Nerve Conduction and F-wave Findings in Patients With Postoperative Numbness After Reverse Shoulder Arthroplasty: A...

Neurologic symptoms such as ulnar-sided numbness can occur after reverse shoulder arthroplasty (RSA), and the lesion level may not be uniform across patients. This case series aimed to describe postoperative numbness and electrophysiological findings, with an exploratory assessment of F-wave findings in addition to standard nerve conduction studies.

We retrospectively analyzed patients who underwent RSA and had both preoperative and postoperative nerve conduction studies. Postoperative numbness was assessed clinically at six weeks. Motor and sensory conduction studies (MCS/SCS) in the ulnar nerve distribution and F-wave parameters were evaluated. F-wave abnormality was defined as either 1) prolongation of the minimum F-wave latency with a pre-to-post change of ≥2.0 ms or 2) reduced F-wave persistence of 50% or less.

Thirteen patients were included. Postoperative numbness was observed in four patients (30.8%). Overall, five patients (38.5%) met the criteria for F-wave abnormality. F-wave abnormalities were observed in three of four patients with postoperative numbness and in two of nine patients without numbness. Two patients met electrodiagnostic criteria for cubital tunnel syndrome, and both had postoperative numbness. Additionally, two patients demonstrated isolated F-wave abnormalities with normal MCS/SCS, which may indicate electrophysiological changes not captured by conventional distal conduction studies alone.

In this case series of RSA patients, postoperative ulnar-sided numbness showed heterogeneous electrophysiological patterns. F-wave assessment, combined with MCS/SCS, may provide supplementary electrophysiological information in cases with normal distal conduction findings. Larger studies with longitudinal follow-up are warranted to clarify symptom-electrophysiology relationships and clinical implications.