Comparison of orthodromic and antidromic sensory nerve conduction velocity measurements in the carpal tunnel syndrome

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.

Normal reference value of orthodromic and antidromic sensory nerve conduction velocity of median nerve with intact palmaris longus tendon in apparently healthy individuals

OBJECTIVES

The aim of this study was to determine normative electrophysiological reference values of median sensory nerve conduction studies among security guards with the palmaris longus tendon (PLT).

METHODS

Sensory nerve conduction studies of the median nerve using antidromic and orthodromic methods were conducted in the upper limbs of 101 healthy male security guards between the ages of 21 and 42 years. The presence of the PLT was recorded in both hands using a standard test. A scatter plot was used to determine the correlation between different parameters using the ortho and antidromic methods.

RESULTS

The mean age (years), weight (kg), height (cm), and BMI (kg/m2) were 28.77 ± 5.14, 70.53 ± 11.28, 171.71 ± 7.12, and 23.91 ± 3.45, respectively. In the median nerve (sensory) by antidromic method, the mean distal latency (DL) was 2.65 ± 0.33 ms and 2.64 ± 0.37, SNCV (sensory nerve conduction velocity) was 53.45 ± 5.28 m/s and 53.84 ± 5.68 and the amplitude was 27.33 ± 12.38 µV and 29.41 ± 12.97 in the left- and right-hand wrist, respectively. By orthodromic method the DL was 2.54 ± 0.53 ms and 2.51 ± 0.44, SNCV was 55.93 ± 6.09 m/s and 55.93 ± 5.24 and the sensory nerve action potential amplitude was 12.00 ± 8.82 µV and 11.72 ± 6.24 in the left and right hand, respectively. Spearman correlations were used to determine the variables influenced by hand sidedness.

CONCLUSIONS

The normative reference parameters of sensory nerve conduction velocity of the median nerve were established by both methods using a standardized technique.

References Values for the Current Perception Threshold in the Pharynx Based on a Study of a Healthy Population

OBJECTIVES

The application of the current perception threshold (CPT) in the diagnosis of pharyngeal sensory abnormalities has rarely been studied, and there is a lack of reference values for this application. This study established a normal reference range for CPT in the pharynx based on a study of a healthy population.

METHODS

The CPT values of the palatoglossal arch, posterior 1/3 of the lingual body and hard palate were measured in 60 healthy individuals at 2000, 250, and 5 Hz. The influencing factors were analyzed, and reference values for the CPT were established.

RESULTS

There was no correlation between the CPT value and gender. Age was only correlated at 250 Hz level in the hard palate. The CPT values of the palatoglossal arch were 324.95 ± 82.422 at 2000 Hz, 66.90 ± 38.622 at 250 Hz, and 13 ± 14.93 (7.83-22.75) at 5 Hz. The CPT values of the posterior 1/3 of the lingual body were 359.17 ± 76.299 at 2000 Hz, 86.92 ± 35.151 at 250 Hz, and 19 ± 15.73 (13.03-28.75) at 5 Hz. The CPT values of the hard palate were 157.5 ± 61.75 (124-185.75) at 2000 Hz, 57.63 ± 28.785 at 250 Hz, and 22 ± 25.73 (11.03-36.75) at 5 Hz.

CONCLUSIONS

The CPT values of the pharynx in healthy people were not related to gender. The CPT values of the hard palate for 250 Hz stimulation were related to age, and there were no relationships between the CPT values and age for the other frequencies and loci. We established a normal reference range of CPT values in the pharynx from measurements obtained from healthy populations.

Current Perception Threshold Testing in Pharyngeal Paresthesia Patients with Depression or Anxiety

PURPOSE

Satisfactory quantitative diagnostic approaches to pharyngeal paresthesia patients with depression or anxiety remain to be explored. This study investigated the plausibility of current perception threshold (CPT) testing in diagnosing pharyngeal paresthesia in patients with depression or anxiety.

PATIENTS AND METHODS

A total of 41 patients with pharyngeal paresthesia with depression or anxiety were recruited as the study group. Additionally, 60 healthy volunteers constituted the control group. The CPT values associated with 5-, 250-, and 2000-Hz electrical stimulation frequencies were measured at the palatal lingual arch and posterior third of the lingual body (two sensory nerve distribution sites in the pharynx). The normal range of CPT values of the above three frequencies was analyzed. The differences in the CPT values for sensory nerves were compared.

