479 - Unexplained Left Hand Weakness After Prolonged Loss of Consciousness

An 85-year-old male presented to an outpatient office for EMG evaluation of the left upper extremity. The patient had an unwitnessed fall with loss of consciousness and unknown downtime. Since then, he developed  generalized paresthesias and weakness of the left hand. Physical therapy offered minimal improvement. Manual muscle testing displayed profound weakness in the left hand, with intact strength in the right hand. Nerve conduction studies showed absent sensory and motor responses in the left median and ulnar nerves, with sensory response also absent in the left radial nerve. Electromyography of the left upper extremity showed fibrillations in the abductor pollicis brevis (APB) and the first dorsal interosseus (FDI), as well as polyphasic motor units throughout the muscles of the hand and forearm. Few motor units were seen in the APB and FDI. Interestingly, diffuse slowing was also present in the median and ulnar nerves in the right hand. 

Discussions:

Ischemic monomelic neuropathy is a rare complication of restricted blood flow to an area that leads to axonal damage in a distal to proximal gradient. Most commonly documented as a complication of vascular access surgery in hemodialysis patients, the prevalence in this population is still only about 0.5%. This patient did not have the classic presentation, but his history of a fall with unknown downtime provides a viable cause for the development of ischemia to the distal nerves. 

Conclusions:

Ischemic monomelic neuropathy is a less common cause of neuropathic symptoms in the general population, and comes with a guarded prognosis. Identifying symptoms early on in the process is key to improving function in these patients. Although uncommon, it’s important to consider this etiology of neuropathy given a relevant history or clinical picture.