The usefulness of ultrasonography in the diagnosis of carpal tunnel syndrome

Values and Diagnostic Accuracy of Electrodiagnostic Findings in Carpal Tunnel Syndrome Based on Age, Gender, and Diabetes

BACKGROUND

Appropriate cut-off values and diagnostic accuracy (DA) [sensitivity, specificity, predictive values, positive (PPV) and negative (NPV)] of electrodiagnostic findings for carpal tunnel syndrome (CTS) based on age, gender, and diabetes mellitus (DM) were not reported.

METHODS

In a retrospective study, we described the latency difference values and DA of comparative latency studies COLS [median to ulnar through palmar difference (palmdiff) and ring difference study (ringdiff), median to radial through thumb difference study (thumbdiff), and combined sensory index (CSI)] among non-CTS and CTS groups based on age, DM, and gender.

RESULTS

We included 632 patients (228 without CTS and 404 with CTS). For PPV > 90% and NPV > 50%, the best cut-offs among patients without DM, were 0.5ms, 0.8-1 ms, 1.4 ms, and 2 ms for palmdiff, thumbdiff, CSI (age < 60 years), and CSI (age > 60 years), respectively. The best cut-offs among patients with DM were 0.5 ms, 1.2 ms, 0.8 ms, 1.0-1.2 ms, 1.8 ms, 1-1.2 ms, 3.0 ms, and 3.5 ms for palmdiff (age < 50 years), palmdiff (age > 50 years), thumbdiff (age < 40 years), thumbdiff (age 40-59 years), thumbdiff (age > 60 years), CSI (age < 50 years), CSI (age 50-59 years), and CSI (age > 60 years), respectively.

CONCLUSION

The cut-off values of COLS to confirm CTS and their DA were different according to age and DM.

Diagnostic efficacy of high-frequency Grey-scale ultrasonography and Sono-elastography in grading the severity of carpal tunnel syndrome in comparison to nerve conduction studies

OBJECTIVES

To correlate the cross-sectional area (CSA) and elasticity of the median nerve (MN) measured at carpal tunnel inlet between healthy controls and various degrees of carpal tunnel syndrome (CTS) graded as per nerve conduction studies (NCS).

MATERIALS AND METHODS

A total of 53 patients (with 81 wrists) presenting with clinical symptoms characteristic of CTS, having their diagnosis confirmed and severity graded by NCS, and 48 healthy controls (with 96 wrists) were included in the study. All the study participants underwent wrist ultrasound which included initial Grey-scale USG followed by strain and shear wave elastography. The CSA and elasticity (in terms of strain ratio and shear modulus) of MN were measured at the carpal tunnel inlet. Statistical analysis was performed using the Mann-Whitney U test to compare between the two groups and for subgroup analysis of cases. The diagnostic performance of each variable was evaluated using the receiver operating characteristic curves.

RESULTS

The mean CSA was 9.20 ± 1.64, 11.48 ± 1.05, 14.83 ± 1.19 and 19.87 ± 2.68 mm2, the mean shear modulus was 17.93 ± 2.81, 23.59 ± 2.63, 32.99 ± 4.14 and 54.26 ± 9.24 kPa and the mean strain ratio was 5.26 ± 0.68, 5.56 ± 0.70, 7.03 ± 0.47 and 8.81 ± 0.94 in control, mild, moderate and severe grades of CTS, respectively (p < 0.001).

CONCLUSION

The combined utility of Grey-scale USG and Elastography may serve as a painless and cost-effective alternative to NCS in grading the severity of CTS.

Evaluation of ultrasound as diagnostic tool in patients with clinical features suggestive of carpal tunnel syndrome in comparison to nerve conduction studies: Study protocol for a diagnostic testing study

BACKGROUND

Carpal Tunnel Syndrome (CTS) is the most common compressive neuropathy, accounting for 90% of all neuropathies. Its prevalence ranges from 3.8%-7.8% in the population. The gold standard for its diagnosis is the neurophysiological study (85% sensitivity and 95% specificity), with the disadvantage of being invasive, complex and expensive, which means an increase in cost and time for the diagnosis of the disease. The main objective of this diagnostic test evaluation study is to investigate the value of ultrasound in the diagnosis of CTS, and among the secondary objectives, to establish the ultrasound parameters that are predictors of CTS in comparison with neurophysiological studies, attempting to standardize a protocol and reference values that determine the presence or absence of CTS.

METHODS

Prospective, cross-sectional study. The reference test with which we compared the ultrasound is the neurophysiological test (NPT). Patients will come consecutively from the Neurophysiology Department of the Virgen Macarena Hospital, with clinical suspicion of CTS and fulfilling the inclusion/exclusion criteria. To calculate the sample size (EPIDAT program) we proposed a sensitivity of 78% and specificity of 87% with a confidence level of 95%, requiring 438 patients (264 NPT positive, 174 NPT negative). We followed an ultrasound study protocol that included the ultrasound variables: cross-sectional area at the entrance and exit of the tunnel, range of nerve thinning, wrist-forearm index, flexor retinaculum bulging, power Doppler uptake and the existence of adjacent wrists or masses. We propose a timeline for the study to be performed between 2020 and 2023. Finally, we propose a cost-effectiveness analysis.

DISCUSSION

Ultrasound not only allows to objectify the alterations of the median nerve but also the underlying pathological mechanisms in CTS. A multitude of ultrasound parameters have been described that should be regarded in syndrome's study, among which we included the cross-sectional area, the range of nerve thinning, the wrist-forearm index, flexor retinaculum bulging, power Doppler uptake and assessment of anatomical alterations. The use of ultrasound as a diagnostic tool in CTS has many advantages for both doctors and the patients, as it is a non-invasive, convenient, and fast tool increasingly accessible to professionals.

TRIAL REGISTRATION

Trials registry number: NCT05556278.

Characteristics of diabetic and non-diabetic carpal tunnel syndrome in terms of clinical, electrophysiological, and Sonographic features: a cross-sectional study

BACKGROUND

Although diabetes is considered a major risk factor for carpal tunnel syndrome (CTS), the characteristics of diabetic CTS have not been fully understood.

OBJECTIVE

This study is aimed at evaluation of the clinical, electrophysiological, and ultrasonographic findings of non-diabetic and diabetic CTS.

METHODS

This retrospective, cross-sectional study included patients diagnosed with CTS. Patient age, sex, involved side, body mass index, clinical and electrophysiological findings, and median nerve cross-sectional area (CSA) were identified. Diabetes was identified through patient or guardian interviews, medical records, and medication history. Linear and binary logistic regression models were established to confirm the associations between the electrophysiological findings, median nerve CSA, and clinical outcomes. Covariates, such as age, sex, body mass index, diabetes, symptom duration, and thenar muscle weakness were adjusted.

