Characteristics of Hirayama Disease in Young South Korean Soldiers

Background and Purpose The purpose of this study was to describe the clinical presentation and features in electrodiagnostic and imaging investigations of young South Korean males diagnosed with Hirayama disease (HD). Methods We reviewed the electronic medical records of South Korean enlisted soldiers who were diagnosed with HD and discharged from military service during 2011-2021. We investigated the clinical characteristics and results of electrodiagnostic and magnetic resonance imaging (MRI) investigations. We analyzed laterality and identified the involved muscles using needle electromyography (EMG). Loss of lordosis, localized cervical cord atrophy, loss of attachment between the posterior dura and subjacent lamina, asymmetric flattening of the cord, crescent-shaped mass in the posterior epidural space, and noncompressive intramedullary T2weighted high signal intensity were investigated using neutral- or flexion-position MRI. Results Forty-two male patients aged 20.2 +/- 0.8 years (mean +/- standard deviation) were identified. All patients complained of hand weakness, and 10 complained of hand tremor (23.8%). Four patients (9.5%) had symptoms in both upper limbs, and five (11.9%) had sensory disturbances. Needle EMG revealed that muscles in the C7-T1 myotome were commonly involved, and C5-C6 involvement of the deltoid (10.5%) and biceps brachii (12.5%) was also observed. In cervical MRI, localized cord atrophy (90.0%) was the most characteristic finding, and cord atrophy was most severe at the C5-C6 level (58.3%). Conclusions This is the first description of a large number of patients with HD in South Korea. The clinical presentation and features found in electrodiagnostic and imaging investigations will improve the understanding of HD in the young South Korean male population.