Forearm Motor Conduction Velocity Research Articles

Neuroelectrophysiological Evaluation of Carpal Tunnel Syndrome before and after Surgical Intervention

Background: Carpal tunnel release operation (CTR) is required to alleviate the symptoms of carpal tunnel syndrome (CTS), the most common entrapment neuropathy. Methods: Thirty-two patients (39 hands) of CTS were subdivided into Group I is moderate CTS (n = 9 hands), Group II is severe CTS (n = 14 hands), and Group III is extreme CTS (n = 16 hands) and underwent conventional electrophysiological evaluation and short segment transcarpal nerve conduction studies preoperatively and 1 and 3 months after open CTR operation. Results: In the case of motor conduction parameter, distal motor latency showed statistically significant improvement after 1 month of CTR (P < 0.05) in all three groups of patients, and improvement consistently increased during 3rd month follow-up (P < 0.001). In Group III patients, preoperatively forearm motor conduction velocity (FMCV) and transcarpal motor conduction velocity (TMCV) were nonrecordable, FMCV became recordable in 6 hands, while TMCV in all 16 hands post CTR. In case sensory parameters, both distal sensory latency (DSL) and sensory nerve conduction velocity (SNCV) showed significant improvement in Group I, and no improvement was noted in Group III patients. Group II (6 of 14 hands) patients showed a reappearance of DSL and SNCV at 1-month follow-up and continued a steady improvement in 3rd month after CTR. Conclusion: We found that TMCV is a more sensitive parameter in assessing improvement of median nerve function after CTR. It is possible to identify patients with a poor outcome by performing electrophysiological studies.

Do Electrodiagnostic Variables Correlate with Functional Outcomes in Carpal Tunnel Syndrome?

Background: The most common entrapment neuropathy seen in electrodiagnostic (EDX) laboratories is carpal tunnel syndrome (CTS). The diagnostic value of EDX with regard to CTS is well-established, but EDX’s predictive value is unclear. To date, only one study has attempted to establish a relationship between EDX findings and a patient’s clinical status pre- and post-treatment, and there was no significant relationship found. Objective: To establish a relationship between EDX variables and clinical severity assessment with Disabilities of the Arm, Shoulder, and Hand (DASH) scores at a single point in time and over a period of time. Methods: The study was a prospective single group cohort. 41 patients referred to an EDX clinic with suspected diagnoses of CTS were enrolled. Patients underwent EDX studies and completed DASH questionnaires at initial and follow-up visits at 8-month to 12-month intervals. Data collected included median sensory, mixed, and motor latencies, amplitudes, conduction velocities, and needle electromyography (EMG). Correlation coefficients were determined between EDX data variables and severity assessment (independent variables) and patients’ DASH questionnaire measures (dependent variables) at initial and follow-up assessments. Results: Change in DASH score over time positively correlated with left distal median motor latency (DMML) decrement and right transcarpal median sensory conduction block and negatively correlated with left median sensory nerve action potential (SNAP) amplitude decrement percentage, right needle EMG motor unit morphology abnormality, and right median forearm motor conduction velocity increment. The correlations observed are of unclear significance since the DASH scores themselves did not change significantly over time. Conclusions: Objective EDX data coupled with patient-reported outcome (PRO) measures such as the DASH score may be more meaningful in directing clinical care than either of them alone.

A study of retrograde degeneration of median nerve forearm segment in carpal tunnel syndrome of variable severities

IntroductionCarpal tunnel syndrome (CTS) is a disorder of the hand which results from compression of the median nerve within its fibro-osseous tunnel at the wrist. The slowing in the forearm motor conduction velocity suggests the presence of retrograde degeneration. Existing studies conflict regarding a correlation between the severities of the entrapment neuropathy in CTS and slowing of median motor nerve conduction velocity in the forearm. AimsThe objective of this work was to study retrograde degeneration (RGD) of the median nerve forearm segment in patients with CTS and its relation to variable severity of CTS in Egyptian patients. Patients and methodsTwenty-four patients with CTS were included in this study. The Forearm mixed nerve conduction is presumed to be indicative of the conduction of the median nerve over the forearm and is used widely to assess the causes of slowing forearm conduction velocity in CTS. In addition to conventional nerve conduction studies of the upper limb, forearm median mixed conduction studies were performed. Median motor forearm amplitudes and nerve conduction velocities (NCVs) as well as forearm median mixed amplitudes and NCVs were considered as parameters of RGD. ResultsThere were statistically significant differences as regards forearm mixed nerve action potential (MNAP) amplitude and median motor amplitude in the forearm segment but there were no statistically significant differences as regards forearm median mixed peak latency and NCV. There was no statistically significant relation between grades of severities of CTS in the studied hands and both forearm median motor NCV and forearm MNAP amplitude using Monte Carlo test (MCp=0.323 and 0.464). ConclusionsRetrograde degeneration exists in patients with CTS. Forearm median motor NCV and median mixed conduction study are valid electrophysiologic tools for the assessment of RGD in patients with CTS. Retrograde degeneration is not related to grade of severity of CTS.

The Real Role of Forearm Mixed Nerve Conduction Velocity in the Assessment of Proximal Forearm Conduction Slowing in Carpal Tunnel Syndrome

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.

Alteration of Proximal Conduction Velocity at Distal Nerve Injury in Carpal Tunnel Syndrome: Demyelinating Versus Axonal Change

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.

Does retrograde axonal atrophy really occur in carpal tunnel syndrome patients with normal forearm conduction velocity?

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.

Conduction velocity in the forearm segment of the median nerve in patients with impaired conduction through the carpal tunnel

Conduction velocity, in the forearm segment of the median nerve, has been investigated in a group of patients with carpal tunnel syndrome. Motor conduction velocity was reduced below 50 m/s in 18% of the sample. Although a correlation between severity of compression and forearm motor conduction velocity was demonstrated, it was weak ( r = 0.51) and slow forearm velocities occurred i n some patients who had only a minor abnormality at the carpal tunnel itself. In patients with uncomplicated carpal tunnel syndrome, slow motor conduction in the forearm segment of the median nerve was accompanied by only a small reduction (approx. 5 m/s) in mixed nerve conduction velocity. By contrast, in patients whose abnormality at the carpal tunnel was accompanied by evidence of a more widespread sensorimotor neuropathy, mixed conduction velocity was reduced in parallel with the change in motor conduction velocity.

The peroneal muscular atrophy syndrome: Clinical, genetic, electrophysiological and nerve biopsy studies part 3. Clinical, electrophysiological and pathological correlations

This report analyses correlations between clinical, electrophysiological and pathological data derived from a series of families with peroneal muscular atrophy. It was found that the observed differences between families in median nerve forearm motor conduction velocity were unlikely to be due to differences in the age or severity of the cases. Similarly it was unlikely that the pathological differences between cases were due to age or severity of the case. The conduction velocity in the Hypertrophic Neuropathy Group tended to increase slightly with age, while that in other cases tended to fall slightly. The conduction velocity and total myelinated fibre counts were inversely related to the degree of segmental demyelination. The Hypertrophic Neuropathy Group and the Intermediate Group of cases were found to behave differently in a number of correlative analyses, thus supporting the suggestion that they represent different disease entities.