"Tethered" median nerve stress test in chronic carpal tunnel syndrome

Tension of the median nerve produced by simultaneous extension of the supinated wrist and distal interphalangeal joint of the index finger was noted to result in proximal volar forearm pain radiation in patients with chronic carpal tunnel syndrome. This sign was less frequent in patients with a more acute syndrome. Adhesions between the median nerve and the overlying transverse carpal ligament and the development of a pseudoneuroma can individually or together occur in the chronic carpal tunnel syndrome limiting distal nerve excursion of the tethered nerve during simultaneous wrist and index finger extension.     

Lack of predictive power of the "tethered" median stress test in suspected carpal tunnel syndrome

OBJECTIVE: To investigate the value of the "tethered" median nerve stress test (TMST) in predicting electrodiagnostically confirmed carpal tunnel syndrome (CTS) in patients with symptoms suggestive of CTS. STUDY DESIGN: Blinded comparison of a clinical diagnostic test with neurophysiologic testing. SETTING: Portland (OR) Veterans Administration Medical Center Electrodiagnostic Laboratory. PATIENTS: One hundred two consecutive patients referred for symptoms suggestive of CTS. Study inclusion criteria were referral for evaluation of symptoms of paresthesia (with or without pain) inclusive of the median nerve distribution distal to the wrist. RESULTS: Fifty-seven percent of referred patients had electrodiagnostically confirmed CTS. The sensitivity of the TMST was 50%. The specificity was 59.1%. The positive predictive value was 61.7%. The negative predictive value was 47.3%. CONCLUSION: The TMST does not have utility in predicting electrodiagnostic consult results in veteran patients with symptoms suggestive of CTS.     

Reduced longitudinal excursion of the median nerve in carpal tunnel syndrome

OBJECTIVE: To determine if longitudinal excursion of the median nerve is reduced in patients with carpal tunnel syndrome (CTS). DESIGN: Case-control study. SETTING: University human movement laboratory. PARTICIPANTS: Nineteen patients with CTS (8 men, 11 women; mean age, 57+/-15 y), and 37 healthy controls (8 men, 29 women; mean age, 48+/-10 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Longitudinal excursion of the median nerve, and the ratio of nerve to flexor digitorum superficialis tendon excursion at the carpal tunnel evoked by finger extension. Measurements were taken using a validated Doppler ultrasound technique, and tests were conducted with the elbow positioned in extension and flexion. RESULTS: Mean longitudinal excursion of the median nerve was significantly greater in controls (11.2+/-2.8 mm) than patients (8.3+/-2.6 mm) with the elbow extended (P=.013), but not with the elbow flexed (controls, 12.5+/-2.5 mm; patients, 10.2+/-3.1 mm; P=.089). Mean nerve/tendon excursion ratios were significantly greater in controls (.32+/-.07) than patients (.23+/-.06), with the elbow extended (P<.001), and flexed (controls, .36+/-.06; patients, .28+/-.10; P=.019). Discriminant analysis identified that 11 (58%) of the 19 patients and 3 (8%) of the 37 controls showed a nerve/tendon excursion ratio of .25 or less when tested with the elbow in extension. CONCLUSIONS: Reduced longitudinal excursion of the median nerve at the carpal tunnel was identified in a substantial proportion of patients with CTS. Further studies are merited to determine if reduced median nerve excursion at the carpal tunnel is clinically relevant in CTS, and can be influenced by movement-based interventions.     

Ultrasound elastographic evaluation of the median nerve in hemodialysis with carpal tunnel syndrome

Purpose

The aim of this study was to compare the elasticity of the median nerve (MN) between hemodialysis (HD) patients without carpal tunnel syndrome (CTS) and with CTS, and to evaluate the diagnostic usefulness of the elasticity of the MN in HD-CTS.

Materials and methods

The MN in 22 HD patients without CTS and 49 HD-CTS patients was studied. The cross-sectional area (CSA) and the elasticity of the MN, which was measured as the subcutaneous fat/median nerve (SF/MN) strain ratio, were evaluated.

