Robby Vanspauwen

Improving Vestibular Evoked Myogenic Potential Reliability by using a Blood Pressure Manometer

Objective/Hypothesis: To improve the reliability of vestibular evoked myogenic potentials (VEMP), we propose a feedback method making use of a readily available blood pressure manometer with inflatable cuff to control the sternocleidomastoid muscle (SCM) contraction.

Vestibular function testing.

Purpose of reviewThis review provides an overview of vestibular function testing and highlights the new techniques that have emerged during the past 5 years. Recent findingsSince the introduction of video-oculography as an alternative to electro-oculography for the assessment of vestibular-induced eye movements, the investigation of the utricle has become a part of vestibular function testing, using unilateral centrifugation. Vestibular evoked myogenic potentials have become an important test for assessing saccular function, although further standardization and methodological issues remain to be clarified. Galvanic stimulation of the labyrinth also is an evolving test that may become useful diagnostically. SummaryA basic vestibular function testing battery that includes ocular motor tests, caloric testing, positional testing, and earth-vertical axis rotational testing focuses on the horizontal semicircular canal. Newer methods to investigate the otolith organs are being developed. These new tests, when combined with standard testing, will provide a more comprehensive assessment of the complex vestibular organ.

Transmastoid repair of superior semicircular canal dehiscence.

Objective/Hypothesis Superior semicircular canal (Sup SC) dehiscence syndrome is a rare condition, causing a variety of auditory and vestibular symptoms. The traditional surgical management is a middle cranial fossa, extradural approach to resurface the Sup SC. Recently, a transmastoid approach for plugging of the Sup SC has been developed. We present further data supporting the use of the transmastoid approach in preference to the middle fossa approach. Design This is a retrospective multi-institutional case series. Method We included 10 patients in this case series from two tertiary otology institutions. Sup SC dehiscence was confirmed by correlation of clinical symptoms with positive audiometric, vestibular evoked myogenic potential, and computed tomography findings. A transmastoid approach was used for plugging of the Sup SC. Either a single fenestration was created at the site of dehiscence or separate fenestrations sited ampullopetal and ampullofugal to the dehiscence. Results All patients who underwent this procedure had good symptom control and hearing preservation postoperatively. Conclusion In patients with adequate temporal bone pneumatization, the transmastoid approach provides a safe and effective alternative to the middle cranial fossa approach. This series has demonstrated excellent symptom control and preservation of hearing with the transmastoid approach.

Pharmaceutical Countermeasures Have Opposite Effects on the Utricles and Semicircular Canals in Man

Introduction: Sensory conflicts in the vestibular system lead to motion sickness of which space motion sickness (SMS) is a special case. SMS affects up to 70% of the astronauts during the first 3 days in space. The search for effective countermeasures has led to several nonpharmacological and pharmacological approaches. The current study focuses on the effects of lorazepam (1 mg), meclizine (25 mg), promethazine (25 mg), and scopolamine (0.4 mg) on the vestibular system, with special focus on the canal and otolith functions separately. Methods: The study had a placebo-controlled, single blind, repeated measures design. Sixteen healthy volunteers were subjected to a total of 7 test sessions, the first and last being without intake of medication. Semicircular canal function was evaluated by means of electronystagmography and otolith function with unilateral centrifugation. The horizontal semicircular canal function was characterized by the vestibulo-ocular reflex (VOR) gain measured during earth vertical axis rotation as well as the total caloric response. The function of the utricles was represented by the utricular sensitivity, reflecting the ocular counter roll relative to the virtual induced head tilt. Results: Promethazine significantly decreased the semicircular canal and utricular parameters. Both scopolamine and lorazepam caused only a decrease in the utricular sensitivity, whereas meclizine only decreased the semicircular canal-induced VOR gain. Discussion: The results show that the drugs affected different areas of the vestibular system and that the effects can thus be attributed to the specific pharmacological properties of each drug. Meclizine, as an antihistaminergic and weak anticholinergic drug, only affected the VOR gain, suggesting a central action on the medial vestibular nucleus. The same site of action is suggested for the anticholinergic scopolamine since acetylcholine receptors are present and utricular fibers terminate here. The global vestibular suppression caused by promethazine is probably a consequence of its anticholinergic, antihistaminergic, and antidopaminergic properties. Based on the fact that lorazepam increased the affinity of gamma-aminobutyric acid (GABA) for the GABAA-receptor and its effects on the utriculi, the site of action seems to be the lateral vestibular nucleus. Conclusion: Meclizine, scopolamine, and lorazepam selectively suppress specific parts of the vestibular system. Selective suppression of different parts of the vestibular system may be more beneficial for alleviating (space) motion sickness than general suppressive agents. Additionally, this knowledge may help the clinician in his therapeutic management of patients with either semicircular canal or otolith dysfunction.

