The N18 component of the median nerve SEP is not reduced by vibration

Objective: To study the interference of mechanical vibration of the palm of the hand on the median nerve short-latency SEP components.Methods: Electrically-elicited short-latency median nerve SEP were obtained before and during mechanical vibration (120 Hz) of the palm in two groups of normal individuals (6 in group I and 9 in group II). the amplitude of the different components was compared between the two conditions through non-parametric statistical tests.Results: A significant reduction in the amplitude of the N9, P13/14 and N20 components was detected, however no overall significant changes were detected for the N18 component.Conclusions: Vibration interference reduced all studied components except the N18. these findings are interpreted as supporting evidence fur the proposed association between the N18 component and the inhibitory activities elicited in the dorsal column nuclei. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.UNIFESP, Escola Paulista Med, Dept Neurol, Clin Neurophysiol Lab, BR-04120040 São Paulo, BrazilUniv São Paulo, Inst Biomed Sci, Dept Physiol & Biophys, São Paulo, BrazilUNIFESP, Escola Paulista Med, Dept Neurol, Clin Neurophysiol Lab, BR-04120040 São Paulo, BrazilWeb of Scienc

A comparison between different parameters in F-wave studies

Ulnar nerve F-waves were studied in 23 healthy volunteers and 27 diabetic patients. Latencies and chronodispersion were analyzed in each group. in the diabetic group all the parameters were normal in 14 patients (52%) and in 13 (48%) at least one parameter was altered. in these patients the most frequently altered parameter was the maximum latency (92%), followed by mean latency (85%), minimum latency (54%) and chronodispersion (54%). These findings suggest that maximum and mean latencies are better parameters to be analyzed in ulnar F-wave studies than minimum latency. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.Universidade Federal de São Paulo, Clin Neurophysiol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Endocrinol, São Paulo, BrazilUniversidade Federal de São Paulo, Clin Neurophysiol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Endocrinol, São Paulo, BrazilWeb of Scienc

Anatomical observations and false motor points in intrinsic foot muscles

Universidade Federal de São Paulo, Disciplina Anat Descrit & Topog, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Setor Neurofisiol Clin, Disciplina Neurol, São Paulo, BrazilUniversidade Federal de São Paulo, Disciplina Anat Descrit & Topog, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Setor Neurofisiol Clin, Disciplina Neurol, São Paulo, BrazilWeb of Scienc

Sample size and the study of F waves

Ulnar nerve F waves were studied in 23 healthy volunteers and 27 diabetic patients. Latencies and chronodispersion were analyzed in each group for different sample sizes. Significant differences were not detected with the different sample sizes for mean latencies, with samples above 16 stimuli or 10 waves for minimum and maximum latencies and above 20 stimuli or 16 waves for chronodispersion. These findings suggest that these limits may be adequate for group comparison. However, for the analysis of individual patients, the evidence suggests that larger samples are required for the determination of the minimum;and maximum latencies and chronodispersion. (C) 1999 John Wiley & Sons, Inc.Universidade Federal de São Paulo, Clin Neurophysiol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biostat, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Endocrinol, São Paulo, BrazilUniversidade Federal de São Paulo, Clin Neurophysiol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biostat, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Endocrinol, São Paulo, BrazilWeb of Scienc

SHORT-LATENCY MEDIAN NERVE SOMATOSENSORY-EVOKED POTENTIAL (SEP) - INCREASE in STIMULATION FREQUENCY FROM 3 TO 30 HZ

Somatosensory evoked potentials were obtained by electrical stimulation of the median nerve in 10 normal subjects at 3 and 30 Hz. At the higher rate of stimulation, a reduction was observed in amplitudes and prolongation of latencies of the N9,N/P13 and N20 components as well as increase of the interpeak latency N9-N/P13. A significant increase between the onsets of the N11 and N20 components was also seen; however, no significant increase of the N/P13-N20 interpeak latency was observed. Analysis suggested that an important reason for this last finding was related to the fact that in some cases different fast frequency components (FFC) determined the N20 peak in the different situations. It was further observed that, in those cases in which at least 3 peaks in the fast frequency components were detected (7/10), a significantly different increase in latency between the first and the third peaks was noted. A possible thalamo-cortical generation of the FFC is discussed.UNIV HOSP São Paulo,CLIN NEUROPHYSIOL LAB,São Paulo,BRAZILESCOLA PAULISTA MED,BIOSTAT DISCIPLINE,São Paulo,BRAZILUNIV HOSP São Paulo,CLIN NEUROPHYSIOL LAB,São Paulo,BRAZILESCOLA PAULISTA MED,BIOSTAT DISCIPLINE,São Paulo,BRAZILWeb of Scienc