Diagnostic specificity of sensory and motor nerve conduction variables in early detection of carpal tunnel syndrome

A systematic review and meta-analysis of the effectiveness of perineural dextrose injection in peripheral compression neuropathies of the upper limbs

Background

Entrapment neuropathies, marked by nerve compression at various anatomical sites, can be effectively managed using conservative approaches like injections. Dextrose 5 % water injection has emerged as a potential therapy by reducing inflammation and promoting tissue regeneration. We aimed to evaluate dextrose injection's efficacy in treating entrapment neuropathies in upper extremities.

Method

We systematically searched EMBASE, Scopus, Web of Science, and PubMed. Our eligibility criteria included participants aged 18 and older who had peripheral upper limb nerve entrapment from non-metabolic and non-traumatic sources. These participants were treated with dextrose injection compared to those receiving other injectables, such as corticosteroids and non-corticosteroid medications. The primary outcome was pain, with secondary outcomes including function, ultrasonographic, and electrodiagnostic findings. The quality of the clinical trials was assessed using Cochrane tools. Random-effect model was employed for meta-analysis.

Results

Thirteen studies, involving 754 patients, were included, with only two showing serious bias risk. Initial findings indicate significant pain relief with dextrose injection within a short time (≤4 weeks) compared to normal saline (MD: -1.30, 95%CI: -2.12; -0.47). Dextrose also demonstrated a significant pain decrease compared to corticosteroids (MD: -0.81, 95 % CI: -1.40; -0.21) with low heterogeneity (I2 = 9 %, P = 0.36), and significantly improved function (MD = -0.46, 95 % CI: -0.76; -0.16) with low heterogeneity (I2 = 17 %, P = 0.31) in mid-term (one to six months).

Conclusion

This meta-analysis suggests dextrose injection as an effective therapy for managing pain and restoring function in entrapment neuropathies. However, further high-quality studies are needed to confirm these findings and establish optimal dosing regimens and injection protocols. Healthcare providers should consider integrating dextrose injection into their treatment strategies for patients with entrapment neuropathies.

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

Diabetes Increases Median Nerve Cross-Sectional Area but Not Disease Severity in Patients with Carpal Tunnel Syndrome

Background

Ultrasonography (US) is a useful diagnostic modality for diagnosis of carpal tunnel syndrome (CTS). Diabetes mellitus is increasingly prevalent and is a risk factor for CTS. Given the increasing use of US in the diagnosis of CTS, our goal was to evaluate the influence of diabetes on CTS severity and the cross-sectional area (CSA) of the median nerve in patients with CTS.

Methods

Patients with clinically diagnosed CTS were seen in the outpatient setting from October 2014 to February 2021. Median nerve CSA and patient reported severity measures were obtained: Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ) and CTS-6. For patients with diabetes, additional parameters were collected including most recent A1c, insulin pharmacotherapy, and polypharmacy.

Results

Ninety-nine patients (122 nerves) without diabetes and 55 patients (82 nerves) with diabetes were recruited for the study. Patients in the diabetes group were more obese and older and had a significantly increased median nerve CSA compared with patients without diabetes. Obesity was associated with higher median nerve CSA in all patients but not in patients with diabetes. There was no difference in disease severity in patients with and without diabetes as reported by BCTSQ or CTS-6 scores. In patients with diabetes, there was significantly decreased median nerve CSA with A1c of 6.5 or higher and a trend to decreased CSA with polypharmacy. There was no influence of insulin therapy on median nerve CSA.

Conclusion

Diabetes is associated with higher median nerve CSA in patients with CTS of similar disease severity. The increased median nerve CSA in patients with diabetes may be reflective of diabetes-related microvascular changes. Interestingly, the trend to decreased median nerve CSA in patients with suboptimal diabetic control (A1c ≥ 6.5) may suggest eventual degenerative changes to the median nerve. In summary, clinicians should be cautious with interpreting a larger median nerve CSA as more severe CTS in patients with diabetes.

Level of Evidence

Level 3 Diagnostic.

A revised electrodiagnosis-based severity classification for carpal tunnel syndrome

BACKGROUND

An electrodiagnostic evaluation is conducted to diagnose carpal tunnel syndrome (CTS) and evaluate its severity.

OBJECTIVE

This study proposes a revised approach for classifying the severity of electrophysiological findings for patients with CTS.

METHODS

This retrospective cross-sectional study included patients with CTS confirmed through electrodiagnostic evaluations. Based on the Stevens' classification, the patients were divided into three groups (mild/moderate/severe). A new intermediate group was defined to identify patients with normal motor nerve conduction studies and abnormal electromyographic results. CTS pain was evaluated using a numeric rate scale. Physical examinations and sonographic evaluation were performed to detect anatomical abnormalities.

RESULTS

Overall, 1,069 CTS hands of 850 CTS patients were included. The mean age was 57.9 ± 10.8 years, and 336 (39.5%) were men. There were 522 (48.8%) mild cases; 281 (26.3%) moderate cases; and 266 (24.9%) severe cases. In the severe group, 49 cases were reclassified into the intermediate group. The median cross-sectional area in the intermediate group significantly differed from that in the severe group. However, the pain score significantly differed from that of the moderate group.

CONCLUSION

The intermediate CTS group showed clinical features that were intermediate to those of the moderate and severe CTS groups.

The sensitivity of median versus ulnar palmar mixed nerve study in the early diagnosis of carpal tunnel syndrome

Background

Electrodiagnostic tests (EDX) are the most frequent and applicable studies in early diagnosis of carpal tunnel syndrome (CTS), but the definitive sensitive and specific tests are still under study. We aimed to evaluate the role of the median versus ulnar palmar mixed nerve study (Mix M-U), and its sensitivity in comparison to other provocative comparison studies, in supporting the early diagnosis of CTS. This cross-sectional study included 142 idiopathic early CTS hands from 100 patients and 71 hands from 50 healthy subjects as a control group. We did routine median motor and sensory studies and 4 comparative tests namely median versus radial sensory study (MVR), Mix M-U, median versus ulnar sensory study (MVU), and median versus ulnar lumbrical-interossei motor study (LU-IN).

Results

The routine median motor and sensory latency and amplitude showed a statistically significant difference between CTS and control groups as (p< 0.05) and a highly statistically significant difference between the 2 groups as regards the 4 comparative tests as (p< 0.0001). The specificities of all the 4 comparative tests were higher than 90%. MVR test had the highest sensitivity (92.2%) and followed by Mix M-U study (82.2%) and MVU (78.7%), and the least sensitive test was the LM-IN (66.9%).

