Vestibular Neuroscience for the Headache Specialist

Altered large-scale internetwork functional connectivity in patients with vestibular migraine and migraine without aura

OBJECTIVE

To investigate large-scale internetwork functional connectivity in patients with vestibular migraine (VM) and migraine without aura (MwoA).

METHODS

Resting-state functional magnetic resonance imaging data from 34 VM patients, 34 MwoA patients, and 33 healthy controls (HCs) were collected and the results were analyzed using independent component analysis (ICA). We also analyzed the correlations between clinical data and internetwork functional connectivity.

RESULTS

In contrast to HCs, MwoA patients showed decreased functional connectivity between the left frontoparietal network (lFPN) and right frontoparietal network (rFPN), with increased functional connectivity between the sensorimotor network (SMN) and lateral visual network (lVN). When compared to MwoA patients, VM patients demonstrated decreased functional network connectivity between the dorsal attention network (DAN) and posterior medial visual network (pmVN), between the SMN and pmVN, and between the SMN and lVN. Meanwhile, increased functional network connectivity was found between the lFPN and rFPN; however, there was no significant difference in functional network connectivity between VM patients and HCs. In addition, associations were found between clinical data and internetwork functional connectivity.

CONCLUSION

Functional connectivity between the lFPN and rFPN was reduced in patients with MwoA compared with HCs, which may indicate functional impairment in cognitive control, attention, somatosensory perception, and emotion regulation in patients with MwoA. VM patients showed decreased functional connectivity between the DAN, SMN, pmVN and lVN compared to patients with MwoA, which could account for the multisensory integration abnormalities and be the cause of vestibular symptoms in VM patients. These findings offer fresh perspectives on the pathophysiology of VM and MwoA.

Vestibular Migraine

PURPOSE OF REVIEW

To explore recent developments in vestibular migraine (VM).

RECENT FINDINGS

This review discusses the current diagnostic criteria for VM in the adult and pediatric populations, as proposed by the International Headache Society and Bárány Society. Recent VM studies confirm the prior findings and reveal new insights, including the wide range of vestibular symptoms, symptoms in the attack-free period, and triggers. Many patients experience persistent vestibular symptoms, even in the absence of acute attacks, which often significantly impact patients' quality of life. The syndrome of benign recurrent vertigo and its relationship to migraine, VM, and Meniere's disease is also discussed. There is a dearth of randomized controlled trials in VM treatment. Prospective and retrospective studies support the benefit of many migraine treatments are effective in VM, including neuromodulation, and calcitonin gene-related peptide monoclonal antibodies. VM affects almost 3% of the population, but remains under-diagnosed. Recent diagnostic criteria can help clinicians diagnose VM in adults and children.

Postural sway does not differentiate individuals with chronic low back pain, single and multisite chronic musculoskeletal pain, or pain-free controls: a cross-sectional study of 229 subjects

BACKGROUND CONTEXT

Physical activity in its various forms are the most recommended prevention and treatment strategy for chronic low back pain (CLBP). Standing postural stability is a prerequisite for many types of physical activities. Systematic reviews have investigated the evidence for an association between CLBP and postural stability but results remain inconclusive.

PURPOSE

Our primary objective was to compare postural stability between pain-free controls and subjects with CLBP with or without leg pain and single and multisite chronic musculoskeletal pain subjects. The secondary objectives were to evaluate the association between postural stability with CLBP intensity and duration, demographics, physical characteristics and validated health and pain-related patient-reported outcome measures (PROMs).

STUDY DESIGN/SETTING

Cross-sectional study in a private chiropractic clinic setting PATIENT SAMPLE: Subjects included 42 pain-free controls and 187 patients with chronic musculoskeletal pain divided into CLBP with or without leg pain and single and multisite pain groups.

OUTCOME MEASURES

Pain intensity was measured using the numerical pain rating scale, PROMs Central Sensitization Inventory, Tampa Scale of Kinesiophobia, The Depression Scale, EuroQol-5D, Roland-Morris Disability Questionnaire, and Pain and Sleep Questionnaire Three-Item Index disability. Group differences were measured using area and velocity of sway on the force plate.

METHODS

Postural stability was assessed using a force plate on four 60-second bipedal quiet stance tests: eyes open on a stable surface, eyes closed on a stable surface, eyes open on an unstable foam surface, eyes closed on an unstable foam surface. Following the clinic visit, subjects completed an online web-based data entry detailing pain history, demographic data, physical characteristics, pain intensity via the numerical pain rating scale, and PROMS.

RESULTS

Postural sway parameters did not differ between pain-free controls and subjects with CLBP with or without leg pain and single and multisite chronic musculoskeletal pain subjects. Furthermore, severity and duration of CLBP pain in addition to central sensitization, kinesiophobia, depression, quality of life, disability, and effect of pain on sleep only had very weak associations with postural stability.