RESULTS

Out of the 920 hands, 126 and 794 belonged to the diabetic and non-diabetic CTS groups, respectively. The patients were significantly older in the diabetic CTS group (P < 0.001). The rate of thenar weakness in the diabetic CTS group was also significantly higher than that in the non-diabetic CTS group (P = 0.009). The diabetic CTS group had a more severe electrodiagnostic grade (P = 0.001). The prolonged onset latency of the compound motor nerve action potential (CMAP) and median nerve CSA were well associated with the degree of clinical symptoms. Increased median nerve CSA was significantly associated with prolonged CMAP onset latency (β = 0.64; P = 0.012), prolonged transcarpal latency (β = 0.95; P = 0.044), and decreased CMAP amplitude (β = -0.17; P = 0.002) in the non-diabetic CTS group.

CONCLUSION

Diabetic CTS had more profound electrophysiological abnormalities. Distal motor latency and median nerve CSA were not only associated with each other, but also with clinical symptoms. Further studies are needed to investigate the pathophysiological mechanisms underlying diabetic CTS.

Ultrasound Measurements of the Median Nerve at the Distal Wrist Crease Correlate With Electrodiagnostic Studies

Background: Carpal tunnel syndrome (CTS) is the most common nerve entrapment neuropathy and is commonly evaluated using electrodiagnostic studies (EDSs). Ultrasound (US) has emerged as a potentially easier and more comfortable alternative to EDSs. The purpose of this study is to evaluate whether measurements of the cross-sectional area (CSA) of the median nerve via US correlate with the severity rating of CTS based on EDSs. Methods: A retrospective review of patients aged 18 years or older who underwent US and EDSs of the median nerve for CTS was performed. Sensory nerve action potential, distal motor latency, and compound muscle action potential were measured, and severity was graded on American Association of Neuromuscular and Electrodiagnostic Medicine guidelines. Cross-sectional area of the median nerve was measured via US at the wrist crease. Results: There was a significant association between increasing CSA and increasing EDS severity (P < .0001). The mean CSA for normal, mild, moderate, and severe CTS was 7.48 ± 2.00, 10.36 ± 2.53, 12.01 ± 3.64, and 14.34 ± 4.77 mm2, respectively. The area under the curve demonstrated the ability of median nerve CSA to discriminate between normal and abnormal EDSs with an optimal cutoff CSA of ≥10 mm2, as well as, the ability to discriminate between mild CTS and moderate to severe CTS at a cutoff CSA of greater than or equal to 12 mm2. Conclusions: The results of this study show that US measurements of the median nerve at the distal wrist crease discriminate between normal and abnormal EDSs, and between mild CTS and moderate to severe CTS.

Ultrasonographic measurement of median nerve and wrist skin thickness in patients with carpal tunnel syndrome: relationship with clinical, electrophysiologic and functionality

The study aimed to investigate the relationship between the proximal and distal cross-sectional area (CSA) of the median nerve and wrist skin thickness measured by ultrasound in patients with carpal tunnel syndrome (CTS), demographics, disease characteristics, electrophysiological measurements, symptom severity, functionality, and symptom severity. 98 patients with electrophysiological diagnoses of CTS in the dominant hand were included in the study. Proximal and distal CSAs of the median nerve and wrist skin thickness were measured ultrasonographically. Demographic and disease characteristics of the patients were recorded. Patients were evaluated with the Historical-Objective scale (Hi- Ob) for clinical staging, the Functional status scale (FSS) for functional status, and the Boston symptom severity scale (BSSS) for symptom severity. Ultrasonographic findings were correlated with demographic and disease characteristics, electrophysiological findings, Hi-Ob scala, Functional status scale (FSS), and Boston symptom severity scale (BSSS). Proximal median nerve CSA median was 11.0 (7.0-14.0) mm2, distal median nerve CSA median was 10.5 (5.0-18.0) mm2, and wrist skin thickness was measured 1.10 (0.6-1.40) mm. Median nerve CSAs were positively correlated with the CTS stage and FSS, negatively correlated with the sensory nerve action potential of the median nerve (SNAP) and the compound muscle action potential of the median nerve (CMAP) ( p<0.05). Wrist skin thickness was positively correlated with disease characteristics, including the presence of paresthesia and loss of dexterity and FSS and BSSS levels. Ultrasonographic measurements in CTS are associated with functionality rather than demographics. Especially the increase in wrist skin thickness leads to an increase in symptom severity.

The cross-sectional morphology of median nerve in carpal tunnel of healthy, adult population: A systematic review and meta-analysis

The cross-section area is a crucial parameter to assess peripheral neuropathy. The ultrasonographic evaluation of cross-section area of median nerve is a low-cost and readily available tool for diagnosis and assessment. However, the intra-nerve dimensional variability and its normative reference value in a healthy subject are missing. The current meta-analysis aims to capture the median nerve cross-section area for healthy subjects and generate a comprehensive ultrasonographic reference data set for each population.

METHODS

The full text of manuscripts were collected after short-listing the abstracts collected from search strategy. A quality assurance tool was used to capture the risk of bias of each study after reviewing the included manuscripts. The pooled estimate of cross-section area was stratified according to anatomical landmarks, sex, and ancestry.

RESULTS

A total of 97 observational studies dealt with 6679 wrists of healthy subjects were included. The pooled estimate of the cross-section area of median nerve at carpal tunnel inlet was 8.54mm² [95% CI: 8.34-8.74mm²]. The same pooled estimate at carpal tunnel outlet was 8.03mm² [95% CI: 7.46-8.60mm²]. Both these pooled estimates have significant correlation with mean age of population. Age and sex were two primary predictors of the cross-section of median nerve. The flattening ratio, circularity, and wrist-forearm ratio of median nerve were also computed.

CONCLUSION

These normative data could serve as a reference for assessing median nerve pathologies, including carpal tunnel syndrome. The ethnic variation of pooled estimate and heterogeneity will guide clinician set up the reference value for diagnostic criteria.

Clinical Relevance of Ultrasonographic and Electrophysiological Findings of the Median Nerve in Unilateral Carpal Tunnel Syndrome Patients

Few studies have compared the unaffected and affected sides in the same carpal tunnel syndrome (CTS) patients using ultrasonography and electrophysiological tests. We focused on unilateral idiopathic CTS patients to investigate whether clinical test results differ between the unaffected and affected sides. The bilateral wrist joints of 61 unilateral idiopathic CTS patients were evaluated. The median nerve cross-sectional area of ultrasound image, and latencies of the compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) were measured. The values obtained were compared between the affected and unaffected sides. The diagnostic accuracies of each parameter were assessed, and cut-off values were defined. Significant differences were observed in all parameters between the affected and unaffected sides (p < 0.01). Area under the curve (AUC) values were 0.74, 0.88, and 0.73 for the cross-sectional area, CMAP distal latency, and SNAP distal latency, respectively. Cut-off values were 11.9 mm2, 5.1 ms, and 3.1 ms for the cross-sectional area, CMAP distal latency, and SNAP distal latency, respectively. The most reliable parameter that reflected clinical symptoms was the distal latency of CMAP. Cut-off values for each parameter are considered to be an index for the onset of the clinical symptoms of CTS.

