Bifid Median Nerve in Patients With Carpal Tunnel Syndrome

Objective. The aim of this study was to investigate the frequency of the anatomic variation of a bifid median nerve in patients with carpal tunnel syndrome (CTS) and to determine the size criteria for sonography. Methods. On axial sonograms of 320 hands of 170 patients with CTS and 240 hands of 120 unaffected individuals, the median nerve was evaluated morphologically for a bifid median nerve, and the cross‐sectional area was measured at 3 levels (radial‐ulnar junction, pisiform, and hook of the hamate). Electrophysiologic studies were performed in addition to clinical and sonographic evaluations in all patients, controls with a bifid median nerve, and controls with a cross‐sectional area of greater than 0.09 cm². Results. A bifid median nerve was seen in 32 (19%) of 170 patients and 11 (9%) of 120 controls. It occurred relatively frequently in patients with CTS (P < .01). The cross‐sectional area of the bifid median nerve was relatively higher than that of the nonbifid median nerve in controls at 2 of the 3 levels (P < .001; P = .226; P < .01). The cutoff values for the cross‐sectional area at the level of the pisiform were 0.11 cm² (sensitivity, 90%; specificity, 99%; P < .001) for patients with a bifid median nerve and 0.10 cm² (sensitivity, 98%; specificity, 81%; P < .001) for patients with a nonbifid median nerve. Conclusions. A bifid median nerve occurs relatively frequently in patients with CTS. It may facilitate compression of the median nerve in the carpal tunnel because of its relatively higher cross‐sectional area compared with a nonbifid median nerve. The size criterion for CTS in patients with a bifid median nerve is slightly higher than in those with a nonbifid median nerve.     

Transverse Ultrasound Assessment of Median Nerve Deformation and Displacement in the Human Carpal Tunnel during Wrist Movements

The symptoms of carpal tunnel syndrome, a compression neuropathy of the median nerve at the wrist, are aggravated by wrist motion, but the effect of these motions on median nerve motion are unknown. To better understand the biomechanics of the abnormal nerve, it is first necessary to understand normal nerve movement. The purpose of this study was to evaluate the deformation and displacement of the normal median nerve at the proximal carpal tunnel level on transverse ultrasound images during different wrist movements, to have a baseline for comparison with abnormal movements. Dynamic ultrasound images of both wrists of 10 asymptomatic volunteers were obtained during wrist maximal flexion, extension and ulnar deviation. To simplify the analysis, the initial and final shape and position of the median nerve were measured and analyzed. The circularity of the median nerve was significantly increased and the aspect ratio and perimeter were significantly decreased in the final image compared with the first image during wrist flexion with finger extension, wrist flexion with finger flexion and wrist ulnar deviation with finger extension (p < 0.01). There were significant differences in median nerve displacement vector between finger flexion, wrist flexion with finger extension and wrist ulnar deviation with finger extension (all p's < 0.001). The mean amplitudes of median nerve motion in wrist flexion with finger extension (2.36 ± 0.79 normalized units [NU]), wrist flexion with finger flexion (2.46 ± 0.84 NU) and wrist ulnar deviation with finger extension (2.86 ± 0.51 NU) were higher than those in finger flexion (0.82 ± 0.33 NU), wrist extension with finger extension (0.77 ± 0.46 NU) and wrist extension with finger flexion (0.81 ± 0.58 NU) (p < 0.0001). In the normal carpal tunnel, wrist flexion and ulnar deviation could induce significant transverse displacement and deformation of the median nerve.     

Comparison of Proximal and Distal Cross-Sectional Areas of the Median Nerve,Carpal Tunnel,and Nerve/Tunnel Index in Subjects With Carpal Tunnel Syndrome

Objectives

To provide a quantitative analysis of ultrasonographic measurements and possible pathophysiology of carpal tunnel syndrome by comparing cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index and the difference in ultrasonographic findings between affected and nonaffected hands and between sexes.

Design

Blinded comparison study.

Setting

Secondary referral and training hospital of institutional practice.

Participants

Patients (N=51; 42 women, 9 men) with suspected carpal tunnel syndrome who underwent sonography within 1 week after the electrodiagnostic study.

Interventions

Not applicable.

Main Outcome Measures

Electrodiagnostic and ultrasonographic studies were conducted on both upper extremities. Cross-sectional areas of the median nerve and carpal tunnel were measured at 2 separate levels; proximal and distal cross-sectional areas of the carpal tunnel were each measured at the scaphoid-pisiform and trapezium-hamate levels, respectively.

