Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay
Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay
Ethics
This study was a graduation thesis numbered 436 and ethically approved by the review board of Shahid Beheshti University of Medical Sciences. Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay. The written consent including all purposes and methods of the study, benefits and disadvantages of techniques and the declaration of financial support to patients involved with our study, were signed by patients and the control group.
Study methods
This was a cross sectional study which assessed the diagnostic values of ultrasound for diagnosing CTS among patients with RA. All patients with Rheumatoid Arthritis (RA) attending to the Rheumatology clinic of Loghman Hakim hospital from April 2017 to January 2018 were considered for this study. Those with medical history of diabetes, hypothyroidism, pregnancy, any types of polyneuropathy, history of injury or prior surgery at wrist, and age> 70 years were excluded. A total of 38 patients were included in our final analysis.
Demographic data including age, sex, height and weight were documented. EDx and nerve sonography were performed in an equipped center by qualified specialists. Nineteen healthy individuals were convinced and considered as the control group. Median nerve ultrasonography was performed for each healthy individual if EDx result was normal.
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Electro Diagnostic test (EDx)
EDx was performed by a physical medicine specialist evaluating both motor and sensory median nerve conduction pathways according to the American Association of Neuromascular & Electrodiagnostic Medicine (AANEM). Device settings order included 20 microV/Div sensitivity and 2 ms/Div sweep speed to check the SNAP and 4000 microV/Div sensitivity and 5 ms/Div sweep speed for CMAP. Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay. The following were recorded for the upper limb: Sensory Nerve Action Potential, Compound Muscle Action Potential, Distal Motor Latency, and Nerve Conduction Velocity. CTS diagnosis was confirmed if Median peak latency in distance of 14 cm to 3rd finger was more than 3. 5 ms, distal motor onset latency of Median nerve with 8 cm distance with thenar area was above 4. 1 ms, and subtraction of peak latency of SNAP of Median and ulnar nerve to 4th finger was more than 0. 5 ms. According to the EDx findings, patients were divided into 3 groups of mild, moderate and severe CTS.
Ultrasonography
Ultrasonography was performed by the same specialist, using a Philips HD6 scanner (Philips Ultrasound, Bothell, WA) and a 3–12-MHz linear probe. The patients were seated facing the examiner with the forearm in extended supination, the wrist in neutral position and the fingers rested on a hard surface in semi extended position. The sonogram linear probe was put on the wrist longitudinally and in perpendicular position to identify the median nerve and longitudinal, FDP, and FDS views. No pressure was added by the specialist while performing the examination. The patients were asked to move the fingers, making both the tendons and median nerve to move. Slower movement of median nerve provided a better view of the MNCSA at distal wrist crease level while the probe was rotated 90 degrees. The measurement of the MNCSA in mm2 was calculated by direct method, in which electronic calipers of the ultrasound machine was placed around the margin of the nerve. In this measurement, perineurium between neural fascicles was considered hypoechoic while median nerve sheath was considered hyperechoic. The measurement was performed three times for each patient and average values were calculated and recorded for the final analysis. The MNCSA was evaluated by means of Ultrasonography and linear probe. In each patient, one CTS hand with the longer sensory latency was chosen. If both hands had equal latencies, the dominant hand was chosen for the final analysis. Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
Statistical Analysis
Data analysis was performed using the SPSS version 22 software (SPSS Inc, Chicago, IL). Mean (± SD) was used to describe the MNCSA. Quantitative data in each group were compared by using independent samples t-test, and differences between the qualitative data in each group were analyzed using Chi-Square test. To evaluate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ultrasonography in CTS diagnosis, receiver operating characteristic (ROC) curve was used to find out the cutoff point. The cutoff point accuracies were determined, as well. Cutoff point in ROC curve was chosen based on the optimum point with the most sensitivity and specificity. P value less than 0. 05 was considered significant.