Diagnostic Utility of Superb Microvascular Imaging and Power Doppler Ultrasonography for Visualizing Enriched Microvascular Flow in Patients With Carpal Tunnel Syndrome

Recent studies suggest that blood flow changes in the median nerve may help confirm a diagnosis of carpal tunnel syndrome (CTS). Herein, we examined the utility of superb microvascular imaging (SMI), a new ultrasonographic (US) technique for visualizing microvascular flow, for detecting blood flow differences between CTS patients and healthy controls. We performed a retrospective analysis of 28 hands with suspected CTS. Patients received both nerve conduction and US examinations. Ten healthy volunteers were enrolled as the control group. The nerve compression ratio and the blood flow signal area were quantified using color Doppler US (CDUS), power Doppler US (PDUS), and SMI. Correlation analyses between the blood flow signal area, the compound muscle action potential of the thenar muscle, and the nerve compression ratio were performed. As a result, the mean nerve compression ratio was found to be significantly higher in the CTS group. There were no differences in the blood flow signal area between the groups using CDUS, while PDUS and SMI showed higher blood flow signals in the CTS group. The blood flow signal area measured by SMI had stronger correlations with the compound muscle action potential amplitude and the nerve compression ratio than those for PDUS. The diagnostic utility of SMI was equivalent to PDUS, but superior to conventional CDUS. Nevertheless, the blood flow signal by SMI was more strongly correlated with the electrophysiological severity and compression ratio than for PDUS. Use of SMI in future studies may help clarify the underlying mechanisms of blood flow changes in CTS.

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.

Influence of Disease Activity and Body Composition Parameters on Cross-Sectional Area of the Median Nerve in Acromegalic Patients

Carpal tunnel syndrome (CTS) is neuropathy that occurs due to compression of the median nerve in the carpal tunnel. Acromegaly is one of the important causes of CTS. The aim of this study was to examine median nerve with ultrasound in acromegalic patients and to assess the relationship with activity, duration of disease and body composition parameters. We prospectively examined the cross-sectional area (CSA) of the median nerve with high-resolution ultrasound in 107 acromegalic patients – control group (70 females and 37 males) and 107 healthy controls (70 females and 37 males) matched for age, gender, and BMI. Body composition parameters were assessed by dual-energy X-ray absorptiometry (DXA). The Student t-tests and Pearson correlation were used for data analysis. The cross sectional area of the median nerve was increased in acromegalic patients compared to controls (11.9±4.8 mm2 vs. 7.7±2.4 mm2, P<0.001). Positive correlation was found between IGF-1 levels and CSA in the acromegalic group (R = 0.400, P<0.001). Relationship between CSA and duration of acromegaly was not confirmed. In acromegalic patients, BMI correlated with the CSA (R=0.294, P=0.002). There was no significant difference in BMI, fat mass between the acromegalic and control group, but lean mass was higher in acromegalic patients compared with controls (54.8±13.3 vs. 51±11.6, P=0.047). Lean mass and LMI (total body lean mass/height) positively correlated with CSA in acromegalic patients (R=0.340, P<0.001; R=0.424, P<0.001). No correlation was observed between fat mass and CSA of median nerve in all groups. We confirmed the enlargement of the median nerve in acromegalic patients. This enlargement is proportional to the degree of IGF-1 levels and is not dependent on the duration of the disease. The enlargement of the median nerve in acromegalic patients also depends on lean body mass and is not dependent on fat body mass.

Influence of Disease Activity and Body Composition Parameters on Cross-Sectional Area of the Median Nerve in Acromegalic Patients

Carpal tunnel syndrome (CTS) is neuropathy that occurs due to compression of the median nerve in the carpal tunnel. Acromegaly is one of the important causes of CTS. The aim of this study was to examine median nerve with ultrasound in acromegalic patients and to assess the relationship with activity, duration of disease and body composition parameters. We prospectively examined the cross-sectional area (CSA) of the median nerve with high-resolution ultrasound in 107 acromegalic patients (70 females and 37 males) and 107 healthy controls (70 females and 37 males) matched for age, gender, and BMI. Body composition parameters were assessed by dual-energy X-ray absorptiometry (DXA). The Student t-tests and Pearson correlation were used for data analysis. The cross sectional area of the median nerve was increased in acromegalic patients compared to controls (11.9 ± 4.8 mm2 vs. 7.7 ± 2.4 mm2, P < 0.001). Positive correlation was found between IGF-1 levels and CSA in the acromegalic group (R = 0.400, P < 0.001). Relationship between CSA and duration of acromegaly was not confirmed. In acromegalic patients, BMI correlated with the CSA (R = 0.294, P = 0.002). There was no significant difference in BMI, fat mass between the acromegalic and control group, but lean mass was higher in acromegalic patients compared with controls (54.8 ± 13.3 vs. 51 ± 11.6, P = 0.047). Lean mass and LMI (total body lean mass/height) positively correlated with CSA in acromegalic patients (R = 0.340, P < 0.001; R = 0.424, P < 0.001). No correlation was observed between fat mass and CSA of median nerve in either group. We confirmed the enlargement of the median nerve in acromegalic patients. This enlargement is proportional to the degree of IGF-1 levels and is not dependent on the duration of the disease. The enlargement of the median nerve in acromegalic patients also depends on lean body mass and is not dependent on fat body mass.

Does Patient Sex Affect Ultrasound Cutoff Values for Severity Grading of Carpal Tunnel Syndrome?

PURPOSE

A growing body of evidence supports ultrasound (US) as an alternative first-line confirmatory test for carpal tunnel syndrome (CTS). Recent studies have demonstrated a correlation of US cross-sectional area with electrodiagnostic (EDX)-determined severity; however, it is unclear whether patient sex affects the cutoff values used for determining severity. The purpose of this study was to determine if patient sex affects US graded severity when using EDX as the reference standard.

METHODS

A cohort of 367 women and 46 men, aged 18-90 years, from 1 orthopedic hand surgeon's practice underwent EDX and US. Distal motor latency and distal sensory latency of the median nerve were recorded. Severity was classified using a modified Bland severity scale. The US measurements of the cross-sectional area of the median nerve at the wrist crease were acquired by a fellowship-trained hand surgeon. Separate receiver operator characteristic curve analyses of the male and female groups were performed for US cutoff values.

RESULTS

The cutoff value in both the female (F) and male (M) patients was 11 mm² for mild (area under the curve = 0.76 F; 0.78 M), 12 mm² for moderate (area under the curve = 0.75 F; 0.73 M), and 13 mm² for severe (area under the curve = 0.75 F; 0.71 M) CTS. The sensitivity of the cutoffs for mild, moderate, and severe CTS in the female and male groups was 49% and 56%, 44% and 50%, and 49% and 44%, respectively. The specificity of the cutoffs for mild, moderate, and severe CTS in the female and male groups was 75% and 79%, 74% and 82%, and 83% and 78%, respectively.

