A 9-year-old girl presented with gradually progressive weakness and wasting of the right hand, without pain, paresthesia, or numbness. There was no trauma, exposure to toxins, leprosy, or any relevant family history. On examination, there was weakness and wasting of the adductor and flexor pollicis and all the interossei muscles of the right hand. The abductor pollicis brevis and opponens pollicis were normal, as were the abductor, opponens, and flexor digiti minimi. The results of the rest of the neurologic and systemic examination were normal. Because the clinical findings involved lower motor neuron weakness restricted to the hand in the ulnar distribution, compression of the deep motor branch of the ulnar nerve was considered.
Jacob A, Moorthy TK, Thomas SV, Sarada C. Compression of the Deep Motor Branch of the Ulnar NerveAn Unusual Cause of Pure Motor Neuropathy and Hand Wasting. Arch Neurol. 2005;62(5):826. doi:10.1001/archneur.62.5.826