Tendon and nerve displacement at the wrist during finger movements

BACKGROUND: Repetitive motion of the hand has been suggested as a major factor of pathogenesis of cumulative trauma disorders (e.g., carpal tunnel syndrome). The purpose of this study was to investigate the 3D displacement of the median nerve and extrinsic finger flexor tendons (flexor digitorum superficialis; flexor digitorum profundus) as a function of flexion/extension of metacarpophalangeal joints of the index and middle fingers. METHODS: Shim markers were placed on the median nerve, flexor digitorum superficialis, and flexor digitorum profundus tendons at the wrist region of seven cadaveric specimens for the purpose of digitization of tendon and nerve locations. The metacarpophalangeal joint of the index or middle finger was moved from 15 degrees extension to 75 degrees of flexion while the markers were digitized at increments of 15 degrees. Marker displacements were determined in the longitudinal, radial-ulnar, and dorsal-palmar directions. FINDINGS: Movement of metacarpophalangeal joint of the index or middle finger caused tendon and nerve displacements in the longitudinal, radial-ulnar, and dorsal-palmar directions. The longitudinal displacements of the median nerve and the flexor tendons were linearly correlated with angular movement of the metacarpophalangeal joint. The maximum longitudinal displacements of the flexor digitorum superficialis tendon, flexor digitorum profundus tendon, and median nerve were, on average, 14.7 mm, 11.9 mm, and 3.0 mm, respectively, for the index finger; and 18.4 mm, 14.5 mm, and 4.0 mm, respectively, for the middle finger. The radial-ulnar and dorsal-palmar displacements were irregular and relatively small. The maximum displacements in these transverse directions fell in the range of 1.4-5.1 mm for the median nerve and 1.9-7.3 mm for the flexor tendons. INTERPRETATIONS: Finger flexor tendons and median nerve move not only concurrently, but also differentially, in all anatomical directions. Tendon and nerve movement during prolonged repetitive hand movement may cause hand disorders such as carpal tunnel syndrome.     

Do 'sliders' slide and 'tensioners' tension? An analysis of neurodynamic techniques and considerations regarding their application

Despite the high prevalence of carpal tunnel syndrome and cubital tunnel syndrome, the quality of clinical practice guidelines is poor and non-invasive treatment modalities are often poorly documented. The aim of this cadaveric biomechanical study was to measure longitudinal excursion and strain in the median and ulnar nerve at the wrist and proximal to the elbow during different types of nerve gliding exercises. The results confirmed the clinical assumption that 'sliding techniques' result in a substantially larger excursion of the nerve than 'tensioning techniques' (e.g., median nerve at the wrist: 12.6 versus 6.1mm, ulnar nerve at the elbow: 8.3 versus 3.8mm), and that this larger excursion is associated with a much smaller change in strain (e.g., median nerve at the wrist: 0.8% (sliding) versus 6.8% (tensioning)). The findings demonstrate that different types of nerve gliding exercises have largely different mechanical effects on the peripheral nervous system. Hence different types of techniques should not be regarded as part of a homogenous group of exercises as they may influence neuropathological processes differently. The findings of this study and a discussion of possible beneficial effects of nerve gliding exercises on neuropathological processes may assist the clinician in selecting more appropriate nerve gliding exercises in the conservative and post-operative management of common neuropathies.     

Changes in geometry of the finger flexor tendons in the carpal tunnel with wrist posture and tendon load: an MRI study on normal wrists.

