Muscle biopsy in the ‘floppy’ infant
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Introduction Although neuromuscular disease in infants is rare, it is not uncommon for these infants to come to the operating theatre for a muscle biopsy. Also, as these children get older, other surgical procedures (particularly orthopaedic procedures) are often indicated. Neuromuscular disease may present as ‘floppiness’ (hypotonia) in infancy. Hypotonia may result from a wide variety of neuromuscular diseases and occasionally from some non-neuromuscular disorders. Although diagnostic information may be gathered from the presenting signs, the physical exam, the family history, biochemical studies and electromyography (EMG), a muscle biopsy is often required for definitive diagnosis.
Case history JL, a 5-month-old boy presented for muscle biopsy because of a history of hypotonia. He had been born at 37 weeks’ gestation to a 32-year-old gravida 4, para 3 woman whose previous obstetric history included the delivery of a 30-week gestation baby which had exhibited decreased movement in utero, and had died shortly after birth from respiratory failure. Two other siblings, aged 6 and 10 years, were normal. JL appeared normal at birth, but from 3 months of age had exhibited progressive loss of head control, loss of the ability to elevate his trunk when placed in a prone position, and floppy extremities. He had no history of reflux or aspiration pneumonia. On physical examination, his weight was 5.2 kg, temperature 36.7 °C, BP 85/55 mmHg, HR 110, and RR 38. He smiled and interacted with the examiner. Respirations appeared relaxed, but he displayed some abdominal breathing. There was global hypotonia and some evidence of