CONCLUSIONS

Chronic musculoskeletal pain appears not to influence bipedal postural stability.

Chronic Central Vestibulopathies for the Otolaryngologist

Central vestibulopathies involve disorders of the central nervous system that lead to problems with balance, often manifested as dizziness, vertigo, and gait difficulty. Central vestibulopathies can be distinguished from peripheral vestibulopathies with the use of certain tests, including nystagmography and posturography. The neuroanatomy of individuals with central vestibulopathies can reveal structural abnormalities in the posterior cerebrum or cerebellum. Various medications can be used to manage central vestibulopathies, including vestibular migraine.

Vestibular Migraine and Its Comorbidities

Vestibular migraine (VM) is one of the most common neurologic causes of vertigo. Symptoms and International Classification of Headache Disorders criteria are used to diagnose VM because no objective tests, imaging or audiologic, have been shown to reliably diagnose this condition. Central auditory, peripheral, and central vestibular pathway involvement has been associated with VM. Although the interaction between migraine and other vestibular disorders can be a challenging scenario for diagnosis and treatment, there are data to show that vestibular rehabilitation and a variety of pharmacologic agents improve reported symptoms and vertigo frequency.

Calcitonin Gene-Related Peptide Receptor Antagonists (Gepants) for the Acute Treatment of Nausea in Episodic Migraine: A Systematic Review and Meta-Analysis

OBJECTIVE

To synthesize the evidence on the efficacy of calcitonin gene-related peptide receptor antagonists (gepants) from all clinical trials addressing nausea treatment for episodic migraine.

INTRODUCTION

Nausea is one of the most bothersome symptoms in patients with migraine. The most bothersome symptom is part of the outcomes explored in clinical trials.

METHODS

Published clinical trials for this project were identified via searches of 4 bibliographic databases: PubMed (includes MEDLINE), Embase, Web of Science, and the Cochrane Library. Individual search strategies included terms related to calcitonin gene-related peptide, nausea, and vomiting. Random-effects meta-analysis was conducted to estimate the overall efficacy of gepants for nausea treatment. Heterogeneity, publication bias, small-study bias, and potential confounders were explored using Galbraith plot, sensitivity analysis, meta-regression, and Egger's regression tests. Cumulative meta-analysis was done to detect temporal trend from accumulating trials.

RESULTS

The meta-analysis involved 23,008 participants in 65 clinical trials from 14 published articles; 10,770 subjects participated in gepant treatment arms while 12,238 subjects participated in placebo or non-gepant arms (85% females, mean age 41 years in both arms). Nearly all studies used a 2-hour incidence of nausea as an outcome measure. An overall combined effect size with an odds ratio of 1.29 (95% CI 1.18, 1.40, P = .001; I²  = 42.8%) showed the efficacy of gepants for the treatment of nausea in episodic migraine. Galbraith plot demonstrated that 98.4% of studies were within 2 standard deviations from the regression line, indicating lack of significant heterogeneity and outliers. Meta-analysis results were robust to sensitivity analysis, small-study bias, and publication bias (Kendall's Tau -0.09, P = .29; Egger's regression P = .67). Meta-regression showed that both age and sex ratio were not confounding the meta-analysis (omnibus P = .69). Cumulative meta-analysis indicated that the effect size remained stable for studies conducted after 2011, with accumulating evidence continuing to favor efficacy of gepants for the treatment of nausea in episodic migraine.

CONCLUSION

There is sufficient evidence to support the efficacy of gepants for the treatment of nausea in episodic migraine. Future research may focus on examining this efficacy in under-represented patient populations (males, older age groups) and in chronic migraine.

Sensory Neuromodulation

We describe a model of neurological disease based on dysfunctional brain oscillators. This is not a new model, but it is not one that is widely appreciated by clinicians. The value of this model lies in the predictions it makes and the utility it provides in translational applications, in particular for neuromodulation devices. Specifically, we provide a perspective on devices that provide input to sensory receptors and thus stimulate endogenous sensory networks. Current forms of clinically applied neuromodulation, including devices such as (implanted) deep brain stimulators (DBS) and various, noninvasive methods such as transcranial magnetic stimulation (TMS) and transcranial current methods (tACS, tDCS), have been studied extensively. The potential strength of neuromodulation of a sensory organ is access to the same pathways that natural environmental stimuli use and, importantly, the modulatory signal will be transformed as it travels through the brain, allowing the modulation input to be consistent with regional neuronal dynamics. We present specific examples of devices that rely on sensory neuromodulation and evaluate the translational potential of these approaches. We argue that sensory neuromodulation is well suited to, ideally, repair dysfunctional brain oscillators, thus providing a broad therapeutic approach for neurological diseases.