OBJECTIVES: (1) To develop a methodology to determine the trajectories of the digital flexor tendons using MRI. (2) To examine changes in tendon trajectories due to wrist posture, with and without pinch force. (3) To calculate the radius of curvature of the flexor tendons and note implications for contact forces on the median nerve. (4) To assess the use of Landsmeer's models at the wrist. DESIGN: Finger flexor tendon centroids were digitized from magnetic resonance images of the carpal tunnel and the tendon paths were determined analytically. Radii of curvature were calculated from the tendon paths. BACKGROUND: Landsmeer's models of joint-tendon interaction (Landsmeer, 1961) have been used to determine moment arms and radius of curvature of the tendon paths about articulations. An explanation for a biomechanical cause of work-related carpal tunnel syndrome originated from these models. METHODS: Three healthy male participants had their right wrist scanned while splinted in four wrist postures (flexed to 20 degrees, 45 degrees, neutral, extended to 20 degrees ) with and without maintaining a 10 N pinch grip. 20-24 cross-sectional images were used for each condition. RESULTS: Volar movement of the tendons was seen with wrist flexion and the opposite was true with extension. Tendon intersection angles were calculated between the tendon as it entered the carpal tunnel and as it exited the tunnel and were 50-65% of the wrist angle (R(2)=0.81-0.96). The radius of curvature was smallest (mean=82-127 mm) with an active pinch grip with the wrist splinted at 45 degrees of flexion (mean actual wrist angle 37 degrees ). CONCLUSIONS: The radius of flexor tendon curvature is not constant as previously assumed and is larger than previous estimates. The addition of tendon force with the wrist flexed acts to reduce the radius of curvature which further increases the contact stress on the median nerve and other wrist structures. The use of MRI to determine the tendon paths has provided new insight into the relationships between the finger flexor tendons and other structures at the wrist. RELEVANCE: These findings provide data for biomechanical models of the carpal tunnel and predict the possible pathophysiology of work-related carpal tunnel syndrome.     

The deformation and longitudinal excursion of median nerve during digits movement and wrist extension

The use of electronic devices, such as mobile phones and computers, has increased drastically among the young generation, but the potential health effects of carpal tunnel syndrome (CTS) on university students has not been comprehensively examined. Thirty-one university students aged 18 to 25 y with no symptoms of CTS were successfully recruited in this study. By using noninvasive ultrasonography, the morphological characteristics of the median nerve of each volunteer, and the extent of its longitudinal excursion movement under experimental conditions, in which a real operating environment of electronic devices was simulated, were quantified. The results demonstrated that the median nerve at the carpal tunnel inlet was flattened during wrist extension: the flattening ratio increased from 3.40 ± 0.91 at the neutral position to 4.10 ± 1.11 at the angle of 30° and 4.09 ± 1.11 at the angle of 45°. In addition, the median nerve became swollen after the students performed rapid mobile-phone keying for 5 min, indicated by a significant increase in the cross-sectional area from 6.05 ± 0.97 mm² to 7.56 ± 1.39 mm². Passive longitudinal excursion was observed at the median nerve when the students performed mouse-clicking (2.4 ± 1.0 mm) and mobile-phone keying tasks (1.7 ± 0.6 mm), with the mouse-clicking task generating a greater extent of longitudinal excursion than the mobile-phone keying task did. In conclusion, the findings of the present study verify the potential harm caused by using electronic devices while maintaining an inappropriate wrist posture for a substantial period.     

Restless hand symptoms in carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a nerve entrapment disorder, involving the median nerve when it passes the carpal tunnel at the wrist. Using a case-control methodology, 312 electrophysiologically confirmed CTS patients with mean age of 51.3+/-9.4 (27-74) years (81.7% women) and 100 controls with mean age of 50.4+/-9.2 (21-88) years (75% women) were examined utilising a questionnaire similar to the clinical diagnostic criteria of restless legs syndrome (RLS). Forty-four (14.1%) of the CTS patients have symptoms compatible with restless hand syndrome compared with none (0%) in the control group (p < 0.0001). The severity of CTS was not significantly associated with the motor restlessness. Our observations suggest that entrapment syndromes such as CTS can be associated with a form of restlessness in the hands, analogous to RLS.     

Comparative diagnostic sensitivities of orthodromic or antidromic sensory inching test in mild carpal tunnel syndrome

