Anatomic variations of the median nerve in carpal tunnel release

Carpal tunnel syndrome (CTS) is a well-known clinical entity. Release of the transverse carpal ligament is considered to be the treatment of choice. Both open and endoscopic release of the transverse carpal ligament in CTS has yielded satisfactory results. Although these procedures are very common in surgical practice, inadequate release and intraoperative damage to neural elements are very frustrating complication for both the patient and the surgeon. The purpose of this study was to demonstrate incidental intraoperative findings of variations of the standard median nerve anatomy. We obtained incidental intraoperative identification of median nerve variations in 110 consecutive patients operated with open release of the transverse carpal ligament in CTS. Using the Amadio classification, we found intraoperatively variations of median nerve at the wrist in 11 patients. In three patients, there was an aberrant sensory branch arising from the ulnar side of the median nerve and piercing the ulnar margin of the transverse carpal ligament. Neural variations arising from the ulnar aspect of the median nerve were common and could be a cause of iatrogenic injury during endoscopic or open release. Surgeons should be aware of anomalous branches, which should be recognized and separately decompressed if needed.     

腕管内容物测量在临床中的应用

目的观测腕管内容物并描述其相互间关系,为临床手外科学和显微外科学中的应用提供参考。方法采用游标卡尺对22具本成人尸体（男16具,女6具）,44侧标本成人尸体标本腕管内容物测量,腕管解剖学观察、腕管内容物、腕横韧带的厚度测量等。结果腕管为纤维性骨管,略呈扁圆柱形,男性：狭窄部内外径（25．0±2．6）mm,前后径（10．2±1．1）mm;女性：狭窄部内外径（17．0±2．5）mm,前后（10．4±1．5）mm。腕横韧带男性：长（25．5±4．7）mm,宽（22．1±2．2）mm,厚2．3mm,下界距腕远纹（28．4±2．6）mm;女性：长（22．7±3．3）mm,宽（20．1±2．5）mm,厚3．1mm,下界距腕远纹（27．5±2．1）mm。腕管的断面,男性第1断面：（189．7±17．5）mm2,第2断面：（182．1±13．7）mm2,第3断面：（223．4±29．8）mm2;女性第1断面：（172．4±15．2）mm2,第2断面：（153．1±17．3）mm2,第3断面：（178．1±11．6）mm2。结论男性腕管宽短,女性腕管狭长,腕横韧带上半部薄,下半部厚,坚韧而缺乏弹性,女性腕管比男性狭窄,可能是好发疾病的原因之一。     

微移技术在腕管综合征中的应用价值

目的：探讨微移技术（inching）在腕管综合征（CTS）中的应用价值。方法：对符合临床诊断标准的41例CTS患者和32例正常对照者,均进行微移技术、常规法及比较法的神经传导检测,比较三者对诊断CTS的敏感性及特异性。结果：微移技术检测显示CTS组在腕下2cm至腕下3cm节段的正中神经潜伏期差值显著长于对照组,并且检测的敏感性最高（92．7％）,明显高于常规法及比较法（除外正中／尺神经环指－腕末端感觉潜伏期差）,阳性预测值及阴性预测值均大于90％,具有较高的诊断价值。结论：微移技术检测是一个敏感、安全、简便、实用的方法,对CTS的诊断、定位及治疗方式的选择均有重要意义。     

The influence of wrist posture,grip type,and grip force on median nerve shape and cross‐sectional area

During grasping, the median nerve undergoes mechanical stress in the carpal tunnel which may contribute to carpal tunnel syndrome. This study investigated the effects of wrist posture, grip type, and grip force on the shape and cross‐sectional area of the median nerve. Ultrasound examination was used to obtain cross‐sectional images of the dominant wrist of 16 healthy subjects (8 male) at the proximal carpal tunnel during grasping. The cross‐sectional area, circularity, and axis lengths of the median nerve were assessed in 27 different conditions (3 postures × 3 grip types × 3 force levels). There were no significant changes in median nerve cross‐sectional area (P > 0.05). There were significant interactions across posture, grip type, and grip force affecting nerve circularity and axis lengths. When the wrist was flexed, increasing grip force caused the median nerve to shorten in the mediolateral direction and lengthen in the anteroposterior direction (P < 0.04), becoming more circular. These effects were significant during four finger pinch grip and chuck grip (P < 0.05) but not key grip (P > 0.07). With the wrist extended, the nerve became more flattened (less circular) as grip force increased during four finger pinch grip and chuck grip (P < 0.04) but not key grip (P > 0.3). Circularity was lower during the four finger pinch compared to chuck or key grip (P < 0.03). The findings suggest that grip type and wrist posture significantly alter the shape of the median nerve. Clin. Anat. 30:470–478, 2017. © 2017 Wiley Periodicals, Inc.     

