Carpal tunnel syndrome: usefulness of sonography

The aim of this study was to evaluate sonographic signs described for carpal tunnel syndrome (CTS). Sixty-four wrists from 40 patients with CTS confirmed by electromyography, and 42 wrists from 24 healthy individuals, were examined using sonography. Cross-sectional area, flattening ratio in proximal, middle and distal segments of the carpal median nerve and bowing of the flexor retinaculum were measured. The accuracies of the sonographic diagnostic criteria for CTS were assessed using receiver-operating-characteristic (ROC) analytical techniques. A significant swelling of the median nerve was observed at the proximal (p < 0.001), middle (p < 0.0001) and distal (p < 0.0001) segments and a significant bowing of the flexor retinaculum in CTS patients with respect to healthy subjects. No significant differences were found in the mean value of flattening ratio between the groups. The sensitivity, specificity, positive predictive value, and the negative predictive value were 73.4, 57.1, 72.3 and 58.5 %, respectively, in the proximal and middle segments; 75, 57.1, 72.7 and 60 % in the distal segment for areas greater than 11 mm²; and 81.3, 64.3, 77.6 and 69.2 % for the bowing of the flexor retinaculum greater than 2.5 mm. All sonographic criteria were found in 34 CTS patients (53.1 %) and none in 3 patients. Sonography may be useful in the diagnosis of CTS. The most reliable sign was increased bowing of the flexor retinaculum and cross-sectional area of median nerve with specificity close to 60 %. Received: 29 September 1999; Revised: 11 February 2000; Accepted: 2 May 2000     

Dynamic MR imaging of carpal tunnel syndrome

 Objective. To evaluate the diagnostic value of the MR imaging syndrome before and after performance of provocative exercises in patients with dynamic carpal tunnel syndrome. Design. Fat-suppressed proton-density and T2-weighted spin-echo images of the wrist were obtained prior to and after provocative, standardized exercises. Images were interpreted in masked fashion with regard to six MR criteria of carpal tunnel syndrome: (a) bowing of the transverse ligament, (b) and (c) deformation of the median nerve at the pisiform and hamate levels respectively, (d) signal abnormality of the median nerve, (e) presence of fluid in the wrist joints and/or carpal tunnel, and (f) presence of synovial swelling. Patients. Twenty-one wrists in 20 patients with subjective complaints of carpal tunnel syndrome and equivocal or negative clinical findings and negative electrodiagnostic examinations were included (age range 21–61 years, mean 37 years, 2 men and 18 women). The diagnosis of dynamic carpal tunnel syndrome was made and confirmed by surgery in 18 of the 21 symptomatic wrists. The control group consisted of 15 asymptomatic wrists in volunteers (age range 22–60 years, mean 35 years, 8 men and 7 women). Results and conclusions. Sensitivities and specificities of the six MR criteria were 90.5–100%, and 6.7–86.7%, respectively, both before and after exercise. Likelihood ratios proved statistically significant differences between the symptomatic and asymptomatic wrists (P<0.0001–0.0002) for the prevalence of all MR criteria with the exception of fluid within the carpal joints and/or carpal tunnel. Changes of the MR appearance after exercise had a low sensitivity (4.8–71.4%) but high specificity (86.7–100%) for dynamic carpal tunnel syndrome. In conclusion, MR imaging contributes to the diagnosis of carpal tunnel syndrome when clinical signs are confusing and electrodiagnostic studies are negative. Dynamic examinations improve specificity of MR imaging for such diagnosis.     

