-gated channel subfamily J member 2 mutations had an early decline after exercise (5.7 ± 4.9 minutes) and patients with calcium voltage-gated channel subunit alpha 1S mutations have a relatively lower baseline amplitude (4.6 ± 2 mV). Specific patterns were characterized in patients with Becker disease and paramyotonia congenital after short exercise. CONCLUSIONS:Myotonic discharges help to discriminate chloride and sodium from other channelopathies. Early decline and low baseline compound motor action potential amplitude in long exercise test are significant in patients with potassium voltage-gated channel subfamily J member 2 and calcium voltage-gated channel subunit alpha 1S mutations, respectively. Electromyographic patterns in the electromyography study and exercise test may help in better providing the comprehensive picture for patients with primary skeletal muscle channelopathies.