正中神经掌皮支形态特点及其临床意义

目的：为腕掌部手术避免损伤掌皮支提供解剖学基础。方法：在双目放大镜下对５０侧成人上肢正中神经掌皮支的来源、走行及分支进行解剖和观测。结果：５０侧均存在掌皮支，距离“Ｏ”点即远侧腕横纹４６．０ｍｍ处自正中神经桡侧发出，穿出前臂筋膜处距Ｏ点１９．６ｍｍ；穿出掌腱膜处距Ｏ点８．３ｍｍ。掌皮支长４８．５ｍｍ，起点宽１．２ｍｍ，距舟骨结节垂直距离８．２ｍｍ。掌皮支有３个分支的２８侧（５６．０％）；只有外侧支和中间支的１１侧（２２．０％）；只有内侧支和外侧支的４侧（８．０％）；只有外侧支的４侧（８．０％）；只有中间支的３侧（６．０％）。结论：掌皮支的来源、行程较恒定。腕掌部手术应尽量靠近尺侧，采取纵行切口，免伤掌皮支。     

正中神经前臂段运动传导与腕管综合征严重程度的相关性研究

目的：探讨正中神经前臂段运动传导（fMCV）与腕管综合征（CTS）疾病严重程度的相关性,并初步探讨其发生机制。方法：以符合纳入标准的CTS患者66例（126只患手）为病例组,年龄、性别匹配的96例健康志愿者的非利手为对照组,均行神经电生理检测。采用正中神经末端运动潜伏期（DML）和复合肌肉动作电位（CMAP）作为CTS严重程度指标,并研究其与fMCV的相关性。结果：①尺神经：病例组与对照组的各电生理参数间比较差异均无显著意义（t检验,P〉0．05）;②正中神经：在病例组（n=126）和对照组（n=96）,DML（ms）分别为5．0±1．3、3．0±0．3,腕-掌段正中神经运动传导速度（m／s）分别为22．2±7．3、56．9±8．3,fMCV（m／s）分别为53．7±5．5、59．2±3．6,拇短展肌CMAP波幅（mV）分别为7．3±2．9、10．1±1．9。以上所有参数的值均经t检验,P〈0．05,差异有显著意义;③相关性：在病例组,fMCV与DML呈负相关（r=-0．35,P〈0．05）,与拇短展肌CMAP呈正相关（r=0．18,P〈0．05）。结论：fMCV的异常与CTS患者的严重程度相关,且正中神经逆行性变为其可能的发生机制。     

Novel surgical approach to the carpal tunnel: cadaveric feasibility study

Carpal tunnel syndrome is the most common entrapment neuropathy dealt with by the clinician. Multiple techniques have been used to surgically treat this pathological condition and all of these approach the carpal tunnel from the palmar surface of the hand or wrist. We have developed a novel endoscopic approach to the carpal tunnel utilizing a dorsal approach that necessitates a good appreciation of the anatomy of this region. This approach was carried out in 10 hands. Through a single dorsal incision we were able to transect the flexor retinaculum in all specimens without obvious damage to neural or vascular tissues. The microscissors used in our study were found to be too delicate for transection of the flexor retinaculum thus another cutting tool should be considered. Our dorsal approach with visualization of the internal aspect of the flexor retinaculum may obviate many of the complications that are seen with the current techniques used to surgically treat carpal tunnel syndrome such as injury to the median nerve and its branches. Clinical trials are now necessary with prospective randomized studies that will determine which techniques are most efficacious and minimize complications most effectively.     

Transverse carpal muscle in association with carpal tunnel syndrome: report of three cases

Anomalous muscles of the upper extremity are common, however, symptomatic anomalies causing CTS are rare. Three cases of CTS that are believed to be caused by an anomalous muscle located palmar to the transverse carpal ligament with transversely oriented muscle bundles is presented. Despite the arguments in literature, this is certainly an anomalous muscle that can be encountered during carpal tunnel release and be problematic to manipulate when minimally invasive approaches are chosen.     