Conclusions

Although the patients’ results fall within the normal range according to the reference range in the literature, it showed a statistically significant difference when compared to controls. A high percentage of those symptomatic patients showed results of typical CTS when tested with the comparative studies so there is a need to use these sensitive tests to diagnose cases with early CTS. According to sensitivity studies, the selection of which tests to do in order is a challenging choice. For the diagnosis of cases with early CTS with a normal ordinary motor and sensory studies, MVR comparative technique appeared as the best sensitive and specific provocative electrophysiological test followed by the Mix M-U test. We recommend the use of a combination of both tests first in the diagnosis of early CTS and if one of them was negative we can use the other comparative studies MVU and then LM-IN studies.

Role of High Frequency Ultrasound in Diagnosing Carpal Tunnel Syndrome as Compared with Conventional Nerve Conduction Studies

Objective:

Our aim was to evaluate High Frequency Ultrasonography as a tool for diagnosis in patients withcarpal tunnel syndrome in comparison with electrophysiological study.

Methods:

Thirty- one patients [56 hands] with CTS and twenty-five asymptomatic controls [50 hands] were assessed and underwent ultrasonography of the wrists and electrophysiological testing. Data from the patient and the control groups was compared for both the investigations to determine the CTS and the grade of severity.

Results:

There was a high degree of correlation between the conduction abnormalities of the median nerve as detected by electrodiagnostic tests, historic and objective scale [Hi-Ob] and the measurement of the cross-sectional area of the nerve by US (P < 0.05). A cut-off point of 0.88 mm² for the mean cross-sectional area of the median nerve was found to be the upper limit for normal values. Compared to Ultrasonography which found one hand negative, six hands (10%) were negative on the electrophysiological tests. Using critical CSA value of 1.0 mm² in these CTS cases by US with sensitivity and specificity of 100% and 88%. Based on the results of this study, ultrasonography of wrist is another useful tool along with nerve conduction studies as per sensitivity and specificity patterns found in our study in diagnosis of carpal tunnel syndrome.

Conclusion:

High-frequency US examination of the median nerve and measurement of its cross-sectional area can be strongly considered as useful diagnostic diagnostic modality for the evaluation of CTS along with nerve conduction studies. In addition to its high diagnostic accuracy it is able to define the cause of nerve compression, aids treatment planning and provides a reliable method to follow response to therapy.

Ultrasonography and electrophysiological study of median nerve in patients with essential tremor

Essential tremor (ET) is a common movement disorder characterized by postural or kinetic tremor. We aimed to evaluate median nerve enlargement in patients with ET using ultrasonography (USG). Thirty-eight hands from 19 patients with ET and 24 hands from 13 controls underwent nerve conduction studies (NCS) and USG at the wrist. Tremor severity was measured using the Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS). The median nerve cross sectional area (mCSA) in USG and NCS parameters were compared using ANCOVA. We evaluated the correlation between mCSA and NCS parameters or FTM-TRS scores using linear regression analysis. mCSA was significantly larger (p<0.001) and NCS parameters were different in two groups. Also, mCSA was negatively correlated with part B and C scores of FTM-TRS (p<0.001 and p = 0.039, respectively). In conclusion, median nerve enlargement with the changes of NCS parameters was observed and correlated with the severity of tremor in patients with ET.

Ring finger sensorial conduction studies in grading carpal tunnel syndrome: Part II

BACKGROUND

Comparison of sensory conduction of median nerve (MN) with the one of ulnar nerve (UN) over writs-to-ring finger (RF) segment is useful in electrodiagnosis of carpal tunnel syndrome (CTS). However, there is not any consensus regarding the usage of this technique in grading of CTS.

OBJECTIVES

To determine whether the hands of CTS with elicitable MN sensory responses on index finger, but not on RF (non-respondings) compose a more severe electrophysiologic grade than the hands with elicitable responses on both fingers (respondings).

MATERIAL AND METHODS

The patients with bilateral moderate grade of CTS in whom one hand was responding and the contralateral hand was non-responding were included. Conduction study results of MN and UN were compared between respondings and non-respondings.

RESULTS

A total of 19 patients were included. Mean distal sensory onset latency (DSOL) of MN over index finger was longer (4.26 ± 0.49 msec versus 3.44 ± 0.39 msec; p< 0.001), sensory conduction velocity (SCV) was slower (33.7 ± 4.3 m/sec versus 40.2 ± 3.0 m/sec; p< 0.001), SNAP amplitude was smaller (10.3 ± 3.3 μV versus 19.1 ± 7.7 μV; p< 0.001), distal motor latency was longer (5.69 ± 0.60 msec versus 4.63 ± 0.32 msec; p< 0.001), and minimum F wave latency was longer (29.3 ± 1.7 msec versus 26.8 ± 1.4 msec; p< 0.001) in non-respondings than respondings. The nonresponding hand had a longer MN DSOL and slower SCV on index finger compared with contralateral responding hand in all of 19 patients.

CONCLUSION

Non-responding hands have more progressed median neuropathies, and represent a more severe electrophysiologic grade than responding hands. Further studies are warranted to determine whether the absence of MN sensory responses on ring finger is related with forthcoming NCS worsening and a preferable hallmark for deciding surgical intervention or not.

Lumbrical-interosseous recording technique versus routine electrodiagnostic methods in the diagnosis of carpal tunnel syndrome

Objectives

We aimed to evaluate the sensitivity of second lumbrical-interosseous (L-I) technique and to compare the results with other electrophysiological methods in patients with carpal tunnel syndrome (CTS).

Patients and methods

This cross-sectional study was conducted in an electrophysiology laboratory of a university hospital between January 2003 and January 2004. A total of 102 patients with CTS (174 hands) and 40 healthy controls (80 hands) were included. Median motor nerve conduction studies were obtained with recordings from the abductor pollicis brevis (APB), median sensory nerve conduction studies from digits I-III and at palm-wrist segment (P-W), median-ulnar sensory comparison at digit IV (M-U), and median-radial sensory comparison at digit I (M-R) were along with L-I technique.

Results

The highest sensitivities were found in the median sensory conduction velocity across the palm-wrist (88%), and digit I-wrist segments (80%), median motor distal latency over the APB (77%), and L-I study (76%). The specificities of conventional tests were higher than the sensitivity of L-I method (63%).

Conclusion

L-I method has a good diagnostic sensitivity in CTS; however, P-W, median sensory nerve conduction velocity at digit I and median distal motor latency are more sensitive than L-I method. Therefore, L-I method can be applied as a supportive technique in the evaluation of patients with CTS.

