Disclosures: Laura M. Mattson, DO: No financial relationships or conflicts of interest

Case Description: The patient presented with 2 months of insidious onset, slowly progressive ascending lower extremity numbness and a decline in athletic performance. One month later, he endorsed new onset L’Hermitte’s phenomenon and an aching, band-like sensation in the lower trunk. He denied gait imbalance, neck or leg pain, bowel or bladder changes, recent trauma, upper extremity symptoms, or family history of neurologic disease. Exam revealed normal muscle bulk and full strength throughout the upper and lower extremities. Vibration sense was impaired in a length-dependent fashion in the lower extremities and normal in the upper extremities. There was diffuse hyperreflexia, with 5 beats of ankle clonus bilaterally, but negative Hoffmann’s.

Setting: Tertiary care teaching hospital

Patient: 21-year-old healthy male rower Assessment/

Results: Electrodiagnostic study of bilateral lower extremities was normal. MRI of the cervical spine revealed focal myelomalacia at C5-6, however on flexion views there was marked engorgement of the posterior epidural space, suggestive of Hirayama disease.

Discussion: Hirayama disease is a rare, self-limited disease which classically manifests as insidious onset, asymmetric forearm and hand weakness (C7-T1 myotomes) in young males. Pathogenesis relates to forward displacement of the posterior dural sac during neck flexion, leading to anterior cord compression and focal lower cervical myelopathy. Lower motor neuron signs, such as atrophy and fasciculations, are common, whereas sensory disturbances and upper motor neuron signs are rarely described. This case exemplifies a predominantly upper motor neuron pathologic presentation that clinically spares the upper extremities. We speculate that repetitive neck flexion from routine rowing may have contributed to pathogenesis.

Conclusion: Hirayama disease may present atypically with myelopathic signs and symptoms. To our knowledge, this is the first report of Hirayama disease presenting without upper limb symptoms. Flexion MRI of the cervical spine may be considered in evaluation of patients with signs of myelopathy and appropriate predisposing factors.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/hirayama-disease-an-atypical-presentation-with-lower-limb-myelopathic-findings-only/