The superficial branch of the radial nerve and sensory disturbance in the radial forearm flap donor-site

Abstract

Introduction: Sensory disturbance due to injury of the superficial branch of the radial nerve (SBRN) is a donor-site morbidity of the radial forearm (RF) flap. The relationship between the SBRN preservation method and the post-operative sensation at the flap donor-site was retrospectively investigated.

Methods: We included 39 patients who underwent head and neck reconstruction with a free RF flap at Hyogo Cancer Center between April 2014 and March 2018. The patients were classified into the following three groups according to the SBRN preservation method: group 1, zero preservation, excision of the entire SBRN; group 2, main trunk preservation, excision of all branches except the main trunk of the SBRN; and group 3, complete preservation, preservation of the entire SBRN. Objective sensations and subjective symptoms at the flap donor-site were analyzed.

Results: The mean objective sensory scores were 3.18, 2.97, and 1.78 in groups 1, 2, and 3, respectively. Differences between groups 1 and 3 and between groups 2 and 3 were significant (p = 0.0035 and p = 0.037, respectively). The mean subjective symptom scores were 2.40, 1.33, and 1.40 in groups 1, 2, and 3, respectively. Differences between groups 1 and 2, and between groups 1 and 3 were significant (p = 0.032 and p = 0.019, respectively).

Conclusions: Zero preservation method had a higher risk of subjective symptoms and objective hypoesthesia development at the flap donor-site than the complete preservation method. Despite inevitable objective hypoesthesia, the main trunk preservation prevented the development of subjective symptoms. Complete preservation is optimal for RF flap harvest; however, in case of perforator crossing, main trunk preservation is another option.

Keywords: Donor-site; Radial forearm flap; Reconstructive surgery; Sensory disturbance; Superficial branch of the radial nerve.

Fig. 1

A "perforator crossing" case a) The main trunk (arrowhead) and branch (arrow) of the SBRN are observed during RF flap harvest. The dotted circle denotes the area of the perforator from the RA crossing the branch of the SBRN (perforator crossing). b) High-magnification view of the perforator crossing site. We are required to excise either the branch or the perforator. c) A scheme of the perforator crossing site. Abbreviations: APL, abductor pollicis longus; ECR, extensor carpi radialis; RA, radial artery; RF, radial forearm; SBRN, superficial branch of the radial nerve; -m, main trunk; and -b, branch.

Fig. 2

Objective sensory scores for points 1 to 4 a) The four examination points: point 1, interphalangeal joint; point 2, metacarpal phalangeal joint; point 3, carpometacarpal joint; and point 4, snuff box of the dorsal thumb. b) The objective sensory scores at point 1. The gray bars represent the affected side (A/S), and the gray dashed bars represent the unaffected side (uA/S). The scores for c) point 2, d) point 3, and e) point 4. The objective sensory scores display a similar tendency among the four points, despite some minor differences. ∗p < 0.05, ∗∗p < 0.005, and ∗∗∗p < 0.0005.

Fig. 3

Mean objective sensory scores The mean objective sensory scores (the average scores for points 1 to 4) of the three groups are denoted as gray bars on the affected side (A/S), and as gray dashed bars on the unaffected side (uA/S). For the A/S, a significant difference is evident between groups 1 and 3 and between groups 2 and 3 but not between groups 1 and 2. ∗p < 0.05, ∗∗p < 0.005, and ∗∗∗p < 0.0005.

Fig. 4

Subjective symptom scores ∗ p < 0.05, ∗∗p < 0.005.

Fig. 5

SBRN preservation strategy Abbreviations: SBRN, superficial branch of the radial nerve.