Large Vestibular Aqueduct Syndrome

Large Vestibular Aqueduct Syndrome (LVAS) is an uncommon disorder described as sudden and progressive sensorineural hearing loss. The vestibular aqueduct is a narrow, bony canal that connects the inner ear and the cranial cavity. It is related to the bony labyrinth of the inner ear. LVAS is also known as Enlarged Vestibular Aqueduct syndrome (EVAS) and Vestibular Aqueduct syndrome (VAS). LVAS received its name in 1978 simply because the large vestibular aqueduct was the only part of the disorder visible on a CT scan.

LVAS develops when the vestibular aqueduct becomes larger than it is suppose to be. It should not be larger than 1.5 millimeters. This is the result of an abnormal or delayed development of the inner ear. LVAS usually begins in infancy, but it also can occur in childhood and more rarely adolescence. In a patient with LVAS progressive hearing loss may be triggered by head trauma or anything else that may cause a sudden fluctuation in the cerebrospinal fluid.

CT Scans are the test of choice to provide the evidence needed to make a diagnosis of LVAS. Other tests that may be used to confirm diagnosis include Magnetic Resonance Imaging (MRI) and a Axial CT Scan.

LVAS can be associated with Pendreds syndrome and Mondini’s syndrome, but it can occur by itself. Characteristics of LVAS include large vestibular aqueduct on a CT scan, hearing loss, sudden hearing loss after minor head trauma and vertigo or dizziness.