Results
According to the eligibility criteria, 38 patients with RA and 19 healthy individuals as control group were enrolled to this study. EDx and ultrasonography were performed consecutively for all individuals. The study population consisted of 4 men (7%) and 53 women (92. 9%); the mean (±SD) age was 51. 9 (±9. 3) years, and the mean (±SD) body mass index (BMI) was 27. 9 (±4. 9). Of total 57 cases, 17 patients (29. 8%) had RA with CTS, 21 patients (36. 8%) had RA without CTS. Nineteen individuals were considered as healthy control group (33. 3%) had none. The overall mean value (±SD) of the MNCSA was 10. 3 (±1. 5) mm2 ranging from 7. 4 to 14. 9 mm2, and it was 11. 86 (±1. 87) mm2, 10. 16 (±1. 71) mm2, 9. 42 (±1. 46) mm2 in RA patients with CTS, RA without CTS, and the healthy control group respectively.Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay. There was a statistically significant association between the mean MNCSA and BMI of all individuals (P=0. 019). There was a statistically significant association between the mean MNCSA and sensory latency in control group (P=0. 04), But no statistically significant association was found between the mean MNCSA and sensory latency in patients with RA and CTS and RA without CTS group (P>0. 1). The mean MNCSA in RA patients with CTS and the control group were not statistically different (P=0. 386). A statistically significant correlation was observed between the MNCSA and sensory latency in RA patients with CTS and control group (P=0. 016). Significant difference in MNCSA was found between RA patients with CTS and RA without CTS group, which was significantly higher in the RA patients with CTS group (P=0. 003). There was no statistically significant association between the MNCSA and severity (mild, moderate, severe) of CTS (P>0. 05). No statistically significant correlation was found between the MNCSA and time duration after RA diagnosis (P=0. 301).
Accuracy of Ultrasonography in CTS DiagnosisThe diagnostic accuracy of the sonographic measurement of the MNCSA was evaluated and presented by applying ROC curve (Figure 1). The area under the ROC curve (accuracy) was 0. 793 (95% CI, 0. 67–0. 91). Cutoff point of the MNCSA was determined as 9. 98 mm2 on the basis of this analysis. Finally, sonographic measurement diagnosed 32 cases with CTS. According to Kappa test, there was statistically significant association between the results of EDx (standard diagnostic test) and sonographic measurement of the MNCSA (P<0. 005). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the MNCSA measured by sonography was 88%, 57%, 88% and 57. 5% respectively. Based on the cutoff point of 9. 98 mm2 for the MNCSA, 12 cases from RA patients with CTS, 4 cases from RA without CTS, and 4 cases from control group had median nerve cross sectional area above the Cutoff point (Table 3, Figure 243). Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
Discussion
In this study, the mean value of MNCSA measured by sonographic method was significantly associated with EDx results, and it was statistically higher in RA patients with CTS patients than RA without CTS patients and healthy individuals. The MNCSA in RA patients without CTS was similar to the healthy individuals. With a 9. 98 mm2 Cutoff point of the MNCSA at carpal tunnel level in our study, the accuracy, sensitivity and specificity were 79. 3%, 88% and 57%, respectively. Positive and negative predictive values were 88% and 57. 5% respectively for the same cutoff point value.
Based on our findings, ultrasonography showed high sensitivity and specificity in CTS diagnosisand can be analternative to EDx, especially when that standard diagnostic test is not available. Also having a high sensitivity, sonographic measurement of MNCSA can be considered as a screening test for CTS diagnosis. Known et al. compared sonographic and electrodiagnostic methods for CTS diagnosis, in which the sensitivity and specificity of sonography with a 10. 7 mm2 cutoff point were 66% and 63% respectively.Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
Also the sensitivity and specificity of Eletrodiagnostic test were 78% and 83% respectively. The study did not find the sonographic method an accurate diagnostic test for CTS. In a study by Mohammadi et al, EDx was used as the gold standard test for CTS diagnosis and ultrasonography was found an acceptable substitute for EDx. However, it could not accurately measure the severity of CTS. Hammer et al. assessed the MNCSA in RA patients with and without CTS by using sonography methods. The measured value in RA patients with CTS was significantly higher than RA patients without CTS which was similar to our findings.
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Another study by Hammer et al. revealed that there was no statistically significant difference in the MNCSA measured by sonography in RA patients without CTS and the healthy control group. Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay. This similar finding to our study indicates that isolated RA disease may not increase the MNCSA if there is no CTS. In this study, there was no statistically significant correlation between the MNCSA and RA duration after diagnosis, implying that longer duration of RA onset is not an effective factor in developing RA. The presence of median bifid or trifid nerve with other variations like persistent median artery and aberrant muscle may predispose an individual to develop CTS. As sonography can evaluate the median nerve anatomy and causes of secondary CTS, it seems to be superior to EDx especially when median nerve anatomy is supposed to be evaluated. The prevalence of bifid median nerve has been reported as 2. 8% in some previous studies and 6. 8% in our study, including 2 cases in RA without CTS, 1 in healthy control and 1 in RA with CTS.
