Prevalence of Bifid Median Nerve and the Cross-Sectional Area as Assessed by Ultrasonography in Healthy Japanese Subjects

Abstract

Purpose: Ultrasonography is useful for evaluating anatomical variations of the median nerve and aids in diagnosing carpal tunnel syndrome by assessing the cross-sectional area (CSA) at the carpal tunnel inlet. The purposes of this study were to investigate the prevalence of the bifid median nerve and to establish reference values for the CSA at the carpal tunnel inlet in healthy participants. Methods: A total of 349 Japanese participants were included (121 men and 228 women, mean age 66.3 years). Study participants underwent ultrasonography to assess the CSA of the median nerve at the carpal tunnel inlet of the bilateral wrist. First, we investigated the prevalence of the bifid median nerve in 349 participants. Then, we assessed the relation between the CSA and clinical factors (age, height, weight, body mass index, fat mass, fat-free mass, bilateral grip strength, and key pinch strength) in healthy participants. Results: Among the 349 participants, 59 (16.9%) had a bifid median nerve. Mean CSA in healthy participants (no bifid median nerve) was 9.7 ± 2.9 mm 2 in women and 9.0 ± 1.8 mm 2 in men (both: 9.4 ± 2.6 mm 2). In women, mean CSA in subjects in their sixties was significantly higher than in younger subjects, and we found a significant positive correlation between the CSA and the fat-free mass. Conclusions: In this observational study of healthy Japanese, the prevalence of the bifid median nerve was 16.9%; the mean CSA was 9.7 ± 2.9 mm 2 in women and 9.0 ± 1.8 mm 2 in men. Older women had a larger CSA than did younger women. Clinical relevance: This study describes the prevalence of the bifid median nerve and normative values for the CSA of the median nerve precisely diagnose carpal tunnel syndrome to more by ultrasonography.

Evaluation of the Effect of Age on Median Nerve Cross-sectional Area: A Cross-sectional Study

“…Data from 196 hands of 46 men and 52 women (a total of 98) were analyzed. The mean age of subjects was In a study on 349 Japanese participants, there was a significant difference in CSA between women in their sixties and those who were younger (P = 0.02) [29]. In their study, Alsop Loh et al found that aging increases MNCSA [30].…”

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

“…The second screening was conducted as the full‐text manuscript was sorted. In total, 29 studies were included (Lanz, 1977; Tountas et al, 1987; Amadio, 1988; Iannicelli et al, 2000; Propeck et al, 2000; Gassner et al, 2002; Lindley & Kleinert, 2003; Bayrak et al, 2008; Szopinski & Mazurczak‐Pluta, 2009; Pierre‐Jerome et al, 2010; Granata et al, 2011; Klauser et al, 2011; Mhoon et al, 2012; Walker et al, 2013; Agarwal et al, 2014; Beary et al, 2014; Duymuş et al, 2014; Kasius et al, 2014; Sripathi, Sripathi et al, 2016; Billakota & Hobson‐Webb, 2017; Cartwright et al, 2017; Chen et al, 2017; Kalathummarath, 2017; Petrover et al, 2017; Trachani et al, 2018; Shinagawa et al, 2019; Haris et al, 2021; Park et al, 2021; Dag et al, 2022). These studies were divided into two groups: (a) seven cross‐sectional studies with matching normal or healthy controls, in which the pooled odds ratio and mean difference in CSA were computed (five studies); and (b) 24 cross‐sectional studies without matching control or CTS subjects, in which only the pooled prevalence was computed. The pooled odds ratio of BMN between CTS and normal or control population: 248 BMNs were reported from 2186 CTS wrists, and 100 were reported from 1311 normal (control) wrists.…”

Nerve Imaging in the Wrist

“…Some studies showed an increased prevalence of a bifid median nerve in patients with CTS compared with volunteers; other studies showed a similar prevalence. 14,15 The prevalence of a bifid median nerve in these studies ranges from 10% to 20%. A persistent median artery is a common vascular variant occurring in 10 to 15% of the population.…”