CONCLUSIONS

Patient sex does not appear to have a significant impact on the determination of CTS severity graded using US cutoff values. Ultrasound can be used to grade the severity of CTS with a 75% to 85% specificity but low sensitivity. A cutoff value of 13 mm² can be used to classify CTS as severe.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Reduction in median nerve cross-sectional area at the forearm correlates with axon loss in carpal tunnel syndrome

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The median nerve CSA at the forearm is smaller when CTS is involved with axon loss.

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WFR of the median nerve is highest when CTS causes slight axon loss.

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Axon loss of the median nerve in CTS hampers the diagnostic value of wCSA and WFR.

Objective

To explore the relationship between axon loss and measured cross-sectional areas of the median nerve (MN) in severe carpal tunnel syndrome (CTS).

Methods

In this retrospective study of 158 examined wrists, we compared axon loss to the ultrasound parameters MN cross-sectional area at the wrist (wCSA), MN cross-sectional area at the forearm (fCSA) and wrist-to-forearm ratio (WFR), in patients with moderate to extreme CTS. Axon loss was evaluated by needle electromyography (EMG) of the abductor pollicis brevis muscle (spontaneous activity and reduction of interference pattern).

Results

Both the spontaneous activity and interference pattern reduction correlated negatively to fCSA (r = −0.189, p = 0.035; r = −0.210, p = 0.019; respectively). In moderate CTS, both the spontaneous activity and interference pattern reduction correlated positively to WFR (r = 0.231, p = 0.048; r = 0.232, p = 0.047; respectively). The WFR was highest when slight spontaneous activity was detected. Neither wCSA nor WFR correlated with axon loss in severe and extreme CTS.

Conclusions

The fCSA is smaller when axon loss in CTS is more prominent. The WFR is highest when CTS is associated with slight axon loss of the MN.

Significance

CTS might cause retrograde axonal atrophy detected as small fCSA. Prominent axon loss in CTS may reduce the diagnostic value of WFR.

High prevalence of carpal tunnel syndrome in individuals with rare nerve growth factor-beta mutation

In Sweden, a large family with a point mutation in the nerve growth factor-beta gene has previously been identified. The carriers of this mutation have reduced small-fibre density and selective deficits in deep pain and temperature modalities. The clinical findings in this population are described as hereditary sensory and autonomic neuropathy type V. The purpose of the current study was to investigate the prevalence of carpal tunnel syndrome in hereditary sensory and autonomic neuropathy type V based on clinical examinations and electrophysiological measurements. Furthermore, the cross-sectional area of the median nerve at the carpal tunnel inlet was measured with ultrasonography. Out of 52 known individuals heterozygous for the nerve growth factor-beta mutation in Sweden, 23 participated in the current study (12 males, 11 females; mean age 55 years; range 25–86 years). All participants answered a health questionnaire and underwent clinical examination followed by median nerve conduction study in a case–control design, and measurement of the nerve cross-sectional area with ultrasonography. The diagnosis of carpal tunnel syndrome was made based on consensus criteria using patient history and nerve conduction study. The prevalence of carpal tunnel syndrome in the hereditary sensory and autonomic neuropathy group was 35% or 52% depending on whether those individuals who had classic symptoms of carpal tunnel syndrome but negative nerve conduction studies were included or not. Those who had a high likelihood of carpal tunnel syndrome based on classic/probable patient history with positive nerve conduction study had a significantly larger median nerve cross-sectional area than those who had an unlikely patient history with negative nerve conduction study. The prevalence of carpal tunnel syndrome was 10–25 times higher in individuals heterozygous for the nerve growth factor-beta mutation than the general Swedish population. Further studies are needed to better understand the underlying pathophysiological mechanisms.

Recent Advances in Ultrasound Diagnosis of Carpal Tunnel Syndrome

With the widespread use of high-resolution ultrasonography, ultrasonic examination has been shown to be useful as a diagnostic method for carpal tunnel syndrome. The main advantages of ultrasonography are that it is simple, quick, non-invasive, and economical. Another advantage is that tissue dynamics can be observed with real-time imaging. In recent reports, it has been shown that ultrasonic examination can provide similar diagnostic accuracy as nerve conduction study in the diagnosis of carpal tunnel syndrome. It has been expected that ultrasound demand in daily medical care will continue to increase. Ultrasonography in carpal tunnel syndrome shows an enlarged median nerve in proximal carpal tunnel, thickening of the flexor retinaculum, and edema around flexor tendons in cross-sectional images. In addition, with the introduction of new technologies such as ultrasonic elastography and speckle tracking, it has become possible to quantify dynamics and material property changes of nerves, tendons, and their surrounding structures. In this review, we describe recent advancements of carpal tunnel syndrome diagnosis based on ultrasound dynamic images, and discuss its pathology.

Recent Advances in Ultrasound Diagnosis of Carpal Tunnel Syndrome

With the widespread use of high-resolution ultrasonography, ultrasonic examination has been shown to be useful as a diagnostic method for carpal tunnel syndrome. The main advantages of ultrasonography are that it is simple, quick, non-invasive, and economical. Another advantage is that tissue dynamics can be observed with real-time imaging. In recent reports, it has been shown that ultrasonic examination can provide similar diagnostic accuracy as nerve conduction study in the diagnosis of carpal tunnel syndrome. It has been expected that ultrasound demand in daily medical care will continue to increase. Ultrasonography in carpal tunnel syndrome shows an enlarged median nerve in proximal carpal tunnel, thickening of the flexor retinaculum, and edema around flexor tendons in cross-sectional images. In addition, with the introduction of new technologies such as ultrasonic elastography and speckle tracking, it has become possible to quantify dynamics and material property changes of nerves, tendons, and their surrounding structures. In this review, we describe recent advancements of carpal tunnel syndrome diagnosis based on ultrasound dynamic images, and discuss its pathology.

Recent Advances in Ultrasound Diagnosis of Carpal Tunnel Syndrome

With the widespread use of high-resolution ultrasonography, ultrasonic examination has been shown to be useful as a diagnostic method for carpal tunnel syndrome. The main advantages of ultrasonography are that it is simple, quick, non-invasive, and economical. Another advantage is that tissue dynamics can be observed with real-time imaging. In recent reports, it has been shown that ultrasonic examination can provide similar diagnostic accuracy as nerve conduction study in the diagnosis of carpal tunnel syndrome. It has been expected that ultrasound demand in daily medical care will continue to increase. Ultrasonography in carpal tunnel syndrome shows an enlarged median nerve in proximal carpal tunnel, thickening of the flexor retinaculum, and edema around flexor tendons in cross-sectional images. In addition, with the introduction of new technologies such as ultrasonic elastography and speckle tracking, it has become possible to quantify dynamics and material property changes of nerves, tendons, and their surrounding structures. In this review, we describe recent advancements of carpal tunnel syndrome diagnosis based on ultrasound dynamic images, and discuss its pathology.