As a conclusion, ultrasonographic measurement of the MNCSA is an accurate method to diagnose CTS and it can be regarded as a non-invasive and less expensive diagnostic and even screening method instead of the previously introduced standard one, EDx. Also, we found that the presence of isolated RA disease without CTS does not increase the MNCSA that raises further evaluations in this field. We had some potential limitations in our study. First, we had a small sample size especially in RA patients with CTS group. Second, all the EDx and sonographic studies were performed by one specialist. Future research with larger sample size and more clinicians should be conducted to validate the findings of this study. Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
Carpal tunnel syndrome (CTS) is the commonest entrapment neuropathy. The aim of this study was to assess the accuracy and validity of high resolution musculoskeletal ultrasound (US) in the diagnosis of CTS in the Saudi population.
Methods
Sixty patients were diagnosed clinically to have CTS involving 89 wrists that were confirmed by neurophysiologic studies. Each affected wrist was characterized as idiopathic or associated with either diabetes mellitus or hypothyroidism and were assigned a severity grade based on results of neurophysiologic studies. Seventy-six healthy wrists from fifty age, sex and BMI matched healthy subjects were included in the control group. High resolution ultrasound (US) was performed to assess median nerve cross sectional area distal (CSAd) at the entry to the carpal tunnel and proximally (CSAp) at the level of pronator quadratus muscle with a further calculation of their difference (ΔCSA) and their mean average or CSAd+CSAp/2 (CSApd). Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
Results
There was a significant difference between both groups regarding mean ± SD of CSAd, CSAp, ∆CSA, and CSApd (p = 0.0001). A positive significant correlation was also found between the CSAd, ∆ CSA and the CSApd measurements with neurophysiologic severity grade of CTS (P = 0.001). A ∆CSA threshold of 2.5 mm2 showed the highest sensitivity and specificity to diagnose CTS in Saudis.
Conclusion
High resolution ultrasound is a valid and accurate diagnostic modality in carpal tunnel syndrome and correlated to CTS severity. A ∆CSA greater than 2.5 mm2 is considered a valid diagnostic value for CTS in our Saudi population. CTS in our patients with diabetes tend to have greater median nerve US measurement values.
Background
Carpal tunnel syndrome (CTS) is the most frequent nerve entrapment neuropathy; it occurs secondary to compression of the median nerve under the flexor retinaculum of wrist joint and leads to an enlargement of its cross-sectional area (CSA) just proximal to the site of entrapment (1).
CTS is considered an idiopathic condition, however, characteristic anatomical variations may participate in development of CTS, such as persistent median artery, or a bifid median nerve (2). It may also result from traumatic injury, inflammatory arthritis such as rheumatoid arthritis, or in association of hypothyroidism, diabetes mellitus, or pregnancy (3, 4).
Early diagnosis is essential to alleviate permanent nerve damage and functional disability. The diagnosis of CTS is usually based on clinical and neurophysiological studies (1).
US is a diagnostic imaging modality is being used more often in daily clinical practice not only to confirm the diagnosis of CTS but also it can detect anatomical variations, nerve shape and space-occupying lesions as tenosynovitis and ganglion cysts (5, 6).
Modern US equipment allows freehand tracing of the circumference of the median nerve proximal to the site of entrapment and calculation of the cross-sectional area (CSA). Unfortunately, there is no clear cut and generally accepted cutoff value of a single CSA measurement to diagnose CTS as different studies have producing widely variable results with various cutoff threshold for establishing the diagnosis of CTS which appear to be affected by group ethnicity. (7,8,9,10,11,12,13,14,15,16). Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay. Although studies had investigated median nerve CSA at the wrist in CTS patients exclusively with diabetes and hypothyroidism (17,18,19), a comparison of different US parameters, especially the CSA, in patients with idiopathic CTS versus those with CTS associated with diabetes and hypothyroidism has not been compared in the same study.
Klauser et al., assessed the CSA of median nerve distally at the region of maximal enlargement, usually just proximal to the carpal tunnel, and proximally at the level of pronator quadratus muscle, thereby using the same nerve as its own control, to improve the precision of CTS diagnosis (20).
The aim of this study was to assess the accuracy of ultrasound in diagnosis of CTS in the Saudi population using the method developed by Klauser et al. (i.e. ΔCSA) and also the mean of the proximal and distal (mean CSApd) measurements. The median nerve US measurements were further analyzed to detect any difference in the parameters between idiopathic CTS and CTS associated with diabetes mellitus or hypothyroidism.
