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Objectives: This study aimed to compare the efficacy of laser acupuncture (LA) treatment with that of placebo LA treatment in patients with idiopathic, mild-to-moderate carpal tunnel syndrome (CTS), as measured by subjective symptom assessments and objective changes in nerve conduction studies (NCSs). Design: A randomized, single-blinded, controlled study. Settings: A Teaching Hospital in the Taichung, Taiwan between March 2013 and November 2013. Subjects: 84 consecutive treatment-naive patients with CTS. Interventions: Participants were randomly divided into two treatment arms: (1) LA, administered at traditional Chinese acu-points on the affected side, once a day, 5 times a week, for 4 weeks (N = 43); and (2) placebo LA, administered using the same device and protocol, with the LA device switched off (N = 41). Outcome measures: Patients completed the Global symptom score (GSS) at baseline and two and four weeks later. The primary outcome was changes in GSS. NCSs were performed at baseline and repeated at the end of the study as a secondary outcome. Results: There was a significantly greater reduction in GSS in the LA group than in the placebo group at week 2 (-9.30 ± 4.94 vs. -2.29 ± 4.27, respectively, P < 0.01) and at week 4 (-10.67 ± 5.98 vs. -2.90 ± 5.61, respectively, P < 0.01). However, NCSs did not show significant difference between the two groups. Conclusions: LA may be more effective than placebo LA in the treatment of mild-to-moderate idiopathic CTS in terms of subjective measurement. For patients who fear needle-based treatment, such as acupuncture or local injections, or those who do not opt for early surgical decompression, LA treatment can be considered as an effective and alternative form of acu-points stimulation therapy.

Objective: We investigate electrodiagnostic markers to determine which parameters are the best predictors of spontaneous electromyographic (EMG) activity in carpal tunnel syndrome (CTS)., Methods: We enrolled 229 patients with clinically proven and nerve conduction study (NCS)-proven CTS, as well as 100 normal control subjects. All subjects were evaluated using electrodiagnostic techniques, including median distal sensory latencies (DSLs), sensory nerve action potentials (SNAPs), distal motor latencies (DMLs), compound muscle action potentials (CMAPs), forearm median nerve conduction velocities (FMCVs) and wrist-palm motor conduction velocities (W-P MCVs). All CTS patients underwent EMG examination of the abductor pollicis brevis (APB) muscle, and the presence or absence of spontaneous EMG activities was recorded. Normal limits were determined by calculating the means ± 2 standard deviations from the control data. Associations between parameters from the NCS and EMG findings were investigated., Results: In patients with clinically diagnosed CTS, abnormal median CMAP amplitudes were the best predictors of spontaneous activity during EMG examination (p<0.001; OR 36.58; 95% CI 15.85-84.43). If the median CMAP amplitude was ≤ 2.1 mV, the rate of occurrence of spontaneous EMG activity was >95% (positive predictive rate >95%). If the median CMAP amplitude was higher than the normal limit (>4.9 mV), the rate of no spontaneous EMG activity was >94% (negative predictive rate >94%). An abnormal SNAP amplitude was the second best predictor of spontaneous EMG activity (p<0.001; OR 4.13; 95% CI 2.16-7.90), and an abnormal FMCV was the third best predictor (p=0.01; OR 2.10; 95% CI 1.20-3.67). No other nerve conduction parameters had significant power to predict spontaneous activity upon EMG examination., Conclusions: The CMAP amplitudes of the APB are the most powerful predictors of the occurrence of spontaneous EMG activity. Low CMAP amplitudes are strongly associated with spontaneous activity, whereas high CMAP amplitude are less associated with spontaneous activity, implying that needle EMG examination should be recommended for the detection of spontaneous activity in those CTS patients whose NCS reveals CMAP amplitudes between 2.1 mV and the lower normal limit (4.9mV in the present study)., Significance: Using NCS, electromyographers can predict the presence of spontaneous EMG activity in CTS patients., (Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