Blood flow velocity but not tendon mechanics relates to nerve function in carpal tunnel syndrome patients

Carpal tunnel syndrome (CTS) develops from chronic compression of the median nerve. Chronic compression results in a number of vascular, structural and functional changes to the carpal tunnel tissues which ultimately manifest in the characteristic symptoms of CTS. The purpose of this study was to investigate the interplay of median nerve function, median nerve hemodynamics, and finger flexor tendon and subsynovial connective tissue (SSCT) mechanics in CTS patients. Thirty-five patients were recruited following nerve conduction study for this double-blinded imaging study. Ultrasound B-mode, pulse-wave Doppler, and colour Doppler images and videos were collected at the proximal carpal tunnel to quantify: (1) median nerve cross-sectional area, (2) intraneural blood flow velocity in 3 wrist postures (neutral (0°), flexion (15°), extension (30°)), and (3) flexor digitorum superficialis and SSCT displacement. Results demonstrate that intraneural blood flow velocity is dependent on median nerve function and wrist posture such that patients with mild CTS are more susceptible to the effects of non-neutral wrist postures. Tendon-SSCT mechanics do not appear to differ based on severity. This study stresses the importance of limiting exposure to non-neutral wrist postures in patients with early signs of the condition.

The diagnostic accuracy of median nerve ultrasonography in elderly patients with carpal tunnel syndrome: sensitivity and specificity assessment

Background

Accurate diagnosis of carpal tunnel syndrome (CTS), the most common entrapment neuropathy, and its differentiation from other diseases are essential, especially in older individuals with advanced symptoms and modified electrophysiological abnormalities. The current study was conducted to evaluate the diagnostic accuracy of ultrasonography (US), regarding sensitivity and specificity in the diagnosis of CTS in elderly patients.

Methods

Individuals with upper limb complaints and reference subjects were recruited from the Rofaydeh Hospital, Tehran, Iran, from June 2013 to October 2014 – (15 months). We evaluate case and control subjects for health status, demographics, clinical characteristics of CTS, median nerve physiology by electrodiagnostic tests, and anatomy by US. Median nerve cross-sectional area (CSA) at precanal, tunnel inlet, midcanal, tunnel outlet, and antecubital levels was measured applying US examination.

Results

Of the 723 complaining patients, we assessed 380 patients with CTS symptoms. Electrodiagnostic studies (EDX) confirmed the CTS diagnosis in 203 of these clinically diseased patients. A total of 103 patients (of the 113 reference subjects) had normal EDX in the reference group. Comparisons of wrists between the afflicted and reference subjects demonstrated the CSA at precanal, tunnel inlet, midcanal, and tunnel outlet levels being significantly more abundant in the diseased hands than in the nondiseased hands. CSA at the tunnel inlet and the inlet-to-antecubital CSA ratio with a threshold of 8.5 mm² and 0.65 gave the best diagnostic accuracy with a sensitivity and specificity of 96.9 and 93.6% for the inlet CSA and 99 and 28% for the CSA ratio, respectively.

Conclusion

The US as a noninvasive diagnostic method may serve for the investigation of CTS in elderly patients with excellent sensitivity and specificity.

Ultrasound-guided needle release of the transverse carpal ligament with and without corticosteroid injection for the treatment of carpal tunnel syndrome

BACKGROUND

To compare the clinical effectiveness of ultrasound-guided needle release of the transverse carpal ligament (TCL) with and without corticosteroid injection in carpal tunnel syndrome (CTS).

METHODS

From June 2016 to June 2017, 49 CTS patients (50 wrists) were included in this study. Twenty-five wrists were treated with ultrasound-guided needle release of the TCL plus corticosteroid injection (group A), and 25 wrists were treated with single ultrasound-guided needle release of the TCL (group B). The following parameters were assessed and compared including postprocedure results according to relief of symptoms, ultrasound parameters (cross-sectional area of the median nerve at the levels of pisiform, flattening ratio of median nerve at the levels of the hamate bone, and the thicknesses of TCL on the cross-section at the level of the hamate bone), and electrophysiological parameters (distal motor latency and sensory conduction velocity).

RESULTS

Group A had higher overall excellent and good rate 3 months after the procedure than group B (84 vs 52%, P < 0.05). There were significant differences regarding the above ultrasonic and electrophysiological parameters between the baseline and postprocedure values in both groups (all P < 0.05). There were significant differences regarding the postprocedure values of above ultrasonic and electrophysiological parameters between the two groups (all P < 0.05). No complications such as infection or tendon rupture were noted. No procedures were converted to the open release.

CONCLUSIONS

Both techniques are effective in treating CTS. Ultrasound-guided needle release of the TCL with corticosteroid injection had better treatment benefits than single ultrasound-guided needle release of the TCL in treating CTS.

Evaluation of median nerve by shear wave elastography and diffusion tensor imaging in carpal tunnel syndrome

PURPOSE

The aim of the current study is to investigate the diagnostic role of shear-wave elastography and diffusion tensor imaging in patients with carpal tunnel syndrome.

MATERIAL AND METHODS

The study included a total of 77 wrists; 18 normal, 35 wrists with mild, 9 wrists with moderate and 15 wrists with severe carpal tunnel syndrome. Elastography of the median nerve was performed by defining the boundaries of a segment of the nerve at sagittal plane at the level of proximal carpal row. Additionally, the cross-sectional area of the median nerve was evaluated. Fractional anisotropy and apparent diffusion coefficient measurements were carried out by placing region-of-interest at three levels: at pisiform bone (carpal tunnel inlet), mid carpal tunnel, and hook of hamate (carpal tunnel outlet).

RESULTS

Patients with carpal tunnel syndrome had higher elasticity values of median nerve (53.0 kPa; IQR 40.8-77.0 kPa) compared to control subjects. (36.8 kPa; IQR 31.0-39.9 kPa) Patients with moderate-severe carpal tunnel syndrome had higher elasticity values (82 kPa; IQR 64.0-95.5 kPa) compared to patients with mild carpal tunnel syndrome. (44 kPa; IQR 32.5-59.5 kPa) Patients with carpal tunnel syndrome had lower fractional anisotropy at mid-carpal level (0.382; IQR 0.330-0.495) compared to the control group. (0.494; IQR 0.434-0.537) Patients with moderate-severe carpal tunnel syndrome had lower fractional anisotropy values (0.366; IQR 0.331-0.407) and higher apparent diffusion coefficient values (1.509 mm²/s; IQR 1.374-1.733 mm²/s) compared to patients with mild carpal tunnel syndrome. (0,423; IQR 0.324-0.526 and 1.293 mm²/s; IQR 0.967-1.514 mm²/s) CONCLUSION: Shear-wave elastography and diffusion tensor imaging are helpful imaging modalities in diagnosing carpal tunnel syndrome and assessing its severity.

Comparison of the Clinical Effectiveness of Ultrasound-Guided Corticosteroid Injection with and without Needle Release of the Transverse Carpal Ligament in Carpal Tunnel Syndrome

BACKGROUND

To compare the clinical effectiveness of ultrasound-guided corticosteroid injection with and without needle release of the transverse carpal ligament (TCL) in carpal tunnel syndrome (CTS).