Technical advances in ultrasound and MR imaging of carpal tunnel syndrome

The aim of this study was to compare the latest ultrasound-array technology to a conventional “high-resolution” transducer, modified MRI technique, and nerve conduction studies (NCS), in the diagnosis of carpal tunnel syndrome (CTS). In 19 normal wrists and 15 wrists with CTS, US with two different transducers was performed: a conventional linear-array transducer (LA) and a newly developed Multi-D linear-array transducer (MDA) were used. The US images were evaluated determining the swelling and the flattening ratios of the median nerve and correlated to respective findings in MRI (1.5 T) and to NCS. The NCS confirmed CTS in all 15 wrists. Measures of median nerve compression (swelling and flattening ratios) were significantly different in patients with CTS and controls (p < 0.01) with both types of US transducers and MRI. The MDA yielded higher correlation to MRI than the LA. Using critical values of 1.3 for the swelling and 3.4 for the flattening ratio, MRI, and US with the MDA yielded a sensitivity of 100 % each. Modern imaging modalities allow for an exact diagnosis of CTS even in cases with only slight median nerve pathology. Received: 24 June 1999; Revised: 8 October 1999; Accepted: 25 February 2000     

High-resolution MRI predicts steroid injection response in carpal tunnel syndrome patients

Objectives

To correlate median nerve T2 signal and shape at the carpal tunnel with steroid injection (SI) response in carpal tunnel syndrome (CTS) patients.

Methods

One hundred and sixty-three CTS wrists of 92 consecutive patients who were scheduled to undergo SI were prospectively evaluated with 3-T magnetic resonance imaging (MRI) and a nerve conduction study. All patients underwent axial high-resolution T2-weighted MRI (in-plane resolution of 0.25?×?0.25 mm). The CTS wrists were classified into three groups according to the nerve T2 signal and the flattening ratio at the hook of hamate level: group 1, high and oval; group 2, high and flat; group 3, low and flat. Clinical response to SI was evaluated at 6 months after injection.

Results

One hundred and thirteen of the 163 wrists (69.3 %) responded well to SI. The percentage of improvement was 81.7 % (49/60) in group 1, 69.9 % (51/73) in group 2, and 43.3 % (13/30) in group 3 (P?<?0.01). On stepwise logistic regression analysis high-resolution MRI was the only significant independent factor for SI response in CTS patients (P?<?0.01).

Conclusions

High-resolution MRI correlates well with SI response in CTS patients and seems useful for predicting SI response.

Key Points

? MRI may help determine appropriate care in carpal tunnel syndrome. ? MRI helps in therapeutic decision-making whenever steroid injection is considered. ? T2 signal decrease of the median nerve correlates with poor outcome. ? T2 signal decrease of median nerve may reflect fibrosis and amyloid deposition.     

MR imaging of the carpal tunnel syndrome

Magnetic resonance (MR) imaging of the carpal tunnel was performed in 23 wrists of 13 patients who were suspected to have carpal tunnel syndrome (CTS). In ten out of 23 wrists, diagnostic images of the carpal tunnel could be obtained. MR images were analysed retrospectively as to swelling of the median nerve, signal intensity of the median nerve on T2 weighted image, and swelling of the tendon sheath. In 8 wrists the median nerve was significantly swollen at the inlet of the carpal tunnel. Four of them showed increased signal intensity of the median nerve on T2 weighed image at the inlet. Swelling of the tendon sheath was demonstrated in two cases. These finding seem to represent edematous change of the median nerve due to compression. Surgical correlation was obtained in two wrists. Since MR imaging is capable of demonstrating pathological changes of the median nerve in CTS, it can be a diagnostic tool in selected cases.     

腕管综合征的MRI诊断

研究腕管综合征（CTS）的MRI特征及应用价值。材料和方法：经临床及手术证实的CTS12例，行MRI检查，以横断面为主。结果：12例CTS的MRI表现为：正中神经进入腕管时肿胀增粗12例，正中神经肿胀率（MNSR）为2．25：1。正中神经腕管内受压变扁12冽，正中神经扁平率（MNFR）为3．4。腕横韧带向掌侧膨隆10例，腕横韧带膨隆率（BR）为15．8％。T2WI像正中神经信号增高12例。结论：MRI对CTS的诊断、治疗方式的选择及疗效观察有重要的价值。     

Ultrasonography Findings of the Carpal Tunnel after Endoscopic Carpal Tunnel Release for Carpal Tunnel Syndrome