Unlabelled: We prospectively followed up patients with carpal tunnel syndrome (CTS) in our previous study for 1 year. A total of 77 consecutive patients with electrophysiologically confirmed mild-to-moderate idiopathic CTS were randomized and assigned into 2 treatment arms: 1) 2 weeks of prednisolone 20 mg daily followed by 2 weeks of prednisolone 10 mg daily (n = 39); and 2) acupuncture administered in 8 sessions over 4 weeks (n = 38). In the current study, the patients were further followed up at 7 and 13 months using Global symptom score (GSS) assessments and nerve conduction studies repeated again at 13 months. When comparing with baseline levels, the percentages of patients with treatment failure, moderate improvement, and good improvement were significantly different between the 2 groups at month 7 [10.5, 2.6, and 86.8% for the acupuncture group and 33.3, 7.7, and 59% for the steroid group, respectively (P = .014)] and month 13 [15.8, 2.6, and 81.6% versus 51.3, 0, and 48.7%, respectively (P = .002)]. The acupuncture group had a significantly better improvement in GSS, distal motor latencies and distal sensory latencies when compared to the steroid group throughout the 1-year follow-up period (P < .01). Furthermore, significant correlation was observed between changes of GSS (month 13-baseline) and all parameters of the electrophysiological assessments except for compound muscle action potential amplitude., Perspective: This article demonstrates that short-term acupuncture treatment may result in long-term improvement in mild-to-moderate idiopathic CTS. Acupuncture treatment can be considered as an alternative therapy to other conservative treatments for those who do not opt for early surgical decompression., (Copyright © 2011 American Pain Society. Published by Elsevier Inc. All rights reserved.)

The purpose of this study is to investigate which electrodiagnostic techniques are better in clinically diagnosed patients with carpal tunnel syndrome (CTS) and patients with CTS with normal distal conduction study. A total of 230 clinically diagnosed patients with CTS and 100 normal control subjects were enrolled. All subjects were evaluated by eight electrodiagnostic techniques, including conventional conduction studies: median distal sensory latency and distal motor latency; short distance conduction studies across wrist, including wrist-palm sensory conduction time and wrist-palm motor conduction velocity; comparison of median sensory conduction across the wrist with radial or ulnar nerves in the same limb (median-radial sensory latency difference [M-R] or median-ulnar sensory latency difference [M-U]); and comparison of median wrist-palm and palm-index conduction, including distoproximal conduction time difference and distoproximal conduction time ratio. Normal limits were derived by calculating the mean ± 2 standard deviations from the data of the controls. The sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve with 95% confidence interval of each test were calculated. In clinically diagnosed patients with CTS, M-R is the best diagnostic technique with significant difference in area under the receiver operating characteristic curve (0.912) compared with other tests except that of M-U. The sensitivity, specificity, positive predictive value, and negative predictive value of M-R were 84.3%, 98%, 99%, and 73.1%, respectively. Further evaluation of patients with CTS with normal distal latencies also revealed the best diagnostic value of M-R and M-U with significance to other tests in area under the receiver operating characteristic curve. In clinical practice, after conventional median distal sensory latency and distal motor latency studies, the authors suggest performing M-R or M-U studies instead of segmental conduction or comparative studies of median nerves in the patients with CTS with normal distal latencies.

