Pharmacologic Dissection of Vestibular Migraine and Chronic Subjective Dizziness: A Double-Blind Parallel Group Trial Comparing Response to Verapamil Versus Sertraline

Chronic dizziness and recurrent vertigo are frequent complaints in primary and specialty medical care settings. Two common causes of these symptoms are vestibular migraine (VM) and chronic subjective dizziness (CSD), which may be seen in up to 25% of patients examined in tertiary neurotology centers. However, VM and CSD are relatively new diagnoses that have not yet been validated. Furthermore, recent research found that they co-exist 30% of the time with overlap in several features. From a clinical standpoint, this makes it difficult to diagnose and treat them well. From a research standpoint, it confounds subject selection for mechanistic investigations.

The primary goal of this study was to dissect VM and CSD in order to identify the key features and clarify the diagnostic criteria of each condition. Subjects diagnosed with coexisting VM-CSD were treated with either verapamil or sertraline. It was hypothesized that a differential treatment response to these two pharmacologic probes would help to tease apart the unique clinical features of VM and CSD and identify risk factors that are shared or separate between the two conditions. It was hoped that the different mechanisms of action of the two study medications might also shed light on the physiologic underpinnings of VM and CSD.

This project was a 14-week, prospective, randomized, double-blind, parallel group, pharmacologic dissection (PD) trial. A 12-week treatment period followed 2 weeks of baseline observation. Patients charted daily headache and vestibular symptoms. VM and CSD symptoms and potential confounds such as anxiety and depression were measured at two week intervals. Data were analyzed for differential and shared treatment effects that align with or oppose current concepts of VM and CSD.

A PD trial uses response to one or more pharmaceutical probes (drugs) to study physiologic mechanisms of illness. A PD trial may provide data to separate overlapping manifestations of comorbid illnesses. This is useful for conditions that lack biomarkers. It also may provide data to identify characteristics of illnesses (symptoms, signs, cellular processes) that are associated with specific pharmacologic mechanisms.