Fabry Disease and Hearing
Hearing loss and vertigo are common symptoms of Fabry disease. This article discusses how Fabry disease may affect your hearing, and looks at ways that doctors may diagnose and treat hearing problems.
How do hearing and balance work?
Hearing is a complicated process that involves multiple structures in the ear. The ear has three major parts: the outer, middle, and inner ear. The outer, visible portion of the ear, or pinna, first collects sounds and funnels them down to the ear canal. These structures make up the outer ear.
As the sound arrives at the end of the ear canal, it runs into and vibrates the tympanic membrane (eardrum). A series of three small bones called the ossicles of the middle ear transfer these vibrations from the eardrum to another membrane called the oval window. This membrane connects to an organ in the inner ear called the cochlea.
The cochlea is full of fluid. Vibrations of the oval window move this fluid, activating special nerve cells in the cochlea called hair cells. The hair cells then convert the movement into nerve signals that travel along the auditory nerve to the brain, which interprets them as sounds.
Another part of the inner ear, called the vestibular system, is made up of the semicircular canals and the otolith organs, which are also filled with fluid and involved in the sense of orientation and balance. When you rotate your head at different angles or move it up and down, these structures — with their fluid and sensory hair cells — move accordingly. They detect the change in your head’s orientation, and send signals to the brain that help with balance.
How does Fabry disease affect hearing?
Researchers reported several different hearing-related problems in Fabry disease patients, such as vertigo with nausea and dizziness; tinnitus (ringing in the ears); gradual hearing loss, especially at higher frequencies; and sudden deafness.
Studies have found that roughly 40% to 55% of patients report hearing loss, but measurable hearing loss could be as high as 86% among Fabry patients. Hearing loss tends to be worse in males, and its overall pattern is of a slow progressive loss that resembles the age-related hearing loss seen in the general population, but starts earlier (typically, middle age) and advances more quickly.
Some studies also report cases of hearing loss in children with the disease, but these issues in young patients are unusual. More common is that children with Fabry have poorer hearing thresholds than do their age-matched, healthy peers.
Researchers don’t understand the exact cause of hearing problems in Fabry disease. However, some have suggested that they may be due to the accumulation of globotriaosylceramide (Gb3) in the layer of the inner ear that contains blood vessels and some nerve cells. The buildup of Gb3 may cause low blood flow to the nerve cells of the ear, and damaging or disrupting the signals from the semicircular canal to cause vertigo and nausea.
How do doctors diagnose hearing problems?
To detect hearing loss and changes in hearing of frequencies, doctors usually use a technique called pure-tone audiometry. In these tests, patients wear headphones and listen to pure tones of a single frequency or pitch, like a “beep.” The audiologist plays these tones at different intensities (degrees of loudness), and asks the patient whether or not they could hear the sound.
Doctors may also test how well a patient can distinguish words at different sound intensities or volumes. During this form of testing, they play recorded speech through the headphones and ask patients to repeat the word or phrase.
How do they treat them?
The likely treatment given will depend on the patient’s symptoms. For vertigo, doctors usually prescribe anti-nausea medication. For sudden hearing loss, they may prescribe vasodilators (medications that open or expand blood vessels) and steroids. With more gradual and progressive hearing loss, they usually suggest hearing aids. In severe cases of profound deafness, they may suggest cochlear implants, which stimulate the nerves of the cochlea directly.
Research into the effects of enzyme replacement therapy on hearing loss is limited, but has shown small improvements in hearing with continued usage in those with mild to moderate loss.
Last updated: Jan. 15, 2021
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