Transcarpal conduction techniques are commonly used to be supplementary techniques to distal sensory and motor latencies (DSL and DML) in the electrodiagnosis of carpal tunnel syndrome (CTS). However, which transcarpal conduction techniques, or combination of techniques, are the most sensitive for the electrodiagnosis of CTS is unknown. To determine which transcarpal conduction technique is the most sensitive for the electrodiagnosis of CTS, we prospectively conduct this study. Study subjects were 100 patients with CTS and 50 controls. In addition to DSL and DML determinations, all subjects were evaluated using four transcarpal conduction techniques. These were (1) median wrist-palm sensory conduction time (W-Psen CT); (2) median wrist-palm mixed nerve conduction time (W-Pmix CT); (3) the difference of conduction time across wrist between median and ulnar nerves (W-Pmix M-U CT); and (4) median wrist-palm motor conduction velocity (W-Pmot CV). The sensitivities and specificities of these tests were compared. Ninety patients had one or more electrophysiologic abnormalities. The DSL and DML diagnostic sensitivities were 74% and 72%, respectively. Better sensitivities were obtained with W-Psen CT (82%), W-Pmot CV (81%), W-Pmix CT (78%), and W-Pmix M-U CT (79%). Compared between four transcarpal conduction techniques, there was no significant difference in sensitivity. Of 26 patients with CTS with normal DSL, additional electrophysiologic abnormalities were revealed with W-Psen CT (30.7%), W-Pmot CV (53.8%), W-Pmix CT (30.7%), or W-Pmix M-U CT (38.5%). When W-Pmot CV was compared with W-Psen CT and W-Pmot CV versus W-Pmix CT, calculated probabilities (P = 0.07) showed a clear trend toward statistical significance. Furthermore, of 20 patients with normal DSL and DML, five patients had abnormality for W-Psen CT, eight for W-Pmot CV, four for W-Pmix CT, and six for W-Pmix M-U CT. On the basis of the results, we concluded that the most simple and reliable transcarpal conduction for electrodiagnosis of CTS was W-Psen CT. The most sensitive technique was W-Pmot CV in subjects with normal DSL or with normal DSL and DML. Evaluation of transcarpal motor conduction affords a useful supplementary technique to W-Psen CT.

Objectives: To investigate the efficacy of acupuncture compared with steroid treatment in patients with mild-to-moderate carpal tunnel syndrome (CTS) as measured by objective changes in nerve conduction studies (NCS) and subjective symptoms assessment in a randomized, controlled study., Methods: A total of 77 consecutive and prospective CTS patients confirmed by NCS were enrolled in the study. Those who had fixed sensory complaint over the median nerve and thenar muscle atrophy were excluded. The CTS patients were randomly divided into 2 treatment arms: (1) 2 weeks of prednisolone 20 mg daily followed by 2 weeks of prednisolone 10 mg daily (n = 39), and (2) acupuncture administered in 8 sessions over 4 weeks (n = 38). A validated standard questionnaire as a subjective measurement was used to rate the 5 major symptoms (pain, numbness, paresthesia, weakness/clumsiness, and nocturnal awakening) on a scale from 0 (no symptoms) to 10 (very severe). The total score in each of the 5 categories was termed the global symptom score (GSS). Patients completed standard questionnaires at baseline and 2 and 4 weeks later. The changes in GSS were analyzed to evaluate the statistical significance. NCS were performed at baseline and repeated at the end of the study to assess improvement. All main analyses used intent-to-treat., Results: A total of 77 patients who fulfilled the criteria for mild-to-moderate CTS were recruited in the study. There were 38 in the acupuncture group and 39 in the steroid group. The evaluation of GSS showed that there was a high percentage of improvement in both groups at weeks 2 and 4 (P < 0.01), though statistical significance was not demonstrated between the 2 groups (P = 0.15). Of the 5 main symptoms scores (pain, numbness, paresthesia, weakness/clumsiness, nocturnal awakening), only 1, nocturnal awakening, showed a significant decrease in acupuncture compared with the steroid group at week 4 (P = 0.03). Patients with acupuncture treatment had a significant decrease in distal motor latency compared with the steroid group at week 4 (P = 0.012). Acupuncture was well tolerated with minimal adverse effects., Conclusions: Short-term acupuncture treatment is as effective as short-term low-dose prednisolone for mild-to-moderate CTS. For those who do have an intolerance or contraindication for oral steroid or for those who do not opt for early surgery, acupuncture treatment provides an alternative choice.