ObjectiveTo investigate changes in the median nerve, retinaculum, and carpal tunnel on ultrasound after successful endoscopic carpal tunnel release (ECTR).Materials and MethodsThis prospective study involved 37 wrists in 35 patients (5 male, 30 female; mean age ± standard deviation [SD], 56.9 ± 6.7 years) with primary carpal tunnel syndrome (CTS). An in-house developed scoring system (0–3) was used to gauge the clinical improvement after ECTR. Ultrasound was performed before ECTR, and at 1, 3, and 12 months post-ECTR. Changes in the median nerve, flexor retinaculum, and carpal tunnel morphology on ultrasound after ECTR were analyzed. Ultrasound parameters for different clinical improvement groups were compared.ResultsAll patients improved clinically after ECTR. The average clinical improvement score ± SD at 12 months post-ECTR was 2.2 ± 0.7. The median nerve cross-sectional area proximal and distal to the tunnel decreased at all time intervals post-ECTR but remained swollen compared to normal values. Serial changes in the median nerve caliber and retinacular bowing after ECTR were more pronounced at the tunnel outlet than at the tunnel inlet. The flexor retinaculum had reformed in 25 (68%) of 37 wrists after 12 months.ConclusionPostoperative changes in median nerve and retinaculum parameters were most pronounced at the tunnel outlet. Even in patients with clinical improvement after ECTR, nearly all ultrasound parameters remain abnormal at one year post-ECTR. These ultrasound parameters should not necessarily be relied upon to diagnose persistent CTS after ECTR.     

Carpal tunnel: MR imaging. Part II. Carpal tunnel syndrome

The magnetic resonance (MR) images of 14 wrists of patients with carpal tunnel syndrome (CTS) were studied. Four general findings visible regardless of the cause of CTS included swelling of the median nerve, best evaluated at the level of the pisiform bone; flattening of the median nerve, most reliably judged at the hamate level; palmar bowing of the flexor retinaculum, best visualized at the level of the hamate bone; and increased signal intensity of the median nerve on T2-weighted images. Findings related to cause were tendon sheath edema in traumatic tenosynovitis, synovial hypertrophy in rheumatoid tenosynovitis, a ganglion cyst, and excessive amount of fat within the carpal tunnel, a persistent median artery, and a large adductor pollicis muscle. Knowledge of these findings may permit more rational choice of treatment. In four cases in which symptoms persisted after surgery, findings valuable in explaining or predicting the failure included incomplete incision of the flexor retinaculum, excessive fat within the carpal tunnel, persistent neuritis of the median nerve, and development of neuromas.     

Contribution of power Doppler and gray-scale ultrasound of the median nerve in evaluation of carpal tunnel syndrome

Aim of the work

To assess the role of gray-scale and power Doppler ultrasound (US) of the median nerve at the wrist in evaluating carpal tunnel syndrome (CTS).

Materials and methods

Seventy-one wrists in 51 patients with CTS in addition to 50 healthy volunteers that served as the control group were enrolled in this study. The following sonographic parameters were evaluated in both patients and controls: cross sectional area of the median nerve just proximal to the tunnel inlet (CSA1), at the pisiform bone level (CSA2), the CSA difference (ΔCSA), flattening ratio of the median nerve and bowing of the flexor retinaculum. The power Doppler US was used to assess the number of nerve vessels with estimation of the vascularity score.

Results

The ΔCSA revealed an excellent discriminative ability (AUC = 0.988) in differentiating patients with CTS at an optimal cut-off value of 3.9 mm². Intraneural hypervascularization was significantly correlated with the ΔCSA of the median nerve (P < 0.001), while not significantly correlated with the age of patients, median nerve flattening ratio and bowing of flexor retinaculum.

Conclusion

The ΔCSA and vascularity score of the median nerve are important and useful sonographic parameters in evaluation of CTS.     

Median nerve stiffness measurement by shear wave elastography: a potential sonographic method in the diagnosis of carpal tunnel syndrome

Objectives

To measure the median nerve (MN) stiffness by quantitative shear wave elastography (SWE) at the carpal tunnel inlet and to determine whether SWE can be used in the diagnosis of carpal tunnel syndrome (CTS).