OBJECTIVES: To compare the reliability, sensitivity, and specificity of the "inching test" (IT) or "centimetric test," performed orthodromically (OIT) and antidromically (AIT). METHODS: Incremental palmar study of the sensory fibers of the median nerve was evaluated over 10cm across the wrist in 20 patients with mild carpal tunnel syndrome (CTS) and in 20 controls. Mild CTS was defined as clinical features of CTS with normal electrophysiologic findings by standard methods. The CTS patients were preselected with abnormal orthodromic median-ulnar latency difference of the fourth digit (mean .66+/-.21ms; nl < .40ms). RESULTS: In controls, the mean conduction delay per centimeter (CD/cm) was .192ms for OIT and .191ms for AIT; the mean maximum conduction delay per centimeter (MCD/cm) was .250+/-.032ms for OIT and .344+/-.10ms for AIT. MCD/cm was located inside the carpal tunnel in 85% of patients (OIT) versus 80% for AIT. No MCD/cm was greater than .32ms (OIT) or .60ms (AIT). With corresponding pathologic thresholds of .36ms (mean + 3.4 standard deviation [SD]) for OIT and .64ms (mean + 2.6 SD) for AIT, IT was abnormal in 20 patients (100%) with OIT compared with only 4 patients (20%) with AIT. CONCLUSIONS: The orthodromic method was superior to the antidromic method in controls and in patients (chi2 = 23; p = 1.8 x 10(-6)). These findings suggest that orthodromic IT should be used when standard electrodiagnostic tests fail to reveal median nerve sensory abnormality in persons with mild CTS.     

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。     

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.     

In vivo study of nerve movement and mechanosensitivity of the median nerve in whiplash and non-specific arm pain patients

Chronic pain following whiplash injury and non-specific arm pain (NSAP, previously termed diffuse repetitive strain injury) present clinicians with problems of diagnosis and management. In both patient groups there are clinical signs of altered nerve movement and increased nerve trunk mechanosensitivity. Previous studies of NSAP patients have identified altered median nerve movement at the wrist. The present study uses high frequency ultrasound imaging to examine changes to median nerve movement and clinical examination to assess altered mechanosensitivity of the median nerve. Longitudinal median nerve movement was measured in the forearm during maximal inspiration in nine post-whiplash patients with chronic neck and arm pain and eight controls subjects. Eight NSAP patients and seven controls were also studied. Transverse median nerve movement at the proximal carpal tunnel during 30 degrees wrist extension to 30 degrees flexion was also measured. A clinical examination of nerve trunk allodynia was performed in all subjects. Longitudinal nerve movement in the forearm was reduced by 71% in the post-whiplash patients and by 68% in NSAP patients compared to controls. In the whiplash patients the pattern of transverse median nerve movement at the proximal carpal tunnel was significantly different to controls (patient mean=2.57+/-0.80 mm (SEM) in a radial direction; control mean=0.39+/-0.52 mm in an ulnar direction). Signs of neural mechanosensitivity (i.e. painful responses to median nerve trunk and brachial plexus pressure and stretch) were apparent in both patients groups. Change in nerve tension and neural mechanosensitivity may contribute to symptoms in whiplash and NSAP patients.     

Relative Motion of the Connective Tissue in Carpal Tunnel Syndrome: The Relation with Disease Severity and Clinical Outcome

Excursion of the median nerve and the surrounding subsynovial connective tissue (SSCT) is diminished in patients with carpal tunnel syndrome (CTS). This study sought to determine if SSCT excursion could be utilized to predict surgical outcome. Idiopathic CTS patients were reviewed with ultrasound and electrodiagnostic tests at baseline. A speckle tracking algorithm was used to determine SSCT relative to tendon motion (shear index). Analysis of variance tests were used to compare SSCT motion with disease severity at baseline. Adjusted linear regressions were used to test the association with patient-reported outcome. A total of 90 CTS patients were analyzed and found to have an average shear index of 79% (95% confidence interval: 76.3%–81.6%). SSCT motion was lower in CTS patients with increasing electrophysiological severity (p = 0.0475). There was no significant association of pre-operative SSCT motion with symptomatic improvement (p = 0.268). Overall, SSCT motion is decreased in CTS patients, but exhibits limited correlation with clinical severity.     

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.     

"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.     

