Why is the electromyogram in obstetric brachial plexus lesions overly optimistic?

✍ Scribed by J. Gert van Dijk; Martijn J.A. Malessy; Dick F. Stegeman

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 58 KB
• Volume: 21
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199802)21:2<260::aid-mus20>3.0.co;2-4

✦ Synopsis

Myositis occurs in a large and heterogenous group of disorders resulting from diverse pathogenesis. 2 Although the clinical manifestations and the distribution of the impaired skeletal muscles are highly variable, clinical features are rarely confined to the calf muscles in benign adultonset myositis. We report here a case of benign focal myositis with transient, painful swelling of the calves and fever.

A 55-year-old woman consulted a physician on April 26, 1995, with a complaint of sore throat and cough. Although cold medicine was prescribed, the symptoms persisted. About 6 weeks later, high fever and severe myalgia of the calf muscles developed. On admission to the hospital on June 7, 1995, the patient, despite having only mild muscle weakness, had difficulty in walking owing to swollen and painful calves. No other muscle groups were involved and results of a neurologic examination were otherwise normal. Laboratory findings included elevated serum creatine kinase, 793 U/L (normal 50-230 U/L); serum aldolase, 5.0 U/L (normal 0.5-3.1 U/L); erythrocyte sedimentation rate, 48 mm at 1 h; and C-reactive protein, 14.1 mg/dL. Various viral antibody titers, antilipid complement fixation titers of Mycoplasma pneumoniae, and markers of collagen diseases and malignancies in serum were not significantly increased. Computed tomography confirmed a swelling of the calf muscles bilaterally and normal thigh muscles. Electromyography revealed no obvious myopathic changes in either symptomatic or asymptomatic muscles. A biopsy of gastrocnemius muscle 10 days after the onset of severe myalgia revealed necrotic fibers with prominent phagocytosis (Fig. 1). Histochemical examinations did not reveal specific changes indicative of congenital myopathy, metabolic myopathy, or mitochondrial myopathy. The clinical symptoms and laboratory abnormalities resolved spontaneously within 3 weeks after the onset of myalgia.

Our patient had severe myalgia confined to the calves with pathologic findings of myositis. The spontaneous remission resembled that seen in benign acute childhood myositis. 1,3 Thus, this may be a unique case of benign adult-onset focal myositis confined to the calves.