An explanation for this erosion of the bone has not yet been found. Diagnosis
The presence of dehiscence can be detected by a high definition (0.6 mm or less) coronal CT scan of the temporal bone, currently the most reliable way to distinguish between superior canal dehiscence syndrome (SCDS) and other conditions of the inner ear involving similar symptoms such as Ménières disease, perilymphatic fistula and cochlea-facial nerve dehiscence. Other diagnostic tools include the vestibular evoked myogenic potential or VEMP test, videonystagmography (VNG), electrocochleography (ECOG) and the rotational chair test. An accurate diagnosis is of great significance as unnecessary exploratory middle ear surgery may thus be avoided. Several of the symptoms typical to SCDS (e.g. vertigo and Tullio) may also be present singly or as part of Ménières disease, sometimes causing the one illness to be confused with the other. There are reported cases of patients being affected by both Ménières disease and SCDS concurrently.As SCDS is a very rare and still a relatively unknown condition, obtaining an accurate diagnosis of this distressing (and even disabling) disease may take some time as many health care professionals are not yet aware of its existence and frequently dismiss symptoms as being mental health-related. Treatment
Once diagnosed, the gap in the temporal bone can be repaired by surgical resurfacing of the affected bone or plugging of the superior semicircular canal. These techniques are performed by accessing the site of the dehiscence either via a middle fossa craniotomy or via a canal drilled through the transmastoid bone behind the affected ear.
Additionally they may hear the creaking and cracking of joints, the sound of their footsteps when walking or running, their heartbeat and the sound of chewing and other digestive noises. Some sufferers of this condition experience such a high level of conductive hyperacusis that a tuning fork placed on the ankle will be heard in the affected ear. The bizarre phenomenon of being able to hear the sound of the eyeballs moving in their sockets (e.g. when reading in a quiet room) "like sandpaper on wood" is one of the more distinctive features of this condition and is almost exclusively associated with SCDS. Tullio phenomenon, another of the more identifiable symptoms leading to a positive SCD diagnosis is sound-induced loss of balance. Patients showing this symptom may experience a loss of equilibrium, a feeling of motion sickness or even actual nausea, triggered by normal everyday sounds. Although this is often associated with loud noises, volume is not necessarily a factor. Patients describe a wide range of sounds that affect balance: the rattle of a plastic bag; a cashier tossing coins into the register; a telephone ringing; a knock at the door; music; the sound of children playing and even the patients own voice are typical examples of sounds that can cause a loss of balance when this condition is present, although there are countless others.