Chronic carpal tunnel syndrome caused by covert tophaceous gout: A case report

Carpal tunnel syndrome (CTS) is well recognized as the most common type of peripheral neuropathy. A rare cause of CTS is tophaceous gout. Tophi deposits can accumulate in various structures including the flexor tendons, tendon sheaths, the carpal tunnel floor, transverse carpal ligament, and even the median nerve, causing various symptoms such as pain, numbness, and weakness. Tophi forming in the carpal canal can compress the median nerve, leading to CTS. Here, we describe a 25-year-old male with a family history of tophaceous gout who presented with typical CTS symptoms. Although he had chronic numbness in his right hand, he failed to present with any obvious palpable masses on his forearm or hand. However, his family history, laboratory, clinical, and magnetic resonance imaging findings were consistent with tophi deposits. CTS symptoms were eased through surgical removal of tophi and decompression of the median nerve. No recurrences of gout and CTS symptoms were reported at a one-year follow-up. This case shows that CTS symptoms could be the initial manifestation of tophaceous gout. In patients with a family history of gout and with CTS symptoms, imaging examinations are critical for early diagnosis and selecting appropriate treatment. Surgical removal of “covert” tophi and decompression of the median nerve is an effective option for eliminating symptoms.     

Randomized controlled trial of nocturnal splinting for active workers with symptoms of carpal tunnel syndrome

OBJECTIVES: To determine whether nocturnal splinting of workers identified through active surveillance with symptoms consistent with carpal tunnel syndrome (CTS) would improve symptoms and median nerve function as well as impact medical care. DESIGN: Randomized controlled trial. SETTING: A Midwestern auto assembly plant. PARTICIPANTS: Active workers with symptoms suggestive of CTS based on a hand diagram. INTERVENTION: The treatment group received customized wrist splints, which were worn at night for 6 weeks; the control group received ergonomic education alone. MAIN OUTCOME MEASURES: Change in wrist, hand, and/or finger discomfort, carpal tunnel symptom severity index, median sensory nerve function, and the percentage of subjects who had carpal tunnel release surgery. RESULTS: The splinted group, unlike the controls, had a significant reduction in wrist, hand, and/or finger discomfort and a similar trend in the Levine carpal tunnel symptom severity index, which was maintained at 12 months. A secondary analysis showed that more median nerve impairment at baseline was associated with less clinical improvement among controls but not among the splinted group. CONCLUSIONS: Workers identified with CTS symptoms in an active symptom surveillance tended to benefit from a 6-week nocturnal splinting trial, and the benefits were still evident at the 1-year follow-up. The splinted group improved in terms of hand discomfort regardless of the degree of median nerve impairment, whereas the controls showed improvement only among subjects with normal median nerve function. Results suggest that a short course of nocturnal splinting may reduce wrist, hand, and/or finger discomfort among active workers with symptoms consistent with CTS.     

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.     

Quantitative in vivo studies of median nerve sliding in response to wrist, elbow, shoulder and neck movements

Objective. To examine median nerve sliding in response to upper limb movements in vivo. To determine whether the median nerve can be unloaded.

Design. Exploratory study in healthy subjects.

Background. Impaired sliding may lead to neuropathic symptoms. In vivo results for neural dynamics in normal subjects are essential to understand changes in upper limb disorders.

Methods. Ultrasound imaging of the median nerve during 40° wrist extension, 80° shoulder abduction, 90° elbow extension, and 35° contralateral neck side flexion. Frame by frame cross-correlation of image sequences to measure nerve sliding and strain.

Results. Nerve excursion in the forearm and upper arm ranged from 0.3 mm for neck side flexion to 10.4 mm for elbow extension. Additional strain in the forearm for wrist extension was 1.1% (SEM, 0.2%), for shoulder abduction 1.0% (SEM, 0.2%), and for neck side flexion 0.1% (SEM, 0.1%). With the limb flexed, sliding was delayed and sometimes the nerve or the nerve fascicles had a wavy appearance.

Conclusion. The median nerve is unloaded when the shoulder is adducted or elbow flexed. When the arm is extended (90° shoulder abduction, 60° wrist extension, and elbow straight) the total additional strain in the forearm will be 2.5–3.0%. Even in this position the strain is likely to be below levels that impair blood flow or conduction. Therefore, the median nerve appears well designed to cope with changes in bed length caused by limb movements.Relevance

These results will provide baseline data that can be used to examine entrapment neuropathies.     

