Simultaneous Median-Radial Nerve Electrical Stimulation Revisited: An Accurate Approach to Carpal Tunnel Syndrome Diagnosis and Severity.

PURPOSE: To assess the accuracy of an unusual test for CTS investigation and correlate it with clinical symptoms. METHODS: Initially, we applied a visual analog scale for CTS discomfort (CTS-VAS) and performed a standard electrophysiologic test for CTS diagnosis (median-ulnar velocity comparison). Posteriorly, a blinded neurophysiologist performed the orthodromic simultaneous median-radial nerve stimulation (SMRS) at the thumb, with recording of both action potentials over the lateral aspect of the wrist. RESULTS: All hands (106) showed median-radial action potential splitting using the SMRS technique, in which was possible to measure the interpeak latencies (IPLs) between action potentials. The IPL and median nerve conduction velocity were different according to CTS intensity (Bonferroni; P < 0.001). There was significant correlation between IPL and median nerve conduction velocity (Spearman; r = -0.51; P < 0.01). In the same way, there was a significant correlation between IPL and median nerve conduction velocity with CTS-VAS (r = 0.6 and r = -0.3, respectively). The duration and unpleasantness of the SMRS procedure were lower when compared with standard approach (t Student < 0.001 for both comparisons). Twenty-nine symptomatic patients (39 hands) who did not fulfill criteria for CTS based on standard approach showed abnormal IPLs. CONCLUSIONS: The SMRS technique is a simple, sensitive, and tolerable approach for CTS diagnosis. Apart from that, the data from SMRS correlated better with clinical impact of CTS in comparison with the standard approach. Therefore, this method might be useful as adjunct to standard electrophysiologic approaches in clinical practice.

Brazilian Portuguese validation of the Leeds Assessment of Neuropathic Symptoms and Signs for patients with chronic pain.

BACKGROUND: Neuropathic pain (NP) is a very frequent and unrecognized condition in clinical practice. Therefore, it is important to have a reliable instrument to assess pain subtypes in various cultures. The Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) has been widely used and validated in many countries. Up to now, there has been no reliability study of this instrument in Brazil. METHODS: The scores of the Brazilian Portuguese version of the LANSS were studied in a sample of 90 chronic pain outpatients from southern Brazil. LANSS was translated into Portuguese and then back translated to English. Intraclass correlation coefficient (ICC) and internal consistency (IC) were estimated. The intensity of pain complaints, other demographic data, and LANSS scores distribution according to pain subtypes (nociceptive, neuropathic, and mixed) were also evaluated. RESULTS: The Brazilian Portuguese version of the LANSS showed good ICC (r = 0.97) and IC (Cronbach's α = 0.67 for total LANSS score). Patients with NP provided significant higher LANSS scores (19.1 ± 3.3) in comparison with those with nociceptive (7.3 ± 4.5) and mixed (13.9 ± 3.7) types of pain. CONCLUSIONS: This LANSS version was found to be a reliable instrument for the evaluation of pain complaints due to a variety of causes. The profile of pain scores was similar to that observed in other countries.

Sympathetic skin responses evoked by muscle contraction.

INTRODUCTION: Voluntary muscle contraction is accompanied by an increase in sympathetic nerve activity. The sympathetic skin response (SSR) is a simple and non-invasive method of autonomic assessment that reflects a synchronized activity of the sweat glands. The aim of our study was to examine the possible relationship between isometric muscle contraction (IC) and changes in the SSR. METHODS: In 11 healthy right-handed volunteers, we recorded the SSR from the palm of the hand induced by contralateral triceps IC (mSSR) of variable intensities and durations. We measured the latency, duration, amplitude, waveform and habituation index (HI) of the mSSR, in comparison to the SSR induced by supramaximal electrical stimulation (eSSR) of the brachial plexus at the axillae. RESULTS: A single mSSR was always present at a mean latency of 1.34+/-0.5s after the onset of IC. Response amplitude, but not latency or duration, correlated positively with the intensity of IC (r=0.67; p<0.001). The latency was shorter, the duration was longer and the HI was reduced in the mSSR in comparison to the eSSRs (ANOVA; p<0.05 for all comparisons). CONCLUSIONS: The mSSR is likely generated endogenously together with the motor commands since inputs from muscle afferents cannot account for response onset. This, together with its low level of habituation, underscores the possibilities of physiological and clinical studies using the mSSR, especially in the assessment of autonomic function in patients with nerve afferent problems.