METHODS

Between May 2014 and June 2016, 52 patients (56 wrists) with CTS were included in this study. Among these patients, 28 wrists were treated with ultrasound-guided corticosteroid injection plus needle release of the TCL (group A) and 28 wrists were treated with a single ultrasound-guided corticosteroids injection (group B). The following parameters were assessed and compared including postoperative results of procedure based on relief of symptoms, electrophysiological parameters (distal motor latency, sensory conduction velocity, and sensory nerve action potential of median nerve), and ultrasound parameters (anteroposterior diameter and cross-sectional area of the median nerve at the levels of pisiform and hamate bone, and the thicknesses of TCL on the cross-section at the level of hamate bone).

RESULTS

The overall excellent and good rate regarding the postoperative results of procedure based on the relief of symptoms at 1 month postoperatively was 82.1% in group A and 46.4% in group B (p = 0.004). There was significant difference in the above electrophysiological and ultrasound parameters between the preoperative and postoperative values in both groups (all p < 0.05). Furthermore, a significant difference was also observed in the postoperative values of the above-mentioned electrophysiological and ultrasound parameters in the 2 groups (all p < 0.05).

CONCLUSIONS

Both approaches had treatment benefit in CTS. Ultrasound-guided corticosteroid injection in combination with needle release of the TCL is superior to the single ultrasound-guided corticosteroids injection.

Morphologic change of nerve and symptom relief are similar after mini-incision and endoscopic carpal tunnel release: a randomized trial

BACKGROUND

The symptoms in carpal tunnel syndrome (CTS) can be ameliorated by open and endoscopic release of the transverse carpal ligament. It is unknown whether a mini-incision or endoscopic carpal tunnel release more effectively reverses the pathological changes that are observed in the median nerve in patients with CTS and these morphologic changes correlates with the subjective outcomes after carpal tunnel release. We hypothesized that (1) at 24 weeks after surgery, the subjective outcomes of mini-incision release and endoscopic release would not differ in patients with CTS; and (2) the ultrasonographic (US) morphology of the median nerve reverses similarly after mini-incision and endoscopic release; (3) the subjective outcomes correlates with these morphologic changes.

METHODS

Between November 2011 and January 2013, 67 patients with CTS in their dominant wrist were randomized to either mini-incision (n = 32) or endoscopic (n = 35) release. Each patient was assessed by both the Boston Carpal Tunnel Questionnaire (BCTQ) and the Disabilities of the Arm, Shoulder, and Hand (DASH) pre-operatively and 24 weeks' post-operation. An US examination was conducted at both time points to measure the cross-sectional area (CSA) at the inlet, middle, and outlet (CSA-I, CSA-M and CSA-O) and the flattening ratio (FR) at the middle and outlet (FR-M and FR-O) of the median nerve.

RESULTS

The post-operative mean BCTQ and DASH scores were improved significantly from the pre-operative scores in both groups (p < 0.001). The mean CSA-I decreased and CSA-M and CSA-O increased similarly in both groups (by 3.3, 3.0, and 3.8 mm² in the mini-incision group and 2.9, 3.1. and 2.7 mm² in the endoscopic group. The mean FR-M/FR-O decreased similarly from 3.6/4.2 to 3.2/3.0 in the mini-incision group and 3.8/4.3 to 3.2/2.9 in the endoscopic group. There were no significant differences in the subjective outcome scores or median nerve measures between the two groups. Improvement in the BCTQ-S only was significantly correlated with changes in the CSA at the inlet.

CONCLUSIONS

Mini-incision and endoscopic release both similarly relieved subjective symptoms and functions along with the pathological changes in the median nerve morphology along the carpal tunnel in patients with idiopathic CTS. Symptom relief after surgical decompression seems to correlate with reduced nerve swelling at carpal inlet and reversed nerve flattening inside carpal tunnel.

TRIAL REGISTRATION

This study was retrospectively registered in "ClinicalTrials.gov" at Oct 18th, 2013, and the registration number was NCT01972165 .

Review of Ultrasonography in the Diagnosis of Carpal Tunnel Syndrome and a Proposed Scanning Protocol

Carpal tunnel syndrome is the most common peripheral compressive neuropathy. Ultrasonography (US) is an emerging technology that can be used in the diagnosis of carpal tunnel syndrome. Although the cross-sectional area is the most studied and validated measurement for carpal tunnel syndrome, there is no standardized neuromuscular US scanning protocol. We review the most studied neuromuscular US characteristics and protocols in the evaluation of carpal tunnel syndrome and propose a standardized protocol for evaluating carpal tunnel syndrome with neuromuscular US based on current literature.

Grey-scale sonography and sonoelastography for diagnosing carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a common peripheral entrapment neuropathy of the median nerve at wrist level, and is thought to be caused by compression of the median nerve in the carpal tunnel. There is no standard quantitative reference for the diagnosis of CTS. Grey-scale sonography and sonoelastography (SEL) have been used as diagnostic tools. The most commonly agreed findings in grey-scale sonography for the diagnosis of CTS is enlargement of the median nerve cross-sectional area (CSA). Several authors have assessed additional parameters. “Delta CSA” is the difference between the proximal median nerve CSA at the pronator quadratus and the maximal CSA within the carpal tunnel. The “CSA ratio” is the ratio of CSA in the carpal tunnel to the CSA at the mid forearm. These additional parameters showed better diagnostic accuracy than CSA measurement alone. Recently, a number of studies have investigated the elasticity of the median nerve using SEL, and have shown that this also has diagnostic value, as it was significantly stiffer in CTS patients compared to healthy volunteers. In this review, we summarize the usefulness of grey-scale sonography and SEL in diagnosing CTS.

Comparison of high-resolution sonography and electrophysiology in the diagnosis of carpal tunnel syndrome

Background:

The diagnostic accuracy of high-resolution ultrasonography (HRUS) in comparison to electro-diagnostic testing (EDX) in carpal tunnel syndrome (CTS) is debatable.

Objective:

The aim of this study was to compare the diagnostic accuracy of HRUS with EDX in patients with various grades of CTS and CTS associated with peripheral neuropathy (CTS + PNP).

Materials and Methods:

A prospective cohort of 57 patients with possible CTS was studied along with matched controls. The cross-sectional area (CSA) of the median nerve at the inlet of carpal tunnel was assessed by a sonologist blinded to the clinical and EDX data. Palm wrist distal sensory latency difference (PWDSLD), second lumbrical-interosseus distal motor latency difference (2LIDMLD) and CSA were compared in patients with different grades of severity of CTS and CTS+PNP.

Results:

Total 92 hands of 57 patients met the clinical criteria for CTS. Mean CSA at the inlet of carpal tunnel was 0.11 ± 0.0275 cm². It had the sensitivity, specificity, positive predictive value and negative predictive values of 76.43%, 72.72%, 89.47% and 68%, respectively (P < 0.0001). Overall, HRUS had good correlation with PWDSLD and 2LIDMLD electro-diagnostic studies in all grades of CTS and CTS + PNP.