Results

Comparison between normative (n=24) and abnormal hands (n=78) revealed the following: the mean proximal cross-sectional areas of the median nerve, carpal tunnel, and nerve/tunnel index of electrodiagnostically normative hands were 10.941mm², 192.43mm², and 5.635%, respectively, whereas those of abnormal hands were 13.74mm², 208.87mm², and 6.693%, respectively, showing statistically significant differences for all (P<.05). Distal measurements of the cross-sectional area of the median nerve, carpal tunnel, and nerve/tunnel index were 10.088mm², 150.4mm², and 6.762%, respectively, in normative hands, and 11.178mm², 149.6mm², and 7.493%, respectively, in abnormal hands, showing no statistically significant differences (P>.05). In women, proximal cross-sectional areas of the median nerve and nerve/tunnel index of abnormal hands showed statistically significant differences, but no ultrasonographic measurement with a statistically significant difference was observed in men.

Conclusions

Compared with nonaffected hands, the proximal cross-sectional areas of the median nerve and carpal tunnel were greater, but the distal ultrasonographic measurements were not in affected hands. Ultrasonographic findings of carpal tunnel syndrome were different according to sex.     

Automated Segmentation of the Median Nerve in the Carpal Tunnel using U-Net

Nerve area and motion in carpal tunnel syndrome (CTS) are currently under investigation in terms of prognostic potential. Therefore, there is increasing interest in non-invasive measurement of the nerve using ultrasound. Manual segmentation is time consuming and subject to inter-rater variation, providing an opportunity for automation. Dynamic ultrasound images (n = 5560) of carpal tunnels from 99 clinically diagnosed CTS patients were used to train a U-Net-shaped neural network. The best results from the U-Net were achieved with a location primer as initial region of interest for the segmentations during finger flexion (Dice coefficient = 0.88). This is comparable to the manual Dice measure of 0.92 and higher than the resulting automated Dice measure of wrist flexion (0.81). Although there is a dependency on image quality, a trained U-Net can reliably be used in the assessment of ultrasound-acquired median nerve size and mobility, considerably decreasing manual effort.     

正中神经压迫试验对腕管综合征神经传导速度的影响

目的比较正中神经压迫试验对腕管综合征（carpal tunnel syndrome,CTS）患者正中神经传导速度的影响。方法设置CTS组和对照组两个组别,共29例受试者纳入研究。CTS组为14例CTS患者,对照组为15例健康受试者。神经传导速度测定包括正中神经和尺神经的感觉传导末端潜伏期（distal sensory latency,DSL）、感觉神经动作电位（sensory nerve action potential,SNAP）、跨腕关节感觉传导速度（sensory conduction velocity,SCV）、运动传导末端潜伏期（distal motor latency,DML）及复合肌肉动作电位（compound muscle action potential,CMAP）。先测感觉传导,再测运动传导。正中神经压迫试验5min后再次测量上述指标。结果正中神经压迫试验前后电生理检查考虑诊断CTS分别为22侧和24侧。压迫正中神经后,CTS组正中神经DSL较压迫前显著延长（P〈0.05）。CTS组尺神经和对照组正中神经及尺神经的各参数在压迫前后均无显著改变（P〉0.05）。与对照组相比,在压迫试验前后CTS组的正中神经DSL和DML均明显延长（P〈0.05）,尺神经DSL和DML均无显著改变（P〉0.05）。结论正中神经压迫试验5min能使CTS患者正中神经的感觉传导末端潜伏时明显延长,有助于提高神经传导测定对早期CTS的诊断率。     

Measurement of Median Nerve Strain and Applied Pressure for the Diagnosis of Carpal Tunnel Syndrome

The objective of this study was to evaluate the diagnostic utility of strain and applied-pressure measurements of the median nerve in carpal tunnel syndrome (CTS). Thirty-five wrists of 23 idiopathic CTS patients and 30 wrists of 15 normal patients were examined. Median nerve strain, pressure to the skin and the pressure/strain ratio were measured at the proximal carpal tunnel level. Parameters were compared between CTS patients and controls. The areas under the receiver operating characteristic curves (AUCs) were compared for the parameters. Median nerve strain was significantly lower in the patients than in the controls (p < 0.01). Pressure and pressure/strain ratio were significantly higher in the patients than in the controls (p < 0.05: pressure, p < 0.01: ratio). The AUCs were 0.926, 0.681 and 0.937 for strain, pressure and pressure/strain ratio, respectively. Pressure/strain ratio is useful for evaluating the condition of the median nerve with respect to the hardness of the surrounding structures in CTS.     

Predominant Patterns of Median Nerve Displacement and Deformation during Individual Finger Motion in Early Carpal Tunnel Syndrome

Idiopathic carpal tunnel syndrome (CTS) is a common neuropathy, yet the pathologic changes do not explain the fleeting dynamic symptoms. Dynamic nerve-tendon interaction may be a contributing factor. Based on dynamic ultrasonographic examination of the carpal tunnel, we quantified nerve-tendon movement in thumb, index finger and middle finger flexion in normal subjects and those with mild-idiopathic CTS. Predominant motion patterns were identified. The nerve consistently moves volar-ulnarly. In thumb and index finger flexion, the associated tendons move similarly, whereas the tendon moves dorsoradially in middle finger flexion. Nerve displacement and deformation increased from thumb to index finger to middle finger flexion. Predomination motion patterns may be applied in computational simulations to prescribe specific motions to the tendons and to observe resultant nerve pressures. By identification of the greatest pressure-inducing motions, CTS treatment may be better developed. Symptomatic subjects displayed reduced nerve movement and deformation relative to controls, elucidating the physiologic changes that occur during mild CTS.     

