الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Cervical MPS affecting the trapezius muscle is common contributing factor in neck pain. The trapezius muscle is innervated by SAN which has been reported to be entrapped by MTrPs. The trapezius itself has not been found to entrap the nerve and may be weakened by entrapment of SAN motor nerve fibers between taut bands of SCM. Electrodiagnosis is used to assess the SAN parameters as an extension to clinical examination. Needle EMG can reflect SAN entrapment neuropathy and identify the underlying disorder.
The aim of this study was to assess the SAN conduction in patients with cervical MPS.
The study included 25 patients fulfilling the criteria for the diagnosis of MPS (group I) and 20 healthy subjects (group II). Patients included 4 men and 21 women. Mean age was 37.76 ± 13.45 years. The right side was affected in 14 patients (56%) and the left side was affected in 11 patients (44%). Pain severity median was 5.
Clinical evaluation included thorough history taking and clinical examination stressing on SCM and trapezius muscles. Neurological examination was carried out. Electrophysiological evaluation included MNCS of the SAN (bilaterally) and nEMG of the trapezius muscle on the symptomatic side (at rest, during minimal volition, and during maximal volition). Needle EMG of the trapezius MTrPs had been performed. Sensory nerve conduction study of the sural nerve was performed to exclude peripheral neuropathy. Needle EMG of the deltoid, biceps and supraspinatus muscles was performed on the affected side to exclude C5 and C6 radiculopathy.
There was no statistical difference between groups I and II regarding age, sex and occupation. Electrodiagnosis revealed significantly prolonged latency of the SAN on the affected side in comparison to unaffected side (P=0.016) and control group (P=0.001). Amplitude of CMAP did not significantly differ between both groups. Individually; latency was prolonged in 7 patients (28%) and amplitude was reduced in one of them (4%). The nEMG of upper trapezius in patients group revealed abnormal neuropathic units and incomplete interference pattern in the patient who showed low CMAP amplitude. Abnormal rest potentials were absent in all Patients. Also, nEMG of The MTrPs were silent. Patients with abnormal EDX had more severe pain (range=5-10, median=10, mean=7.63±1.89) than those without. They represented 87% of patients who had tenderness over two MTrPs of the trapezius muscle.
This study concluded that SAN neuropathy is not uncommon among patients with MPS of trapezius muscle, and can contribute to increased pain severity and worsening of symptoms in MPS patients. Electrodiagnosis is a good modality for identifying subclinical SAN entrapment neuropathy in cervical MPS patients.