Non-Invasive Neuromodulation Using Time-Varying Caloric Vestibular Stimulation

Abstract

Caloric vestibular stimulation (CVS) to elicit the vestibulo-ocular reflex has long been used in clinical settings to aid in the diagnosis of balance disorders and to confirm the absence of brainstem function. While a number of studies have hinted at the potential therapeutic applications of CVS, the limitations of existing devices have frustrated that potential. Current CVS irrigators use water or air during short-duration applications; however, this approach is not tenable for longer duration therapeutic protocols or home use. Here, we describe a solid-state CVS device we developed in order to address these limitations. This device delivers tightly controlled time-varying thermal waveforms, which can be programmed through an external control unit. It contains several safety features, which limit patients to the prescribed waveform and prevent the potential for temperature extremes. In this paper, we provide evidence that CVS treatment with time-varying, but not constant temperature waveforms, elicits changes in cerebral blood flow physiology consistent with the neuromodulation of brainstem centers, and we present results from a small pilot study, which demonstrate that the CVS can safely and feasibly be used longitudinally in the home setting to treat episodic migraine. Together, these results indicate that this solid-state CVS device may be a viable tool for non-invasive neuromodulation.

Preventing Episodic Migraine With Caloric Vestibular Stimulation: A Randomized Controlled Trial

“…The side effects from the device were expected to be significantly attenuated in prevalence and severity compared to those reported from water and air irrigation . In line with this prediction, the cases of dizziness and/or nausea (also common symptoms in migraineurs) were limited (4 active, 2 placebo, and 3 partially active placebo cases, see Table ).…”

“…Based on the above findings, we gathered preliminary clinical evidence for CVS‐mediated prevention of episodic migraine by conducting a three‐subject pilot study that assessed the feasibility and safety of longitudinal CVS treatment in the home setting. All three episodic migraineurs demonstrated reduced headache frequency after 6 weeks of CVS therapy . Notably, all subjects demonstrated excellent treatment adherence, and no adverse events were reported.…”

“…These currents cause cupular deflection, which alters the tonic firing rate of the vestibular nerves and, in turn, elicits broad autonomic responses, including the vestibular‐ocular reflex. While CVS has a long history of clinical safety, exploration into its therapeutic potential has been hindered by the unpleasant side effects, thermal imprecision, lack of dose control and administration complexity of standard water and air irrigation methods, impediments that were overcome with the development of a solid‐state device for delivering CVS …”

“…C). Furthermore, recent transcranial Doppler sonography data demonstrate that CVS treatment with the device elicits changes in cerebrovascular dynamics that point to brainstem neuromodulation . Second, irrigation calorics have been shown, albeit in small, uncontrolled samples, to acutely mitigate pain, including pain experienced during migraine attacks …”

“…Notably, all subjects demonstrated excellent treatment adherence, and no adverse events were reported. To further assess the efficacy and safety of the CVS device developed by Scion NeuroStim, LLC, for the prevention of episodic migraine, we then conducted a prospectively powered, randomized, placebo‐controlled clinical trial (NCT01899040; http://www.clinicaltrials.gov). The results are described herein.…”