Conclusion:

HRUS can be used as a complementary screening tool to EDX. However, EDX has been found to be more sensitive and specific in mild CTS.

Assessment of the utility of ultrasonography with high-frequency transducers in the diagnosis of entrapment neuropathies

The primary aim of this paper was to assess the relevance of high-frequency ultra-sound examination in qualifying patients for either surgical or conservative treatment of peripheral entrapment neuropathies. The study was conducted in a group of 55 patients aged 7–83 (mean age 43.6), including 28 males and 27 females, who in 2009–2011 were referred to an ultrasound examination due to a clinical suspicion of entrapment neuropathies. For the purposes of the analysis, the patients were divided into four groups: carpal tunnel syndrome (1), ulnar nerve entrapment (2) (cubital tunnel syndrome and Guyon's canal syndrome), posterior interosseous nerve syndrome (3) and other entrapment neuropathies (4). The cases of isolated idiopathic carpal tunnel syndrome were excluded from the analysis. All patients underwent the interview, physical examination and ultrasound examination. Ultrasound examinations were performed with Esaote MyLab 50 and MyLab 60 systems using high-frequency broadband linear transducers: 6–18 MHz. Sixty-seven percent of patients (37 persons) underwent a neurophysiological test. Nerve echostructure, its hyperemia as well as nerve cross-sectional area or, in the case of small nerves, diameter were assessed in all patients. Furthermore, the following were assessed in individual groups: notch sign in group 1, nerve instability in a dynamic ultrasound examination in group 2, nerve angulation in a dynamic ultrasound examination and tenderness on nerve compression at the site of the visualized pathology in group 3. The analyses of the collected material were performed by means of descriptive statistics. The results of clinical and surgical verification were consistent with ultrasound findings in 96.4%. The results indicate that high-frequency ultrasonography is a valuable method in qualifying patients for various types of treatment of peripheral neuropathies resulting from compression.

The role of ultrasound in the diagnosis and management of carpal tunnel syndrome: a new paradigm

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, affecting 9% of women, and it is responsible for significant morbidity and occupational absence. Clinical assessment is used for initial diagnosis and nerve conduction (NC) studies are currently the principal test used to confirm the diagnosis. Sensitivity of NC studies is >85% and specificity is >95%. There is now good evidence that US can be used as an alternative to NC studies to diagnose CTS. US can assess the anatomy of the median nerve and also identify pathology of the surrounding structures that may compress the nerve. Median nerve enlargement (cross-sectional area ≥10 mm(2) at the level of the pisiform bone or tunnel inlet) is the most commonly used parameter to diagnose CTS on US, and sensitivity has been reported to be as high as 97.9% using this parameter. US may also be used to guide therapeutic corticosteroid injection into the carpal tunnel--thus avoiding median nerve injury--and to objectively monitor the response to treatment. There is now sufficient evidence to propose a new paradigm for the diagnosis of CTS that incorporates US. US is proposed as the initial diagnostic test in CTS based on similar sensitivity and specificity to NC studies but higher patient acceptability, lower cost and additional capability to assess carpal tunnel anatomy and guide injection.

No correlation between sonographic and electrophysiological parameters in carpal tunnel syndrome

A prospective study was carried out to investigate any correlation between electrophysiological and sonographic findings in patients with a clinical diagnosis of carpal tunnel syndrome. A total of 113 patients (113 wrists) in 90 women and 23 men, with a mean age of 60 years, underwent sonographic and electrophysiological examination. Fifty-five patients (48%) had mild, 43 (38%) moderate and 12 (11%) had severe conduction disturbances and three patients had normal conduction. Sonographic measurements showed a cross-sectional area of the median nerve of 9.9 mm(2) at the forearm and 17.8 mm(2) at the tunnel inlet. The mean anteroposterior diameter (height) of the nerve at the tunnel inlet was 2.7 mm, and the lowest height inside the tunnel was 1.8 mm. No correlation was found between sonographic and electrophysiological parameters.

Does measuring the median nerve at the carpal tunnel outlet improve ultrasound CTS diagnosis?

INTRODUCTION

Nerve conduction is often regarded as more sensitive than ultrasonography (US) for diagnosing carpal tunnel syndrome (CTS). The diagnostic value of US derives from median nerve enlargement occurring at both ends of the carpal tunnel resulting in a dumbbell-like swelling from carpal tunnel pressure. An important reason for the inferior sensitivity of US may be because measurements are restricted to the carpal tunnel inlet. We investigate the value of including median nerve enlargement at the carpal tunnel outlet for diagnosing CTS.

METHODS

Retrospective cohort study of nerve conduction verified CTS, determining sensitivity, specificity, and positive and negative predictive values of carpal tunnel inlet and outlet median nerve cross sectional area as determined by US for the diagnosis of CTS. Nerve conduction graded CTS severity.

RESULTS

127 hands from 77 patients with CTS and 35 control healthy hands were assessed. US sensitivity for diagnosing CTS increased from 65% to 84% by including outlet enlargement of the median nerve. Specificity changed from 94% to 86%, positive predictive value from 98% to 96% and the negative predictive value from 43% to 60%. 25 hands out of the 127 from CTS patients showed enlargement restricted to the outlet and mainly occurred in moderate CTS.

CONCLUSION

In our population, the use of carpal tunnel outlet median nerve enlargement in addition to inlet median nerve size increases sensitivity for diagnosing CTS by 19%.

Median neuropathy in malunited fractures of the distal radius

PURPOSE

Irritation of the median nerve is a well-characterized complication after acute fractures of the distal radius, but there is limited literature on median neuropathy in malunited fractures. The aims of our prospective study were to estimate the prevalence of the median neuropathy, explore the relationship between radiographic findings and the condition, and investigate whether corrective osteotomy without carpal tunnel release was a sufficient treatment.

METHODS

Thirty consecutive patients, who were referred to us for treatment of symptomatic distal radial malunion, underwent nerve conduction studies of both wrists by one board-certified neurologist under standardized conditions. Test results were correlated with conventional radiographic parameters (radial tilt, radial inclination, palmar shift, ulnar variance, radiolunate and capitolunate angle) and computer tomography (CT) based measurements of the cross-sectional area of the carpal tunnel. After corrective osteotomy without carpal tunnel release, 10 of 13 patients with unilateral preoperative median neuropathy agreed to an electrodiagnostic re-examination by the same neurologist.

RESULTS

Nineteen patients demonstrated abnormal test results, but only seven patients complained about paresthesias of median-innervated fingers. There was no correlation between median neuropathy and conventional radiographic parameters. Surprisingly, the cross-sectional area of the carpal canal was significantly greater for patients with median neuropathy. Symptoms resolved in all patients after corrective osteotomy. Postoperatively, six of ten patients demonstrated improved nerve conduction studies, although only four patients demonstrated normal test results.

