Disclosures: Swaramsi Katragadda, MD: No financial relationships or conflicts of interest

Case Diagnosis: Partial Median Neuropathy

Case Description: A 33-year-old female presented with persistent pain and numbness affecting the volar aspect of thumb. She had a motor vehicle accident 5 months prior, and she underwent open reduction and internal fixation for a distal radial fracture with carpal tunnel release (CTR). She experienced partial relief of pain and numbness following the CTR, but the thumb symptoms persisted. An electrodiagnostic study showed a very prolonged median motor latency with small amplitudes. The median sensory studies demonstrated a normal recording from digit II and a minimally prolonged but significantly lower amplitude response from digit 1. She was referred for an ultrasound evaluation for clarification of the unusual findings.

Setting: Outpatient ClinicAssessment/

Results: Ultrasound demonstrated a mildly enlarged median nerve cross-sectional area of 15mm2 at the carpal tunnel inlet and normal cross-sectional area of 7-8mm2 throughout the remainder of the forearm. There was mild overlying scarring, but no significant compressive notching. There was notable isolated enlargement of selective radial-sided fascicles of the nerve. The abnormalities of these fascicles were further illuminated with the use of ultra-high-frequency ultrasound and were followed to confirm their destinations as the proper palmar digital branches to the thumb and the recurrent motor branch. The more distal aspects of those branches were normal.

Discussion: Selective fascicle injuries of this nature can create confusion for reliable identification and localization with electrophysiologic techniques alone. Ultrasound provided valuable anatomic information concerning both the structure of the nerve and relative influence of the surrounding tissue. The electrophysiologic techniques provided useful physiologic information.

Conclusion: This case emphasizes the utility of ultra-high frequency ultrasound for assessment of complex peripheral nerve injuries with selective fascicular injury. The clinical complaints and the electrodiagnostic findings correlated precisely with the visualization of the fascicular topography with ultrasound, and accurate identification of the injury led to appropriate management.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/direct-visualization-of-focal-fascicular-injury-in-the-median-nerve-via-ultra-high-frequency-ultrasound-with-correlated-electrodiagnostic-findings-a-case-report/