Gliding characteristics of flexor tendon and tenosynovium in carpal tunnel syndrome: a pilot study

The characteristic pathological finding in carpal tunnel syndrome (CTS) is noninflammatory fibrosis of the synovium. How this fibrosis might affect tendon function, if at all, is unknown. The subsynovial connective tissue (SSCT) lies between the flexor tendons and the visceral synovium (VS) of the ulnar tenosynovial bursa. Fibrosis of the SSCT may well affect its gliding characteristics. To investigate this possibility, the relative motion of the flexor tendon and VS was observed during finger flexion in patients undergoing carpal tunnel surgery, and for comparison in hands without CTS, in an in vitro cadaver model. We used a camera to document the gliding motion of the middle finger flexor digitorum superficialis (FDS III) tendon and SSCT in three patients with CTS during carpal tunnel release and compared this with simulated active flexion in three cadavers with no antemortem history of CTS. The data were digitized with the use of Analyze Software (Biomedical Imaging Resource, Mayo Clinic, Rochester, MN). In the CTS patients, the SSCT moved en bloc with the tendon, whereas, in the controls the SSCT moved smoothly and separately from the tendon. The ratio of VS to tendon motion was higher for the patients than in the cadaver controls. These findings suggest that in patients with CTS the synovial fibrosis has altered the gliding characteristics of the SSCT. The alterations in the gliding characteristics of the SSCT may affect the ability of the tendons in the carpal tunnel to glide independently from each other, or from the nearby median nerve. These abnormal tendon mechanics may play a role in the etiology of CTS.     

Palmaris profundus: One name,several subtypes,and a shared potential for nerve compression

The palmaris profundus is a rare, but known anatomic variation which may lead to compression of the median nerve and/or its branches. Two patients with carpal tunnel syndrome are presented in whom a palmaris profundus was discovered at operation. In these cases, median nerve compression at the wrist was attributed to the course of the extra tendon and its local mass effect on the nerve (i.e., the palmaris profundus and median nerve shared a common sheath); more commonly, the resultant decreased available space for the median nerve within the carpal tunnel due to the presence of an accessory (10th) flexor tendon is thought to be responsible. Postoperative 3 Tesla magnetic resonance imaging (MRI) was performed to demonstrate the full course of the variant muscle; despite variations in the size and longitudinal extent of the accessory musculotendinous unit, an important similarity was noted: the intimate relationship of the median nerve and the palmaris profundus. These two cases and our review of the literature highlight the fact that one name (i.e. palmaris profundus) reflects several anatomic subtypes. However, the close relationship of the palmaris profundus with the median nerve in the forearm and the palm is a common theme which emphasizes the potential pathoanatomic consequences of this relationship: nerve compression. Clin. Anat. 22:643–648, 2009. © 2009 Wiley‐Liss, Inc.     

掌到腕正中神经感觉传导速度在轻、中度腕管综合征诊断中的应用

目的：寻找诊断轻、中度腕管综合征（CTS）敏感的电生理检查方法。方法：对临床症状、体征符合CTS，电生理学检查为轻、中度的CTS患者24例（41手）和年龄、性别相匹配的健康对照组14例（28手），采用顺向性感觉神经传导速度（SCV）测定法分别测定指3-腕、指3-掌、掌-腕正中神经（MN）SCV及MN远端潜伏期（DML）。（重症CTS者因易于诊断，不列入本研究。）结果：掌到腕MN SCV％47．12m／s，考虑诊断CTS。在所有诊断轻、中度CTS的研究组中，指3到腕MNSCV减慢的占63％，掌到腕MNSCV减慢的占95％，指3到掌MNSCV减慢的占10％。结论：用指3刺激，腕记录和指3刺激，掌记录（掌至腕测量距离为7～8cm）来分别检测并计算出指3到掌和掌到腕段的SCV，在诊断轻度、中度CTS方面是一个非常敏感的方法，在怀疑CTS时此诊断方法可作为常规的电生理检查。     

Density mapping of nerve endings in the skin of the palm and flexor retinaculum of the hand. Application to open carpal tunnel release

