Effect of caffeine on cervical vestibular-evoked myogenic potential in healthy individuals1

Evaluation of cervical vestibular miogenic evoked potential and electrococleography in the diagnosis of vestibular migraine

OBJECTIVES

Vestibular migraine is a neurological disorder characterized by the association of vertigo and headache, affecting up to 1% of the population. Among its differential diagnoses is endolymphatic hydrops. The aim of this study was to investigate the role of cervical vestibular-evoked myogenic potential and electrocochleography in the diagnosis of vestibular migraine.

METHOD

Thirteen women with clinical diagnosis of vestibular migraine (mean age 44 years) and 13 healthy volunteers without auditory and/or vestibular complaints matched for sex and age were evaluated by performing hydrops examinations of cervical vestibular-evoked myogenic potential and electrocochleography.

RESULTS

The presence of vertigo and headache was reported by all members of the group with vestibular migraine, associated with symptoms such as nausea, photophobia, and phonophobia. Tinnitus was the most frequent auditory complaint. A significant increase in P1 and N1 latencies was observed in the test group. There was no significant difference in the occurrence of asymmetry and decreased amplitude of the cervical vestibular-evoked myogenic potential. Electrocochleography showed an increase in amplitude of the summation potential. The altered SP/AP ratio was double in the group with vestibular migration, without statistical significance.

CONCLUSIONS

Changes in latency increase of cervical vestibular-evoked myogenic potential suggests a central lesion. Patients with vestibular migraine may present electrocochleography compatible with endolymphatic hydrops.

LEVEL OF EVIDENCE

Level 4.

Characterization of electrocorticographic, electromyographic and electrocardiographic recordings after the use of caffeine in Wistar rats

Objective:

To describe electrocorticographic, electromyographic and electrocardiographic profiles to report the electrophysiological effects of caffeine in Wistar rats.

Methods:

Male adult Wistar rats weighing 230g to 250g were used. Rats were allocated to one of two groups, as follows: Group 1, Control, intraperitoneal injection of 0.9% saline solution (n=27); and Group 2, treated with intraperitoneal injection of caffeine (50mg/kg; n=27). The rats were submitted to electrocorticographic, electromyographic and electrocardiographic assessment.

Results:

Brain oscillations (delta, theta, alpha, beta and gamma) in the frequency range up to 40Hz varied after caffeine administration to rats. Powers in delta and theta oscillations ranges were preponderant. The contractile force of the skeletal striated and cardiac muscles increased. Electrocardiogram analysis revealed shorter RR, QRS and QT intervals under the effect of caffeine.

Conclusion:

In the central nervous system, there was an increase in the delta, theta and alpha amplitude spectrum, which are related to memory encoding and enhanced learning. With regard to skeletal muscle, increased contraction of the gastrocnemius muscle was demonstrated, a clear indication of how caffeine can be used to enhance performance of some physical activities. Electrocardiographic changes observed after caffeine administration are primarily related to increased heart rate and energy consumption.

A comprehensive review of the effects of caffeine on the auditory and vestibular systems

Coffee, of which caffeine is a critical component, is probably the most frequently used psychoactive stimulant in the world. The effects of caffeine on the auditory and vestibular system have been investigated under normal and pathological conditions, such as acoustic trauma, ototoxicity, auditory neuropathy, and vestibular disorders, using various tests. Lower incidences of hearing loss and tinnitus have been reported in coffee consumers. The stimulatory effect of caffeine is represented by either a shorter latency or enhanced amplitude in electrophysiological tests of the auditory system. Furthermore, in the vestibular system, oculomotor testing revealed significant effects of caffeine, while other tests did not reveal any significant caffeine effects. It could be that caffeine improves transmission in the auditory and vestibular systems' central pathways. Importantly, the effects of caffeine seem to be dose-dependent. Also, inconsistent findings have been observed regarding caffeine's effects on the auditory and vestibular systems and related disorders. Overall, these findings suggest that caffeine does not strongly influence the peripheral auditory and vestibular systems. Instead, caffeine's effects seem to occur almost solely at the level of the central nervous system.

Effects of Caffeine on Auditory- and Vestibular-Evoked Potentials in Healthy Individuals: A Double-Blind Placebo-Controlled Study

BACKGROUND AND OBJECTIVES

The blockage of adenosine receptors by caffeine changes the levels of neurotransmitters. These receptors are present in all parts of the body, including the auditory and vestibular systems. This study aimed to evaluate the effect of caffeine on evoked potentials using auditory brainstem responses (ABRs) and cervical vestibular-evoked myogenic potentials (cVEMPs) in a double-blind placebo-controlled study.

Subjects and METHODS

Forty individuals (20 females and 20 males; aged 18-25 years) were randomly assigned to two groups: the test group (consuming 3 mg/kg pure caffeine powder with little sugar and dry milk in 100 mL of water), and the placebo group (consuming only sugar and dry milk in 100 mL water as placebo). The cVEMPs and ABRs were recorded before and after caffeine or placebo intake.

RESULTS

A significant difference was observed in the absolute latencies of I and III (p<0.010), and V (p<0.001) and in the inter-peak latencies of III-V and I-V (p<0.001) of ABRs wave. In contrast, no significant difference was found in cVEMP parameters (P13 and N23 latency, threshold, P13-N23 amplitude, and amplitude ratio). The mean amplitudes of P13-N23 showed an increase after caffeine ingestion. However, this was not significant compared with the placebo group (p>0.050).

CONCLUSIONS

It seems that the extent of caffeine's effects varies for differently evoked potentials. Latency reduction in ABRs indicates that caffeine improves transmission in the central brain auditory pathways. However, different effects of caffeine on auditory- and vestibular-evoked potentials could be attributed to the differences in sensitivities of the ABR and cVEMP tests.

Effect of caffeine on vestibular evoked myogenic potential: a systematic review with meta-analysis

Introduction

Caffeine can be considered the most consumed drug by adults worldwide, and can be found in several foods, such as chocolate, coffee, tea, soda and others. Overall, caffeine in moderate doses, results in increased physical and intellectual productivity, increases the capacity of concentration and reduces the time of reaction to sensory stimuli. On the other hand, high doses can cause noticeable signs of mental confusion and error induction in intellectual tasks, anxiety, restlessness, muscle tremors, tachycardia, labyrinthine changes, and tinnitus.

Objective

Considering that the vestibular evoked myogenic potential is a clinical test that evaluates the muscular response of high intensity auditory stimulation, the present systematic review aimed to analyze the effects of caffeine on vestibular evoked myogenic potential.

Methods

This study consisted of the search of the following databases: MEDLINE, CENTRAL, ScienceDirect, Scopus, Web of Science, LILACS, SciELO and ClinicalTrials.gov. Additionally, the gray literature was also searched. The search strategy included terms related to intervention (caffeine or coffee consumption) and the primary outcome (vestibular evoked myogenic potential).

Results

Based on the 253 potentially relevant articles identified through the database search, only two full-text publications were retrieved for further evaluation, which were maintained for qualitative analysis.

Conclusion

Analyzing the articles found, caffeine has no effect on vestibular evoked myogenic potential in normal individuals.