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Case Reports
. 2023 Aug 16;15(8):e43601.
doi: 10.7759/cureus.43601. eCollection 2023 Aug.

The Isolated Motor Branch of the Ulnar Nerve Injury During Open Carpal Tunnel Release

Wuttipong Siriwittayakorn  1 , Warangkana Fongsri  2 , Kraisong Watatham  2 , Wattanai Atthakorn  1
Affiliations
Case Reports

The Isolated Motor Branch of the Ulnar Nerve Injury During Open Carpal Tunnel Release

Wuttipong Siriwittayakorn et al. Cureus. .

Abstract

A 76-year-old woman underwent open carpal tunnel release (OCTR). She had sudden sharp shooting pain in her hand, in the mid-palmar area, during the operation. She was then unable to abduct or adduct her thumb and fingers after surgery. She had no sensation impairment of the ulnar digit. The nerve conduction study confirmed a complete transection of the motor branch of the ulnar nerve (MUN). The MUN was repaired, and the patient recovered her intrinsic hand muscle function two years after the operation. The mechanism of injury, related anatomy and potentially dangerous area, clinical findings, management, and prevention are discussed.

Keywords: carpal tunnel syndrome; motor branch; open carpal tunnel release; ulnar nerve; ulnar nerve injury; ulnar nerve palsy.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Clinical pictures of the patient.
(A) The patient presented with intrinsic hand muscle atrophy one month after surgery. (B) Intraoperative findings revealed proximal and distal stumps of the nerve (indicated by black arrowhead) during microsurgical nerve repair. (C) Two years after the nerve repair, the contour of the first dorsal interosseous muscle and adductor pollicis muscle was observed. (D) The patient regained the ability to adduct her thumb and fingers again.
Figure 2
Figure 2. Anatomic relationship between MUN and its surrounding structures.
(A) The green pin indicates the center of the palpable surface of the hook of the hamate. The central axis of the ring finger is indicated by the white dashed line. The hook of the hamate situates along the axis of the ring finger. (B) The turning point of the MUN is located distal to the hook of the hamate, aligning with the axis of the ring finger. It is safer to operate along the vertical axis of the third web space (blue dashed line) as the MUN is covered by flexor tendons in this axis. (C) The turning point of the MUN lies just below the level of the TCL before coursing under the flexor tendons. TCL, transverse carpal ligament; MUN, motor branch of the ulnar nerve
See this image and copyright information in PMC

References

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