Evaluation of bifid median nerve with sonography and MR imaging.

Bifid median nerve is an anatomic variation that may be associated with carpal tunnel syndrome. It is important for the surgeon to be aware of the existence of this condition preoperatively in order to plan the carpal tunnel release. We report the correlation between ultrasonographic findings and magnetic resonance imaging results in six patients with bifid median nerve, selected from a population of 294 patients with carpal tunnel syndrome, who were studied by ultrasonography using a high frequency transducer. Sonography showed two structures inside the carpal tunnel with the same pattern as the median nerve in all six patients. Magnetic resonance imaging confirmed the sonographic findings. The patients underwent open surgery, and a bifid median nerve was found. In conclusion, bifid median nerve is an anatomic variant that can be demonstrated ultrasonographically. It is important to be aware of this anomaly when planning carpal tunnel release surgery.     

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.     

Sonographic diagnosis of anatomical variations associated with carpal tunnel syndrome

Bifid median nerve is an anatomic variation that occurs in about 18% of patients with symptoms suggestive of carpal tunnel syndrome and in about 15% of symptom‐free subjects. Reversed palmaris longus is a rare anatomic muscular variation. The simultaneous presence of a bifid median nerve and a reversed palmaris longus has been very rarely described, usually during surgical exploration or in cadavers. We present two cases where ultrasound showed the presence of both abnormalities, allowing a correct diagnosis and influencing the treatment plan. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound 42 :371–374, 2014     

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.     

高频超声在腕管综合征病因学评价中的应用

目的探讨高频超声在评价腕管综合征病因中的作用。 方法选取2015年3月至2019年12月在解放军总医院经电生理检查诊断或手术证实腕管综合征的患者,首先对腕管进行灰阶超声检查,观察腕管内正中神经的位置、走向,神经受压情况、神经束结构、神经外膜回声以及神经周围结构的异常,横切面扫查腕管及正中神经时观察正中神经横截面情况、测量豌豆骨平面正中神经的横截面积以及观察神经周围结构的异常;应用能量多普勒超声以观察正中神经及腕管内其他结构的血流情况。采用独立样本t检验比较患侧腕和无症状侧腕豌豆骨平面正中神经横截面面积的差异。利用受试者操作特征（ROC）曲线分析豌豆骨平面正中神经的横截面面积的诊断价值并找出最佳的诊断界值。 结果腕管综合征患者63例,共95侧腕。腕管综合征患者高频超声表现为腕管内正中神经的卡压近端肿胀、增粗,神经束结构模糊,神经外膜增厚。能量多普勒超声显示正中神经内血流信号增加。患侧腕与无症状侧腕的豌豆骨平面正中神经横截面面积比较［（15.91±5.95）mm² vs（8.71±1.62）mm²］,差异具有统计学意义（t=-2.51,P＜0.001）,ROC曲线下面积为0.946,截断值为10.5 mm2时,敏感度为89.5%,特异度为83.9%。高频超声诊断为特发性腕管综合征者73侧腕（76.8%,73/95）,可明确诊断病因的共22侧腕（23.2%,22/95）,其中13侧腕（13.7%,13/95）为腕管内屈肌腱腱鞘炎,1侧腕（1.1%,1/95）为腕管内屈肌腱腱鞘积液,2侧腕（2.1%,2/95）为腕管内腱鞘囊肿,1侧腕（1.1%,1/95）为腕管内实性肿块,2侧腕（2.1%,2/95）为腕管内指浅屈肌肌腹过低,2侧腕（2.1%,2/95）为正中神经高位分叉伴永存正中动脉,1侧腕（1.1%,1/95）为桡骨远端术后瘢痕压迫正中神经。 结论高频超声可作为评估腕管综合征病因的一种手段。     

In-continuity neuroma of the median nerve after surgical release for carpal tunnel syndrome: case report

Iatrogenic injuries of the median nerve after surgical release for carpal tunnel syndrome resulting in the formation of a neuroma are rare. We present here the case of two patients, one with a bifid median nerve, showing in-continuity neuroma after surgical release for carpal tunnel syndrome. The patients reported persistent post-operative pain and showing symptoms. In both cases, ultrasound showed an in-continuity neuroma with a hypoechoic and enlarged median nerve at the carpal tunnel. The case report shows that ultrasound may be helpful in confirming the clinical diagnosis of neuroma and it is useful for evaluation of the percentage of the area affected by the tear.     