The decrease of forearm median motor conduction velocity (CV) in carpal tunnel syndrome (CTS) is a common electrodiagnostic finding in clinical practice and is possibly secondary to either conduction block at wrist or retrograde conduction slowing (RCS). This study is attempted to confirm the existence of RCS and to explore why this controversy occurs for a long time. Eighty CTS patients and controls were recruited. In addition to conventional electrodiagnosis, subjects received further electrodiagnostic protocol. First, a recording electrode was placed over the wrist and then at elbow with palm stimulation to calculate indirect forearm mixed nerve CV (forearm-mix CV) that represented real measurement of nerve fibers through the carpal tunnel. Then, direct measurement of forearm-mix CV was performed with recording at the elbow and stimulation at the wrist. CTS patients had markedly prolonged distal motor and sensory latencies and significantly prolonged wrist-palm sensory and motor conduction. There was a significant decrease in forearm median motor CV; however, there was no difference in ulnar distal motor latency and forearm motor CV. The mild decrease of forearm median motor CV was not proportional to the marked reduction of W-P MCV and there was no demonstrated conduction block at wrist, implying the reduction of forearm median motor CV is unlikely due to conduction blockage or slowing of the large myelinating fibers at the wrist and RCS really occurs over the forearm median nerve. In addition, the direct Forearm-mix CV was similar in CTS and controls; however, there was a significant decrease in indirect forearm-mix CV only in the CTS. Moreover, the difference between direct and indirect forearm-mix CV was significantly greater and poor consistency of direct and indirect forearm-mix CV in CTS, suggesting that direct and indirect forearm-mix CV represent CV from quite different nerve fibers. Therefore, we conclude that RCS really does occur in CTS and the direct forearm-mix CV reflects the CV of nerve fibers without damage in CTS. The misinterpretation and measurement of different components of forearm-mix CV results in the existence of this controversy till now.

Objective: A decrease of forearm median motor conduction velocity (CV) is a common electrophysiological finding in carpal tunnel syndrome (CTS), ascribed to two possible mechanisms: either conduction block or slowing of the fastest myelinating fibers in the carpal tunnel, or retrograde axonal atrophy (RAA) with retrograde conduction slowing (RCS). We hope to utilize both direct and derived forearm median mixed nerve conduction studies to clarify the mechanism of the decrease of forearm median motor CV in CTS., Methods: Seventy-five CTS patients and 75 age-matched control subjects received conventional motor and sensory nerve conduction studies of median and ulnar nerves and forearm median mixed nerve conduction techniques. First, direct measurement of forearm median mixed conduction velocity (Forearm mixed CV) and nerve action potential amplitude (Forearm mixed amplitude) was determined with recording at elbow and stimulation at wrist. Then, stimulating electrode was placed over palm and recording at elbow and then at wrist to calculate the derived Forearm mixed CV. Electrophysiological parameters, including direct Forearm mixed CV and amplitude and derived Forearm mixed CV, were compared between CTS patients and controls., Results: CTS patients had significantly prolonged wrist-palm sensory and motor conduction, significantly decreased forearm median motor CV, and normal ulnar nerve conduction. The direct Forearm mixed amplitude was significantly decreased in CTS patients. The direct Forearm mixed CV was similar in CTS patients and controls, but there was a significant decrease in derived Forearm mixed CV in CTS group. The difference between direct and derived Forearm mixed CV was significantly greater in the CTS, suggesting that direct and derived Forearm mixed CV represent CV from different nerve fibers, one passing outside carpal tunnel without undergoing RAA or the other through the carpal tunnel with occurrence of RAA., Conclusion: A decrease of direct Forearm mixed amplitude really occurs in CTS, implying that RAA and RCS will develop over proximal median nerve at distal nerve injury and the decreased forearm median motor CV is best ascribed to RAA and RCS. Furthermore, in CTS, the direct Forearm mixed CV measures the CV from undamaged nerve fibers without passing through carpal tunnel, resulting in the misinterpretation of the cause of proximal conduction slowing secondary to conduction block or slowing over the wrist., Significance: We provide a direct evidence of the occurrence of RAA and RCS that would explain the cause of proximal median nerve conduction slowing. However, the clinical significance of RAA and RCS is uncertain.