Practical approach to electrodiagnosis of the carpal tunnel syndrome: A review

Despite being the most common entrapment neuropathy and the most common reason for referral to the electromyography (EMG) laboratory, the diagnosis of carpal tunnel syndrome (CTS) continues to be challenging due to a large number of electrodiagnostic (EDX) tests available. We present a flowchart and propose a practical approach to the diagnosis of CTS using the available literature and the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) guidelines and the Practice Parameter for Electrodiagnostic Studies in Carpal Tunnel Syndrome.

[The arteriovenous fistula is an additional risk factor for developing carpal tunnel syndrome in hemodialysis patients]

INTRODUCTION

Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy reported in patients with renal failure undergoing periodic haemodialysis. The role of arteriovenous fistula was discussed. The aim of this study was to investigate this relationship.

METHODS

Subjects for this study were hemodialysis patients who underwent systematic electroneuromyography between January 2003 and December 2010. Only patients with unilateral fistulae were included for the study.

RESULTS

One hundred and thirty-four out of 155 patients were examined. CTS was noted in 106 patients and was detectable only in ENMG in 42% of cases. It was more frequent (P<0.001) and more severe in the side of fistulae (P=0.08). Besides, development of CTS was only correlated with the longer duration of dialysis (P=0.005). This duration was significantly shorter in patients with CTS and diabetes.

CONCLUSION

The positive correlation between CTS and aretriovenous fistulae confirms the pathogenic role of this latter. The risk rises in these patients with the duration of hemodialysis and the presence of diabetes.

Intradermal therapy (mesotherapy) for the treatment of acute pain in carpal tunnel syndrome: a preliminary study

Background

The carpal tunnel syndrome (CTS) is the most common cause of severe hand pain. In this study we treated acute pain in CTS patients by means of local intradermal injections of anti-inflammatory drugs (mesotherapy).

Methods

In twenty-five patients (forty-five hands), CTS diagnosis was confirmed by clinical and neurophysiological examination prior to mesotherapy. A mixture containing lidocaine 10 mg, ketoprophen lysine-acetylsalycilate 80 mg, xantinol nicotinate 100 mg, cyanocobalamine 1,000 mcg plus injectable water was used. Sites of injection were three parallel lines above the transverse carpal ligament and two v-shaped lines, one at the base of the thenar eminence, and the other at the base of the hypothenar eminence.

Results

The day after the treatment, all but four patients reported a significant reduction in pain and paresthesias. After 12 months, 17 patients had a complete pain relief, eight patients reported recurrence of pain and sensory symptoms and four out of them underwent surgical treatment.

Conclusions

With the obvious limits of a small-size open-label study, our results suggest that mesotherapy can temporary relieve pain and paresthesias in most CTS patients and in some cases its effect seems to be long-lasting. Further controlled studies are needed to confirm our preliminary findings and to compare mesotherapy to conventional approaches for the treatment of CTS.

Nerve conduction studies of median motor nerve and median sensory branches according to the severity of carpal tunnel syndrome

OBJECTIVE

To evaluate each digital branch of the median sensory nerve and motor nerves to abductor pollicis brevis (APB) and 2nd lumbrical (2L) according to the severity of carpal tunnel syndrome (CTS).

METHODS

A prospective study was performed in 67 hands of 41 patients with CTS consisting of mild, 23; moderate, 27; and severe cases, 17. Compound muscle action potentials (CMAPs) were obtained from APB and 2L, and median sensory nerve action potentials (SNAPs) were recorded from the thumb to the 4th digit. Parameters analyzed were latency of the median CMAP, latency difference of 2L and first palmar interosseous (PI), as well as latency and baseline to peak amplitude of the median SNAPs.

RESULTS

The onset and peak latencies of the median SNAPs revealed significant differences only in the 2nd digit, according to the severity of CTS, and abnormal rates of the latencies were significantly lower in the 2nd digit to a mild degree. The amplitude of SNAP and sensory nerve conduction velocities were more preserved in the 2nd digit in mild CTS and more affected in the 4th digit in severe CTS. CMAPs were not evoked with APB recording in 4 patients with severe CTS, but obtained in all patients with 2L recording. 2L-PI showed statistical significance according to the severity of CTS.

CONCLUSION

The branch to the 4th digit was mostly involved and the branch to the 2nd digit and 2L were less affected in the progress of CTS. The second digit recorded SNAPs and 2L recorded CMAPs would be valuable in the evaluation of severe CTS.

How to make electrodiagnosis of carpal tunnel syndrome with normal distal conductions?

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.

Sensitivities of conventional and new electrophysiological techniques in carpal tunnel syndrome and their relationship to body mass index

The purpose of this study is to evaluate prospectively the sensitivities of conventional and new electrophysiological techniques and to investigate their relationship with the body mass index (BMI) in a population of patients suspected of having carpal tunnel syndrome (CTS). In this study, 165 hands of 92 consecutive patients (81 female, 11 male) with clinical diagnosis of CTS were compared to reference population of 60 hands of 30 healthy subjects (26 female and 4 male). Extensive sensory and motor nerve conduction studies (NCSs) were performed in the diagnosis of subtle CTS patients. Also, the patients were divided into subgroups and sensitivities were determined according to BMI. The mean BMI was found to be significantly higher in the CTS than in the control group (p < 0.001). The sensitivity of the median sensory nerve latency (mSDL) and median motor distal latency (mMDL) were 75.8% and 68.5%, respectively. The most sensitive parameters of sensory and motor NCSs were the difference between median and ulnar sensory distal latencies to the fourth digit [(D4M-D4U), (77%)] and the median motor terminal latency index [(mTLI), (70.3%)], while the median-to-ulnar sensory action potential amplitude ratio (27%) and the median-thenar to ulnar-hypothenar motor action potential amplitude ratio (15%) were least sensitive tests. Sensory tests were more sensitive than motor NCSs. Combining mSDL with D4M-D4U, and mMDL with mTLI allowed for the detection of abnormalities in 150 (91%) and 132 (80%) hands, respectively. Measurements of all NCSs parameters were abnormal in obese than in non-obese patients when compared to the BMI. The newer nerve conduction techniques and combining different NCSs tests are more sensitive than single conventional NCS test for the diagnosis of suspected CTS. Meanwhile, CTS is associated with increasing BMI.

Pain and motor function in carpal tunnel syndrome: a clinical, neurophysiological and psychophysical study

OBJECTIVE

Patients with carpal tunnel syndrome (CTS) complain of motor symptoms. The study is aimed to understand which features are associated with the presence of motor symptoms in CTS.

METHODS

We recruited 282 consecutive CTS patients. After selection, 129 patients (203 hands) were included. Patients were asked about the presence and severity of hand weakness (HW) and hand clumsiness (HC). They underwent a self-administered questionnaire on symptoms, clinical evaluation and neurographic study. Quantitative sensory testing (QST) was performed on the patients with unilateral right CTS.