RESULTS

There were no significant differences in age and sex between the study and control groups. The CPT values of the pharynx at the two tested sites were not significantly correlated with age and gender. The CPT value of the study group was significantly lower than that of the control group in the palatal lingual arch and posterior third of the lingual body at an electrical stimulation of 5 Hz (p<0.05). No significant differences in the CPT values at other frequencies were found between the two groups.

CONCLUSION

CPT testing is effective in determining pharyngeal paresthesia in patients with depression and anxiety. Paresthesia of the pharyngeal sensory nerve region is caused by damaged C fibers.

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.

Antidromic vs orthodromic sensory median nerve conduction studies

Objective

Median sensory nerve conduction studies are arguably the most often performed electrodiagnostic tests worldwide. Routine tests in clinical practice are done using either antidromic or orthodromic techniques type of stimulation, with no universal agreement on the use of one or the other technique.

Methods

We review the advantages and drawbacks of antidromic and orthodromic as well as their particularities for clinical application and research.

Results

The two techniques differ on how physical and physiological changes affect the action potential. Near-nerve recording is better suited for the orthodromic than for the antidromic technique, while studies of nerve excitability are better suited for the antidromic than for the orthodromic technique.

Conclusion

Both techniques are equally suitable for routine tests but research studies may specifically demand one or the other.

Surface recording of orthodromic sensory nerve action potentials in median and ulnar nerves in normal subjects

Reference values of sensory nerve compound action potentials (CAP) were established in 50 healthy subjects by examination with surface electrodes placed in a transverse and a longitudinal position at the wrist. Longitudinal electrodes record potentials of larger amplitude and shorter duration than transversally recorded CAPs. Both amplitude and duration were increased by an increase of interelectrode distance. The use of amplitude and duration as variables is encouraged by the well-defined biologic variation obtained when fixed interelectrode distance is used and when values are corrected for age and temperature. The strong correlation between amplitude and duration might indicate that the decrease of amplitude with age is caused by the reduction of conduction velocity rather than axonal loss. The ulnar nerve CAPs differ from those of the median nerve mostly with regard to influence of age and temperature. The reasons for this are discussed.

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.

Relative slowing of the median antidromic sensory nerve conduction velocity to the ring finger in screening for carpal tunnel syndrome

PURPOSE

This study analyzed the accuracy of the relative slowing of the antidromic sensory conduction velocity of the median nerve in comparison with the ulnar nerve, from the wrist to the ring finger, in the diagnosis of carpal tunnel syndrome (CTS).

METHODS

Eighty-two patients had been referred consecutively to our department to confirm or exclude CTS. The antidromic sensory conduction velocities of the median nerve and the ulnar nerve from the wrist to the ring finger were determined. The difference between the 2 values was calculated to express the relative slowing of the median nerve compared with the ulnar nerve. Carpal tunnel syndrome was diagnosed when the patient had clinical symptoms compatible with CTS confirmed by an established electrophysiologic investigation. The accuracy of a relative slowing of 5 m/s, 10 m/s, and 15 m/s of the median antidromic sensory conduction velocity to the ring finger was determined to diagnose CTS.

RESULTS

At a cut-off value of 5 m/s the sensitivity was 95%, the specificity was 63%, and the efficiency was 79%. At a cut-off value of 10 m/s the sensitivity was 90%, the specificity was 85%, and the efficiency was 88%. At a cut-off value of 15 m/s the sensitivity decreased to 83%, the specificity increased to 93%, and the efficiency was 88%.

CONCLUSIONS

A high accuracy is achieved in the diagnosis of CTS by determining the relative slowing of the median antidromic sensory nerve conduction velocity from the wrist to the ring finger.