In order to re‐evaluate the safest area to incise skin and the flexor retinaculum (FR) when performing a carpal tunnel release (CTR), we carried out a mapping study of the nerve endings in the skin and FR on cadaver specimens, which, unlike previous studies for the first time, includes histomorphometry and image digital analysis. After dividing the skin and FR into 20 and 12 sections, respectively, we carried out a histomorphological analysis of nerve endings. The analysis was performed by two neutral observers on 4‐μm histological sections stained with hematoxylin–eosin (H‐E), and Klüver–Barrera with picrosirius red (KB + PR) methods. A semi‐automatic image digital analysis was also used to estimate the percentage of area occupied per nerve. We observed a lower quantity of nerve endings in the skin of the palm of the hand in line with the ulnar aspect of the 4th finger. The ulnar aspect of the FR was the most densely innervated. However, there are no statistically significant differences between sections in the percentage of area occupied per nerve both in the skin and in the FR. We concluded that there is not a safe area to incise when performing carpal tunnel surgery, but taking into account the quantity of nerve endings present in skin and FR, we recommend an incision on the axis of the ulnar aspect of 4th finger when incising skin and on the middle third of the FR for CTR.     

神经根型颈椎病和腕管综合征的神经肌电图诊断与鉴别诊断

目的：探讨神经肌电图检查在神经根型颈椎病和腕管综合征中诊断及鉴别诊断的意义。方法：对临床上诊为神经根型颈椎病和腕管综合征的病例142例进行神经肌电图检查。结果：56例临床诊为神经根型颈椎病病例的肌电图中24例（43％）符合神经根型颈椎病,10例（18％）符合腕管综合征。86例临床诊为腕管综合征的患者,其中,42例（49％）符合腕管综合征,10例（12％）符合神经根型颈椎病。两组共有15例（11％）符合神经根性颈椎病合并腕管综合征。神经根型颈椎病神经原性损害主要在C6,C7水平。腕管综合征主要表现正中神经受损,其神经原性损害主要在C8水平（拇短展肌）。结论：神经肌电图检测对神经根型颈椎病和腕管综合征的诊断及鉴别诊断有重要价值。     

正常人腕管内正中神经的超声解剖学研究及其意义

目的：探讨腕管内正中神经的超声解剖测量方法及各项指标,为临床提供正常解剖参数。方法应用高频超声检查60侧正常人腕管段正中神经,分别测量其腕管入口、中点和出口平面的横截面积,腕管中点平面正中神经的扁平率和屈肌支持带的厚度。应用超声剪切波弹性成像技术测量30侧腕管内正中神经近1/3段、中1/3段、远1/3段的硬度值。结果腕管入口、中点、出口平面正中神经截面积分别为（0.09±0.02）、（0.08±0.02）、（0.10±0.03）cm2,不同部位截面积均值无统计学差异(P<0.01);腕管中点平面正中神经的扁平率3.12±0.29;屈肌支持带厚度为（0.33±0.07）cm。正中神经腕管近段、中段、远段最高硬度的分别为（41.3±10.3）、（35.4±5.8）、（38.1±4.3）kPa,不同部位硬度均值无统计学差异(P>0.05)。结论高频超声检查为临床提供了腕管内正中神经形态学解剖参数,剪切波弹性成像提供了神经硬度参数。两者结合应用为腕管综合征的临床诊断提供超声解剖学依据。     

Persistent median artery: cadaveric study and review of the literature

The persistent median artery (PMA) may compress the median nerve (MN) and may be a significant supply of blood to the hand. Two cases of unilateral PMA (4%) were detected during the dissection of 50 upper limbs. The first case was a 75-year-old, right-handed male who suffered from chronic pain in both upper limbs, especially the left side. A dissection of his left upper limb revealed a PMA piercing both the MN and the medial branch of the anterior interosseous nerve. This artery coursed distally, deep to the transverse carpal ligament (TCL), forming a median-ulnar pattern for the superficial palmar arch (SPA). The PMA was superficial to two nerves at the distal edge of the TCL; the extraligamentous recurrent thenar (RT) branch of the MN and the third common digital nerve (TCDN). The second case was from the left side of an 80-year-old female found to have a high origin of the radial artery with trifurcation of the latter into PMA, common interosseous, and ulnar arteries. The PMA passed deep to the TCL forming a radial-median-ulnar pattern of SPA. Both the transligamentous RT branch of the MN and the TCDN passed deep to the PMA inside the carpal tunnel, before the abnormal crossing of the latter nerve ventral to the SPA on its way to the digits. The relationships of the PMA to various MN branches may have important implications regarding the diagnosis and treatment of MN compressive neuropathies.     