RESULTS

HW and HC may be found in 56 % and 48 % of CTS hands, respectively. HW was related to the severity of sensory symptoms (pain, numbness and tingling) but not to clinical-neurographic measures of median nerve involvement. HC was related to the severity of sensory symptoms and to the clinical-neurographic signs of motor but not sensory nerve damage. Motor symptoms were significantly more frequent in right hands. QST showed a relationship between the presence and severity of HW and HC and the warm threshold.

CONCLUSIONS

Motor symptoms may be found in approximately half of CTS hands. Clinical and neurographic signs of median nerve motor damage appear to be poorly correlated to motor symptoms. The factor that can help reconcile the discrepancy between motor symptoms and motor signs is pain. Pain modulation on motor function may take place at various anatomical levels in CTS. Nociceptive C-fibers may be involved in pain-motor interactions finally leading to motor symptoms.

Clinical diagnosis of carpal tunnel syndrome: old tests-new concepts

BACKGROUND

The diagnosis of carpal tunnel syndrome (CTS) continues to be neurophysiologically and clinically controversial. Earlier data concluding that the higher prevalence of persons with symptoms suggestive of CTS but without evidence of median mononeuropathy highlights the need for a better understanding of the underlying pathophysiology and natural history of CTS to provide a less empirical foundation for diagnosis and clinical management.

OBJECTIVE

To examine the relationship between the clinical manifestations of CTS with the outcome of the diagnostic tools (nerve conduction tests and ultrasonography), and its implication for clinical practice.

METHODS

Two-hundred and thirty-two patients (69 male and 163 female, ages ranging between 20 and 91 years) with CTS manifestations and 182 controls were included in this study. Diagnosis of CTS was based on the American Academy of Neurology clinical diagnostic criteria. All patients and controls completed a patient oriented questionnaire, were subjected to clinical testing for provocative tests for carpal tunnel syndrome (Tinel's, Phalen's, Reverse Phalen's and carpal tunnel compression tests), blood check for secondary causes of carpal tunnel syndrome, nerve conduction testing as well ultrasonographic assessment of the carpal tunnel and median nerve.

RESULTS

One-hundred and seventy-seven out of 232 (76.3%) had abnormal nerve conduction studies. Forearm symptoms and tenosynovitis confirmed by US examination were found in 51.3% of cases. No significant difference was found on comparing anthropometric measures in the affected hands to the control group hands. A higher prevalence of positive Phalen's and CT compression were found in patients suffering from tenosynovitis regardless of their nerve conduction study results. Sensitivity of Tinel's, Phalen's, Reverse Phalen's and carpal tunnel compression tests was higher for the diagnosis of tenosynovitis than for the diagnosis of CTS (Tinel, 46% vs. 30%; Phalen's, 92% vs. 47%; Reverse Phalen's, 75% vs. 42%; carpal tunnel compression test, 95% vs. 46%). Similarly, higher specificity of these tests was found with tenosynovitis than CTS.

CONCLUSION

The results of this study revealed that Tinel's, Phalen's, Reverse Phalen's and carpal tunnel compression tests are more sensitive, as well as being specific tests for the diagnosis of tenosynovitis of the flexor muscles of the hand, rather than being specific tests for carpal tunnel syndrome and can be used as an indicator for medical management of the condition.

Sensory-motor index is useful parameter in electroneurographical diagnosis of carpal tunnel syndrome

It was performed electroneurographic (ENG) studies with surface electrodes and examined nervus medianus (NM) in 60 patients (38 females), average age of 50,28 years (X+/-SD=50,28+/-11), with clinical diagnosis of carpal tunnel syndrome (CTS) and at least one border or discrete abnormal value of conventional electrophysiological tests. It was also examined 57 healthy individuals (33 females) as control group, average age of 45,65 years (X+/-SD=45,65+/-9,68). The sensitivity and specificity of sensory-motor index (SMI), terminal latency index (TLI) and residual latency (RL) were calculated and compared. SMI is determinate by using following formula: distal distance (DD) (in cm)/distal motor latency (DML) (in ms) + sensory conduction velocity (SCV) (in m/s)/motor conduction velocity (MCV) (in m/s) of NM. SCV of NM was measured by antidromic technique in segment wrist-index finger and MCV of NM in forearm segment above wrist. SMI mean value of control group was 3,45 (X+/-SD=3,45+/-0,45) with lower limit of normal value 2,82 and in patients with CTS 2,13 (X+/-SD=2,13 +/-0,37). The sensitivity of SMI in patients with CTS was 98,51%. SMI is useful parameter in electroneurographical diagnosis of CTS and it's determination is easy and fast and specially important in cases with border or discrete abnormal values of other NM electrophysiological parameters, when SMI values can indicate incipient phase of CTS evolution. In rare cases (about 1%) of CTS with selective NM motor axons affection, SMI may have normal value (false negative result), but DML is always prolonged in this cases. SMI is not dependent on age and DD values in patients with CTS and control subjects.

Sensitivities of Sensory Nerve Conduction Study Parameters in Carpal Tunnel Syndrome

It is generally accepted that median sensory nerve conduction studies are more sensitive than motor nerve conduction studies in the electrodiagnostic evidence of carpal tunnel syndrome (CTS). This study was conducted to compare the sensitivities of various parameters of sensory nerve conduction studies in the diagnosis of CTS. This prospective study included 88 consecutive patients (151 hands) with CTS and 106 control subjects. CTS was diagnosed clinically by two neurologists. Median sensory nerve responses with wrist stimulation were determined. The onset and peak latencies, peak-to-peak amplitudes, negative peak duration, and area were measured. The differences between the peak and onset latencies were also calculated as a measure of waveform temporal dispersion. Among each measured parameter, values between the 2.5th and the 97.5th percentile range of the control subjects served as the normal limits. Among the 151 hands with suspected CTS, five (3.3%) had normal electrodiagnostic studies and 146 (96.7%) had at least one abnormal electrodiagnostic study. Among the 146 hands with an abnormality, 138 had abnormal onset latency, 143 had abnormal peak latency, and 88 had abnormal difference between peak and onset latency. In addition, 87 had abnormal amplitude, 70 had abnormal duration, and 59 had abnormal area. The sensitivity was 91.4% for onset latency, 94.7% for peak latency, 58.3% for difference between peak and onset latency, 57.6% for amplitude, 46.4% for duration, and 39.1% for area. Our study shows that in patients with CTS, the most sensitive sensory nerve conduction parameter is the peak latency. Studying various additional sensory nerve conduction parameters did not significantly increase the diagnostic yield.

