Hirayama disease is a rare neuromuscular disorder with peak age of onset at 15 to 17 years among young males. We report a male adolescent presenting with symmetric weakness and atrophy of bilateral upper extremities progressing for 2 years before stabilizing. Otherwise, he did not complain of any sensory disturbance. Electrophysiological findings revealed motor neuron damage at the C7-T1 spinal segments. Cervical magnetic resonance imaging revealed a high-signal mass of posterior dural sac at the C5-T5 vertebral level during neck flexion. Specifically, he had elevated serum total immunoglobulin E level, which had been postulated to be a precipitating factor in Hirayama disease. Early recognition and intervention of this unique neuromuscular disorder is important to avoid ongoing damage to motor neurons. Through this report, we would like to emphasize the crucial role of a pediatric neurologist in averting the progression of Hirayama disease at an early stage.