1541 - From weakness to muscle atrophy: Hirayama Disease Clinical Case Report

A 27-year-old male with no prior medical history developed progressive distal weakness and hand atrophy beginning at age 17, with functional limitation by age 19. Examination revealed atrophy of the intrinsic muscles of the right hand, sensory loss in the C5 dermatome. Cervical MRI in the neutral position demonstrated right hemicord atrophy with T2-STIR hyperintensity from C4–C7. Electrodiagnostic studies showed preserved sensory nerve conduction, but reduced amplitude and prolonged latency of the right ulnar motor response. Needle EMG revealed positive sharp waves, fibrillations, fasciculations and reduced recruitment patterns in the right abductor pollicis brevis, first dorsal interosseous, deltoid, thenar and hypothenar muscles. The patient underwent a multidisciplinary rehabilitation program, including electrical stimulation, strengthening exercises, stretching, isometric exercises and occupational therapy. After rehabilitation, partial improvement in muscle strength was observed, however, significant muscle atrophy and restricted range of motion persisted.

Discussions: This case highlights the classical clinical and paraclinical features of Hirayama Disease and the need to consider it in the differential diagnosis of asymmetric distal atrophy in young adults. Also, the role of rehabilitation in functional recovery, despite irreversible structural and electrophysiological deficits. Accurate recognition is crucial to avoid misdiagnosis such as ALS or radiculopathy.

Conclusions:

Hirayama disease should be suspected in young patients with distal hand atrophy. Early recognition, multidisciplinary management, and individualized rehabilitation strategies are key to preserving long-term function and quality of life.