The objective of this study was to determine the cause of median forearm motor conduction velocity (FMCV) slowing in patients with carpal tunnel syndrome, due to either focal conduction abnormality over wrist or retrograde conduction slowing, and to decide whether the slowing is related to severity of compression or not. Fifty carpal tunnel syndrome patients confirmed by conventional nerve conduction study with abnormal electromyography of the abductor pollicis brevis muscle were group 1, and 100 with normal electromyography, group 2. One hundred volunteers served as controls. In addition to conventional nerve conduction study of median and ulnar nerves, palmar stimulations for median mixed and motor nerves were also performed to calculate wrist-palm mixed nerve conduction time and motor conduction velocity (W-P MCV). For group 1, group 2, and control subjects, respectively, W-P MCV were 19.73+/-7.65 (mean+/-SD), 32.7+/-6.83, and 52.75+/-6.4 m/s, whereas median FMCV were 48.63+/-8.32, 54.42+/-2.11, and 57.86+/-4.24 m/s. There was a significant reduction in the W-P MCV (62.6%, P<0.00001) and a decrease in the median FMCV (15.95%, P<0.00001) in group 1, and 38% reduction in W-P MCV (P<0.00001) and 5.9% decrease in median FMCV (P<0.00001) in group 2 when compared with controls, but ulnar FMCV and sensory nerve conduction study results did not, suggesting the reduction of median W-P MCV is not parallel with that of median FMCV in both patients groups. Furthermore, there is a poor correlation of median FMCV and W-P MCV in patient groups, implying conduction blockage of the large myelinating fibers at the wrist, leaving only slower axons to be measured, is not the likely cause of reduction of FMCV. In addition, the reduction of compound muscle action potential amplitude of abductor pollicis brevis muscle, conduction block at wrist and weak correlation of median FMCV and compound muscle action potential amplitude of abductor pollicis brevis exclusively occurred in group 1. Therefore, the retrograde conduction slowing really occurs among patients with carpal tunnel syndrome-markedly in those with abnormal electromyography and mildly in those with only demyelination. This finding counters conventional wisdom that nerve function changes only in segments distal to injured sites.

Objective: To compare the sensitivity of median wrist-palm motor conduction velocity (W-P MCV) with those of standard sensory conduction techniques in the electrodiagnosis of carpal tunnel syndrome (CTS)., Methods: This study included 280 consecutively suspected CTS patients (360 hands) referred for evaluation and 150 volunteers who served as controls. We determined and calculated (1) median W-P MCV, (2) median motor distal latencies (DL) and median sensory DL for (3) thumb (D1), (4) index (D2) and (5) ring finger (D4), (6) median wrist-palm sensory conduction velocity (W-P SCV) and sensory conduction time (W-P SCT) for index finger and sensory latency differences between (7) median-radial (M-R) for thumb and (8) median-ulnar (M-U) nerves for ring finger. The normal limits were calculated from the median of normal controls +/-2.5 standard deviations. The sensitivities of each test were determined and compared., Results: Among the 360 hands with suspected CTS, 32 hands (8.9%) had normal electrodiagnostic studies and 328 (91.1%) had at least one abnormal electrodiagnostic study. Among the 328 hands with abnormalities, 234 (65%) had abnormal motor DL and 294 (81.7%) had abnormal W-P MCV. The sensitivity was 80.3% for D1, 72.5% for D2, 76.7% for D4, 86.7% for M-R (specificity, 98.7%), 87.2% for M-U (specificity, 96.7%), 80.8% for sensory W-P SCT and 73.6% for W-P SCV., Conclusions: W-P MCV is a valuable motor conduction technique for the diagnosis of CTS and it is confirmed again that W-P MCV is equal to or more sensitive than W-P SCV and W-P SCT. Furthermore, the findings of the present study are in agreement with the conventional wisdom that internal comparison of latency differences between median and ulnar or radial nerves is the best method for a diagnosis of patients with suspected CTS. Therefore, we recommend that CTS patients be studied according to the following steps: (1) routine sensory and motor DL, (2) if step 1 is negative, then perform and determine W-P MCV or SCT. This may increase the diagnostic yield of 10%, (3) if step 2 is negative, measure the M-U or MR. These are the final and more sensitive techniques in making a diagnosis with an additional diagnostic yield of 10%., Significance: We provide the evidence of W-P MCV that could be a standard technique for electrodiagnosis of CTS. Furthermore, we make a reasonable flow chart and recommendation for electrodiagnosis of CTS for electromyographers.