正中和尺掌-腕混合神经潜伏期差在腕管综合征诊断中的应用

目的:评估正中和尺掌-腕混合神经潜伏期差在腕管综合征(CTS)诊断中的应用价值。方法:选取2019年1月至2019年12月在常熟市中医院门诊诊断为CTS的患者47例(77只手掌)作为研究组,同时收集同时段在体检中心健康检查的志愿者46名(69只手掌)作为对照组,分别记录正中神经腕-拇短展肌的远端运动潜伏期(DML)、腕-中指的感觉神经传导速度(SCV)、感觉神经动作电位(SNAP)波幅及正中和尺掌-腕混合神经潜伏期差(ΔDSL)。结果:研究组与对照组比较,腕-拇短展肌DML延长[(4.49±0.97)ms比(3.16±0.42)ms],腕-中指SCV减慢[(42.62±7.35)m/s比(60.65±6.70)m/s],SNAP波幅下降[(11.89±8.05)μV比(22.07±7.22)μV],正中和尺掌-腕混合神经ΔDSL延长[(0.84±0.34)ms比(0.23±0.10)ms],差异均具有统计学意义(P<0.05)。腕-拇短展肌DML、腕-中指SCV、正中和尺掌-腕混合神经ΔDSL诊断特异度分别为97.1%、100%、98.6%(P>0.05),诊断敏感度分别为66.2%、59.2%、90.1%(P<0.05)。结论:正中和尺掌-腕混合神经ΔDSL用于诊断CTS是比较敏感的,尤其可以提高早期CTS的阳性检出率。     

正中神经在肘部和肘上部受压综合征的有关解剖结构

在40具成人尸体的80侧上肢中观测了正中神经在肘部和肘上部的受压因素。肘上部臂筋膜和肘部肱二头肌筋膜的增厚和紧张、异常的腱性结构、Struthers 韧带等,均可造成正中神经受压。本文并利用700侧成人干燥肱骨,统计和观察了肱骨髁上突的出现率和形态。     

Anatomic variations of the median nerve within the carpal tunnel

Two hundred seventy-five consecutive carpal tunnel releases were reviewed to identify anomalies of median nerve anatomy. High division of the median nerve was observed in nine cases; in two of these the nerve divided proximally and then rejoined distally as a “closed loop.” In 42 cases the motor branch passed through the flexor retinaculum. Multiple motor branches were present in 13 cases. The palmar cutaneous branch passed through the flexor retinaculum in seven cases. In three cases, the distal communicating sensory ramus between the medial and ulnar nerves arose proximal to the superficial arch. Median nerve anomalies within the region of the carpal tunnel are common. Knowledge of such anomalies is important to avoid iatrogenic injury.     

High prevalence of carpal tunnel syndrome in children with mucopolysaccharidosis type II (Hunter syndrome)

Although carpal tunnel syndrome (CTS) is the most common compressive neuropathy seen in the upper extremity of adults, it is rarely seen in children. Several reports have shown that mucopolysaccharidosis type II (Hunter syndrome), a rare genetic disorder, is one of the causes of CTS in children. Usual symptoms of CTS are pain, weakness, and paresthesias in the hand and digits. However, the diagnosis of CTS in Hunter syndrome is often delayed or unrecognized because of atypical symptoms and cognitive impairment. Here, we report the prevalence, clinical manifestation, and nerve conduction profiles of CTS in 45 Hunter syndrome patients. The mean age of the study participants was 117.1 (74.9) months (range: 4-408 months); all patients were male. Forty-three (96.0%) of the 45 patients with Hunter syndrome had CTS. Bilateral CTS was observed in all patients; 73 (82.0%) of the patients' hands had severe degree of CTS. Intriguingly, in contrast with other nerve velocities, decreases in forearm conduction velocities of the median nerve were observed in 28 (31.5%) of 89 hands with CTS. There was a significant difference in age (P < 0.001) between hands with normal, mild, moderate, and severe grades of CTS. The compound muscle action potential and sensory nerve action potential amplitudes of the median nerves decreased with age (CMAP, r = -0.526, P < 0.001; SNAP, r = -0.564, P < 0.001). Early recognition and intervention to ameliorate the symptoms of CTS are important in improving the quality of life of Hunter syndrome patients.