Enlarged vestibular aqueduct (EVA) related with recurrent benign paroxysmal positional vertigo (BPPV)

Abstract

The vestibular aqueduct is a bony canal related to the bony labyrinth of the inner ear and represents the non-sensory components of the endolymph-filled, closed, membranous labyrinth. The association of congenital sensorineural hearing loss with a large or enlarged vestibular aqueduct is well known as the large vestibular aqueduct syndrome (LVAS). The enlarged VA (EVA) comprises abnormalities not only in the structure of the inner ear, but also in the physiology of the auditory and vestibular systems. The clinical picture of this clinical entity is variable [Yetiser S, Kertment M, Ozkaptan Y. Vestibular disturbance in patients with Large Vestibular Aqueduct Syndrome (LVAS). Acta Otolaryngol (StochK) 1999;119: 641-646]. Signs and symptoms of the auditory impairment are more commonly described in the literature: hearing loss ranges from mild to profound, arising from fluctuating to stepwise progressive or sudden. Vestibular disturbances, ranging from mild imbalance to episodic vertigo, are rarely described in the literature. Benign paroxysmal positional vertigo (BPPV) is a labyrinthine disorder with a typical behavior: intense crises of rotational vertigo induced by postural changes of the head, with short duration and usually good responsiveness to rehabilitative maneuvers. These maneuvers are effective in about 80% of patients with BPPV. BPPV often recurs. About 1/3 of patients have a recurrence in the first year after treatment, and by five years, about half of all patients have a recurrence. Vestibular aqueduct has been demonstrated by conventional tomography and computed tomography (CT), however, CT scans cannot show the membranous labyrinth itself. On MR images it is not the vestibular aqueduct that is visualized but its contents, the endolymphatic duct and sac, and can show the abnormalities of the fluid spaces related to the membranous labyrinth. It is proposed that recurrent benign paroxysmal positional vertigo (BPPV) is related with volumetric abnormalities of vestibular aqueduct. This verifiable hypothesis tries to define this rapport and explore new diagnostic and therapeutic possibilities.