Mobile Communication Devices, Ambient Noise, and Acoustic Voice Measures

OBJECTIVES The ability to move with mobile communication devices (MCDs; ie, smartphones and tablet computers) may induce differences in microphone-to-mouth positioning and use in noise-packed environments, and thus influence reliability of acoustic voice measurements. This study investigated differences in various acoustic voice measures between six recording equipments in backgrounds with low and increasing noise levels. METHODS One chain of continuous speech and sustained vowel from 50 subjects with voice disorders (all separated by silence intervals) was radiated and re-recorded in an anechoic chamber with five MCDs and one high-quality recording system. These recordings were acquired in one condition without ambient noise and in four conditions with increased ambient noise. A total of 10 acoustic voice markers were obtained in the program Praat. Differences between MCDs and noise condition were assessed with Friedman repeated-measures test and posthoc Wilcoxon signed-rank tests, both for related samples, after Bonferroni correction. RESULTS (1) Except median fundamental frequency and seven nonsignificant differences, MCD samples have significantly higher acoustic markers than clinical reference samples in minimal environmental noise. (2) Except median fundamental frequency, jitter local, and jitter rap, all acoustic measures on samples recorded with the reference system experienced significant influence from room noise levels. CONCLUSIONS Fundamental frequency is resistant to recording system, environmental noise, and their combination. All other measures, however, were impacted by both recording system and noise condition, and especially by their combination, often already in the reference/baseline condition without added ambient noise. Caution is therefore warranted regarding implementation of MCDs as clinical recording tools, particularly when applied for treatment outcomes assessments.

No effects of anti-motion sickness drugs on vestibular evoked myogenic potentials outcome parameters

Objective: To investigate the effects of meclizine (50 mg), baclofen (10 mg), cinnarizine (20 mg) + dimenhydrinate (40 mg), and promethazine (25 mg) + dextro-amphetamine (5 mg) on the parameters of the vestibular evoked myogenic potential (VEMP) test. Study Design: Double-blind placebo-controlled prospective randomized trial. Setting: University hospital. Subjects: Twenty-four (first block: baclofen versus placebo) and 20 healthy male subjects (second block: meclizine, cinnarizine + dimenhydrinate and promethazine + dextro-amphetamine versus placebo). Interventions: VEMP test. Main Outcome Measures: Threshold, p13 and n23 latencies, p13-n23 latency difference, p13-n23 peak-to-peak amplitude, mean rectified voltage of the sternocleidomastoid muscle contraction and the corrected amplitude. Results: There were no clinically significant pharmacologic effects on the VEMP outcome parameters. However, there was a statistically significant left-right asymmetry after intake of the combination promethazine + d-amphetamine for the parameters p13 and latency difference. Conclusion: The absence of clinically significant effects can be explained by the predominant presence of the target receptors for the applied drugs in the medial vestibular nucleus, which receives the lowest grade of saccular projections. It also can be hypothesized that the VEMP methodology and techniques in general do not allow determining pharmacologic effects in a healthy group of subjects because of a too small discriminative power. The left-right asymmetry can be explained by a depressive action of the drugs on the central compensation mechanisms. Because there were no significant differences between the VEMP parameters obtained after intake of the placebos of both blocks, we concluded that there were no training effects.