腕管综合征46例临床与神经电生理分析

目的：探讨腕管综合征的临床特点和神经电生理检测的诊断价值。方法：回顾性分析46例腕管综合征的临床特征和神经电生理检测结果。结果：46例腕管综合征中76．1％为女性，共有病变71侧，单侧病变21例，双侧病变25例。以桡侧3个半手指为主29侧，5个手指均有症状42侧。临床表现为手指麻木、疼痛，可向肘部和肩部放射。电生理检查正中感觉神经传导速度异常占95．8％，正中运动神经潜伏期延长占67．6％，运动传导速度异常53．5％，拇展短肌呈神经源性损害占31％。结论：腕管综合征以中年女性多见，临床上以手指麻木、疼痛为主要特点，活动和甩手可使症状减轻。神经电生理检测对腕管综合征的诊断与鉴别诊断具有重要价值。     

Idiopathic Carpal Tunnel Syndrome: Evaluation of the Depth of the Carpal Tunnel by Ultrasonography

The objective of the work described here was to evaluate the depth of the carpal tunnel (DCT) in patients with idiopathic carpal tunnel syndrome (CTS) and healthy volunteers by ultrasonography (US), through measurement of the distance from the flexor retinaculum to the surface of the capitate bone at the carpal tunnel outlet, and compare it with other ultrasonographic and electrophysiologic parameters in CTS. The study was conducted in 60 non-diabetic patients with idiopathic carpal tunnel syndrome (unilateral n = 37, bilateral n = 23) evidenced by electrophysiologic diagnosis according to the criteria of the American Association of Electrodiagnostic Medicine (AAEM). Furthermore, 40 hands from 20 healthy volunteers were examined. Median nerve cross-sectional area (CSA); flattening ratio (FR), the ratio of the length to the width of the median nerve; and DCT at the canal outlet were measured for all participants. The mean age was 35.6 ± 9.48 y. The female-to-male ratio was 47:13 in the CTS patients. The sensitivity and specificity were 82% and 95% for CSA, 75% and 60% for FR and 75% and 87.5% for DCT, respectively. Differences between patients and healthy controls were significant for all three parameters, greatest for DCT, followed by CSA and then FR. We conclude that DCT increased in CTS and this new parameter is comparable in sensitivity and specificity to CSA and FR. DCT increased independently of the cause of the CTS (decrease in size of canal or increase in contents).     

Sonographic Evaluation of the Median Nerve in Diabetic Patients

Objective. Diabetes mellitus is becoming a major cause of premature disability in Japan, and peripheral neuropathy is a common complication of diabetes. The aim of this study was to evaluate the relationship between the results of nerve conduction studies (NCS) and the size of the nerve determined by sonography in diabetic patients. Methods. Twenty diabetic patients (mean age ± SD, 57.1 ± 13.6 years) and 20 healthy volunteers (mean, 61.1 ± 8.9 years) were enrolled in this study. Patients' wrists that had symptoms of carpal tunnel syndrome were not included in the study; those that were included had negative Phalen test results. We then divided the patients into 2 groups (patients with and without diabetic symmetric polyneuropathy [DPN]). The cross‐sectional area (CSA) was measured in the carpal tunnel 5 cm proximal to the wrist and elbow joint of the median nerve. Results. There was a significant increase in the CSA in patients with DPN in the carpal tunnel compared with the control participants (P < .01) and patients without DPN (P < .01). The CSA in the carpal tunnel showed a significant correlation with the motor nerve conduction velocity (r = ?0.473). Conclusions. The CSA of the median nerve in the carpal tunnel of patients with DPN is greater than that in patients without DPN and healthy individuals and correlates with NCS.     

Median nerve conduction study through the carpal tunnel using segmental nerve length measured by ultrasonographic and conventional tape methods

Rha D-W, Im SH, Kim S-K, Chang WH, Kim KJ, Lee SC. Median nerve conduction study through the carpal tunnel using segmental nerve length measured by ultrasonographic and conventional tape methods.

Objective

(1) To determine whether a 5-cm segment includes the entire anatomic carpal tunnel in live subjects, and to compare surface, ultrasonographic, and direct measures of the median nerve length in human cadavers. (2) To investigate the actual difference of sensory conduction velocities between the conventional tape method and the ultrasonographic method.

Design

Cross-sectional study.

Setting

University rehabilitation hospital.

Participants

Healthy volunteers (N=40; 20 men, 20 women).

Interventions

Not applicable.

Main Outcome Measures

Onset latencies at the palm and wrist, nerve conduction velocity (NCV) in nerve conduction study (NCS), median nerve length measured by ultrasound and tape method.

Results

A real-time ultrasonographic study revealed that a 5-cm segment included the entire carpal tunnel. In the cadaveric study, the median nerve length measured by ultrasound was closer to the actual nerve length than the conventional surface length. The median nerve length in the wrist-to-palm segment measured by ultrasound was shorter than the surface distance. The sensory NCV using the nerve length measured by ultrasound was slower than that using the surface distance (P<.05).