Methods

The study included 37 consecutive patients (60 wrists) with a definitive diagnosis of CTS and 18 healthy volunteers (36 wrists). The MN cross-sectional area (CSA) by ultrasound and stiffness by SWE were studied. The difference between CTS patients and controls, and the difference among subgroups based on electrodiagnostic tests were studied by the Student’s t test. Interobserver variability and ROC analysis were performed.

Results

The MN stiffness was significantly higher in the CTS group (66.7 kPa) when compared to controls (32.0 kPa) (P?<?0.001), and higher in the severe or extreme severity group (101.4 kPa) than the mild or moderate severity group (55.1 kPa) (P?<?0.001). A 40.4-kPa cut-off value on SWE revealed sensitivity, specificity, PPV, NPV and accuracy of 93.3 %, 88.9 %, 93.3 %, 88.9 % and 91.7 %, respectively. Interobserver agreement was excellent for SWE measurements.

Conclusions

Median nerve stiffness at the carpal tunnel inlet is significantly higher in patients with carpal tunnel syndrome, for whom shear wave elastography appears to be a highly reproducible diagnostic technique.

Key Points

? Clinical examination is important for diagnosis of carpal tunnel syndrome ? Shear wave elastography (SWE) offers new clinical opportunities within diagnostic ultrasound ? SWE is highly reproducible in evaluation of median nerve stiffness ? Median nerve stiffness is significantly increased in carpal tunnel syndrome ? Elastography could become useful in diagnosis of carpal tunnel syndrome     

Carpal tunnel syndrome: diagnosis with high-resolution sonography.

OBJECTIVE. Carpal tunnel syndrome is characterized by typical anatomic changes that can be shown with high-resolution sonography. To determine whether these findings are reliable and can be used to establish the diagnosis, sonograms of patients with the disease were compared with sonograms obtained in patients with normal wrists. Also compared were sonograms and MR images obtained in the patients with carpal tunnel syndrome. SUBJECTS AND METHODS. Twenty wrists in 18 consecutive patients with clinical symptoms of carpal tunnel syndrome and with abnormal nerve conduction studies were examined with real-time sonography and MR imaging. The sonograms and MR images were evaluated quantitatively by two unbiased observers with regard to the size and shape of the median nerve and the palmar bowing of the flexor retinaculum. A t test was used to compare these data with those from previous sonographic studies of 28 normal wrists. Correlation coefficients for the measurements obtained with sonography and with MR were calculated. The relative accuracies of different diagnostic criteria for the diagnosis of carpal tunnel syndrome were assessed by using receiver-operating-characteristic analytical techniques. RESULTS. Characteristic findings on both MR and CT scans of the 20 wrists with carpal tunnel syndrome included swelling of the median nerve in the proximal part of the carpal tunnel in 16 wrists, flattening of the median nerve in the distal part of the carpal tunnel in 13 wrists, and increased palmar bowing of the flexor retinaculum in nine wrists. Comparison with the data of 28 normal wrists proved that these findings were significant (p less than .01 to p less than .001). Receiver-operating-characteristic analysis showed that the discrimination between wrists in normal subjects and in patients with carpal tunnel syndrome achieved with each of the three diagnostic criteria was not significantly different. Measurements of the size and flattening of the median nerve obtained from sonograms were similar to those on MR images, whereas sonography was less accurate for measuring the palmar bowing of the flexor retinaculum. CONCLUSION. We conclude that the results of sonography are reliable, and that the diagnosis of carpal tunnel syndrome can be established on the basis of sonographic findings.     

3-T MRI with diffusion tensor imaging and tractography of the median nerve

Objective

To apply diffusion tensor imaging (DTI) and tractography to the median nerve by use of a 3-T MRI device in order to demonstrate potential differences in diffusion parameters between healthy subjects and patients with carpal tunnel syndrome (CTS).