Changes in motor axon recruitment in the median nerve in mild carpal tunnel syndrome

OBJECTIVE

To determine whether patients with mild carpal tunnel syndrome (CTS) and conventional electrodiagnostic evidence of selective involvement of sensory conduction show changes in motor axon recruitment in the median nerve.

METHODS

Wrist-to-abductor pollicis brevis (APB) motor axon conduction was studied by analysing the relationship between the intensity of electrical stimulation and the size of motor response (input-output curve) in 30 CTS patients with conventional electrodiagnostic evidence of selective involvement of sensory conduction. Parameters (threshold, slope and plateau) of input-output curves were compared with those obtained in 30 controls.

RESULTS

The slope of the input-output curve of CTS patients was less steep than that of controls. For stimulus intensity above M-wave threshold (MTh), fewer motor axons were recruited in patients than controls.

CONCLUSIONS

Motor fibres are affected in CTS when conventional electrodiagnostic tests show normal motor conduction. Altered recruitment of motor axons could mainly be due to impairment of energy-dependent processes which affect temporal dispersion of the compound volley or axonal conduction block.

SIGNIFICANCE

In mild CTS, motor fibres are more often affected than was originally thought. The sensitivity of wrist-to-APB motor conduction studies may be increased by using submaximal stimulus intensities.

Sensitivity, specificity, and variability of nerve conduction velocity measurements in carpal tunnel syndrome

OBJECTIVE

To explore the diagnostic values of 8 commonly used electrodiagnostic techniques for measuring median nerve conduction velocity (NCV) in carpal tunnel syndrome (CTS).

DESIGN

Sensitivity and specificity analyses.

SETTING

A hospital-based electrodiagnostic laboratory.

PARTICIPANTS

Forty-four normal hands and 136 symptomatic hands.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

(1) Long-segment studies: antidromic wrist-to-digit sensory NCV without subtraction, (2) short-segment studies: transcarpal palm-to-wrist mixed NCV without subtraction, and (3) 2 segment studies: antidromic transcarpal sensory NCV with subtraction (differential calculation from wrist-to-digit and palm-to-digit segments). Both onset and peak latency values were obtained for calculating the NCV. Sensitivity, specificity, and coefficient of variance were calculated for each NCV study.

RESULTS

The short-segment, onset latency-based transcarpal mixed NCV yielded the highest sensitivity (75%).

CONCLUSIONS

Results from measurement of a single, short-nerve segment tended to be superior to results obtained by either long-segment studies or differential subtraction between 2 segments of the same nerve in the electrodiagnosis of CTS. Explanations for our results are offered from both electrophysiologic and statistical perspectives.

Clinical and electrodiagnostic testing of carpal tunnel syndrome: a narrative review

Carpal Tunnel Syndrome (CTS) is a pressure-induced neuropathy that causes sensorimotor disturbances of the median nerve, which impair functional ability. A clear history that elicits relevant personal and work exposures and the nature of symptoms can lead to a high probability of a correct diagnosis. Hand diagrams and diagnostic questionnaires are available to provide structure to this process. A variety of provocative tests have been described and have variable accuracy. The Phalen's wrist flexion and the carpal compression tests have the highest overall accuracy, while Tinel's nerve percussion test is more specific to axonal damage that may occur as a result of moderate to severe CTS. Sensory evaluation of light touch, vibration, or current perception thresholds can detect early sensory changes, whereas 2-point discrimination changes and thenar atrophy indicate loss of nerve fibers occurring with more severe disease. Electrodiagnosis can encompass a variety of tests and is commonly used to assess the presence/severity of neuropathic changes and to preclude alternative diagnoses that overlap with CTS in presentation. The pathophysiologic changes occurring with different stages of nerve compression must be considered when interpreting diagnostic test results and predicting response to physical therapy management.

Comparison of sensory conduction techniques in the diagnosis of mild idiopathic carpal tunnel syndrome: which finger, which test?

To compare the sensitivity of different electrodiagnostic tests on the same hand affected by mild carpal tunnel syndrome (CTS), 189 hands with the clinical diagnosis of CTS and 61 hands of healthy persons were evaluated prospectively. On all hands, median sensory studies from digits 1, 2, 3, 4, and the palm-to-wrist segment from digit 3 and medial motor latency were recorded. Sixty-two hands with delayed motor latency (>4.2 ms) were excluded to ensure that only mild cases were enrolled. Sensory median-radial latency differences from the thumb, median-ulnar latency difference between second and fifth digits, and median-ulnar latency difference from the fourth digit were calculated in each limb. Sensory studies of only one median innervated digit failed to diagnose 15-20% of hands. Conduction velocity at the palm-to-wrist segment was the most sensitive, diagnosing 99% of cases. In comparative tests, median radial sensory latency difference from the first digit was the most sensitive (94%), and median ulnar latency difference from the fourth digit was the least (85%) sensitive. Segmental measurement has the highest diagnostic yield and may be used first in the evaluation of CTS.

Sensitivity of Median Sensory Nerve Conduction Tests in Digital Branches for the Diagnosis of Carpal Tunnel Syndrome

OBJECTIVE

To compare the sensitivity of median sensory nerve conduction tests performed by stimulating digital branches in patients with carpal tunnel syndrome.

DESIGN

A prospective study in 506 hands of patients with carpal tunnel syndrome diagnosed electrophysiologically.

RESULTS

The sensitivity of median sensory nerve conduction tests across the first three digit-to-wrist segments and palm-to-wrist segment was determined. The most common abnormal electrophysiologic finding was the slowing of sensory nerve conduction velocity over the palm-to-wrist segment, which was detected in 98.5% of the hands. Slowing of sensory nerve conduction velocity over the digit 1-, 2-, and 3-to-wrist segments of the median nerve was found in 95.4%, 88%, and 82% of the hands, respectively.

CONCLUSION

The sensory nerve conduction velocity test of the digit 1-to-wrist segment has the most sensitivity among the three digital branches of the median sensory nerve, and it may be used more widely in the electrodiagnosis of carpal tunnel syndrome.

Usefulness of additional nerve conduction techniques in mild carpal tunnel syndrome

This study was done to assess the percentage of abnormality in additional nerve conduction techniques after normal median distal latency (routine) in mild carpal tunnel syndrome (CTS). Bilateral nerve conduction studies were carried out in 116 consecutive symptomatic CTS patients (153 hands). Mild cases were based on normal routine (< 3.7 ms, peak-measured, 14 cm) and at least one technique abnormal of the following: sensory median-radial difference (MR); sensory median-ulnar difference (MU4); mixed palm median-ulnar difference (MUP); median palm latency (PW); and motor median distal latency (MDL). After normal cut-off values for routine, 3.1 to 3.6 ms (< 3.7 ms), we found an abnormal MR, ranging from 86.6 to 93.4%, followed by MU4 (40 to 81.7%), MUP (20 to 71.2%), PW (0 to 41.1%), and MDL (0 to 19.6%). The most frequent abnormal association were MR plus MU4 in 90.1%, followed by MR plus MUP and MU4 plus MUP. The most frequent abnormal additional nerve conduction technique for mild CTS electrodiagnosis was MR, followed by MU4 and MUP. Percentage of MR abnormality was very high regardless of the median routine latency cut-off (< 3.1 to < 3.6 ms).

