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.     

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.     

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。     

Increase of vibration threshold during wrist flexion in patients with carpal tunnel syndrome

The most prominent symptoms of carpal tunnel syndrome (CTS) are sensory, with intermittent numbness, paraesthesiae and pain in the fingers innervated by the median nerve. No consistent signs are found by neurological examination, however. Conventional sensibility tests are positive in only about 50% of the cases. This applies also to quantitative tests such as measurement of the perception threshold for vibration (VT). In an attempt to find a more reliable indication and improve the diagnostic value of sensory testing, determination of VT was combined with provocation by means of wrist flexion. In a patient group with neurophysiologically verified CTS, all patients exhibited an increase to at least twice the VT value in the fingers innervated by the median nerve. No increase was seen in the little finger or in a control group of patients with digital paraesthesiae but with normal neurophysiological findings. It is concluded that VT measurements during wrist flexion can be used as a supplementary or alternative diagnostic criterion to indicate that the nerve dysfunction is located in the carpal tunnel.     

"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.     

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.

     

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.     

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.     

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.     

Effectiveness of ultrasound and median nerve gliding with and without shock-wave therapy in patients with moderate carpal tunnel syndrome

[Purpose] The aim of this research was to see how ultrasound and nerve gliding with and without shock wave therapy effects on clinical and sonographic data of patients with carpal tunnel syndrome (CTS). [Participants and Methods] Forty four patients with moderate carpal tunnel syndrome participated in this research. One group got shock-wave therapy in addition to median nerve glide exercises and ultrasound, whereas the other group received median nerve glide exercises and ultrasound alone. Hand grip strength (HGS), pinch grip strength (PGS), Visual Analogue Scale (VAS)-pain, Boston Questionnaire (BQ), and Cross-sectional area (CSA) of median nerve were examined before and after 10 sessions of treatment. [Results] HGS, PGS, VAS, BQ and CSA of median nerve improved considerably after therapy. [Conclusion] Patients with moderate CTS who received ultrasound and median nerve glide exercises with and without shock-wave therapy improved considerably without preference of adding shock-wave therapy to other treatment.     

Anatomic observations in carpal tunnel syndrome as they relate to the tethered median nerve stress test

The Tethered Median Nerve Stress Test (TMNST) has proved to be a reliable clinical tool in the diagnosis of chronic, low-grade carpal tunnel syndrome (CTS). The TMNST consists of hyperextending the index finger at the distal interphalangeal joint with the wrist maintained in a supinated position. Proximal volar forearm pain radiation is experienced by patients with chronic CTS during this maneuver. This investigation shows that significant distal excursion of the median nerve occurs with hyperextension of the index finger and to a greater degree than with hyperextension of the adjacent digits. Pain experienced during the TMNST appears to be vascular in origin and its severity is directly related to the duration of testing. This finding emphasizes the important role of ischemia in chronic entrapment neuropathies.     

Ulnar neuropathy at the wrist in a patient with carpal tunnel syndrome after open carpal tunnel release

Ulnar neuropathy at the wrist is rarely reported as complications of carpal tunnel release. Since it can sometimes be confused with recurrent median neuropathy at the wrist or ulnar neuropathy at the elbow, an electrodiagnostic study is useful for detecting the lesion in detail. We present a case of a 51-year-old woman with a two-week history of right ulnar palm and 5(th) digit tingling sensation that began 3 months after open carpal tunnel release surgery of the right hand. Electrodiagnostic tests such as segmental nerve conduction studies of the ulnar nerve at the wrist were useful for localization of the lesion, and ultrasonography helped to confirm the presence of the lesion. After conservative management, patient symptoms were progressively relieved. Combined electrodiagnostic studies and ultrasonography may be helpful for diagnosing and detecting ulnar neuropathies of the wrist following carpal tunnel release surgery.     

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.     

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.