Methods

The median nerve of 15 patients and 20 healthy volunteers was examined in two sequences: DTI and a high-resolution T1-weighted sequence. Mean fractional anisotropy (FA) and mean apparent diffusion coefficient (ADC) were measured based on tractography findings. Mean FA was significantly lower in CTS patients (P?=?0.01) whereas no significant difference was found in mean ADC. Focal measurements of FA and ADC were also obtained at three locations along the course of the median nerve.

Results

We observed a highly significant difference (P?<?0.0001) between FA measured at the proximal carpus and FA measured at the distal carpus in healthy subjects and CTS patients. Focal FA values along the median nerve showed an opposite trend in the two groups: in healthy subjects FA tended to increase (P?<?0.05) whereas in subjects with CTS it tended to decrease (P?=?0.0001). We defined a threshold value of ?0.058 (FA3-FA1) that was sensitive and specific for nerve compression.

Conclusion

DTI and tractography can detect chronic nerve compression.

Key Points

? Diffusion tensor magnetic resonance imaging offers new information about carpal tunnel syndrome. ? Diffusion tensor MRI of the median nerve provides some functional data. ? Mean fractional anisotropy (FA) was lower in patients with CTS than volunteers. ? There was no significant difference in ADC values between patients and volunteers. ? Fractional anisotropy seems a sensitive and specific predictor of chronic nerve compression.     

Comparison of Magnetic Resonance Imaging and Ultrasonography in Diagnosing and Grading Carpal Tunnel Syndrome: A Prospective Study

ObjectiveTo use anatomic measurements on magnetic resonance imaging (MRI) and ultrasonography (USG) in diagnosing and grading carpal tunnel syndrome (CTS) using nerve conduction studies (NCS) as the gold standard.Material and methodsIn this prospective study, 26 patients with CTS (45 wrists; 22 female and 4 male patients; mean ± SD age of 49.42 + 14.47 years) and 19 age and sex matched healthy volunteers (32 wrists; 15 female and 4 male volunteers, mean ± SD age of 42.52 + 10.85 years) underwent MRI and USG. Cross-sectional area (CA) of median nerve was measured using free hand ROI at four levels: hamate hook (H0), pisiform bone (PI0), 1 cm proximal (PI1) and 2 cm proximal to PI0 (PI2). Relative median nerve signal intensity (MNSI) was calculated as ratio of median nerve signal intensity with hypothenar muscle signal intensity. Flexor retinacular bowing was calculated at hamate hook level. Echogenicity and Power Doppler vascularity of median nerve were assessed on USG. Independent t-test, chi square test and receiver operating characteristic curve analysis were used as appropriate.ResultsOn USG, CA measured at PI0 (95% confidence interval of 0.872-0.987) and retinacular bowing (0.816-0.912), while, on MRI, CA at PI1 (0.874-0.997) were most useful in diagnosing CTS based on the ROC and Zombie plot analysis. Area under curves for CA measurements on USG and MRI were not significantly different. CA at PI1 on MRI (0.752-0.965) was significantly different between minimal to moderate CTS and severe to extreme CTS groups (on NCS).ConclusionCA of median nerve is the most useful parameter to diagnose and grade CTS and USG and MRI are comparable for measurements. Increased retinacular bowing on USG and hypoechogenicity of median nerve increase the diagnostic confidence while MRI helps in picking up important associated conditions.     

Ultrasonographic assessment of mild and moderate idiopathic carpal tunnel syndrome