DISCUSSION

There is a high rate of subclinical median neuropathy in malunited distal radial fractures that cannot be predicted by conventional radiographic parameters. Corrective osteotomy without carpal tunnel release is a sufficient treatment for neuropathy in malunited distal radius fractures.

Evidence-based guideline: neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome

INTRODUCTION

The purpose of this study was to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS).

METHODS

Two questions were asked: (1) What is the accuracy of median nerve cross-sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2).

RESULTS

Neuromuscular ultrasound measurement of median nerve cross-sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B).

Assessing strength of evidence in diagnostic tests

Clinical encounters between clinicians and patients begin with an attempt at diagnosis, a foundational element in determining a patient's ultimate outcome. Diagnosis that is expedient and accurate will result in a treatment that is expedient, appropriate, and cost-effective. In essence, evidence-based diagnosis is as vital as evidence-based intervention and treatment. If surgeons are committed to making expedient and accurate diagnoses, they must strive to apply diagnostic tests not just on the basis of ease, novelty, or availability but for the soundness of evidence behind them. In the scopes of both aesthetic and reconstructive surgery, advocating evidence-driven diagnostic test use is relevant. A pertinent example of how this relates to plastic surgery is the U.S. Food and Drug Administration recommendation to screen asymptomatic women with silicone breast implants with magnetic resonance imaging. For an important recommendation such as this that has tremendous cost implications to patients, sound study design and rigorous evaluation of the accuracy of magnetic resonance imaging as a screening tool has important health policy implications. The authors demonstrate how to determine the accuracy of diagnostic tests and, more importantly, illustrate the essential qualities of any study to establish the accuracy of a diagnostic test.

Pictorial essay: Role of ultrasound in failed carpal tunnel decompression

USG has been used for the diagnosis of carpal tunnel syndrome. Scarring and incomplete decompression are the main causes for persistence or recurrence of symptoms. We performed a retrospective study to assess the role of ultrasound in failed carpal tunnel decompression. Of 422 USG studies of the wrist performed at our center over the last 5 years, 14 were for failed carpal tunnel decompression. Scarring was noted in three patients, incomplete decompression in two patients, synovitis in one patient, and an anomalous muscle belly in one patient. No abnormality was detected in seven patients. We present a pictorial review of USG findings in failed carpal tunnel decompression.

The sensitivity and specificity of ultrasound for the diagnosis of carpal tunnel syndrome: a meta-analysis

BACKGROUND

Carpal tunnel syndrome (CTS) is the most commonly diagnosed compression neuropathy of the upper extremity. Current AAOS recommendations are to obtain a confirmatory electrodiagnostic test in patients for whom surgery is being considered. Ultrasound has emerged as an alternative confirmatory test for CTS; however, its potential role is limited by lack of adequate data for sensitivity and specificity relative to electrodiagnostic testing.

QUESTIONS/PURPOSES

In this meta-analysis we determined the sensitivity and specificity of ultrasound in the diagnosis of CTS.

METHODS

A PubMed/MEDLINE search identified 323 articles for review. After applying exclusion criteria, 19 articles with a total sample size of 3131 wrists were included for meta-analysis. Three groups were created: a composite of all studies, studies using clinical diagnosis as the reference standard, and studies using electrodiagnostic testing as the reference standard.

RESULTS

The composite sensitivity and specificity of ultrasound for the diagnosis of CTS, using all studies, were 77.6% (95% CI 71.6-83.6%) and 86.8% (95% CI 78.9-94.8%), respectively.

CONCLUSIONS

The wide variations of sensitivities and specificities reported in the literature have prevented meaningful analysis of ultrasound as either a screening or confirmatory tool in the diagnosis of CTS. The sensitivity and specificity of ultrasound in the diagnosis of CTS are 77.6% and 86.8%, respectively. Although ultrasound may not replace electrodiagnostic testing as the most sensitive and specific test for the diagnosis of CTS given the values reported in this meta-analysis, it may be a feasible alternative to electrodiagnostic testing as the first-line confirmatory test.

LEVEL OF EVIDENCE

Level III, systematic review of Level III studies. See Guidelines for Authors for a complete description of levels of evidence.

Median nerve deformation and displacement in the carpal tunnel during index finger and thumb motion

The purpose of this study was to investigate the deformation and displacement of the normal median nerve in the carpal tunnel during index finger and thumb motion, using ultrasound. Thirty wrists from 15 asymptomatic volunteers were evaluated. Cross-sectional images during motion from full extension to flexion of the index finger and thumb were recorded. On the initial and final frames, the median nerve, flexor pollicis longus (FPL), and index finger flexor digitorum superficialis (FDS) tendons were outlined. Coordinate data were recorded and median nerve cross-sectional area, perimeter, aspect ratio of the minimal-enclosing rectangle, and circularity in extension and flexion positions were calculated. During index finger flexion, the tendon moves volarly while the nerve moves radially. With thumb flexion, the tendon moves volarly, but the median nerve moves toward the ulnar side. In both motions, the area and perimeter of the median nerve in flexion were smaller than in extension. Thus, during index finger or thumb flexion, the median nerve in a healthy human subject shifts away from the index finger FDS and FPL tendons while being compressed between the tendons and the flexor retinaculum in the carpal tunnel. We are planning to compare these data with measurements in patients with carpal tunnel syndrome (CTS) and believe that these parameters may be useful tools for the assessment of CTS and carpal tunnel mechanics with ultrasound in the future.

Current concepts of carpal tunnel syndrome: pathophysiology, treatment, and evaluation

The current concepts of carpal tunnel syndrome (CTS) with respect to its pathophysiology, treatment, and evaluation are discussed. With regard to the pathophysiology of idiopathic CTS, biomechanical studies to determine the kinematics of the flexor tendon, and the median nerve inside the carpal tunnel may provide valuable insights. Different degrees of excursion between the flexor tendons and the median nerve could cause strain and microdamage to the synovial tissue; this has been microscopically observed. A biomechanical approach for elucidating the events that trigger the development of CTS seems interesting; however, there are limitations to its applications. Endoscopic carpal tunnel release (ECTR) is a useful technique for achieving median nerve decompression. However, it is not considered superior to conventional open carpal tunnel release in terms of fast recovery of hand function. Unless the effect of inserting a cannula into the diseased carpal tunnel on the median nerve function is quantitatively elucidated, ECTR will not be regarded as a standard procedure for relieving the median nerve from chronic compression. The treatment of CTS should be evaluated on the basis of patient-oriented questionnaires as well as conventional instruments because these questionnaires have been validated and found to be highly responsive to the treatment. It should be noted that nerve conduction studies exclusively evaluate the function of the median nerve, whereas patient-oriented questionnaires take into account not only the symptoms of CTS but other accompanying pathologies as well, such as flexor tenosynovitis. In Japan, the number of CTS patients is expected to rise; this may be attributed to a general increase in the life-span of the Japanese and increase in the number of diabetic patients. Thus, more efforts should be directed toward elucidating the pathophysiology of so-called idiopathic CTS, so that new treatment strategies can be established for CTS of different pathologies.