Objective: The cause of decreased median forearm motor conduction velocity (FMCV) in carpal tunnel syndrome (CTS) is best ascribed to retrograde axonal atrophy (RAA); however, the relationships between the occurrence of RAA and electrophysiological or clinical severity remains controversial. We attempt to determine whether RAA really occurs in CTS patients with normal median FMCV and to investigate any relationships between RAA and severity of compression at the wrist., Methods: Consecutive CTS patients were enrolled and age-matched volunteers served as controls. We performed conventional nerve conduction studies (NCS) and measured median and ulnar distal motor latencies (DML), FMCV, compound muscle action potential (CMAP) amplitudes, distal sensory latencies (DSL), and sensory nerve action potential (SNAP) amplitudes. Furthermore, palmar median stimulation was done to calculate the wrist-palm motor conduction velocity (W-P MCV). Patients included for analysis should have normal FMCV and needle examination. We compared each electrodiagnostic parameters between the patient group and controls., Results: The mean+/-SD of the W-P MCV for patients and controls were 33.26+/-6.74 and 52.14+/-5.85 m/s and those of median FMCV were 55.26+/-3.56 and 57.82+/-3.9 m/s, respectively. There was a significant reduction in the W-P MCV (36.2%, P<0.00001), significant decrease in the median FMCV (4.43%, P<0.00001) and SNAP amplitudes, and an increase of the DML and DSL in the patient group (P<0.00001) compared to the controls; however, there were no differences in median and ulnar CMAP amplitudes, ulnar FMCV and DML between the controls and patients., Conclusions: RAA and relatively slowed median FMCV do occur in CTS patients with normal median FMCV, regardless of severity of clinical manifestations and electrophysiological abnormalities., Significance: This article provides new information for research of the electrophysiological changes of the proximal nerve part at distal injury.

Background: The exact cause of decreased forearm median motor conduction velocity (FMMCV) in carpal tunnel syndrome (CTS) is still a subject of controversy. A conduction block or an axonal loss in the large myelinating fibers upon wrist compression, or retrograde axonal atrophy, is suspected., Methods: In order to attempt a determination of the cause, 10 patients with clinical symptoms and signs of CTS, confirmed using standard electrodiagnosis and with a slowed FMMCV <50m/s, were included in this study. Serial standard median motor conduction studies were performed at baseline, 1 week, 2 weeks, 4 weeks, 8 weeks, and 12 weeks after endoscopic ligament release. Serial median motor distal latencies (MMDL), compound muscle action potential (CMAP) amplitudes, and FMMCV, were determined and compared., Results: Significant improvement in MMDL had occurred at the 1-week follow-up examination; however, no such improvement in FMMCV was observed. Furthermore, a significant increase in CMAP amplitude was evidenced beginning 4 weeks after surgery. The results revealed an improvement in median motor conduction, across the wrist segment, that did not parallel the increase in FMMCV, suggesting that a conduction block or axonal loss at wrist compression was not the likely cause of the decreased FMMCV., Conclusions: Retrograde axonal atrophy, not selective damage to the large myelinating fibers at the wrist, is the direct cause of decreased FMMCV in CTS.