AIM: To investigate the diagnostic value of ultrasonography in mild and moderate idiopathic carpal tunnel syndrome (CTS). MATERIALS AND METHODS: Cross-sectional areas (CSA), flattening ratios at three different levels, swelling ratio, and palmar displacement were analysed in 26 patients (14 with bilateral and 12 with unilateral disease, 40 wrists in total) for the presence and the severity of CTS. Twenty had normal nerve conduction studies (NCS) defined as "mild", and 20 of them had abnormal NCS defined as "moderate". The control group consisted of 20 healthy participants. RESULTS: All parameters were significantly different between patient and control groups. Palmar displacement, swelling ratio, CSA at all levels and distal flattening ratio had the highest significance (p < 0.0001). The criterion with the highest sensitivity was the swelling ratio > or = 1.3 (72.5%), followed by the middle CSA > 9 mm2 and the palmar displacement > 2.5 mm. All of these criteria had a higher sensitivity in diagnosing moderate cases (85-100%) than diagnosing mild cases (30-55%). There was a significant difference between normal and mild CTS groups regarding palmar displacement, distal flattening ratio, middle CSA and swelling ratio (p < 0.0001 for all) and between normal and moderate groups regarding all parameters (p < 0.01 - 0.0001) When combined middle CSA, palmar displacement and swelling ratio had an overall discriminatory accuracy of 83.8%. CONCLUSION: Additional diagnostic confirmation can be provided by ultrasonography and may be preferred as the initial step instead of electrophysiological studies. Detection of at least two of the three criteria (median nerve CSA > 9 mm2 at pisiform level, swelling ratio > or = 1.3, and palmar displacement > 2.5 mm) may be helpful for the verification of the diagnosis.     

Ultrasound features of carpal tunnel syndrome: a prospective case-control study

Purpose The purpose of the study was to examine the most adequate cut-off point for median nerve cross-sectional area and additional ultrasound features supporting the diagnosis of carpal tunnel syndrome (CTS). Material and methods Forty wrists from 31 CTS patients and 63 wrists from 37 asymptomatic volunteers were evaluated by ultrasound. All patients were women. The mean age was 49.1 years (range: 29–78) in the symptomatic and 45.1 years (range 24–82) in the asymptomatic group. Median nerve cross-sectional area was obtained using direct (DT) and indirect (IT) techniques. Median nerve echogenicity, mobility, flexor retinaculum measurement and the anteroposterior (AP) carpal tunnel distance were assessed. This study was IRB-approved and all patients gave informed consent prior to examination. Results In CTS the median nerve cross-sectional area was increased compared with the control group. Median nerve cross-sectional area of 10 mm² (DT) and 9 mm² (IT) had high sensitivity (85% and 88.5%, respectively), specificity (92.1% and 82.5%) and accuracy (89.3% and 82.5%) in the diagnosis of CTS. CTS patients had an increased carpal tunnel AP diameter, flexor retinaculum thickening, reduced median nerve mobility and decreased median nerve echogenicity. Conclusion Ultrasound assists in the diagnosis of CTS using the median nerve diameter cut-off point of 10 mm² (DT) and 9 mm² (IT) and several additional findings.     

A comparison of the performance of anatomical MRI and DTI in diagnosing carpal tunnel syndrome

Purpose

To compare the performance of anatomical magnetic resonance imaging (MRI) with that of diffusion tensor imaging (DTI) in the diagnosis of carpal tunnel syndrome (CTS).

Materials and methods

We performed 3T anatomical MRI and DTI on 42 patients and 42 age-matched controls. The median nerve cross-sectional area (CSA), relative median nerve signal intensity, and palmar bowing of the flexor retinaculum, assessed with anatomical MRI, and fractional anisotropy (FA) and apparent diffusion coefficient of the median nerve, assessed with DTI, were measured at four locations: the hamate level, the pisiform level (P0), the level located 1 cm proximal to the P0 level (P1), and the distal radioulnar joint level (DR). Adding the ratios and differences of the median nerve parameters between the measurements at the DR and other locations to the diagnostic parameters, we evaluated the area under the receiver operating characteristic curves (AUCs) of all the diagnostic parameters of both scans.

Results

The AUCs of FA(P1) (0.814) and FA(P0) (0.824) in DTI were larger than the largest AUC for anatomical MRI, CSA(P1) (0.759). However, the receiver operating characteristics of the three parameters were not significantly different (P > 0.1). The sensitivity and specificity of CSA(P1) (76.2% and 73.8%) and FA(P1) (73.8% and 76.2%) increased after inclusive and exclusive combination to 90.5% each.