Inter-observer reproducibility and responsiveness of a clinical severity scale in surgically treated carpal tunnel syndrome

OBJECTIVES

To test a recently proposed carpal tunnel syndrome (CTS) clinical severity scale for reproducibility between two observers (neurosurgeon and neurophysiologist) before surgery, for responsiveness to changes in clinical status 6 months after surgery, and for correlations with the electrophysiological findings and 'Boston Carpal Tunnel Syndrome Questionnaire' (BQ).

MATERIAL AND METHODS

The tests were applied prospectively to a consecutive series of 254 hands with idiopathic CTS, referred for surgical decompression. The hands belonged to 219 subjects (177 women and 42 men, mean age 55.6).

RESULTS

Percentage agreement between the two observers in assigning severity to the same class was 78% and Cohen coefficient kappa was 0.69 (P < 0.001). The scale was found to be responsive to changes in clinical status after surgery. Direct correlations were also found between the scale and patient age, duration of symptoms, BQ scores and the neurophysiological severity scale. The significance of these associations was maintained for 6 months after the operation.

CONCLUSION

This clinical severity scale is simple, reproducible and sensitive for evaluating severity of CTS in patients undergoing surgery.

Herpes zoster of the head and limbs: electroneuromyographic and clinical findings in 158 consecutive cases

OBJECTIVES

To quantify electromyographic and neurographic changes and to correlate them with the clinical data of outpatients with herpes zoster.

DESIGN

Prospective case series.

SETTING

Outpatient department.

PATIENTS

A consecutive, unselected series of 158 outpatient cases (88 women, 70 men; mean age, 64y) of herpes zoster of the head and limbs.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Blink reflex and electromyography and motor and sensory nerve conduction velocities of nerves and muscles corresponding to affected dermatomes.

RESULTS

Postherpetic neuralgia (PHN), segmental zoster paresis, and polyneuropathy were found in 31%, 19%, and 2.5% of cases, respectively. Absence or reduction of sensory action potential amplitudes, blink reflex areas, and compound muscle action potential amplitudes were found in 60%, 31%, and 18% of cases, respectively. Sensory and motor conduction velocities and motor and blink reflex latencies were nearly always normal or only slightly slowed. Electromyographic signs of abnormal spontaneous activity were found in 36% of the cases. Electrophysiologic alterations were correlated among themselves, with age, with presence of segmental zoster paresis, and with absence of antiviral therapy. The extent of the skin rash (number of dermatomes affected by herpes zoster) was the only variable predictive of disappearance or improvement of PHN.

CONCLUSIONS

Sensory axonal neuropathy, often associated with similar motor involvement, can be shown by classical electrophysiologic methods in herpes zoster. The severity of damage to motor fibers was related to damage to sensory fibers, but no relation was found between peripheral axon damage and PHN. The site of motor system damage may be the ventral roots, plexus, or peripheral nerve. The probability of complications and the severity of sensory and motor peripheral axonal damage were increased in older patients. Appropriate antiviral therapy seems to reduce the incidence of segmental zoster paresis and the severity of damage to the peripheral fibers. A reduced extent of herpetic rash was the only factor to correlate with a good outcome of PHN.

Carpal tunnel syndrome incidence in a general population

OBJECTIVE

To determine the incidence of carpal tunnel syndrome (CTS) in a general population of a restricted area in the middle part of Italy.

METHODS

Prospective study to identify cases of CTS, newly diagnosed on the basis of clinical symptoms and delay in distal conduction velocity of the median nerve. In the 8-year period from 1991 to 1998, cases were identified by electromyographic services in the Siena area of Local Health District No. 7 of Tuscany (Italy). This area has a population of 120,000.

RESULTS

In the 8-year period, 3,142 cases (79.7% women and 20.3% men; mean age, 55 years; range, 13 to 97 years) were identified. The mean annual crude incidence was 329 cases per 100,000 person-years, and the standardized incidence was 276. The sex-specific incidences were 139 for men and 506 for women. The mean annual incidence for men increased moderately but significantly during the study period, whereas that for women remained constant. The age-specific incidence for women increased gradually with age, reaching a peak between 50 and 59 years, after which it declined. In men, there was a bimodal distribution with peaks between 50 and 59 years and between 70 and 79 years. Rural and industrial areas had higher crude and age- and sex-specific incidences than did urban areas.

CONCLUSIONS

The incidence in the Siena area is about threefold that reported in the Rochester area (Minnesota) and is similar to that of Marshfield (Wisconsin). The different results with respect to US reports may depend on case inclusion criteria and occupational activities of the population at risk.

A new clinical scale of carpal tunnel syndrome: validation of the measurement and clinical-neurophysiological assessment

OBJECTIVE

To validate a new clinical scale of carpal tunnel syndrome (CTS). The scale is based on clinical history and physical examination findings and includes two figures. The first is a score determined by clinical history and objective findings. The second evaluates the presence/absence of pain as a dichotomous categorical score.

METHODS

One hundred and sixty-eight consecutive idiopathic CTS hands were studied in two centers (Rome, Siena). We compare the results of the historical-objective scale (Hi-Ob scale) with the results of other validated measurements of CTS severity: (1) the Italian version of the Boston Carpal Tunnel Questionnaire, (2) the neurophysiological classification adopted by the Italian CTS study group. Furthermore, for the Hi-Ob scale the intra-observer and inter-observer evaluations were assessed.

RESULTS

The main Hi-Ob parameter was positively related to the conventional validated measurements. Conversely, the category 'PAIN' of the Hi-Ob scale appeared unrelated to the other clinical and electrophysiological parameters. Intra- and inter-observer evaluation showed the reproducibility of the Hi-Ob assessment.

CONCLUSIONS

Our data show that the Hi-Ob scale is a reliable measurement which may be useful in CTS evaluation either for clinical or for scientific purposes.

