Amiodarone-associated bilateral vestibulopathy

A Possible Mechanism for Flecainide Induced Dizziness

OBJECTIVE

Flecainide is an oral class IC antiarrhythmic drug whose most common extracardiac adverse reactions are "dizziness" and "visual disturbances." We describe a case of flecainide associated- bilateral vestibulopathy and a literature review of this drug's effect on the vestibular system.

PATIENT

Sixty-nine-year-old man with a 3-month history of unsteadiness and dizziness after an increase in the dose of flecainide.

INTERVENTIONS

Otologic examination, video head-impulse test, vestibular evoked myogenic potentials, pure tone audiometry and high-resolution magnetic resonance imaging.

RESULTS

Otologic examination, including the head-impulse test, and vestibular testing revealed bilateral vestibulopathy.

CONCLUSIONS

Dizziness is a common extracardiac adverse reaction of Flecainide. Based on the clinical case that we present and the literature review carried out, we hypothesized that a possible mechanism by which flecainide might cause dizziness and visual disturbances is bilateral vestibulopathy.

Rare Disorders of the Vestibular Labyrinth: of Zebras, Chameleons and Wolves in Sheep's Clothing

The differential diagnosis of vertigo syndromes is a challenging issue, as many - and in particular - rare disorders of the vestibular labyrinth can hide behind the very common symptoms of "vertigo" and "dizziness". The following article presents an overview of those rare disorders of the balance organ that are of special interest for the otorhinolaryngologist dealing with vertigo disorders. For a better orientation, these disorders are categorized as acute (AVS), episodic (EVS) and chronic vestibular syndromes (CVS) according to their clinical presentation. The main focus lies on EVS sorted by their duration and the presence/absence of triggering factors (seconds, no triggers: vestibular paroxysmia, Tumarkin attacks; seconds, sound and pressure induced: "third window" syndromes; seconds to minutes, positional: rare variants and differential diagnoses of benign paroxysmal positional vertigo; hours to days, spontaneous: intralabyrinthine schwannomas, endolymphatic sac tumors, autoimmune disorders of the inner ear). Furthermore, rare causes of AVS (inferior vestibular neuritis, otolith organ specific dysfunction, vascular labyrinthine disorders, acute bilateral vestibulopathy) and CVS (chronic bilateral vestibulopathy) are covered. In each case, special emphasis is laid on the decisive diagnostic test for the identification of the rare disease and "red flags" for potentially dangerous disorders (e. g. labyrinthine infarction/hemorrhage). Thus, this chapter may serve as a clinical companion for the otorhinolaryngologist aiding in the efficient diagnosis and treatment of rare disorders of the vestibular labyrinth.

Recent advances in idiopathic bilateral vestibulopathy: a literature review

Background

Idiopathic bilateral vestibulopathy (IBV) is an acquired bilateral peripheral vestibular dysfunction of unknown etiology, with persistent unsteadiness but without sensorineural hearing loss (SNHL) other than age-related hearing loss (ARHL).

Main text

The prevalence of IBV is unknown. The most common symptom is persistent unsteadiness, particularly in darkness and/or on uneven ground. The other main symptom is oscillopsia during head and body movements. IBV is neither associated with SNHL, except for ARHL, nor any other neurological dysfunction that causes balance disorders. The clinical time course of IBV can generally be divided into two main types: progressive type and sequential type. The progressive type involves gradually progressive persistent unsteadiness without episodes of vertigo. The sequential type involves recurrent vertigo attacks accompanied by persistent unsteadiness. Originally, IBV was found to exhibit bilateral dysfunction in the lateral semicircular canals (LSCCs) and the superior vestibular nerve (SVN) system. However, recently, with the development of more sophisticated vestibular function tests of the otolith organs and vertical semicircular canals, it has been revealed that IBV involves peripheral vestibular lesions other than those already identified in the LSCC and the SVN system. Furthermore, novel subtypes of IBV that do not involve bilateral dysfunction of the LSCC and/or the SVN system have been proposed. Therapeutically, exercise-based vestibular rehabilitation in adult bilateral vestibulopathy (BVP) patients has resulted in improved gaze and postural stability moderately. There are several technical approaches for the treatment of BVP such as vestibular implants, sensory substitution devices and noisy galvanic vestibular stimulation.

Conclusions

Combined use of various vestibular function tests, including recently developed tests, revealed the diversity of lesion sites in IBV. Further studies are required to determine the therapeutic effects of the technical approaches on IBV.

Bilateral Vestibular Weakness

Bilateral vestibular weakness (BVW) is a rare cause of imbalance. Patients with BVW complain of oscillopsia. In approximately half of the patients with BVW, the cause remains undetermined; in the remainder, the most common etiology by far is gentamicin ototoxicity, followed by much rarer entities such as autoimmune inner ear disease, meningitis, bilateral Ménière’s disease, bilateral vestibular neuritis, and bilateral vestibular schwannomas. While a number of bedside tests may raise the suspicion of BVW, the diagnosis should be confirmed by rotatory chair testing. Treatment of BVW is largely supportive. Medications with the unintended effect of vestibular suppression should be avoided.

Amiodarone: A Newly Discovered Association with Bilateral Vestibulopathy

Background

Bilateral vestibulopathy (BVP) is a debilitating disorder characterized by the hypofunction of both vestibular end organs or nerves. The most frequent identifiable causes of BVP are ototoxic drug effects, infectious and autoimmune disorders. However, the majority of cases remain idiopathic. Very recently, the first discovery of a clinical case of Amiodarone-associated BVP has been reported.

Methods

An overview of the literature concerning the relation between amiodarone toxicity and BVP is presented and discussed.

Results

Older reports on amiodarone-induced symptoms of vertigo and gait instability lack a description of vestibular function test results. Recent evidence from retrospective studies including vestibular function testing in patients taking amiodarone have identified the drug as the hitherto unsuspected potential cause of a relatively large proportion of cases with “idiopathic” BVP.

Conclusion

Patients who receive amiodarone should be monitored with vestibular function testing in order to recognize potential adverse effects on the vestibular system and allow for an informed decision on possible drug reduction or withdrawal.