Segmental neurogenic muscle hypertrophy associated with radiation injury
Introduction
Segmental neurogenic muscle hypertrophy is an uncommon condition reported in association with a variety of denervating processes [1]. Various pathophysiological mechanisms have been postulated [2]. Focal grouped discharges or myokymia may occur in muscles after radiotherapy for malignancies, likely as a result of radiation-induced plexopathy or neuropathy [3], [4], [5]. For the first time, we describe a case of a 48-year old man showing trapezius muscle hypertrophy after radiotherapy for nasopharyngeal carcinoma. Electromyographic (EMG) sampling revealed continuous elctectromyographical myokymic-like discharges consistent with underlying radiation-induced neurogenic injury.
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Case report
A 48-year-old man complained of progressive muscular swelling of the left shoulder region for 1 month associated with twitching for a period of 9 months. He also noticed left shoulder weakness for the same period of time. There was no pain or sensory disturbance. He denied trauma or radicular symptoms in his left arm. There was no history of diabetes mellitus or surgery. There was no significant family history of similar conditions.
He had been diagnosed to have nasopharyngeal carcinoma at age
Discussion
The electrophysiological findings were inkeeping with previous radiation injury involving the left C2, C3, C4, accessory nerve and patchy lesions of nerves supplied by the brachial plexus. The lesion was likely to diffuse, with involvement of upper and lower plexus. This is inkeeping with previous reports on radiation-induced brachial plexopathy [6], [7], [8].
Most cases of neurogenic muscle hypertrophy involve the occurrence of continuous complex repetitive discharges or continuous muscle
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