Methods
Study design
Cross sectional cohort, randomized study
Study population
Sixty consecutive electrophysiologically confirmed CTS patients presenting to a tertiary Saudi medical center (Al Hada Armed Forces Hospital) rheumatology, neurology, neurosurgery out-patients’ clinics, during a six month period underwent US evaluation and fifty age, sex and body mass index (BMI) matched healthy subjects free from CTS manifestation with negative electrophysiologic studies for CTS from the healthy hospital workers were included as a control group for identical US study.
Inclusion criteria
Age > 18 years; right handed patients with paresthesia, numbness or tingling affecting the first three digits and the radial half of the fourth digit, which was confirmed by electrophysiologic study.Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
Exclusion criteria
BMI ≥ 30, past history of traumatic or surgical intervention; arthritis; median nerve injection, history of autoimmune rheumatic disease; bifid median nerve, or intra-articular lesions such as ganglion. Patients with nerve conduction study (NCS) findings suggestive of diabetic neuropathy rather than entrapment neuropathy at the carpal tunnel also were excluded.
Electrophysiologic methods
The electrodiagnostic studies were performed according to standard techniques for motor and sensory nerve conduction studies of median and ulnar nerves. Motor study included the determination of conduction velocity, amplitudes and latencies after stimulation of the median nerve. Sensory nerve conduction studies included the antidromic determination of conduction velocity, latencies and amplitude of the sensory nerve action potential of the median nerve. These studies were performed for all participants within 2 weeks before US examination by using a Dantec Key Point electrophysiologic device at a fixed room temperature of 25 °C during the examination of all patients and controls.
Diagnosis of CTS was based on the measurement of the median nerve compound muscle action potential (CMAP) amplitude and distal latency from the abductor pollicis brevis following stimulation 8 cm proximal to the recording electrode and the sensory nerve action potential (SNAP) obtained from the middle finger with ring-type electrodes. The palmar and wrist stimulations were 7 and 14 cm, respectively, proximal to the recording electrode.
Electrodiagnostic studies were done on both hands by expert neurologist blinded to the clinical data and study purpose. Only patients with three of the following criteria were included: median SNAP peak latency > 3.7 ms; a SNAP peak latency of the proximal 7-cm segment greater than the peak latency of the distal 7-cm segment; SNAP amplitude was < 20 μV including a conduction block (a SNAP amplitude drop of > 50% with respect to the proximal stimulation, as compared with that of the distal stimulation); median CMAP distal latency was > 4.2 ms; and CMAP amplitude was < 4.5 mV. Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay. CTS was diagnosed in patients with diabetic neuropathy if they met the following criteria: the ratio of the distal motor latency of the median to the ulnar nerve was > 1.5; the ratio of the distal sensory latency of the median to the ulnar nerve was > 1.2; the amplitude ratio of the median SNAP to the ulnar SNAP was < 0.6 (21,22,23,24,25).
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The severity of CTS was classified as mild, moderate or severe according to the modified scoring system of Padua et al. (26); Severe (absence of sensory response, abnormal distal motor latency (DML)), Moderate (abnormal sensory nerve conduction velocity (SNCV), abnormal DML), Mild (abnormal SNCV, normal DML). Furthermore, electrophysiologically confirmed CTS patients were stratified as to the etiology: idiopathic, diabetic or hypothyroid.
US technique
Sixty consecutive patients with electrophysiologically confirmed CTS and 50 healthy controls with normal electrophysiologic studies of the median nerve were examined by US by two investigators expert radiologist and rheumatologist blinded to the clinical and electrophysiologic results. 89 out of 120 wrists of the patients fulfilled inclusion criteria and were evaluated by US, whereas 76 of 100 wrists of the healthy controls underwent US evaluation (Philips CX50 scanner, using two multi-frequency linear transducers, 6–18 MHz and 5–12 MHz). Transverse US scanning of the median nerve from the distal forearm to the carpal tunnel outlet was performed with measurement of the median nerve CSA distal (CSAd) at its apparent maximal dimension of the thickest part of median nerve at the tunnel (Figs. 1, 2, 3a). Proximal transverse US scanning for CSA proximal (CSAp) measurement was done over the distal third of the pronator quadratus muscle (Figs. 1, 2, 3b). The median nerve was identified between the flexor digitorum superficialis and flexor pollicis longus muscle/myotendinous junction. Then the difference between CSAd and CSAp (ΔCSA) was calculated for each wrist in both patients and controls (20). A mean of the two CSA’s on each US study was calculated by adding the tabulated values of CSAd and CSAp and dividing the sum by two to get the mean CSAdp (CSAd+CSAp/2).Ultrasound For Detecting Carpal Tunnel Syndrome (CTS) Essay.
