Vestibular evoked myogenic potentials:test-retest reliability

Vestibular evoked myogenic potentials (VEMPs) are myogenic responses induced by stimulation of the saccular macula by intense sound stimuli, The responses are recordable from the sternocleidomastoid (SCM) muscles. We recorded VEMPs from normal subjects (up to three times in each subject) to identify: i) the best recording procedures, ii) the reliability. and iii) the normal limits for both individual point and test-retest evaluation. We adopted a recording setting in which the subjects were asked to simultaneously activate both SCM muscles by pushing their forehead against a load cell during a bilateral acoustic stimulation. This system enabled subjects to monitor their intensity of SCM activation and to keep intensity constant: us to record VEMPs from both sides simultaneously. and thus to minimize the duration of the recording session. For each subject we considered the mean and the difference (divided by the mean) of the values derived from the two SCM muscles of the latency of the P13 and N23 components and of the P13-N23 peak-to-peak amplitude. Reliability was evaluated by estimate of the intraclass correlation coefficient, and was good or excellent for all parameters. with the exception of the P13-N23 amplitude side-difference. To take advantage of all the data available, we computed the normal limits for both individual point and test-retest evaluation by means of the variability indices used for the evaluation of reliability. In this system, VEMP recording is simple, inexpensive and rapid. It is well tolerated by subjects, and easily implemented in laboratories equipped for evoked potential recording

Vestibular evoked myogenic potentials:test-retest reliability.

Vestibular evoked myogenic potentials (VEMPs) are myogenic responses induced by stimulation of the saccular macula by intense sound stimuli, The responses are recordable from the sternocleidomastoid (SCM) muscles. We recorded VEMPs from normal subjects (up to three times in each subject) to identify: i) the best recording procedures, ii) the reliability. and iii) the normal limits for both individual point and test-retest evaluation. We adopted a recording setting in which the subjects were asked to simultaneously activate both SCM muscles by pushing their forehead against a load cell during a bilateral acoustic stimulation. This system enabled subjects to monitor their intensity of SCM activation and to keep intensity constant: us to record VEMPs from both sides simultaneously. and thus to minimize the duration of the recording session. For each subject we considered the mean and the difference (divided by the mean) of the values derived from the two SCM muscles of the latency of the P13 and N23 components and of the P13-N23 peak-to-peak amplitude. Reliability was evaluated by estimate of the intraclass correlation coefficient, and was good or excellent for all parameters. with the exception of the P13-N23 amplitude side-difference. To take advantage of all the data available, we computed the normal limits for both individual point and test-retest evaluation by means of the variability indices used for the evaluation of reliability. In this system, VEMP recording is simple, inexpensive and rapid. It is well tolerated by subjects, and easily implemented in laboratories equipped for evoked potential recording

Saccades and 6-Methylprednisolone Treatment in Multiple Sclerosis

Saccadic eye movements are studied in patients suffering from multiple sclerosis during a worsening of the disease, before and after high-dose 6-methylprednisolone infusions. The quantitative evaluation was based on the amplitude-duration and amplitude-peak velocity relationships, the precision (i.e., the ratio of actual to desired saccade amplitude) and the latency of saccades. At basal recordings, 15 of the 17 patients showed at least one abnormality. The amplitude-duration relationship improved in one patient and worsened in two patients; the amplitude-peak velocity relationship improved in one and worsened in another patient; and the precision and the latency improved in one and seven patients respectively. In the whole group of patients, the only parameter which showed a significant modification (improvement) was the latency. Finally, the neurophysiological modifications did not match clinical changes. © 1994 Elsevier B.V

Vestibular evoked myogenic potentials in multiple sclerosis patients

Objectives: Vestibular evoked myogenic potentials (VEMPs) are saccular responses to loud acoustic stimuli and are recordable from the sterno-cleido-mastoid muscle ipsilaterally to the stimulated ear. This study aimed to investigate VEMPs in patients suffering from multiple sclerosis (MS), and to compare these findings with both clinical and instrumental data. Methods: We recorded VEMPs from 70 MS patients, whose clinical data were retrospectively evaluated for the possible occurrence of: past and current (with respect to VEMP recording) brainstem and/or cerebellar symptoms; current brainstem and/or cerebellar signs. Sixty-five patients underwent brainstem auditory evoked potentials (BAEPs) recording; 63 of the same patients underwent saccadic eye movement recording and subjective visual vertical (SVV) evaluation. Results: VEMPs were abnormal in 31%, BAEPs in 38% and SVV in 21% of the patients. Saccadic eye movements showed a possible brainstem dysfunction in 44.4% of the patients. There was no correlation between the occurrence of abnormalities and the technical means of detection. The same held true for correlations with clinical data, with the exception of the BAEPs; these proved to be more frequently abnormal in patients presenting at neurological examination with brainstem and/or cerebellar signs that were possibly related to the complaint of dizziness. Conclusions: VEMP's should be considered a useful complementary neurophysiological tool for the evaluation of brainstem dysfunction. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved