Surgical Management of Hirayama Disease: A Rare Entity with Unusual Clinical Features

Hirayama disease (HD) is a rare type of cervical myelopathy in young males due to neck flexion causing cervical cord atrophy and asymmetric flattening with preferential involvement of anterior horn cells of the spinal cord. This is due to forward displacement of the cord during neck flexion getting compressed between the posterior part of the vertebral body and the posterior dura. The spinal cord involvement occurs due to repeated flexion and extension motion of the neck leading to selective spinal cells injury and atrophy. Most cases report an asymmetric lower motor neuron type of weakness predominantly involving the forearm and hand muscles. We report here a case of HD in an 18-year-old male who presented to us with weakness and wasting in the right hand. The patient was progressively symptomatic over a period of 1 year before presentation. The etiology and the exact cause of HD largely remain debatable and rely on the understanding of few theories which have been put forward. The natural history of this disease reaches a plateau in terms of neurological involvement after 2-5 years and is considered a self-remitting disorder. The patient was initially managed with a cervical collar immobilization but symptoms were largely not improving which was attributed to poor brace compliance. The patient was then managed surgically with a posterior lateral mass instrumentation without fusion in a lordotic alignment at the levels of maximal dural shift anteriorly. The patient improved neurologically following the surgery and maintained the intact status at the last follow-up.