Ultrasound Elastographic Evaluation in the Diagnosis of Carpal Tunnel Syndrome: Initial Findings

The purpose of this study was to investigate ultrasound (US)- and US elastography-detected changes in the median nerve of patients with carpal tunnel syndrome (CTS). Seventy-four wrists of 41 female patients with CTS (mean age, 47.73 ± 11.45 y) and 45 wrists of 24 asymptomatic female controls (mean age, 42.83 ± 10.66 y) were examined with US and US elastography. Electromyography results confirmed the diagnosis of CTS in the patients. The mean median nerve perimeter (MN-P = 15.26 ± 2.18 mm) and median nerve cross-sectional area (MN-CSA = 11.81 ± 4.05 mm²) of patients with CTS were higher than those of controls (12.08 ± 1.54 mm and 7.76 ± 1.40 mm², respectively) (p < 0.05). Mean tissue strain was lower in the patients with CTS (0.094 ± 0.045 than in the controls (0.145 ± 0.068) (p < 0.05). The most sensitive cut-off value for tissue strain was 0.0635, and the most specific was 0.19. US and US elastography, in addition to electromyography, proved to be beneficial in the diagnosis of CTS. US elastography is a new technique that may well find a place in the diagnosis of nerve entrapment syndromes.     

高频超声在腕管综合征诊断中的应用探讨

【目的】探讨高频超声在诊断腕管综合征（CTS）中的应用价值,并进一步分析神经增粗与神经传导速度及病程的相关性,并证实高频超声在诊断CTS中的临床价值。【方法】对100例健康志愿者及63例经临床和电生理检查确诊的CST进行高频超声腕管内正中神经的检查,并记录神经的横截面积（CSA）,并作CSA与神经电生理及病程的相关性分析。【结果】对照组腕管内正中神经的CSA为（8．60±2．25）mm^2,CST组CSA为（15．61±4．60）mm^2,两组相比较有显著差异（P〈0．01）。CST组CSA与神经电生理（感觉传导速速）的相关系数为-0．74（P〈0．01）,与CTS病程的相关系数为0．79（P〈0．01）。【结论】高频超声在CTS的诊断有重要应用价值,其可作为CTS及周围神经检查新的形态学诊断方法。     

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.     

A comparison of the benefits of sonography and electrophysiologic measurements as predictors of symptom severity and functional status in patients with carpal tunnel syndrome

Kaymak B, Özçakar L, Çetin A, Candan Çetin M, Ak?nc? A, Hasçelik Z. A comparison of the benefits of sonography and electrophysiologic measurements as predictors of symptom severity and functional status in patients with carpal tunnel syndrome.

Objectives

To clarify whether sonography or electrophysiologic testing is a better predictor of symptom severity and functional status in carpal tunnel syndrome (CTS) and to assess the diagnostic value of sonography in patients with idiopathic CTS.

Design

Cross-sectional.

Setting

University hospital physical medicine and rehabilitation clinic.

Participants

Thirty-four hands with CTS and 38 normative hands were evaluated.

Interventions

Not applicable.

Main Outcome Measures

The Boston Carpal Tunnel Questionnaire, which comprised symptom severity and functional status scale, was applied to CTS patients. Bilateral upper-extremity nerve conduction studies of median and ulnar nerves and sonographic imaging of the median nerve were performed in all participants. Sonographic evaluation was performed by a physician blinded to the physical and electrophysiologic findings of the subjects.

Results

Cross-sectional areas (CSAs) of the median nerve at the carpal tunnel entrance and proximal carpal tunnel were 12.5±2.6 and 10.6±2.6 versus 15.6±4.2 and 11.5±3.2 in CTS patients versus controls, respectively. Increased CSA of the median nerve at the carpal tunnel entrance (P<.002) and at the proximal carpal tunnel (P<.000) were detected in the hands with CTS. Flattening ratios did not differ in a statistically significant manner between the groups (P>.05). The best predictor of symptom severity was median nerve sensory distal latency and that of functional status was median nerve motor distal latency. The optimum cutoff value for median nerve CSA was 11.2mm² at the carpal tunnel entrance and 11.9mm² at the proximal carpal tunnel. Sensitivity, specificity, and positive and negative predictive values at the proximal carpal tunnel (88%, 66%, 71%, 80%, respectively) were higher than those at the carpal tunnel entrance (68%, 62%, 65%, 66%, respectively).

Conclusions

The best predictors of symptom severity and functional status in idiopathic CTS seem to be the electrophysiologic assessments rather than sonographic measurements. On the other hand, sonography may be helpful in the diagnosis of idiopathic CTS.