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Endolymphatic Sac Tumor (ELST)

excerpts from VHL Handbook

The screening protocol includes a recommendation that you go regularly for an audiometric hearing examination. You should have a “baseline” study to document the state of your hearing soon after the diagnosis of VHL is made and periodically thereafter to verify that it has not changed.

If you sense changes in your hearing or other indications of inner ear problems, you should follow up with a neurotologist. MRI of the Internal Auditory Canal should be used to check for an Endolymphatic Sac Tumor (ELST), which may occur in about 15% of people with VHL. The combined MRI recommended in the Active Surveillance Guidelines are designed to monitor this area as well.

An ELST forms in the endolymphatic sac behind the inner ear. The endolymphatic duct runs from the inner ear to the back surface of the petrous bone and ends beneath the dura as a flattened expansion, the endolymphatic sac. This tiny structure is filled with fluid (called endolymph) and has a delicate system of pressure regulation that is responsible for balance and equilibrium. Menière’s disease is another condition that is caused by a disturbance in this area. With similar symptoms, ELSTs are often misdiagnosed as Menière’s disease.

People report hearing changes which range from subtle changes in the “texture” of the hearing to profound hearing loss. Hearing loss may occur suddenly or gradually over a period of months. Other symptoms may include tinnitus (ringing in the ears), dizziness, fullness in an ear, or facial weakness.

Once hearing is lost, it is very difficult to regain, making it is very important to watch for early symptoms and address the problem carefully in order to try to preserve hearing. If there is a loss of hearing, swift action is needed if there is to be any hope of preserving it. If your local team is not familiar with ELST, please check with the nearest VHL Clinical Care Center (vhl.org/ccc), or with the VHL Alliance office.

When an ELST is visible on an MRI, surgery should be considered to prevent disease progression and hearing loss. Careful surgical removal of the ELST will stop further damage and can occasionally be done without damaging hearing or balance. This delicate microsurgery usually requires a team made up of a neurosurgeon and a neurotologist in a practice that performs a lot of inner ear surgery. There are occasionally situations where hearing may be affected even though there is no tumor visible by MRI. Tumors as small as 2 mm found during surgery have been seen to affect hearing.

There is one case reported where chronic ear infections were the first sign of an ELST in a 6-year-old. For this reason, a child with known VHL requires tubes for middle ear infections. An MRI of the internal auditory canal should be performed to evaluate for possible ELST and to prevent disease progression and hearing loss.

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