Hirayama Disease: A Rare Case Report and Review.

Hirayama disease, or brachial monomelic amyotrophy, is not a common neurological disease characterized by unilateral or asymmetric bilateral lower motor weakness of distal upper limbs. The basic pathophysiology is compression of the dural sac and spinal cord during flexion of the neck. A case of a 21-year-old male presented with chief complaints of tremors in both hands (right more than left) with gradually progressive weakness of the right hand and forearm. Electromyography (EMG), nerve conduction velocity (NCV), and magnetic resonance imaging (MRI) neck in flexion showed focal atrophy of lower cervical myotomes and confirmed the diagnosis of monomelic amyotrophy.