The Neural Correlates of Chronic Symptoms of Vertigo Proneness in Humans

Vestibular signals are of significant importance for variable functions including gaze stabilization, spatial perception, navigation, cognition, and bodily self-consciousness. The vestibular network governs functions that might be impaired in patients affected with vestibular dysfunction. It is currently unclear how different brain regions/networks process vestibular information and integrate the information into a unified spatial percept related to somatosensory awareness and whether people with recurrent balance complaints have a neural signature as a trait affecting their development of chronic symptoms of vertigo. Pivotal evidence points to a vestibular-related brain network in humans that is widely distributed in nature. By using resting state source localized electroencephalography in non-vertiginous state, electrophysiological changes in activity and functional connectivity of 23 patients with balance complaints where chronic symptoms of vertigo and dizziness are among the most common reported complaints are analyzed and compared to healthy subjects. The analyses showed increased alpha2 activity within the posterior cingulate cortex and the precuneues/cuneus and reduced beta3 and gamma activity within the pregenual and subgenual anterior cingulate cortex for the subjects with balance complaints. These electrophysiological variations were correlated with reported chronic symptoms of vertigo intensity. A region of interest analysis found reduced functional connectivity for gamma activity within the vestibular cortex, precuneus, frontal eye field, intra-parietal sulcus, orbitofrontal cortex, and the dorsal anterior cingulate cortex. In addition, there was a positive correlation between chronic symptoms of vertigo intensity and increased alpha-gamma nesting in the left frontal eye field. When compared to healthy subjects, there is evidence of electrophysiological changes in the brain of patients with balance complaints even outside chronic symptoms of vertigo episodes. This suggests that these patients have a neural signature or trait that makes them prone to developing chronic balance problems.

Space motion sickness countermeasures : a pharmacological double-blind, placebo-controlled study

INTRODUCTION Space motion sickness (SMS), caused by a canal-otolith conflict, is currently treated with intramuscular promethazine. However, the drug has an inconsistent efficacy against SMS. We hypothesize that pharmacological depression of the semicircular canals (SCC) might relieve SMS. The aim of the present study was to identify the effects of meclizine (25 mg), dimenhydrinate (40 mg) combined with cinnarizine (25 mg), and promethazine (25 mg) combined with d-amphetamine (10 mg) on the SCCs and the otoliths. METHODS This double-blind, placebo-controlled study was performed on 20 healthy men. Function of the SCC was evaluated by means of an electronystagmography, whereas utricular function was assessed by a unilateral centrifugation test. A cervical vestibular evoked myogenic potentials test evaluated saccular function. RESULTS Meclizine (0.54 +/- 0.05 vs. 0.38 +/- 0.06) and dimenhydrinate with cinnarizine (0.54 +/- 0.05 vs. 0.45 +/- 0.05) decreased the vestibulo-ocular reflex gain. Promethazine with d-amphetamine decreased the latency of the saccadic eye response (right eye: 185 +/- 3.8 ms vs. 165 +/- 4.5 ms; left eye: 181 +/- 4.9 ms vs. 165 +/- 4.8 ms) and also increased the phase of ocular counterrolling measured during unilateral centrifugation (0.32 +/- 0.35 degrees vs. 1.5 +/- 0.45 degrees). DISCUSSION It is hypothesized that meclizine and dimenhydrinate with cinnarizine affect the medial vestibular nucleus. Promethazine is a vestibular suppressor, but study results show that d-amphetamine counterbalances this depression and abolishes the effect of fatigue on the saccadic reaction time The hypothesis that a SCC-suppression alleviates SMS should be further evaluated.

Conscientiousness in patients with Ménière's disease.