Carpal tunnel syndrome and hand configuration

The likelihood that hand configuration is related to the development of carpal tunnel syndrome (CTS) was examined in this study. Based on neurophysiological criteria, 50 female subjects with CTS and 50 healthy female controls were selected and their external hand dimensions were measured. Our results showed that the palm length and third digit length were significantly shorter and the palm width larger in the subjects with CTS compared with controls. Regression analysis demonstrated that the hand ratio [(palm + third digit length)/palm width] was significantly correlated with median nerve conduction measurements. The hand ratio may be a simple and useful predictive measurement in determining the tendency for CTS.

Provocative tests in different stages of carpal tunnel syndrome

The frequency of positive results of four conventional provocative tests (Phalen sign, Tinel sign, wrist extension and pressure provocation test) was evaluated in 179 patients with clinical and electrophysiological findings consistent with idiopathic carpal tunnel syndrome (CTS), 147 control subjects and 39 patients with polyneuropathy. The diagnostic accuracy was evaluated for each test alone and in combination and the sensitivity correlated with the clinical and electrophysiological severity of CTS. For comparison of the CTS group with the control group, none of the tests reached sufficient diagnostic accuracy. The same was found for comparison of the CTS group with the polyneuropathy group, the Tinel sign being the least accurate. The combination of signs was not found to be more useful than single signs. The sensitivity of all signs was much less in severe clinical stages of CTS, especially for tests that increase the intra-carpal canal pressure. Traditional provocative tests, such as those tested here, have limited or no value for distinguishing patients with and without CTS, one reason being that their sensitivity depends largely on the clinical and electrophysiological severity of CTS. This correlation may also explain the contradictory results in the literature.

Sympathetic skin response before and after surgical release of carpal tunnel syndrome

Sympathetic skin response (SSR) was performed before and 1 year after surgical release of the median nerve in 20 subjects (mean age 52.8 years) with unilateral idiopathic carpal tunnel syndrome (CTS). SSR was evoked by stimulation of the ulnar nerve at the wrist contralateral to the side with CTS, recording from the palm, third (M3) and fifth fingers, and from the third finger contralateral to the side of CTS (M3c). Before surgery, anomalies of M3 SSR were found in 8 hands (40%): M3 SSR was absent in 1 hand; and the M3c/M3 SSR largest area ratio was abnormal in 7 hands, 3 of which also had abnormal mean differences between M3 and M3c SSR latencies. M3 SSRs were not significantly modified after surgery. The absence of postsurgical improvement may be due to the poor reinnervation capacity of sympathetic fibers.

Median nerve motor conduction to the abductor pollicis brevis

The median motor conduction study to the abductor pollicis brevis is one of the most commonly performed electrodiagnostic studies, yet there is a need for a more comprehensive normative database for this test. Demographic subgroups of age, gender, and height need to be evaluated with a large enough sample size using modern statistical and electrodiagnostic techniques. In this study, 249 subjects were tested and the following were recorded: latency, amplitude, area, duration, and nerve conduction velocity (NCV). A repeated measures analysis of variance was performed with the waveform measures as the dependent variables and age, gender, and height as the independent variables. Factors that were significant at the P < or = 0.01 level were used to create separate normative databases. Gender was found to be associated with different results for latency and NCV. Age was found to be associated with different results for latency, amplitude, area, and NCV. Once these statistically significant factors were determined, Tukey adjusted pair-wise comparisons of least squares means were used to collapse categories (by decade for age) that were not significantly different from each other at the P < or = 0.05 level. Categories for measures that differed by clinically insignificant amounts (defined as 0.2 ms or less for time measures, 2 m/s or less for NCV, or 5% or less for amplitude and area) were combined as well. Side-to-side and proximal-to-distal differences were analyzed. The normal range was derived as mean +/- 2 standard deviations and at the 97th (third) percentiles of observed values. The findings are presented in this article but include a mean latency of 3.7 +/- 0.5 ms, a mean amplitude of 10.2 +/- 3.6 mV, and a mean nerve conduction velocity of 57 +/- 5 m/s. Subgroupings based on demographic characteristics, percentile distributions, side-to-side, and proximal-to-distal variations are presented.

Ulnar nerve motor conduction to the abductor digiti minimi

Ulnar motor study to the abductor digiti minimi is commonly performed, but a more extensive database of normative values using modern electrodiagnostic and statistical techniques and temperature control is needed for this test. Demographic subgroups of age, gender, and height should be evaluated using a large subject population to determine whether separate normal ranges should be created for subsets of the general population. In this study, 248 volunteers were tested to measure ulnar motor latency, amplitude, area, duration, and nerve conduction velocity. Side-to-side and distal-to-proximal variability was analyzed. A repeated measures analysis of variance was performed with the waveform measures as the dependent variables and age, gender, and height as independent variables. None of the results were found to vary significantly (at the P < or = 0.01 level) with the subjects' physical characteristics, and thus, the data for all subjects were pooled to create a normative database. The normal range was derived as mean +/- 2 standard deviations and at the 97th (third) percentile of observed values. Mean latency was 3.0 +/- 0.3 ms, and amplitude was 11.6 +/- 2.1 mV. Mean nerve conduction velocity was 61 m/s across all segments tested. The upper limit of normal side-to-side variability (mean + 2 standard deviations) for latency was 0.6 ms; for amplitude, it was 3.6 mV. The upper limit of normal drop in conduction velocity across the elbow was 15 m/s (at the 97th percentile). Additional data are presented for all variables measured, as well as for side-to-side variability and distal-to-proximal change.

Multifocal neural conduction impairment in forestry workers exposed and not exposed to vibration

OBJECTIVE

The aim of the study was to assess peripheral neural involvement induced by exposure to hand-arm vibration.

METHODS

Twenty lumberjacks, working regularly with chain-saws and exposed to hand-arm vibration (group E) and 20 forestry workers performing heavy manual work and not exposed to vibration (group NE) were matched with a control group of 20 healthy non-manual workers (group C). The subjects of groups E and NE, all symptomatic, and of group C underwent extensive bilateral neurophysiological examination consisting of: sensory conduction (velocity and amplitude) of radial, median and ulnar nerves in digit-wrist segments; sensory conduction (velocity) of median nerve in wrist-elbow segment; mixed conduction (velocity and amplitude) of median and ulnar nerves in palm-wrist segments; motor conduction velocity, including distal motor latencies, and amplitude of median (elbow-wrist) and ulnar (elbow-wrist and across the elbow) nerves.

RESULTS

Electrophysiological abnormalities were found in 85% of group E's limbs, versus 62.5% of group NE's limbs. The most frequent pathological pattern in group E was a 'multifocal' impairment (multiple sites of several nerve segments), with a prevalent involvement of sensory rather than motor fibres in the hand, seldom extending to the forearm. Multivariate analysis showed that the neurographic parameters which better characterized workers exposed to hand-arm vibration had a pattern different from that usually found in idiopathic carpal tunnel syndrome (CTS).

