The median to ulnar cross-sectional surface area ratio in carpal tunnel syndrome

Elastography of nerves in the wrists of cyclists

Purpose

This study aimed to investigate changes in the elasticity of the median and ulnar nerves in cyclists.

Material and methods

The study included 30 cyclists and 2 non-biking reference groups that included 32 healthy volunteers and 32 individuals with ulnar nerve entrapment neuropathies. All participants underwent physical, ultrasonographic, and elastographic examinations including assessment of nerve cross-sectional area (CSA) and stiffness (SWE). The cyclists' group was tested before and after a 2-hour workout.

Results

The values of ulnar nerve CSA and stiffness in Guyon's canal in resting cyclists were 5.30 ± 1.51 mm2 and 49.05 ± 11.18 kPa, respectively. These values were significantly higher than in the healthy volunteers, but not higher than in the nerve entrapment group. Median nerve CSA and stiffness at rest were 9.10 ± 2.61 mm2 and 38.54 ± 14.87 kPa, respectively. Both values were higher than respective values in the healthy group. Cycling induced an increase in all these parameters, although the increase in nerve stiffness was more noticeable than in CSA.

Conclusions

The elasticity of the median and ulnar nerve in cyclists remains within normal limits, questioning the belief that cyclists are at risk of nerve palsy in Guyon's canal. However, cycling workout does exert compression, resulting in transient oedema of both nerves. The dynamics of changes was more noticeable in SWE examination than in conventional ultrasound, which may depend on SWE sensitivity.

The Impact of Reference Standard on Diagnostic Testing Characteristics for Carpal Tunnel Syndrome: A Systematic Review

Lack of a reliable reference standard for carpal tunnel syndrome (CTS) diagnosis could impact the diagnostic test characteristics. This systematic review sought to evaluate differences in the accuracy of CTS diagnostic modalities based on the reference standard used.

Methods

A systematic review was performed following PRISMA guidelines to investigate diagnostic modalities used in CTS. A literature search of Embase, PubMed, and Cochrane Reviews was conducted for the years of 2010-2021 for primary data, and 113 studies met final inclusion criteria. Studies were stratified based on the reference standard utilized and diagnostic modality assessed, and the weighted means of the sensitivities and specificities were calculated.

Results

Thirty-five studies used clinical diagnosis alone as a reference standard, and 78 studies used electrodiagnostic study (EDS). The specificity for MRI and ultrasound (US) were substantially lower when EDS was used as the reference standard. MRI was the test most affected by the reference standard used, showing increased sensitivity when using EDS as the reference compared to clinical diagnosis (77.1% versus 60.9%) and decreased specificity (87.6% versus 99.2%). Regardless of the reference standard used, all tests had anticipated false-positive and/or false-negative rates of at least 10%.

Conclusions

Testing characteristics vary greatly based on the choice of reference standard, with the sensitivity of MRI most affected. Regardless of reference standard used, EDS, US, and MRI each had false-positive and/or false-negative rates too great to be appropriate for use as a screening examination.

The role of diagnostic ultrasound in the examination of carpal tunnel syndrome: an update and systematic review

BACKGROUND

Diagnostic ultrasound is becoming more available and has potential for identifying carpal tunnel syndrome (CTS), but there is a lack of consensus on optimal measurement parameters and interpretation.

PURPOSE

The purpose of this systematic review was to analyze and summarize recent published data evaluating measurement properties of diagnostic ultrasound for use in individuals with CTS.

METHODS

Five databases were searched to identify studies reporting on diagnostic measurement in individuals ≥18 years of age. Thirty-four studies underwent critical appraisal using Center for Evidence Based Medicine guidelines for diagnostic study accuracy. Each team member independently reviewed and scored the studies and consensus was reached through discussion.

RESULTS

Seventeen studies evaluating 21 unique nerve or tunnel measurements and 9 measurement ratios were included. Measurements of median nerve cross sectional area (CSA) taken at the carpal tunnel inlet consistently demonstrated good to excellent interrater reliability (ICC=0.83-0.93) and good intrarater reliability (r>0.81). All studies supported inlet CSA in differentiating between individuals with and without CTS. Carpal tunnel inlet CSA measurements demonstrated a moderate correlation to the Padua severity classification (r = 0.71), but this varied between studies. Diagnostic accuracy of CSA measured at the carpal tunnel inlet using diagnostic cutoff values ranging from 8.5 mm² to 12.6 mm² resulted in a range sensitivity (63%-96.9%) and specificity (67.9%-100%).

CONCLUSION

The US measurement most supported was the median nerve CSA measured at the carpal tunnel inlet. There was no evidence supporting the routine use of diagnostic US for individuals with suspected CTS, and no additional evidence to support replacement of electrodiagnostic studies by US. More research is needed to determine use of US for classifying CTS severity or as a differential diagnostic tool for conditions that mimic CTS.

LEVEL OF EVIDENCE

N/A.

Ultrasonography for the diagnosis of carpal tunnel syndrome: an umbrella review

BACKGROUND

Numerous sonographic modalities and parameters have been used to diagnose carpal tunnel syndrome (CTS), with varying accuracy. Our umbrella review aimed to summarize the evidence from systematic reviews and meta-analyses regarding the use of ultrasound imaging to diagnose CTS.

METHODS

Systematic reviews and meta-analyses meeting the inclusion criteria were searched in PubMed, Embase, Medline, Web of Science, and Cochrane databases from inception to March 2022. Critical appraisal, data extraction, and synthesis were performed in accordance with the criteria for conducting an umbrella review.