Conclusions

The 5-cm segment test included the entire carpal tunnel and might be advantageous in the diagnosis of carpal tunnel syndrome (CTS), especially for early lesions. We expect that ultrasonographic measurement of nerve length might raise the sensitivity of NCSs for the diagnosis of CTS.     

Sensitivity of median sensory nerve conduction tests in digital branches for the diagnosis of carpal tunnel syndrome

OBJECTIVE: To compare the sensitivity of median sensory nerve conduction tests performed by stimulating digital branches in patients with carpal tunnel syndrome. DESIGN: A prospective study in 506 hands of patients with carpal tunnel syndrome diagnosed electrophysiologically. RESULTS: The sensitivity of median sensory nerve conduction tests across the first three digit-to-wrist segments and palm-to-wrist segment was determined. The most common abnormal electrophysiologic finding was the slowing of sensory nerve conduction velocity over the palm-to-wrist segment, which was detected in 98.5% of the hands. Slowing of sensory nerve conduction velocity over the digit 1-, 2-, and 3-to-wrist segments of the median nerve was found in 95.4%, 88%, and 82% of the hands, respectively. CONCLUSION: The sensory nerve conduction velocity test of the digit 1-to-wrist segment has the most sensitivity among the three digital branches of the median sensory nerve, and it may be used more widely in the electrodiagnosis of carpal tunnel syndrome.     

Effect of occupational keyboard typing on magnetic resonance imaging of the median nerve in subjects with and without symptoms of carpal tunnel syndrome

OBJECTIVE: To examine the effects of occupational keyboard typing on median nerve shape and T2 relaxation and on forearm muscle T2 in professional typists with and without symptoms of carpal tunnel syndrome. DESIGN: Based on the Levine Carpal Tunnel Syndrome Symptom Severity scale (LCTSS), 12 female professional typist volunteers were divided into asymptomatic (LCTSS < 1.3, n = 5) and symptomatic (LCTSS > 1.3, n = 7) groups. Magnetic resonance images were acquired from wrist and forearms of all subjects before, immediately after, and 8 hrs after 3 hrs of typing. Forearm muscle T2 and median nerve T2 cross-sectional area and long/short axis ratio were evaluated by blinded observers. RESULTS: There was no difference between groups in any measured variable before typing. Median nerve T2 increased and long/short axis ratio decreased in asymptomatic subjects after typing, but there were no significant changes in symptomatic subjects. T2 increased in finger flexor muscles after typing, but there was no difference in the pattern of muscle T2 changes between groups. CONCLUSION: In magnetic resonance images of the median nerve at the carpal tunnel, swelling and T2 increases from baseline are a normal response to typing and may be less likely to occur in subjects with symptoms of carpal tunnel syndrome.     

High-resolution ultrasonography of the carpal tunnel

Twenty-eight wrists of 25 patients with carpal tunnel syndrome (CTS) and 28 wrists of 14 normal control subjects were studied with high-frequency real-time ultrasonography. Three general findings could be observed in CTS, regardless of its cause: swelling of the median nerve at the entrance of the carpal tunnel; flattening of the median nerve in the distal carpal tunnel; and increased palmar flexion of the transverse carpal ligament. Quantitative analysis proved these findings to be significant. We conclude that high-resolution sonography is able to diagnose median nerve compression in the carpal tunnel syndrome and to detect some of its potential causes.     

超声对腕管综合征和肘管综合征的诊断价值

目的探讨超声对腕管综合征、肘管综合征的诊断价值。方法 25例体检健康者为对照组,临床疑诊35例腕管综合征和22例尺神经卡压患者为病变组,超声探查正中神经豌豆骨水平横断面积及其前后径(D1)、钩骨勾水平前后径(D2)、钩骨勾水平远端前后径(D3),肘部尺神经横断面积,计算D1与D2差值(D),D3与D2差值(d),将病变组超声检查结果与术中所见进行比较。结果超声可显示正中神经、尺神经卡压后的形态变化,病变组正中神经横断面积、D、d及尺神经横断面积均大于对照组(P0.03)。与术中所见比较,超声诊断腕管综合征、肘管综合征准确率分别为97.9%、95.4%。结论超声能有效诊断腕管综合征和肘管综合征。     

Acute carpal tunnel syndrome from thrombosed persistent median artery.

We report a case of acute carpal tunnel syndrome from thrombosis of a persistent median artery caused by blunt trauma. The sudden onset of numbness in the median nerve distribution with pain in the fingers in a young adult may provide clues to the diagnosis.     

