Cerebrospinal fluid (CSF) is just underneath the lining of the brain and spine. In some instances an abnormal connection can develop such that this fluid leaks out from the skull. The ear is near the brain in the temporal bone. Sometimes the CSF can leak into the temporal bone. This may cause fluid to build in the middle ear and can cause hearing loss, ringing of the ear and fullness. In many instances this can occur by itself (spontaneously) over time. It can also be associated with trauma to the head or prior surgery. A risk of infection of the lining of the brain known as meningitis can occur.
Often imaging with a CT and/or MRI scan is helpful in the diagnosis. Definitive diagnosis is made by sending a sample of the fluid for special testing.
Surgical repair of the leak is often needed to stop the leak, especially in spontaneously occurring cases. Several different techniques can be used depending on the location and size of the defect. In patients with small defects, repair can be attempted through the mastoid bone behind the ear. In other cases a small craniotomy (temporary window through the skull) above the ear is needed to repair the leak. The leak is then patched.