Results

The mean SF/MN strain ratio in the groups that had received hemodialysis for 0–5, >5–10, and >10–15 years was 1.4 ± 0.28, 1.7 ± 0.18, and 2.0 ± 0.67, respectively. The mean CSA of the MN in the three groups was 9.9 ± 1.30, 11.6 ± 1.61, and 13.4 ± 2.14 mm², respectively. The presence of CTS was predicted by means of SF/MN strain ratio and CSA cutoff values of 1.8 and 11 mm², respectively. Both the SF/MN strain ratio and the CSA in the patients with CTS were higher than those in the patients without CTS (P < 0.05). The sensitivity and specificity of the SF/MN strain ratio and CSA of the MN were 75 and 92 % and 79.2 and 84 %, respectively.

Conclusion

Sonoelastography helps to improve the diagnostic accuracy of the ultrasonographic assessment of CTS.

     

Enhancement in median nerve mobility during radioulnar wrist compression in carpal tunnel syndrome patients

BackgroundCarpal tunnel syndrome is a compression neuropathy at the wrist associated with compromised median nerve mobility. The purpose of this study was to investigate the effects of radioulnar wrist compression on median nerve longitudinal mobility within the carpal tunnel in carpal tunnel syndrome patients as well as healthy subjects.MethodsDynamic ultrasound images captured longitudinal median nerve motion in the carpal tunnel during radioulnar wrist compression force application in 11 healthy subjects and 11 carpal tunnel syndrome patients.FindingsWe found that median nerve mobility was not significantly affected by radioulnar wrist compression in healthy subjects (P = 0.34), but improved by 10 N radioulnar wrist compression in carpal tunnel syndrome patients (P < 0.05). Analysis of segmental median nerve mobility in carpal tunnel syndrome patients showed significantly improved mobility in the proximal tunnel section under 10 N radioulnar wrist compression force condition compared to the no compression condition (P < 0.05).InterpretationModerate radioulnar wrist compression force application helps restore impaired median nerve mobility and may be effective in improve nerve function and symptoms associated with carpal tunnel syndrome.     

超声定量测定正中神经诊断腕管综合征

目的 研究高频超声定量测定正中神经诊断腕管综合征,并探索有价值的诊断指标及其标准.方法 对32例经电生理检查确诊的腕管综合征患者及30例正常人的腕管行高频超声检测,两组间的差异采用t检验,超声诊断标准的确定采用ROC曲线分析.结果 除掌侧位移(PD)和钩骨钩水平膨胀率(SR3)外,腕管综合征患者正中神经的内径(D)、腕管3个水平的横径(a)、前后径(b)、横截面积(CSA)、扁平率(FR)以及SR2均较正常组增大,差异均有统计学意义(t分别=2.45、2.56、3.16、2.51、2.66、2.78、3.05、2.28、4.11、2.89、3.37、2.89、3.06、2.76,P均＜0.05).其中正中神经豌豆骨水平CSA临床诊断价值最大,当其临界值定为＞0.11 cm2时,对应的敏感度、特异度分别为89.60%、95.30%.结论 高频超声测定正中神经是一种能够准确诊断腕管综合征的新方法,其中以豌豆骨水平CSA的诊断价值最大.     

