Mackinac Island
2024
Jeffrey Strakowski
High Frequency Ultrasound Evaluation of Post-Surgical Median Recurrent Branch Neuropathy: A Case Report
The Ohio State University, Columbus, OH
CASE DESCRIPTION: A 69-year-old male presented with complaints of worsened left-hand cramping and weakness following carpal tunnel release 5 months previously. Physical examination demonstrated profound weakness of the left abductor pollicis brevis (APB). The sensory examination was unremarkable. There was a well-healed non-hypertrophic post-surgical scar and palpable tenderness at the proximal aspect of the thenar palmar crease. Repeat electrodiagnostic testing was performed and compared to pre-operative testing. The more recent evaluation showed substantial worsening of the median motor response with recording from the (APB), but relative sparing with recording from the first lumbrical, and no significant change of the median sensory studies.
ASSESSMENT AND RESULTS: High-frequency ultrasound showed focal fascicular enlargement of the radial aspect of the median nerve at and distal to the carpal tunnel outlet, with specific enlargement of the recurrent branch fascicles. There was also marked atrophy and hyperechoic signal change in the APB and opponens pollicis with essentially normal appearance of the first and second lumbricals, reflecting the relative degree of denervation from the injury to the recurrent branch fascicles.
DISCUSSION: High frequency ultrasound provided an excellent adjunctive anatomic assessment to the clinical and electrodiagnostic findings in this case. It provided specific detail of the nature and precise location of the neuropathy and the individual fascicles affected. The muscle echotexture assessment additionally provided further evidence for distinguishing the neuropathic influence of the compression of the main trunk of the median nerve and the injury to the specific fascicles on the radial aspect of the nerve at and distal to the carpal tunnel.
CONCLUSION: High frequency ultrasound can be used in conjunction with electrodiagnosis to add detailed anatomic information in post-surgical complications including conditions of partial fascicular injury. This information has potential to assist with clinical decision making and treatment options.