Bifid median nerve as an anatomical risk factor for carpal tunnel syndrome: A meta‐analysis

Abstract

As the median nerve enters the carpal tunnel, it is a single nerve that soon bifurcates into lateral and medial branches into the hand. If the bifurcation is proximal to the carpel tunnel, a bifid median nerve (BMN) results. Carpal tunnel syndrome is often associated with a BMN with or without a persistent median artery. Individual keywords and MeSH phrases were searched in the Google Scholar, SCOPUS, and PubMed databases. Full texts were then collected and assessed for suitability. The prevalence of BMN at the wrist joint in normal and carpal tunnel syndrome wrists (precanal part) and the mean difference between groups were recorded. Only human data were used to test the findings. The pooled odds ratio (with minimal heterogeneity) was 1.50 [1.17–1.93, 95% CI]. The BMN cross‐sectional area (CSA) was significantly greater than that of a solitary median nerve in normal wrists. The mean difference in CSA between the two was 1.50 mm2 [0.56–2.45 mm2, 95% CI] without heterogeneity (i2 = 0). Sex and laterality distributions scarcely differed between the two types of wrists. Owing to the insufficiency of data, the relationships with mean height and weight were not examined. There was a 50% greater incidence of bifid median nerves in carpal tunnel syndrome patients than in normal subjects. A bifid median nerve increases the mean CSA at the wrist joint by 1.5 mm2. These findings indicate that the bifid median nerve is an anatomical risk factor for carpal tunnel syndrome.

At-Risk Median Motor Branch to the Thenar Musculature Crossing Under the Flexor Carpi Radialis in the Forearm

“…A natomic variations of the median nerve at the wrist are well-documented in the literature 2,[4][5][6][7][8][9][10] . This frequently includes MMB to TM variants, which are most often referenced with respect to the carpal tunnel.…”

“…Henry et al conducted a meta-analysis of 3,918 cases to characterize the prevalence of different median nerve variants 9 . However, they focused strictly on branching in relation to the carpal tunnel, without considering the risk associated with an FCR approach 5 . For this reason and because a carpal tunnel release was not performed in the current case, it is difficult to classify our case for the currently available classification schemes.…”

“…Subsequently, there have been many other unique variants described, but they each have varying degrees of clinical relevance [5][6][7][8][9][10] . In the case of transligamentous MMB to TM, the clinical relevance relates to the potential for injury during carpal tunnel release.…”

Pilot Cadaveric Study of Anatomical Variations of the Median Nerve at the Wrist in the Lithuanian Population

“…The importance of anatomical knowledge of CT is important, and its variations have been described in various studies [ 6 , 14 , 18 , 19 ]. Lanz extended the classification of Poisel and added more detailed anatomical features.…”

“…Not only the results of Lanz group 4A were different compared to other literature. The general incidence of a high division of the MN described in the literature is between 1% and 3.3% [ 19 ]. Asghar et al published in 2022 that the incidence of a high division of the MN in the Bulgarian population was 0.02% [ 19 ].…”