Bilateral symmetrically symptomatic cervical Hirayama disease diagnosed with dynamic magnetic resonance imaging

Background: Hirayama disease is a rare, self-limiting cervical myelopathy characterized by juvenile-onset distal upper-limb unilateral or asymmetrical weakness and wasting. Bilateral and nearly symmetrical involvement is rare and may mimic motor neuron disease. The diagnosis is typically established based on dynamic flexion magnetic resonance imaging (MRI). Case Description: A 23-year-old male presented with a 6-year history of progressive distal upper-limb weakness and atrophy that initially involved the right side and later the left. On examination, he demonstrated bilateral distal upper extremity muscle wasting with preservation of brachioradialis muscle bulk (oblique amyotrophy). Electromyography revealed chronic C7–T1 denervation with preserved sensory potentials. Neutral cervical MRI demonstrated lower cervical cord atrophy, while dynamic flexion MRI showed posterior cervical cord compression with a crescent-shaped enhancing posterior epidural space and multiple flow voids, consistent with Hirayama disease. The patient underwent posterior cervical stabilization using transfacetal cortical screw fixation, resulting in arrest of disease progression and functional improvement. Conclusion: Bilateral Hirayama disease is rare and may mimic motor neuron disease. Dynamic flexion MRI is essential for accurate diagnosis. Posterior cervical stabilization is an effective treatment in progressive cases.