Need for Thorough Standardization of CO2 Laser Evoked Potential Procedure.

PURPOSE: The objective of this study was to determine normative values of laser evoked potentials and anthropometric correlations in a healthy middle-aged working population. METHODS: In 51 subjects, CO2 laser stimulation was applied bilaterally onto dorsal surface of the feet, hands, and neck using constant duration of stimulus and beam diameter, changing just the intensity of stimulation. Amplitudes and latencies of the laser evoked potential negative-positive complex were recorded, and relationship with height, age and gender was statistically analyzed. RESULTS: There was a significant correlation between the latencies obtained for feet, hands, and height. P2 amplitudes for feet, hands, and neck, and negative-positive pk-pk amplitudes for hands and neck correlated negatively with age. The values obtained did not differ significantly between male and female gender, except for N2 latencies for hands. CONCLUSIONS: Clinically useful reference values for laser evoked potentials in a healthy middle-aged population were provided, which are interesting from the physiological point of view.

Ocular and cervical vestibular evoked myogenic potentials in patients with multiple sclerosis.

OBJECTIVES: The aim of this study was to evaluate latencies and corrected p13-n23 cervical vestibular evoked myogenic potentials (cVEMP) and n10-p13 ocular vestibular evoked myogenic potentials (oVEMP) amplitudes in patients with relapsing remitting multiple sclerosis (MS). METHODS: This was a prospective, case-control study. Thirty patients with MS and 15 healthy controls were included. Cervical vestibular evoked myogenic potentials and oVEMP in response to acoustic clicks of 1 ms duration at the intensity of 130 dB SPL and the stimulation frequency of 1 Hz were studied. Signals were divided in segments of 120 ms duration (20 ms before the stimulus and 100 ms after the stimulus) and averaged. RESULTS: In MS group, there was significant latencies prolongation of all sternocleidomastoid responses (p13 and n23) and n10 response of the ocular muscles. The sternocleidomastoid p13-n23 normalized amplitude was significantly higher in MS patients. Prolonged latencies were found in 57% and conduction block in 7% of patients in at least one sternocleidomastoid response in the MS group. Prolonged latencies were found in 30% and conduction block in 40% of patients in at least one ocular response in the MS group. When cVEMP and oVEMP are combined, 80% had pathological finding. When correlating brainstem clinical, brainstem MRI, and cVEMP findings, there was no statistical significance (brainstem clinical vs. cVEMP P = 0.1; brainstem MRI vs. cVEMP P = 0.82). When correlating brainstem clinical, brainstem MRI and oVEMP findings, there was a statistical significant correlation between brainstem clinical versus oVEMP, P = 0.02, whereas there was no statistical significance between brainstem MRI versus oVEMP (P = 0.38). CONCLUSIONS: Combination of cVEMP and oVEMP in MS patients allows better estimation of brainstem lesions.

[Vestibular neuronitis: pathophysiology, diagnosis and treatment]. / Vestibularni neuronitis: patofiziologija, dijagnoza i lijecenje.

Vestibular neuritis (VN) is one of the most common causes of peripheral vertigo. Caloric testing has been the traditional gold standard for detecting a peripheral vestibular deficit, but some recently developed bedside tests (head thrust, head heave, head shake and vibration test) were evaluated as a good alternative with similar sensitivity and specificity. These tests have shown both diagnostic value in the short term and prognostic value in the long term, and have availability and ease of use as an advantage. As an addition to clinical examination, vestibular evoked myogenic potentials can differentiate between involvement of superior and inferior branch of the vestibular nerve, but also between peripheral and central lesions. Although glucocorticoids are currently widely used in the treatment of VN, there is a lack of evidence for the validity of their administration. There are a number of high quality clinical trials that suggest vestibular rehabilitation exercises, which are based on the mechanisms of vestibular compensation, in the managment of VN. This review will focus on the latest developments in the pathophysiology, diagnosis and treatment of patients with VN.

Cognitive auditory evoked potentials in children with special language impairment.

Perception and discrimination of auditory and speech stimuli in children aged 7-9 years with either receptive (n=6) or expressive (n=5) type of special language impairment and 7 healthy age-matched controls was investigated using evoked potential technique. The measurements were performed with a 32-channel Neuroscan electroencephalographic system. Two types of stimuli were applied, pure tones (1 kHz and 2 kHz) and double syllabi consisting of one consonant and one vocal characteristic of Croatian language. The stimuli were presented in an oddball paradigm, requiring a conscious reaction for the subjects. Latencies and amplitudes of P1, N1, P2, N2, P3, N4, and SW waves were analized, as well as the reaction time and number of responses. There were found no statistically significant difference between children with special language impairment and the control group in average response time and number of responses to tone burst or double syllable. Analysis of variance of all used variables showed a statistically significant difference in P3 and Sw wave latencies after double syllable stimulation, P3 and N4 waves latencies after target stimulation, P2 and Sw wave amplitude; and in N1 wave amplitude after pure tone stimulation. Our study showed that children with speech and language disorder take longer time to perceive and discriminate between either tonal or speech auditory stimuli than children with typical speech and language development.

[The effect of antiepileptic drug therapy on cognitive evoked potentials and reaction time]. / Utjecaj terapije antiepilepticima na kognitivne evocirane potencijale i brzinu motoricke reakcije.

UNLABELLED: It is well known that antiepileptic drugs have side effects on cognitive and behavioral functioning of the treated patients. AIM: Our goal was to investigate their effect on cognitive evoked potential peak latencies and patient reaction times to target stimuli for two different, acoustic and visual stimulating paradigms. Therefore, a control group of healthy subjects and three groups of patients treated with antiepileptic drugs (carbamazepine, phenobarbital) were compared. PATIENTS AND METHODS: Group 1 of 19 epileptic patients had undertherapeutic and group 2 of 16 patients had a therapeutic concentration of these drugs. Group 3 of 18 patients were treated with carbamazepine in therapeutic dose for nonepileptic reasons. The N1, P2, N2, P3a and P3b peak latencies as well as reaction time to the same target stimuli were analyzed. RESULTS AND DISCUSSION: Obtained for acoustic and visual stimulating paradigm in the control group showed no significant differences results suggesting it to be sufficient to use simple acoustic paradigm for screening. The hypothesis that antiepileptic drugs influence the parameters of cognitive evoked potentials when used as polytherapy was confirmed. The reaction time measured in the same groups showed statistically significant differences between healthy subjects and drug treated patients. The effect of antiepileptic drugs on peak latencies of cognitive evoked potentials was statistically significant, and an even greater effect was recorded on the reaction time of treated patients. CONCLUSION: The results obtained in the study were in accordance with our hypothesis that this neurophysiological method could be successfully used as a screening method to check the cognitive and motor state of antiepileptic medication.