High-resolution ultrasound visualization of the recurrent motor branch of the median nerve: normal and first pathological findings

Abstract

PurposeTo evaluate in a prospective study the possibility of visualization and diagnostic assessment of the recurrent motor branch (RMB) of the median nerve with high-resolution ultrasound (HRUS).Materials and methodsHRUS with high-frequency probes (18–22 MhZ) was used to locate the RMB in eight fresh cadaveric hands. To verify correct identification, ink-marking and consecutive dissection were performed. Measurement of the RMB maximum transverse-diameter, an evaluation of the origin from the median nerve and its course in relation to the transverse carpal ligament, was performed in both hands of ten healthy volunteers (n = 20). Cases referred for HRUS examinations for suspected RMB lesions were also assessed.ResultsThe RMB was clearly visible in all anatomical specimens and all volunteers. Dissection confirmed HRUS findings in all anatomical specimens. Mean RMB diameter in volunteers was 0.7 mm ± 0.1 (range, 0.6–1). The RMB originated from the radial aspect in 11 (55%), central aspect in eight (40%) and ulnar aspect in one (5%) hand. Nineteen (95%) extraligamentous courses and one (5%) subligamentous course were detected. Three patients with visible RMB abnormalities on HRUS were identified.ConclusionHRUS is able to reliably visualize the RMB, its variations and pathologies.Key Points• Ultrasound allows visualization of the recurrent motor branch of the median nerve.• Ultrasound may help clinicians to assess patients with recurrent motor branch pathologies.• Patient management may become more appropriate and targeted therapy could be improved.Electronic supplementary materialThe online version of this article (doi:10.1007/s00330-016-4671-1) contains supplementary material, which is available to authorized users.

Ultrasound-Guided Surgery for Carpal Tunnel Syndrome: A New Interventional Procedure

“…Several studies have recently demonstrated the interest of ultrasound-guided transection of the retinaculum. [2][3][4][5][6][7] This technique has the advantages of (1) great safety, due to continuous ultrasound monitoring and visualization of variants of the median nerve, [8][9][10] and (2) a decrease in size of the incision, enabling a more rapid return to work and a more aesthetic scar. 6,11 Percutaneous access by ultrasound-guided surgery (UCTR) is, at least, 10 times smaller than with classical surgical techniques.…”

“…Ultrasound assessment of a transligament pathway at risk of iatrogenic injury during transection of the retinaculum 15 is a clear advantage of UCTR. 9,10 The position of the vascular arch is located. Finally, location of a safe zone between the ulnar artery and the median nerve enables visualization of the virtual path of the surgical instruments.…”

Ultrasound Imaging of Disorders of Small Nerves of the Extremities: Less Recognized Locations

“…The small motor branch of the median nerve arises at the level of the carpal tunnel and provides innervation to the muscles of the thenar eminence. Its US appearance has been recently described . Due to its variable origin, the nerve can be injured during a carpal tunnel release.…”

“…Its US appearance has been recently described. [37][38][39] Due to its variable origin, the nerve can be injured during a carpal tunnel Figure 19. Complete section of the radial collateral nerve of the thumb after surgical treatment of trigger thumb syndrome.…”

Anatomic Variations of the Median Nerve Identified during Endoscopic Carpal Tunnel Release with STRATOS

“…Beyond cadaveric studies and operative validation of these variants, new technologies have helped clinicians and surgeons better visualize and characterize these anomalies with the use of high-resolution ultrasound, magnetic resonance imaging, and operative technologies. 3 , 4 An example of an operative technology improvement is the STRATOS endoscopic CTR system (STRATOS, A.M. Surgical, Smithtown, N.Y.). This system provides a clear cannula that aids with visualization of the entire carpal tunnel ( see figure, Supplemental Digital Content 1 , which displays the STRATOS ECTR system with clear cannula and independent blade, http://links.lww.com/PRSGO/A528 ).…”