Cody S. Paul, DO
Physical Medicine and Rehabilitation Resident Physician
University of Toledo
Toledo, Ohio, United States
Ashley Schneider, MD
Physiatrist
University of Toledo
Toledo, Ohio, United States
62-year-old male with worsening right arm numbness, and cramping affecting his whole hand. Six months prior, he underwent open reduction and internal fixation (ORIF) for a right distal humeral fracture. He also noted chronic neck pain with radiation into bilateral arms, but no prior neck surgery. Sensory nerve action potentials (SNAPs) were not detected for the median and ulnar nerve of both the right upper extremity (RUE) and left upper extremity (LUE). Motor unit action potentials (MUAPs) in the LUE median and ulnar nerve had increased onset latency and significantly decreased amplitude. RUE ulnar and median MUAPs were not detected. Needle electromyography (EMG) demonstrated reduced recruitment in RUE biceps brachii, triceps brachii, pronator teres, first dorsal interosseous (FDI), and abductor pollicis brevis (APB); and LUE APB and FDI. Increased duration and polyphasic MUAPS were seen in the left FDI. Fibrillations and positive sharp waves were present in the right APB.
Discussions:
The patient had a known 6-year history of end-stage renal disease on hemodialysis, which likely contributed to his severe neuropathy, limiting EMG efficacy in identifying acute pathology in affected limbs. Significant atrophy of APB and FDI likely contributed to low MUAP amplitudes. While the patient was less likely to have an acute neurologic injury secondary to his distal humeral fracture, given findings of severe neuropathy in bilateral upper extremities (BUE), the study could not wholly exclude peripheral nerve entrapment due to the severity of his neuropathy and limited findings on nerve conduction study.
Conclusions:
EMG can be a helpful tool in assessing the nature and extent of neuropathic pathology. However, it can have limitations in evaluating for acute pathology in a patient with known chronic severe neuropathy.
