Electrophysiologic Evidence of Spinal Accessory Neuropathy in Patients With Cervical Myofascial Pain Syndrome

• Published in: Archives of physical medicine and rehabilitation Vol. 92; no. 6; pp. 935 - 940
• Main Authors: Chang, Chein-Wei, Chang, Kai-Yin, Chen, Yu-Ren, Kuo, Po-Ling
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.06.2011; Elsevier
• Subjects: Accessory nerve; Accessory Nerve - physiopathology; Accessory Nerve Diseases - complications; Accessory Nerve Diseases - physiopathology; Adult; Biological and medical sciences; Chi-Square Distribution; Diseases of striated muscles. Neuromuscular diseases; Diseases of the osteoarticular system; Electrodiagnosis. Electric activity recording; Electromyography; Electrophysiology; Female; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Myofascial pain syndromes; Myofascial Pain Syndromes - complications; Myofascial Pain Syndromes - physiopathology; Nervous system; Neurology; Physical Medicine and Rehabilitation; Prospective Studies; Rehabilitation; NCV; CMAP; Electrophysiology; Myofascial pain syndromes; Accessory nerve; MCD; MUAP; MFPS; Electromyography; Rehabilitation; EMG; SFEMG; NCS; mean consecutive difference; motor unit action potential; nerve conduction study; single-fiber electromyography; electromyogram; nerve conduction velocity; compound muscle action potential; myofascial pain syndrome; Human; Nervous system diseases; Spine; Myalgia; Neuropathy; Electrodiagnosis; Striated muscle disease; Pain; Reeducation; Orthopedics
• ISSN: 0003-9993; 1532-821X; 1532-821X
• DOI: 10.1016/j.apmr.2011.01.010

Chang C-W, Chang K-Y, Chen Y-R, Kuo P-L. Electrophysiologic evidence of spinal accessory neuropathy in patients with cervical myofascial pain syndrome. To evaluate whether or not spinal accessory neuropathy exists in patients with cervical myofascial pain syndrome (MFPS). Prospective study. A neurophysiologic laboratory in a university hospital. Patients with cervical MFPS (n=25) and healthy controls (n=20). Not applicable. We performed nerve conduction studies (NCSs) in bilateral spinal accessory nerves, and electromyography and stimulated single-fiber electromyography in the trapezius muscles of all patients and controls. Parameters including nerve conduction velocities (NCVs), amplitudes and areas of compound muscle action potentials (CMAPs), and mean consecutive differences (MCDs) in single-fiber electromyography were measured, analyzed, and compared with the disease durations of the patients. Spinal accessory NCSs showed normative NCVs but with prominently reduced CMAP amplitude in the patients with cervical MFPS, which is recognized as an axonal neuropathy of the spinal accessory nerves. Electromyography showed prominent evidence of denervation and reinnervation patterns in 48% of the MFPS patients. The abnormal MCDs in single-fiber electromyography indicated a synaptic delay of motor endplates in the motor units, and may signify evolving instability of neuromuscular transmission in the spinal accessory nerves innervating trapezius muscles of the patients. This study demonstrates electrophysiologic evidence of neuroaxonal degeneration and neuromuscular transmission disorder in a significant proportion of patients with cervical MFPS. We suggest that spinal accessory neuropathy may be associated with cervical MFPS.