Park Dougho, Kim Byung Hee, Lee Sang-Eok, Kim Dong Young, Eom Yoon Sik, Cho Jae Man, Yang Joong Won, Kim Mansu, Kwon Heum Dai
Department of Rehabilitation Medicine, Spine and Joint Center, Pohang Stroke and Spine Hospital, Pohang, Republic of Korea.
Department of Orthopedic Surgery, Spine and Joint Center, Pohang Stroke and Spine Hospital, Pohang, Republic of Korea.
J Pain Res. 2021 May 18;14:1259-1269. doi: 10.2147/JPR.S303142. eCollection 2021.
A bifid median nerve (BMN) is not a rare variant. This study aimed to investigate the features of carpal tunnel syndrome (CTS) accompanied by BMN.
In this retrospective study, we defined a BMN group as CTS with BMN and a non-bifid median nerve (NMN) group as CTS without BMN. All hands were assigned to four severity grades according to the findings of electrodiagnosis (EDx): very mild, mild, moderate, and severe. The cross-sectional area (CSA) of the median nerve, palmar bowing of the flexor retinaculum, and persistent median artery (PMA) were assessed by ultrasonography. Numerical pain rating scale (NRS) and symptom duration were assessed as clinical variables.
Sixty-four hands (57 patients) and 442 hands (341 patients) were enrolled in the BMN and the NMN groups, respectively. BMN was prevalent in 12.6% of all CTS hands. The distribution of EDx severity grade was milder in the BMN group than in the NMN group (<0.001). The CSA of the BMN group was 16.2±4.1 mm, slightly larger than 15.1±4.2 mm in the NMN group (=0.056). The BMN group showed higher NRS than the NMN group (5.5±1.5 and 4.4±1.7, respectively; <0.001). In the subgroup analysis, NRS was significantly higher in the BMN group than in the NMN group at all EDx severity grades. In the BMN group, the PMA group showed greater EDx severity (=0.037) and higher NRS (6.0 and 5.0, respectively; =0.012) than the non-PMA group. The radial side branch's CSA was larger than that of the ulnar side branch (10.0 mm and 6.0 mm, respectively; 0.001).
CTS with BMN presented more severe symptoms and relatively milder EDx severity. When assessing the severity of CTS with BMN, the clinical symptoms should primarily be considered, as well as we should complementarily evaluate the EDx and ultrasonography.
正中神经分支（BMN）并非罕见变异。本研究旨在探讨伴有BMN的腕管综合征（CTS）的特征。
在这项回顾性研究中，我们将BMN组定义为伴有BMN的CTS，将非分支正中神经（NMN）组定义为不伴有BMN的CTS。根据电诊断（EDx）结果，将所有手部病例分为四个严重程度等级：极轻度、轻度、中度和重度。通过超声评估正中神经的横截面积（CSA）、屈肌支持带的掌侧弯曲以及正中动脉永存（PMA）情况。将数字疼痛评分量表（NRS）和症状持续时间作为临床变量进行评估。
BMN组纳入64只手（57例患者），NMN组纳入442只手（341例患者）。BMN在所有CTS手中的发生率为12.6%。BMN组的EDx严重程度分级分布比NMN组更轻（<0.001）。BMN组的CSA为16.2±4.1mm，略大于NMN组的15.1±4.2mm（P = 0.056）。BMN组的NRS高于NMN组（分别为5.5±1.5和4.4±1.7；<0.001）。在亚组分析中，在所有EDx严重程度等级下，BMN组的NRS均显著高于NMN组。在BMN组中，PMA组的EDx严重程度更高（P = 0.037），NRS也更高（分别为6.0和5.0；P = 0.012），高于非PMA组。桡侧分支的CSA大于尺侧分支（分别为10.0mm和6.0mm；P<0.001）。
伴有BMN的CTS症状更严重，而EDx严重程度相对较轻。在评估伴有BMN的CTS严重程度时，应首先考虑临床症状，同时还应补充评估EDx和超声检查结果。