Median 14-cm and 7-cm antidromic sensory studies to digits two and three

The purpose of this study was to derive a normative database for the median digital sensory conduction study using a large and varied subject population. Two hundred fifty-eight asymptomatic volunteers were tested with antidromic sensory technique at 14- and 7-cm distances to digits 2 and 3. Onset latency, peak latency, onset-to-peak amplitude, peak-to-peak amplitude, area, rise time, and duration were recorded. A repeated analysis of variance was performed, with the nerve conduction study measures as the dependent variables and age, race, gender, body mass index, and height as the independent variables. Factors that were significant at the P < or = 0.01 level were used to create separate normal ranges. Both increasing age and increasing body mass index correlated with decreasing amplitudes and area. No other correlations were noted between the results and the physical characteristics. For digit 3, the mean 14-cm onset latency was 2.7 +/- 0.3 ms and mean peak latency was 3.4 +/- 0.3 ms. The mean onset-to-peak amplitude was 41 +/- 20 microV for all subjects taken together. Mean rise time was 0.7 +/- 0.1 ms and mean duration was 2.1 +/- 0.4 ms. Mean side-to-side difference in onset and peak latencies was 0.0 +/- 0.2 ms. The upper limits of normal side-to-side differences in amplitudes and area were approximately 50%-60%.

The diagnosis of carpal tunnel syndrome. Sensitivity and specificity of some clinical and electrophysiological tests

The study group consisted of 100 persons referred with suspected carpal tunnel syndrome. Clinical and neurophysiological examinations were performed blinded from each other. The gold standard for the carpal tunnel syndrome (CTS) diagnosis was based on the results of these examinations but relief of CTS symptoms after surgery was also required. The sensitivity and specificity for the combined results of the clinical examinations were 94% and 80% respectively, and for the neurophysiological examinations, 85% and 87%. Of the neurophysiological methods used, the quotient of sensory nerve conduction velocity between palm to wrist and wrist to elbow was best and the cut-off for this test was studied by means of an ROC-curve. According to our results clinical examination by an experienced doctor seems to be sufficient if there are typical symptoms of carpal tunnel syndrome, but if there is a history of pain, atypical symptoms or earlier fractures in the arm, wrist or hand, it is important to add a neurophysiological examination.

Literature review of the usefulness of nerve conduction studies and electromyography for the evaluation of patients with carpal tunnel syndrome. AAEM Quality Assurance Committee

The sensitivity and specificity of nerve conduction studies (NCS's) and electromyography (EMG) for the diagnosis of carpal tunnel syndrome (CTS) were evaluated by a critical review of the literature. With a search of the medical literature in English through May 1991, 165 articles were identified and reviewed on the basis of six criteria of scientific methodology. The findings of 11 articles that met all six criteria and the results of 48 additional studies that met four or five criteria are presented. We concluded that median sensory and motor NCS's are valid and reproducible clinical laboratory studies that confirm a clinical diagnosis of CTS with a high degree of sensitivity and specificity. Clinical practice recommendations are made based on a comparison of the sensitivities of the several different median nerve conduction study (NCS) techniques.

Median sensory distal amplitude and latency: comparisons between nonexposed managerial/professional employees and industrial workers

To test for associations between occupation and median nerve dysfunction, measures of median motor and median and ulnar sensory amplitude and distal latency were compared among three populations: control subjects without occupational exposure to highly forceful or repetitive hand exertions (N = 105), industrial workers with hand/wrist symptoms (N = 103), and asymptomatic industrial workers (N = 137). Mean sensory amplitudes were significantly smaller (p < 0.05) and motor and sensory distal latencies were significantly longer (p < 0.001) in the industrial "asymptomatic hand" population compared to the control population. Prolongation of median relative to ulnar latency was significantly longer in the asymptomatic industrial population (p < 0.05). Results were most plausibly explained by differences in checklist identified ergonomic stressors. Median sensory amplitudes were significantly smaller (p < 0.01) and latencies longer (p < 0.05) for industrial workers with exposure to high grip forces compared to those without. Exposure misclassification may have reduced power to detect statistically significant differences between exposed and nonexposed population groups.