The objective of this study was to determine whether forearm mixed nerve conduction velocity (Fmix) reflects the real conduction velocity of forearm motor nerve (Fmot) and forearm sensory nerve (Fsen) fibers passing through the carpal tunnel. Forearm mixed nerve conduction velocity is presumed to be indicative of the conduction velocity of the median nerve over the forearm. Therefore, Fmix is used widely to assess the causes of slowing forearm conduction velocity in carpal tunnel syndrome. However, some authors claim that Fmix comes chiefly from the undamaged fibers in carpal tunnel syndrome, and thus cannot replace Fmot or Fsen in the evaluation of retrograde axonal atrophy. Patients with clinical symptoms and signs of carpal tunnel syndrome confirmed with standard electrodiagnosis were included. Age-matched volunteers served as control subjects. Conduction velocities across the wrist and over the forearm were measured, including those of the wrist sensory (Wsen), wrist motor (Wmot), and wrist mixed nerves (Wmix); and forearm mixed (Fmix), forearm motor (Fmot), and forearm sensory nerves (Fsen). The authors compared and correlated Wsen, Wmot, and Wmix; and Fmix, Fmot, and Fsen respectively. The mean values of Wsen, Wmot, Wmix, Fmix, Fmot, and Fsen of the control subjects less those of corresponding conduction velocity of carpal tunnel syndrome patients were designated Wsen N, Wmot N, Wmix N, Fmix N, Fmot N, and Fsen N respectively and were compared and correlated again. Wrist motor nerve conduction velocity, Wsen, and Wmix were significantly lower in carpal tunnel syndrome patients, and Fmot and Fsen but not Fmix were reduced significantly when compared with control subjects. Mean wrist sensory nerve conduction velocity, Wmot N, and Wmix N; and Fsen N and Fmot N showed good correlation except for Fmix N, suggesting that Fmix reflects the conduction velocity of undamaged fibers in carpal tunnel syndrome. Forearm mixed nerve conduction velocity cannot replace Fmot or Fsen in the assessment of retrograde axonal atrophy in carpal tunnel syndrome. In the disease state, Fmix possibly represents the conduction velocity of the palmar cutaneous branch.

Objectives: The purpose of this study was to determine whether forearm (wrist-elbow) mixed nerve conduction velocity (W-Emix) represents the actual nerve conduction velocity (CV) of nerve fibers passing through the carpal tunnel., Background: W-Emix is presumed to reflect the actual forearm CV through the carpal tunnel. However, it has been argued that W-Emix chiefly originates from the nerve fibers passing outside the carpal tunnel. Therefore, the direct measurement of W-Emix cannot be used to assess retrograde axonal atrophy in carpal tunnel syndrome (CTS)., Subjects and Methods: Thirty patients with clinical signs and symptoms of CTS were recruited and the diagnosis was confirmed with standard electrodiagnosis. Fifty age-matched volunteers served as control. Recording electrodes were placed over the elbow and index finger for mixed nerve and sensory nerve conduction studies, respectively. Stimulation was applied at the palm and wrist for the measurement of mixed nerve wrist-palm CV (W-Pmix), wrist-elbow CV (W-Emix), and elbow-palm CV (E-Pmix). Stimulation was applied at the elbow, wrist, and palm for the measurement of wrist-elbow sensory CV (W-Esen), wrist-palm CV (W-Psen), and elbow-palm CV (E-Psen). Comparisons were made between W-Pmix and W-Psen, W-Emix and W-Esen, and E-Pmix and E-Psen., Results: Correlations between W-Emix and W-Esen, E-Pmix and E-Psen, and W-Pmix and W-Psen were good in the control. In the patient group, there was a strong positive correlation between W-Pmix and W-Psen, and between E-Pmix and E-Psen. However, W-Esen correlated weakly with W-Emix, suggesting that W-Emix chiefly represents the CV of fibers passing outside the carpal tunnel. Therefore, the direct measurement of W-Emix cannot be used to assess retrograde axonal atrophy. Furthermore, the reduction in W-Psen was more marked than the reduction in W-Esen, implying that a conduction block at the wrist is the least likely cause of proximal slowing in CTS., Conclusions: W-Emix does not reflect the actual CV of the nerve fibers passing through the carpal tunnel. In addition, retrograde axonal atrophy appears to be the primary cause of decreased forearm CV in CTS.