A Cadaveric and Preliminary Clinical Study of Ultrasonographically Assisted Percutaneous Carpal Tunnel Release

The aim of this study was to assess the effectiveness and safety profile of a new technique for ultrasonographically assisted percutaneous carpal tunnel release. Experiments were performed on 40 hands in 20 cadavers. We first performed a detailed ultrasonographic examination and correlation study that included surgical dissection of the transverse carpal ligament, the related neurovascular structures and the bony landmarks of the radiocarpal, midcarpal and carpometacarpal joints of the right hand. We then used the measurements we made for percutaneous carpal tunnel release of the transverse carpal ligament using intra-operative ultrasonography for guidance and a hook knife on the left-hand side. The completeness of the release and the potential risks of injury to the flexor tendon and neurovascular bundles were examined. Using real-time intra-operative ultrasonographic monitoring to clearly delineate these targets, we were able to percutaneously release the transverse carpal ligament completely in 18 (90%) of the 20 hands and partially release it in 2 without injuring any neurovascular bundles. We then performed the procedure on 91 consecutive cases of carpal tunnel syndrome and found that the sensory disturbances disappeared in 100% patients 12 mo post-operatively; only 2 hands were graded as unsatisfactory. There were no intra- or post-operative complications. Based on the results from the cadaveric studies and our successful preliminary clinical outcomes, we conclude that this method is tolerable and that its clinical application can be encouraged.     

高频超声对上肢正中神经正常值的研究

目的通过高频超声获取正中神经的横截面积(cross-sectional area,CSA)正常值并探讨其与周围组织的关系,为临床诊断不同的外周神经疾病提供依据。方法对200例健康志愿者沿正中神经行程进行高频超声观察,依次测量7个位点的CSA[腕横纹、腕管入口(豌豆骨)、腕管出口(钩骨)、腕横纹上6cm、正中神经穿出旋前圆肌处(前臂近端)、肱骨内髁上4cm、肱骨中点],每个位点重复测量3次取其平均值,并进行CSA与身高、体重的相关性分析。结果高频超声下正常人正中神经呈筛网状低回声图像,横截面在不同部位分别表现为圆形、椭圆形或三角形。正中神经在前述7个位点的CSA依次为(8.67±1.24)mm2、(8.68±1.22)mm2、(8.56±1.25)mm2、(7.11±1.33)mm2、(7.08±1.21)mm2、(9.38±1.28)mm2、(9.48±1.28)mm2;左右上肢之间比较CSA差异无统计学意义;正中神经在腕横纹上6cm、肱骨内髁上4cm、肱骨中点处的CSA同年龄组男女之间差异有统计学意义;正中神经在腕横纹处、腕管出入口、肱骨内髁上4cm处中老年人比青年人增粗;CSA与身高、体重有相关性。结论上肢正中神经基本全程可视,在不同部位的正常值及超声声像图略有差异。神经的CSA在上臂段最粗,腕管处次之,前臂段最细,与身高、体重呈正相关性。     

Carpal tunnel syndrome caused by gouty tophus of the flexor tendons of the fingers: sonographic features

We report the case of a 23-year-old male presenting with carpal tunnel syndrome and a swelling over the flexor surface of the wrist. MRI findings were initially suggestive of a median nerve schwannoma but sonography (US) showed a heterogenous mass infiltrating the flexor tendons of the fingers and displacing the median nerve in the carpal tunnel. US findings were confirmed by surgical exploration, which revealed a gouty tophus of the flexor tendons of the fingers at the wrist with secondary median nerve displacement and compression.     

Detection of differential gliding characteristics of the flexor digitorum superficialis tendon and subsynovial connective tissue using color Doppler sonographic imaging.

OBJECTIVE: The subsynovial connective tissue (SSCT) is the most characteristic structure in the carpal tunnel and is substantially affected in cases of carpal tunnel syndrome. We investigated the usefulness of Doppler sonography for measuring velocity differences between the flexor tendon and its associated SSCT in the carpal tunnel of cadaver hands. METHODS: Six human cadaver wrists were used in this study (mean age of death, 82.2 years). The velocity difference between the middle finger flexor digitorum superficialis tendon and its corresponding SSCT was measured on a sonography machine equipped with a fingertip 13-MHz linear probe. RESULTS: At tendon velocities of greater than 2.5 cm/s, the tendon velocity was significantly greater than the SSCT velocity (P < .05). At less than 2.5 cm/s, there was no significant difference between tendon and SSCT velocities. CONCLUSIONS: Color Doppler imaging can identify and track SSCT motion separately from that of its associated tendons. Analysis of SSCT motion characteristics by color Doppler imaging may be useful for studying its function clinically.