The number and strength of SCDS symptoms vary quite dramatically from one patient to another, and in the same patient they may fluctuate from day to day. There are no symptoms that are specific to SCDS. In other words, just because someone has these symptoms does not mean they necessarily have SCDS.
Symptoms quite often gradually creep into the life of a patient, but their onset is very frequently associated with an event in which pressure is involved. Different kinds of pressure affecting the body may be the trigger: a change in barometric pressure or elevated intracranial pressure (ICP) which can be caused by straining, flying or giving birth for example, or other physical trauma (caused for instance by a fall, a car crash etc).
Diagnosing Superior Semicircular Canal Dehiscence is an extensive task. Diagnostic testing requires equipment that is not readily available everywhere. Having a hearing test, and answering a few questions such as ‘Can you hear your eyes move?’ or ‘Do you get dizzy when you have a bowel movement?’ negatively is far from being enough to rule out SCDS, even if a positive answer from the patient should lead the doctor to give serious consideration to SCDS.
- Compatible history
- Objective verification on diagnostic testing
- CT scan confirmation
- Evaluation for other concomitant problems
In recent years it has become apparent that many patients whose Ménière’s symptoms have been considered idiopathic are in fact suffering from SCDS, a condition first identified by Dr Lloyd Minor in 1995, and reported in 1998.
SCDS involves thinning of the temporal bone over the inner ear resulting in holes that cause dizziness, vertigo, autophony (the hearing of self-generated noises such as heartbeat unusually loudly, or the eyes moving), hearing loss, fullness in the ear, nausea, headache, and fatigue. However, it can occur with thin bone and no actual hole.
This condition is very varied in its presentation but is often associated with symptoms of anxiety and panic attacks (which can be seen with any vestibular disorder, not just SCDS), as well as cognitive impairments. SCDS has been described as a great otologic mimicker, so a reasonable degree of suspicion is advisable and a high-resolution CT scan is required. Treatment of SCDS by surgical intervention has been shown to be effective in the majority of cases.
Recent studies have indicated that SCDS is much more common than first thought. Dr Timothy Hain, Professor Emeritus at Northwestern University Medical School, stated in October 2016: ‘We have diagnosed SCDS in 46 patients (as of 2014). This compares to several thousand patients with BPPV, thus SCDS is much less prevalent than BPPV which affects 2% of the population. As it is known that about 2% of the population has thinning of the bone that can lead to SCDS, our estimate of prevalence of symptomatic SCDS is about 0.1% of the population. Dr Gerard Gianoli, at the Ear and Balance Institute in Louisiana, has treated more patients with SCDS than anyone in the world (starting in 1998) and he concurs with this estimate.