RESULTS

Sixteen reviews were included. Three reviews were classified as high quality, one as moderate, four as low, and eight as critically low. The cross-sectional area (CSA) of the median nerve at the carpal tunnel inlet demonstrated the best reliability and diagnostic accuracy among multiple parameters. A cutoff CSA value of 9-10.5 mm² gave the highest diagnostic performance in the general population. The degree of CSA enlargement was correlated with CTS severity. Sonoelastography and Doppler ultrasound might provide additional insights into CTS evaluation as median nerve stiffness and vascularity at the wrist were increased in these patients.

CONCLUSIONS

Sonography is a reliable tool to diagnose CTS, with inlet CSA being the most robust parameter. Sonoelastography and Doppler ultrasound can serve as auxiliary tools to confirm CTS diagnoses. Further studies are needed to expand the use of sonography for diagnosing CTS, especially in the presence of concomitant neuromuscular disease(s).

Cross-sectional Area Ratio of Median-to-Ulnar and Median-to-Superficial Radial Nerve at the Wrist for Diagnosis of Carpal Tunnel Syndrome

Objectives:

This study aimed to evaluate the diagnostic properties for carpal tunnel syndrome (CTS) of the median-to-ulnar cross-sectional area ratio (MUR) and the median-to-superficial radial cross-sectional area ratio (MRR).

Methods:

A case–control study was conducted. A physiatrist, blinded to the CTS status of the subjects, assessed the cross-sectional area of the median nerve (CSA-m), MUR, and MRR at the distal wrist crease for the CTS and control groups. The relationship of CSA-m, MUR, and MRR with CTS severity was tested using Spearman’s correlation. The overall diagnostic accuracy was determined using the area under the receiver operating characteristic curve (AUC). The cut-off values to diagnose CTS were chosen to achieve similar values for sensitivity and specificity.

Results:

There were 32 hands in the CTS group and 33 hands in the control group. The correlations of CSA-m, MUR, and MRR with CTS severity were 0.66, 0.56, and 0.34, respectively. The AUCs of CSA-m, MUR, and MRR were 0.86 (95%CI: 0.77–0.95), 0.79 (0.69–0.90), and 0.69 (0.56–0.82), respectively. The cut-off values of CSA-m, MUR, and MRR were 12 mm² (sensitivity, 81.3%; specificity, 81.8%), 2.6 (sensitivity, 68.8%; specificity, 69.7%), and 10 (sensitivity, 65.6%; specificity, 63.6%), respectively.

Conclusions

: MUR and MRR had acceptable diagnostic abilities but did not show superiority over CSA-m for CTS diagnosis.

Diagnostic utility of median nerve CSA to ulnar nerve CSA ratio in the diagnosis of mild idiopathic carpal tunnel syndrome

Background

Ultrasonography (US) measurement of median nerve cross-sectional area (m-CSA) at pisiform is increasingly utilized in identification of carpal tunnel syndrome (CTS), but there is still no agreement about the ideal cut-off value to employ. The aim of the study was to explore whether the median CSA to ulnar CSA ratio at the level of pisiform may yield a more accurate diagnosis of CTS. The study included 50 patients with mild idiopathic CTS (ICTS), assessed clinically and by nerve conduction studies, and 50 matched controls. M-CSA, median nerve flattening ratio and swelling ratio (m-SR), palmer bowing, and median CSA to ulnar CSA ratio (m-CAS:u-CSA) were measured for patients and controls. The cutoff values for the US parameters for the diagnosis of ICTS were evaluated.

Results

Compared to the control group, the ICTS group had significantly higher m-CSA (p < 0.001), higher m-CSA:u-CSA ratio (p < 0.001), higher m-SR (p = 0.012, and higher palmar bowing (p < 0.001). Use of m-CSA cutoff value of 11.78 mm2 and CSA:u-CSA ratio cut-off point of 2.97 yielded the greatest sensitivity and specificity for the diagnosis of ICTS.

Conclusion

The m-CSA:u-CSA ratio is slightly superior to the m-CSA in the diagnosis of CTS in terms of sensitivity and specificity.

The usefulness of ultrasonography to diagnose the early stage of carpal tunnel syndrome in proximal to the carpal tunnel inlet: A prospective study

This study aimed to investigate the relationship between the change of median nerve cross-sectional area (CSA) and the severity of carpal tunnel syndrome (CTS) determined by electrodiagnostic study based on the area immediately proximal to the carpal tunnel inlet (IPCTI).From December 2016 to August 2017, 34 patients (8 men and 26 women; mean age, 61.68 years ± 11.83; range, 28-80 years) with CTS symptoms were recruited. Electrodiagnostic study was performed in all patients to categorize the severity of CTS according to Bland classification. The CSA of median nerve and carpal tunnel at IPCTI, and carpal tunnel inlet/outlet level was measured by one physician. The Kruskal-Wallis test was used for comparing the CSA of the median nerve and carpal tunnel among CTS severity groups divided by electrodiagnostic study. The Dunn procedure was used for post-hoc comparison.At IPCTI and the carpal tunnel inlet level, the CSA of the median nerve was statistically larger depending on the severity of CTS (P < .01, P < .01). In the post-hoc comparison, only the CSA measured at the IPCTI level could differentiate normal reference values from mild CTS indicating the early stage (P < .05).Measuring the CSA of median nerve in IPCTI level is the most sensitive method to diagnose the early stage CTS.