Conclusion

The individual performances of both scans were not significantly different in diagnosing CTS. Measuring both CSA and FA at P1 may be useful and efficient to utilize the merits of both scans and to increase the CTS diagnostic performance.     

Potential MR signs of recurrent carpal tunnel syndrome: initial experience

OBJECTIVE: In nonoperated patients, the MR diagnosis of carpal tunnel syndrome (CTS) is difficult. In the postoperative patient this difficulty is compounded. Consequently, we sought to evaluate for potential MR signs of postoperative CTS. METHODS: At 1.5 T, 41 wrists in 37 patients with previous CTS release were evaluated by two observers for 1) flexor retinacular regrowth; 2) median nerve: a) high T2 signal, b) proximal enlargement, c) fibrous fixation, d) neuroma, and e) entrapment; 3) flexor tenosynovitis; 4) mass, bursitis, accessory muscle, distal belly progression, or excessive deep fat; 5) hamate fracture; and 6) volar nerve migration. Electromyography (EMG), operative findings, and clinical follow-up were used to determine the presence of recurrent CTS. RESULTS: Fifteen of 41 wrists had recurrent CTS. Retinacular regrowth was seen in 4/15 (27%) with and 7/26 (27%) without recurrent CTS (P=0.7). Excessive fat was seen in 1/15 (7%) with and 2/26 (8%) without CTS (P=0.19). No patient had incomplete resection of flexor retinaculum, scarring, neuroma of nerve, or tendon laceration; bursitis, accessory or distal muscle progression of muscle belly, or hamate fracture. Nerve edema with high T2 signal was seen in 4/15 (27%) with and 3/26 (12%) without CTS (P=0.16); proximal enlargement was seen in 6/15 (40%) with CTS and 2/26 (8%) without CTS (P=0.007). Also, 1 patient with recurrent disease demonstrated a mass and 1 other patient without CTS had nerve entrapment. Tenosynovitis was seen in 9/15 (60%) with and 9/26 (35%) without recurrent CTS (P=0.02). Counterintuitively, the nerve was more palmar with recurrent CTS than without (mean 6.9/8.9 mm). CONCLUSION: Only proximal enlargement, tenosynovitis, and the rare mass may help to diagnose recurrent CTS by MR. However, there appears to be a subgroup of patients with recurrent neuropathy related to an excessively superficial median nerve.     

Erratum to “Sonographic findings of the median nerve and prevalence of carpal tunnel syndrome in patients with Parkinson’s disease” [Eur. J. Radiol. 67 (3) (2008) 546–550]

Purpose

Parkinson’s disease (PD) is a chronic progressive disorder which is characterized by rest tremor, akinesia or bradykinesia and rigidity. Carpal tunnel syndrome (CTS) is caused by compression of median nerve and can occur as a result of repetitive trauma. The aim of this study was to estimate the prevalence of CTS in PD and evaluate the median nerve sonographically.

Materials and methods

Fifty-three wrist of 29 patients with PD were included in the study according to Hoehn and Yahr (H&Y) clinical stage and divided into two groups. The first group consisted of 29 wrists of patients with mild PD (H&Y stage I–II). The second group consisted of 24 wrists of patients with severe PD (H&Y stage III–IV). Thirty-six wrists of 20 age-matched patients were used as control group. Both of the patients with PD and control group underwent sonography and electromyography (EMG). Axial sonograms of the median nerve were obtained at the level of distal radioulnar joint (level 1) and at the level of pisiform bone in the carpal tunnel (level 2). At each level, the cross-sectional area of the median nerve and flattening ratio were calculated.