CONCLUSION

These results suggest that vibration-induced neural involvement can be considered neither pure digital neuropathy, nor definite CTS, as previously described.

Comparison of nerve conduction techniques in 95 mild carpal tunnel syndrome hands

Electrodiagnosis of carpal tunnel syndrome (CTS) were prospectively studied in 95 hands. The following techniques were studied in all hands and when at least one abnormal value was found (onset-measured), it was included on results: 1. wrist-index finger latency (WIF), abnormal > or = 2.8 ms, 140 mm; 2. palm-wrist latency (PW), abnormal > or = 1.8 ms, 80 mm; 3. comparison median/ulnar palm-wrist latency (CPW), abnormal > or = 0.4 ms; 4. comparison median/ulnar latency, wrist-ring finger (CMU), abnormal > or = 0.5 ms, 140 mm; 5. comparison median/radial latency, wrist-thumb (CMR), abnormal > or = 0.4 ms, 100 mm. All 95 CTS hands selected have the WIF < or = 3.5 ms (mild CTS). We found the CMR (97.8%) technique the most sensitive for mild CTS electrodiagnosis and the only comparative method with all potentials recordable when compared to CPW (88.4%), PW (84.2%), CMU (72.6%) and WIF (68.4%).

[Carpal tunnel syndrome. Current approaches]

A clinical, epidemiological and nerve conduction studies report on carpal tunnel syndrome was done after electrophysiological author's experience on 668 cases and literature review. The median nerve underwent focal (nodal) or segmental demyelination after compression on carpal tunnel, 3-4 distal to wrist fold. The symptomatic complex includes nocturnal hands numbness and paraesthesia, mostly bilateral and between 40-60 years old. Familial cases are described and the gene could encode thick transverse carpal ligament. Anthropomorphic findings could also bring about an additional risk, but with low significance. Magnetic resonance could be a useful tool for selected atypical cases. Conservative treatment and controversies on surgery timing are discussed. Classical conduction studies on median nerve reveal a prolonged distal segmental sensory latency and also on distal motor latency. Increasing sensitivity may be reach using additional methods such as, median mixed mid-palm latency, comparative mid-palm latency median/ulnar, comparative sensory latency median/radial and median/ulnar, inching method from wrist to palm recording on index/middle finger and comparative motor median/ulnar recording on lumbrical/interosseous muscle.

[Carpal tunnel syndrome: sensory median-radial latency difference versus conduction studies in 1059 hands (668 cases)]

Between January 1989 and June 1996, 1,059 carpal tunnel syndrome hands (CTS) from 668 patients were studied. None had been previously operated and all had bilateral conduction studies; peripheral neuropathy was excluded. The patients were selected with sensory median/radial difference (MRD) > or = 1.0 ms that strongly supports electrodiagnosis of CTS (standard deviation > 6) after simultaneous stimulation on wrist and recording on thumb. Normal MRD were obtained in 125 hands with upper limit of normality = 0.43 ms (mean + 2SD). The age ranged from 17 to 83 years (mean 47.5) and 91.3% were female. MRD > or = 1.0 ms correlates in 95% with median distal motor latency > 4.25 ms (80 mm distance) and with median distal sensory latency to index finger > or = 3.01 ms, middle finger > or = 3.14 ms and ring finger > or = 3.26 ms, all of them 140 mm distance, antidromic and onset-measured. The results have brought new values for the limit of normality in our EMG laboratory since MRD > or = 1.0 ms is very sensitive for CTS diagnosis.

What do we know about the reliability and validity of physical examination tests used to examine the upper extremity?

The literature regarding the reliability and validity of commonly used clinical tests for disorders of the upper extremity was reviewed. Formal literature search, standard texts, and experts in the field of upper extremity were consulted to locate relevant articles. Range of motion and strength testing of the upper limb have been shown to be reliable, while various tests used for the diagnosis of conditions in the upper limb, such as carpal tunnel syndrome and rotator cuff tendinopathy, have been shown to have varying degrees of validity. Overall, however, we determined that there is little evidence regarding the reliability and validity of physical examination for the upper extremity and specifically less information available regarding the reliability of diagnostic physical examination tests and the validity of impairment measures used for the upper limb. Further studies in this area are warranted in view of the impact of these findings on the treatment of patients.

Pitfalls in using the ring finger test alone for the diagnosis of carpal tunnel syndrome

Latency differences (>0.5 ms) of median and ulnar sensory action potentials (mSAP and uSAP) at the wrist evoked by ring finger stimulation are considered a sensitive and specific test for diagnosis of carpal tunnel syndrome (CTS). In this study, we aimed to assess the practical usefulness of the ring finger test (RFT) in routine electromyography (EMG) examinations. We investigated 2 series of patients: in the first prospective series we considered 300 hands affected by only mild CTS; in the second series we examined retrospectively the EMG charts of 961 hands affected only by CTS but not selected for severity or duration of symptoms. In the first series we found pathological RFT scores in 87% of cases, and pathological RFT or mSAP latency results in 92%. In the second series, pathological RFT scores were found only in 55% of cases, while in 20% where mSAP failed, a volume conducted uSAP had been erroneously interpreted as arising from the median nerve. RFT sensitivity tested in routine EMG examinations of unselected hands affected by CTS drops considerably. Fingers innervated by one only nerve, such as the index and the little fingers, must also be investigated to increase the diagnostic value of RFT.

Electrophysiological evidence of a relationship between idiopathic carpal and tarsal tunnel syndromes

Electrophysiological findings are reported suggesting a relationship between idiopathic tarsal (TTS) and carpal tunnel syndromes (CTS) to explain that the coexistence of both entrapment syndromes in the same patients is not coincidental. Sixty-five patients with idiopathic CTS and 15 with idiopathic TTS were selected. None of the patients with CTS reported any symptoms, nor did they have any signs of TTS, and vice versa. Distal sensory conduction velocity (SCV) of the tibial nerve was reduced in ten of 65 patients with CTS; in five of these ten patients, tibial distal motor latency (DML) was also delayed. Reduced SCV and increased DML were evident in the median nerve of two patients with TTS. The mean of DML and SCV of the tibial nerve in the CTS group and of the median nerve in the TTS group were significantly reduced with respect to the control group without differences in the conduction of the ulnar, deep peroneal and sural nerves. This indicates that there was subclinical involvement of the median and tibial nerves in these patients. Besides having a narrow carpal tunnel, patients with CTS presumably also have a narrow tarsal tunnel and vice versa, and are therefore prone to develop both nerve entrapment syndromes. The different incidence of the two syndromes is explained on the basis of anatomical and functional differences between the two nerves.