实时弹性定量成像技术在腕管综合征正中神经病变中应用及与MRI正中神经扁平率相关性研究

[目的]评估VTIQ的剪切波速度(shear wave velocity,SWV)在CTS患者中的应用,同时分析与MRI钩骨钩水平正中神经扁平率(median nerve flattening ratio MNFR) 相关性,以探讨SWV在诊断CTS中的临床应用价值。[方法]对临床诊断为CTS 40例患者(67只腕关节)及20例健康对照组(40只腕关节)进行VTIQ检测及二维超声检测。评估指标是SWV及CSA。比较两指标CTS组与对照组组间差异。绘制两指标诊断CTS的ROC曲线。回顾性分析临床诊断CTS患者MRI资料,测量MNFR。评估SWV及CSA与MNFR相关性。[结果]CTS组SWV、CSA与对照组比较差异有统计学意义(P＜0.05)。正中神经SWV诊断CTS最佳截值3.30m/s,计算SWV的灵敏度、特异度和准确率高于CSA。两指标联合诊断效能灵敏度,准确率高于单一指标。SWV、CSA与MNFR之间存在相关性。[结论] CSA及SWV两指标的改变反映了CTS患者正中神经形态学增粗,组织学变硬。VTIQ技术与MRI测量结果有较好一致性。遵照规范及指南条件下应用VTIQ技术在诊断CTS患者正中神经病变中有较好的可行价值。VTIQ技术及正中神经横截面积联合应用可以减少漏诊率,可为患者正确规范化治疗CTS提供更丰富的影像诊断依据。     

Day-to-day variability of median nerve location within the carpal tunnel

Background

Carpal tunnel syndrome is a commonly encountered entrapment disorder resulting from mechanical insult to the median nerve. Magnetic resonance imaging (MRI)-based investigations have documented typical locations of the median nerve within the carpal tunnel; however, it is unclear whether those locations are consistent within an individual on different days.

Methods

To determine the day-to-day variability of nerve location, 3.0 T MRI scans were acquired from six normal volunteers over multiple sessions on three different days. Half of the scans were acquired with the wrist in neutral flexion and the fingers extended, and the other half were acquired with the wrist in 35° of flexion and the fingers flexed. Prior to half of the scans (in both poses), subjects performed a preconditioning routine consisting of specified hand activities and several repetitions of wrist flexion/extension. The shape, orientation, location, and location radius of variability of the median nerve and three selected flexor tendons were determined for each subject and compared between days.

Findings

Two of the six subjects had substantial variability in nerve location when the wrist was in neutral, and four of the subjects had high variability in nerve position when the wrist was flexed. Nerve variability was typically larger than tendon variability. The preconditioning routine did not decrease nerve or tendon location variability in either the neutral or the flexed wrist positions.

Interpretation

The high mobility and potential for large variability in median nerve location within the carpal tunnel needs to be borne in mind when interpreting MR images of nerve location.     

Ultrasound imaging of the carpal tunnel during median nerve compression

Median nerve (MN) compression is a recognized component of carpal tunnel syndrome (CTS). In order to document compressive changes in the MN during hand activity, the carpal tunnel was imaged with neuromuscular ultrasound (NMUS). Ten patients with CTS and five normal controls underwent NMUS of the MN at rest and during dynamic stress testing (DST). DST maneuvers involve sustained isometric flexion of the distal phalanges of the first three digits. During DST in the CTS patients, NMUS demonstrated MN compression between the contracting thenar muscles ventrally and the taut flexor tendons dorsally. The mean MN diameter decreased nearly 40%, with focal narrowing in the mid-distal carpal canal. Normal controls demonstrated no MN compression and a tendency towards MN enlargement, with an average diameter increase of 17%. Observing the pathologic mechanism of MN injury during common prehensile hand movements could help better understand how to treat and prevent CTS.     

Ulnar nerve involvement in carpal tunnel syndrome

This is a retrospective study of the involvement of the ulnar nerve in patients with electrodiagnostic evidence of carpal tunnel syndrome as defined by median sensory nerve action potential (SNAP) greater than 3.6msec at the wrist and/or motor distal latency in excess of 4.3msec. The study included 248 patients, 63 (25%) with unilateral and 185 (75%) with bilateral carpal tunnel syndrome. The electrodiagnostic criteria for ulnar nerve involvement was a SNAP peak latency greater than 3.7msec and/or motor distal latency in excess of 4.2msec. One hundred fourteen patients (46%) had delayed ulnar SNAP peak at the wrist; of these, 100 cases had bilateral ulnar nerve involvement and 14 had unilateral abnormalities. Slowing of the motor nerve conduction velocity for the elbow-wrist segment was noted in 24% and 15% of the study group for the median and ulnar nerves, respectively. An incidental finding was the presence of "double crush syndrome" in 35 patients (14%). The results of this study suggest the frequent association of ulnar nerve involvement at the wrist for sensory fibers and carpal tunnel syndrome.     