Effects of age, sex, and anthropometric factors on nerve conduction measures

Associations among measures of median, ulnar, and sural nerve conduction and age, skin temperature, sex, and anthropometric factors were evaluated in a population of 105 healthy, asymptomatic adults without occupational exposure to highly repetitive or forceful hand exertions. Height was negatively associated with sensory amplitude in all nerves tested (P less than 0.001), and positively associated with median and ulnar sensory distal latencies (P less than 0.01) and sural latency (P less than 0.001). Index finger circumference was negatively associated with median and ulnar sensory amplitudes (P less than 0.05). Sex, in isolation from highly correlated anthropometric factors such as height, was not found to be a significant predictor of median or ulnar nerve conduction measures. Equations using age, height, and finger circumference for prediction of normal values are presented. Failure to adjust normal nerve conduction values for these factors decreases the diagnostic specificity and sensitivity of the described measures, and may result in misclassification of individuals.

Location of Impaired Sensory Conduction of the Median Nerve in Carpal Tunnel Syndrome

Sensory conduction of the median nerve at the carpal tunnel for eight consecutive 1 cm segments of the nerve was evaluated in 217 hands of 153 of our patients with carpal tunnel syndrome. Impairment was found to be highly focal and often confined to a single 1 cm segment of the nerve. The section of the nerve at or just distal to the distal margin of the carpal tunnel was affected most frequently, the section within the tunnel was affected less often, and the section proximal to the tunnel at the level of the mid-carpal and radio-carpal joints was affected least. The greatest contrast between frequencies of slowing at adjacent segments occurred at the proximal and distal margins of the carpal tunnel. The distribution of the nerve impairment was similar between the sexes; however, among the men the segment affected most frequently was located 1 cm distal to the segment affected most frequently among the women. The general pattern of slowing which we found does not substantiate some commonly-held opinions about the aetiology of carpal tunnel syndrome.

Ring finger testing in carpal tunnel syndrome: a comparative study of diagnostic utility

Because digit 4 (D4) has dual innervation, median and ulnar sensory latencies can be determined over identical distances. To determine if D4 testing is more sensitive than other commonly used techniques to diagnose carpal tunnel syndrome (CTS), we examined 42 hands with clinical evidence of carpal tunnel syndrome and 43 control hands. D4 latency was significantly longer than controls more often than digit 2 (D2) in patients with CTS. Comparing median to ulnar latencies from D4 was the most sensitive method to make the diagnosis of CTS. In mild CTS, a characteristic double peak potential was seen in recordings from the median nerve after stimulating D4. This potential provided immediate visual confirmation of the diagnosis of CTS. Comparing D4 latency along median and ulnar nerves is useful for detecting mild CTS and should be used whenever there are clinical signs and symptoms of CTS but electrodiagnostic studies are normal or borderline.

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

In the carpal tunnel syndrome (CTS) sensory nerve conduction is more sensitive than motor conduction. However, 8%-25% of the sensory distal latencies in symptomatic hands may still be normal. A systematic study was made of the median, ulnar and radial orthodromic nerve conduction velocities (SNCV) stimulating each of the fingers separately. Four SNCVs from the median nerve, two SNCVs from the ulnar nerve and one from the radial nerve were obtained, and the ratio of the median to radial SNCV and the ratios of the median and ulnar SNCVs were estimated. The significance of these parameters in the diagnosis of the CTS was studied, and a rapid technique for the screening of nerve entrapment in the initial stages of the disease is proposed. Three hundred and seventy-five symptomatic hands were examined. Seventy-five hands showed normal distal latency, in which cases, however, the SNCV of the ring finger was always outside the normal range, while the SNCVs of the thumb, index and middle fingers were abnormal in 64%, 80% and 92% of cases respectively. The amplitudes of the sensory responses were the least sensitive of the parameters studied. Our results suggest that a study of the median nerve digital branch to the ring finger may be of value in providing an easily performed and rapid technique for screening an early median nerve entrapment at the wrist.

AAEE minimonograph #26: The electrodiagnosis of carpal tunnel syndrome

The electrodiagnosis of carpal tunnel syndrome is reviewed, including discussions of old and new techniques of motor and sensory nerve conduction, anomalous innervation, needle electrode examination, and one method of examining a patient with suspected carpal tunnel syndrome. The results of electromyographic testing of 505 patients with carpal tunnel syndrome in Rochester, Minnesota, from 1961 to 1980 are compared with results from previous studies. In the appendixes, a method of performing median motor and sensory nerve conduction studies and Mayo Clinic normal values are provided.