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Rehabilitation Practice and Science

Translated Title

左側橈神經病變合併廣泛性正相尖波：肌電圖疾病

Abstract

Positive sharp waves (PSW) and fibrillations are frequently seen together in a variety of neuromuscular diseases and share the same clinical significance. However, PSW alone are also reported to occur in myotonic disorders, periodic hypokalemic paralysis, and local muscle trauma.Our patient, a 32-year-old man, fractured his left humerus in a traffic accident 3 weeks prior to presentation. He was referred to our electrodiagnostic laboratory due to left wrist and hand drop. On physical examination, he was found to have grade 0 muscle power in his left wrist and finger extensors. There was numbness over the dorsal aspect of the first web of the left hand, and second and third fingers. He had no history of myotonic disorder or clinical evidence of myotonia. No metabolic abnormalities were found. Routine nerve conduction studies of the left upper limb were normal except for a small amplitude of SNAP of left radial superflcial sensory nerve. Needle EMG studies of the left brachioradialis, extensor carpi radialis, and extensor digitorum communis muscles showed massive PSW and fibrillation potential without volitional motor unit potential. However, the other limb muscles, including the right upper limb and bilateral lower limbs, all had diffuse PSW without fibrillation, as well as normal morphology of motor unit potential and full maximal recruitment. The final electrophysiological diagnosis of this patient was a severe left radial nerve lesion at arm level below the branch to triceps associated with “EMG disease”. The patient was considered to have EMG disease because the isolated PSW was not clinically significant. This type of PSW is most likely caused by a needle piercing an unstable muscle cell membrane. This had been reported in an autosomal dominant manner. It is important for clinic physicians to interpret PSW and fibrillation correctly so as to avoid erroneous diagnoses.

Language

Traditional Chinese

First Page

209

Last Page

213

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