Nerve Echogenicity: Changes in High-Resolution Nerve Ultrasound in Carpal Tunnel Syndrome after Surgery

The aim of our prospective study was to detect changes in nerve echogenicity of the median nerve before and after successful surgery in patients with carpal tunnel syndrome (CTS) using high-resolution ultrasound. Fifteen patients with a definite diagnosis of CTS who underwent surgery were scanned by one examiner with high-resolution ultrasound, and images were analyzed by two blinded raters using ImageJ to assess the echogenicity of the median nerve (fraction of black) with a semiautomated thresholding technique before and 3 mo after surgery compared with 15 controls. In CTS patients, nerve echogenicity before surgery was significantly lower compared with that of controls (fraction of black: mean 63.9 vs. 44.6, p < 0.0001). Three months after surgery nerve echogenicity significantly increased (fraction of black was lower, mean 55.5; p < 0.0001) as a possible sign of reduction of intraneural edema, but did not reach the values of healthy controls. Semi-automated evaluation of the echogenicity of the median nerve may be used as a marker of successful carpal tunnel release. Further studies are warranted to detect how nerve echogenicity changes after unsuccessful carpal tunnel release.     

高频超声检查测量成人腕管段正中神经和部分肌腱的正常值及意义

目的 探讨高频超声检测正常成人腕管内正中神经、拇长屈肌腱、第2指深屈肌腱和第3指浅屈肌腱的检查方法、超声表现及宽度和厚度的正常值,为超声诊断腕管内正中神经及肌腱疾病提供对比依据.方法 100例正常成人分男女两组,各50例,分别用高频超声测量双侧腕管内正中神经、拇长屈肌腱、第2指深屈肌腱和第3指浅屈肌腱的宽度和厚度.结果 得出正常成人腕管内正中神经和部分肌腱宽度和厚度的正常值.测得的正中神经、拇长屈肌腱、第2指深屈肌腱和第3指浅屈肌腱的宽度和厚度,男女两组平均数之间比较有显著差异(P<0.05);男子组左腕与右腕之间比较无显著差异(P>0.05);女子组左腕与右腕之间比较无显著差异(P>0.05).结论 超声测得的拇长屈肌腱、第2指深屈肌腱和第3指浅屈肌腱宽度和厚度的正常值,可供超声诊断手腕部疾病及其疗效评价做参考.     

腕管综合征松解术的护理

目的探讨腕管综合征松解术的护理方法。方珐对i5例中晚期腕管综合征患者施行松解术,并采取针对性的护理措施,观察疗效,总结护理体会。结果本组15例患者手术后随访0．5～2．5年,术后恢复优良率为93％。结论针对患者的心理状况,做好细致的心理护理及完善术前准备,术后密切观察病情、预防切口感染、及时止痛、正确的功能锻炼、适当的出院指导,是保证手术效果,改善生活质量的重要措施。     

高频超声引导下针刀松解腕横韧带治疗腕管综合征的疗效及安全性观察

目的 观察高频超声引导下针刀松解腕横韧带治疗腕管综合征的疗效及安全性。方法 收集2015年10月 ~ 2018年5月在我科就诊的50例CTS患者,使用高频超声观察腕管内正中神经卡压情况并使用针刀松解腕横韧带。术后1周、4周、12周随访,评估并发症、复发率、手功能满意度(根据Michigan手功能问卷表评估),同时对3个月时的临床疗效结果进行评定。结果 术后未出现并发症,1例患者术后4周复发,1例术后12周复发。术后1周手功能满意度评分(21.88±2.54)分与术前(22.72±3.32)分无统计学差异,术后4周(19.08±3.07)分及12周(17.82±3.50)分与术前评分差异有统计学意义(P<0.05),且术后12周相比术后4周改善度更佳(P<0.05)。术后3月临床疗效评估优良率为86%。 结论 超声引导下针刀松解腕横韧带治疗CTS具有良好的安全性以及肯定的临床疗效,是一种值得推广的治疗手段。     

Ultrasound-Guided Carpal Tunnel Release Using Dynamic Expansion of the Transverse Safe Zone in a Patient With Postpolio Syndrome: A Case Report

The prevalence of carpal tunnel syndrome (CTS) in patients with postpolio syndrome occurs at a rate of 22%. Irrespective of those with CTS, 74% of postpolio patients weight bear through their arms for ambulation or transfers. As open carpal tunnel release is performed along the weight-bearing region of the wrist, their functional independence may be altered while recovering. This case demonstrates that ultrasound-guided carpal tunnel release was successfully performed in a patient with postpolio syndrome allowing him to immediately weight bear through his hands after the procedure so he could recover at home.