Objective: To assess whether a conscientious personality profile is more prevalent in patients with Ménières disease (MD) in comparison with other vertigo patients. Second, to investigate a sex effect and compare the obtained conscientiousness scores with published normative values. Patients: A total of 108 patients were included and subdivided into one of five pathology groups: MD, benign paroxysmal positional vertigo, vestibular neuritis, vestibular schwannoma, and posttraumatic nonbenign paroxysmal positional vertigo. Intervention: The conscientiousness domain of the self-reporting NEO Five-Factor Inventory questionnaire. Main Outcome Measure: Conscientiousness score. Results: There was no significant difference between the diagnostic groups or a sex effect. MD patients had a higher score than published normal values. Conclusion: As assessed with the NEO Five-Factor Inventory questionnaire, MD patients do not demonstrate a higher conscientious personality profile in comparison with other vertigo patients. Therefore, this limits the clinical use of the personality profile to discriminate between patient groups.

Comparison of Different Electrode Configurations for the ovemp With Bone-conducted Vibration

Objectives: This study was performed to compare three electrode configurations for the ocular vestibular evoked myogenic potentials (oVEMPs)—“standard,” “sternum,” and “nose”—by making use of bone-conducted stimuli (at the level of Fz with a minishaker). In the second part, we compared the test–retest reliability of the standard and nose electrode configuration on the oVEMP parameters. Design: This study had a prospective design. Fourteen healthy subjects participated in the first part (4 males, 10 females; average age = 23.4 (SD = 2.6) years; age range 19.9 to 28.3 years) and second part (3 males, 11 females; average age = 22.7 (SD = 2.4) years; age range 20.0 to 28.0 years) of the study. OVEMPs were recorded making use of a hand-held bone conduction vibrator (minishaker). Tone bursts of 500 Hz (rise/fall time = 2 msec; plateau time = 2 msec; repetition rate = 5.1 Hz) were applied at a constant stimulus intensity level of 140 dB FL. Results: PART 1: The n10–p15 amplitude obtained with the standard electrode configuration (mean = 15.8 &mgr;V; SD = 6.3 &mgr;V) was significantly smaller than the amplitude measured with the nose (Z = −3.3; p = 0.001; mean = 35.0 &mgr;V; SD = 19.1 &mgr;V) and sternum (Z = −3.3; p = 0.001; mean = 27.1 &mgr;V; SD = 12.2 &mgr;V) electrode configuration. The p15 latency obtained with the nose electrode configuration (mean = 14.2 msec; SD = 0.54 msec) was significantly shorter than the p15 latency measured with the standard (Z = −3.08; p = 0.002) (mean = 14.9 msec; SD = 0.75 msec) and sternum (Z = −2.98; p = 0.003; mean = 15.4 msec; SD = 1.07 msec) electrode configuration. There were no differences between the n10 latencies of the three electrode configurations. The 95% prediction intervals (given by the mean ± 1.96 * SD) for the different interocular ratio values were [−41.2; 41.2], [−37.2; 37.2], and [−25.9; 25.9] for standard, sternum, and nose electrode configurations, respectively. PART 2: Intraclass correlation (ICC) values calculated for the oVEMP parameters obtained with the standard electrode configuration showed fair to good reliability for the parameters n10–p15 amplitude (ICC = 0.51), n10 (ICC = 0.52), and p15 (ICC = 0.60) latencies. The ICC values obtained for the parameters acquired with the nose electrode configuration demonstrated a poor reliability for the n10 latency (ICC = 0.37), a fair to good reliability for the p15 latency (ICC = 0.47) and an excellent reliability for the n10–p15 amplitude (ICC = 0.85). Conclusions: This study showed the possible benefits from alternative electrode configurations for measuring bone-conducted-evoked oVEMPs in comparison with the standard electrode configuration. The nose configuration seems promising, but further research is required to justify clinical use of this placement.