Results

There was no significant difference for all parameters, except one parameter, between the patients with PD and control group, and also among mild and severe groups of PD and control group (p > 0.05). Interestingly, amplitude of median nerve in the second finger was significantly lower in PD patients than control group within normal limits (p = 0.010). Of all wrists of PD patients, 13 (24.4%) have been diagnosed as CTS and 7 (19.4%) control wrists had CTS. Median nerve cross-sectional area of CTS patients were more than 10 mm² in 6 (46%) wrists of PD patients but in only 1 (14%) control wrist at each level. Although it was not statistically significant, there was higher cross-sectional area at each level in patients with severe PD (level 1: 10.43 ± 2.30 mm², level 2: 10.35 ± 3.19 mm²) than patients with mild PD (level 1: 9.93 ± 2.61 mm², level 2: 9.51 ± 2.83 mm²) and control group (level 1: 9.69 ± 3.19 mm², level 2: 9.07 ± 3.61 mm²).

Conclusion

PD may pose a risk for the development of CTS due to the repetitive movement of tremor. Although sonography is not an ideal method of diagnosis for CTS, it may take our attention for indicating CTS in patients with PD especially in severe ones.     

Diffusion tensor imaging of the median nerve in healthy and carpal tunnel syndrome subjects

Purpose

To determine if diffusion tensor imaging (DTI) of the median nerve could allow identification of patients with carpal tunnel syndrome (CTS).

Materials and Methods

A total of 13 healthy subjects and 9 CTS patients were scanned on a 3T magnetic resonance imaging (MRI) scanner. The MRI protocol included a DTI sequence from which the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and the parallel and radial diffusivities could be extracted. Those parameters were quantified at different locations along the median nerve (proximal to the carpal tunnel, within the carpal tunnel, and distal to the carpal tunnel).

Results

At the carpal tunnel, the FA, radial diffusivity, and ADC differed significantly between healthy subjects and CTS patients (P < 0.0002). This highly significant difference between the two groups was due to an opposite trend of changes in the DTI indices between the proximal to the carpal tunnel and within the carpal tunnel locations. In healthy subjects the FA increased (+20%, P < 0.001) and the radial diffusivity and ADC decreased (by ?15% and ?8%, respectively, P < 0.05) between the proximal to the carpal tunnel and within the carpal tunnel locations. In CTS subjects the FA decreased (by ?21%, P < 0.05) and the radial diffusivity increased (by +23%, P < 0.01) between the proximal to the carpal tunnel and within the carpal tunnel locations.

Conclusion

DTI enables visualization and characterization of the median nerve in healthy subjects and CTS patients. DTI indices show clear‐cut discrimination between the two groups and in fact enables the of use DTI in the diagnosis of CTS. J. Magn. Reson. Imaging 2009;29:657–662. © 2009 Wiley‐Liss, Inc.

     

Diffusion tensor imaging of the median nerve before and after carpal tunnel release in patients with carpal tunnel syndrome: feasibility study

Objectives

To evaluate diffusion tensor imaging (DTI) indices of the median nerve pre and postoperatively in patients with carpal tunnel syndrome (CTS) to determine whether indices acquired prior to surgery differ from those acquired postoperatively.

Methods

Following IRB approval, ten patients with a diagnosis of CTS were prospectively recruited. Eight patients completed the study (seven women, one man). All had bilateral asymmetric symptoms, with subsequent carpal tunnel release on the more symptomatic side. DTI of both wrists were performed using single-shot spin-echo echo-planar imaging (TR/TE, 7,000/103 ms; b value 1,025 s/mm²) preoperatively, 6 weeks and 6 months after carpal tunnel release. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the median nerve at the level of the distal radioulnar joint and pisiform were determined by one investigator blinded to clinical data, side, and time relative to surgery.

Results

All patients had resolution of symptoms on the surgical side at 6 months. A significant increase in FA (p?=?0.018) and decrease in ADC (p?=?0.017) were found proximally at 6 months compared to baseline on the operative side. A significant increase in FA was observed on the operative side distally at 6 weeks (p?=?0.012) and 6 months (p?=?0.017). There was a significant difference in the percentage change in FA values from baseline to 6 months on the operative side in comparison with the non-operative side (p?=?0.017).

Conclusions

A significant increase in FA and decrease in ADC of the median nerve are seen following decompression surgery in patients with CTS.