Objectives: To elucidate the etiopathogenesis of decreased forearm median motor conduction velocity (FMMCV) in carpal tunnel syndrome (CTS), we used segmental stimulation at the palm, wrist and antecubital fossa to determine conduction block at wrist and calculate and compare the segmental median motor conduction velocity (MMCV) to determine the pathogenesis., Background: The cause of the decreased FMMCV in CTS remains unclear. Animal models have supported retrograde axonal atrophy as the cause. Some authors believe standard FMMCV, calculated by subtracting the distal latency, may not represent an exact assessment of FMMCV but rather the velocity of small fibers that persist throughout the carpal tunnel., Subjects and Methods: Patients with clinical symptoms and signs of CTS which had been confirmed with standard electrodiagnosis, were included. The patients were divided into two groups: one with reduced FMMCV <50m/s (Group I, n=20) and the other with normal FMMCV>50m/s (Group II, n=40). Age-matched volunteers served as controls (n=60). We used palm, wrist and antecubital stimulation, and recorded compound muscle action potential (CMAP) amplitudes at the abductor pollicis brevis (APB) muscle. Based on a ratio of the CMAP amplitudes obtained from wrist and palm stimulation (W/P ratio) and the latency differences, we calculated the W/P ratio and the across wrist MMCV (AWMMCV) and FMMCV and compared and correlated them between two patient groups., Results: There was no difference in median motor and sensory distal latency between Groups I and II. CMAP and sensory nerve action potential amplitudes were reduced in Group I compared with Group II, but the difference was only marginally significant. Four patients had a significant reduction of the W/P ratio in Group I, compared with 7 patients in Group II, which did not reach a significance. Sixteen patients (80%) in Group I demonstrated no conduction block. Furthermore, Group I showed significantly decreased FMMCV when compared with Group II; however, AWMMCV was not significantly reduced in Group I, suggesting that decreased FMMCV does not result from a decrease in AWMMCV., Conclusions: There was no significant motor conduction block and no correlation of the FMMCV and AWMMCV in CTS patients with a decrease of FMMCV, suggesting retrograde axonal atrophy, and not selective conduction block of the large fibers at the wrist, is the direct cause of decreased FMMCV in CTS.

Objective: To compare the sensitivities of motor wrist-to-palm (W-P) conduction velocity and two median-ulnar motor latency differences with that of sensory W-P conduction velocity in the diagnosis of carpal tunnel syndrome (CTS)., Methods: This study included 116 consecutive patients with CTS (160 hands) referred for evaluation and 100 volunteers who served as controls. Median motor and sensory nerve responses with wrist and palm stimulation allowed for the determination of motor and sensory W-P CV (W-P MCV and SCV). Two motor distal latency (MDL) differences between the median-thenar and ulnar-hypothenar (M-U) muscles and between the median-second lumbrical and ulnar-interossei muscles (2L-INT) were measured and calculated. The mean values of controls plus or minus 2.5 SD served as the normal limits., Results: Among the 160 hands with suspected CTS, 11 (6.88%) had normal electrodiagnostic studies and 149 (93.1%) had at least one abnormal electrodiagnostic study. Among the 149 hands with an abnormality, 139 (86.88%) had abnormal W-P MCV and 129 (80.63%) had abnormal W-P SCV. The sensitivity for 2L-INT was 77.5%, and it was 70% for M-U, 68.75% for median MDL, and 73.75% for sensory distal latency. Combining W-P MCV and W-P SCV allowed for the detection of abnormalities in 147 hands (91.88%) and yielded a markedly improved diagnostic rate compared with W-P SCV alone., Conclusion: Motor W-P conduction study is more valuable and no more difficult than sensory W-P conduction study for the diagnosis of CTS. In patients with suspected CTS in whom the results of conventional nerve conduction studies are normal, studying both motor and sensory W-P conduction increases the diagnostic yield.