Third window syndrome is a group of conditions with symptoms caused by the presence of an abnormal structure within the inner ear. Symptoms include perceiving that one's voice and other body sounds are too loud or echo in the ear, feelings of pressure within the ear or sound-induced dizziness, and mixed-pattern hearing loss.
Third window syndrome refers to a set of symptoms caused by the presence of an abnormal third mobile window in the bony labyrinth of the inner ear. The presence of this additional window disrupts the normal biomechanics of the inner ear, which typically has only 2 mobile windows: the oval and round windows. Third window syndrome is most often caused by abnormalities that affect the bony sections that surround the inner ear directly above its internal structures. (See A Look Inside the Ear.)
Symptoms of Third Window Syndrome
The symptoms of third window syndrome include hearing loss, a condition called autophony (increased loudness in hearing one's own voice, footsteps, or other body sounds, including eye movement or blood flow), pressure- or sound-induced dizziness, and trouble focusing.
Diagnosis of Third Window Syndrome
A doctor's evaluation
Hearing assessment
Sometimes imaging (CT scan)
Sometimes more specialized testing
To diagnose third window syndrome doctors first look for abnormal responses to specific tests, such as pressure-induced nystagmus (rapid, uncontrolled eye movements) when a puff of air is delivered to the ear canal with a specialized otoscope (handheld tool used to examine the inner ear). Tuning fork tests, such as the Weber test and the Rinne test, can help doctors distinguish between types of hearing loss.
An audiogram (a graph of the results of a formal hearing test) will typically show a mixed-pattern hearing loss that is better than normal hearing.
The diagnosis of third window syndrome is confirmed with a high-resolution CT scan or a specialized test called the vestibular evoked myogenic potential, which measures the electrical activity of muscles of the vestibule of the inner ear in response to sound stimuli.
Treatment of Third Window Syndrome
Treatment of symptoms
Sometimes surgical repair
The treatment of third window syndrome is tailored to the patient's symptoms. Doctors treat mild symptoms conservatively, which generally involves monitoring their severity and treating those symptoms only as needed. Any coexisting or worsening conditions are also treated.
Surgical repair of the defect can be effective in people with more severe symptoms.
