De Novo Footdrop Resulting From an Isolated Acute Repetitive Strain Injury

Abstract

To report a case of a teenage boy (N.K.) who had a peroneal nerve palsy after an isolated repetitive stain injury from an episode of sustained repetitive kicking and to explore the emergency physician's approach to footdrop or absent dorsiflexion. Chart review. N.K. presented to the emergency department (ED) with right footdrop, inability to dorsiflex. Results of investigations in the ED, including radiographs of his lumbar spine and knees and a magnetic resonance imaging scan of the lumbar spine, were all normal. Electromyography showed that the extensor digitorum brevis muscle was borderline prolonged at 4.1 m/s for 65 mm, whereas the distal latency of the tibial nerve to abductor hallucis muscle was prolonged at 4.8 milliseconds for 7 cm. There were increased insertional activity and 2+ fibrillation potentials in EDB, but motor units were normal, as was recruitment. There was no conduction velocity slowing across the fibular head segment of the peroneal nerve. N.K. did not need any further follow-up because his function was completely regained. Repetitive strain injury, even in acute settings may predispose one to developing a peroneal neuropathy. As in the case of N.K., most cases resolve in weeks to months, and electromyography studies are important to help definitively decide what type of neuronal injury has been sustained.