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.     

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.     

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.     

手掌混合神经电位潜伏时差诊断轻度腕管综合征的价值

目的：分析正中及尺神经手掌一腕混合神经电位潜伏时差在诊断轻度腕管综合征的价值。 方法：回顾性分析经新加坡国家脑神经科学院神经内科门诊神经内科医生临床确诊且临床症状符合腕管综合征的62例患者的正中及尺神经掌-腕混合神经电位潜伏时差，并与同期52例正常对照组的各项神经传导检测结果进行比较。对照组与腕管综合征组患者均检测正中神经、尺神经运动及感觉传导。采用片状表面电极记录运动传导末端潜伏时；采用反向法检测正中神经腕-示指感觉神经电位，主要观察感觉神经电位潜伏时；用顺向法检测正中及尺神经手掌混合神经传导，观察正中神经及尺神经混合神经电位潜伏时差。正中神经运动传导末端潜伏时、腕-示指感觉神经传导电位潜伏时、手掌正中及尺神经混合神经电位混合神经电位潜伏时差大于本实验室同期所做的52例对照组的正常参考值x^-&;#177;1．96s为延长。 结果：腕管综合征患者62例及对照组52人均采集到各项指标，全部进入结果分析。①腕管综合征组患者正中神经运动传导末端潜伏时、腕-示指感觉神经电位潜伏时均与对照组接近，差异无显著性意义（P值分别为0．494和0．144）。②腕管综合征组患者正中及尺神经手掌-腕混合神经电位潜伏时差与对照组比较明显延长，差异有显著性意义[（2．078&;#177;0．316），（1．706&;#177;0．121）ms，t=8．998，P=0．000]。③当正中及尺神经手掌-腕混合神经电位潜伏时差大于对照组x^-&;#177;1．96s时为延长，可得到正常值上限为0．398ms，腕管综合征组患者中此潜伏时差〉0．398ms者55例，占88．7％，即采用正中及尺神经手掌-腕混合神经电位潜伏时差明显的提高了腕管综合征的诊断率，但仍有7例（11．3％）腕管综合征患者其正中及尺神经手掌-腕混合神经电位潜伏时差在0．4ms以内。 结论：正中及尺神经手掌-腕混合神经电位潜伏时差在诊断轻度腕管综合征时具有较高的诊断价值。     

Slowed conduction velocity of the median sensory nerve across the carpal tunnel in normal adults

OBJECTIVE: To examine the difference of using onset or peak latency in the segmental conduction study of the median nerve in normal adults without carpal tunnel syndrome. DESIGN: We investigated 60 hands of 30 young healthy adults (15 men and 15 women; mean age, 27.1 yrs; range, 18-36 yrs). We performed the mid-palm segmental conduction study using antidromic and orthodromic techniques in the median sensory nerves of the second and third digits and the onset and peak latencies of the proximal (wrist-palm) and distal (palm-digit) segments were measured. The distoproximal latency ratios were compared between onset and peak latencies and were compared with the ratios of the superficial radial sensory nerve. RESULTS: Distoproximal peak latency ratios in the median and superficial radial sensory nerves were always >1.0 in both the antidromic and orthodromic conduction studies. However, distoproximal onset latency ratios in the median sensory nerve were >1.0 in only 35% and 21.7% of second digits and in only 25% and 11.7% of third digits in orthodromic and antidromic studies, respectively (P < 0.05). The results of distoproximal onset latency ratios in the superficial radial sensory nerve were 93.3% in the orthodromic study and 86.7% in the antidromic study (P < 0.05). CONCLUSION: Prolongation of onset latency across the carpal tunnel during segmental conduction study of the median sensory nerve was common in healthy adults. When comparing proximal and distal segments for diagnosis of carpal tunnel syndrome, using onset latency as a diagnostic variable may cause greater reporting of false positives.