The SCDS Society

Superior Semicircular Canal Dehiscence Syndrome ( SCDS ) is a medical condition of the inner ear.

The SCDS Society is a non-profit charity – open for membership to everyone who supports our mission.

Our Vision:

A world where Superior Semicircular Canal Dehiscence Syndrome is understood and recognised by all.

Our Mission:

  • To raise public awareness about the syndrome.
  • To work towards the provision of adequate and justifiable diagnostics, and treatment options for patients suffering from the syndrome.
  • To promote research in this field.
  • To inform, support and alleviate the suffering of anyone affected by the syndrome.

Membership is free of charge.

The website is under development and we will keep adding reliable and useful information as things evolve.

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The SCDS Society is non-profit, and all financial support will be used towards our mission

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SCDS

WHat is SCDS

Superior Semicircular Canal Dehiscence Syndrome (usually abbreviated to SCDS or SSCDS) is a medical condition of the inner ear. It is accompanied by a series of symptoms that play out to varying degrees, from asymptomatic (no symptoms) to debilitating, often fluctuating from day to day and differently from patient to patient. Those affected have a thinning, a hole or even a complete absence of the part of the temporal bone overlying the superior semicircular canal of the vestibular system.

Other dehiscences around the labyrinth, i.e. posterior canal, horizontal canal, facial-cochlear, carotid-cochlear can present in an identical manner to SCDS. Collective synonymous terms for all dehiscences around the labyrinth are “Labyrinthine dehiscence”, “Labyrinthine Fistula” and “Otic Capsule Dehiscence”. The otic capsule refers to the dense osseous labyrinth of the inner ear that surrounds the cochlea, the vestibule and the semicircular canals, surrounded by the less dense / pneumatised petrous apex and mastoid part of the temporal bone.

Dr. Minor´s team at John Hopkins Hospital were the first to write about SCDS in the medical literature. They gave the openings in the balance canals the label botanists use to describe holes left behind from a burst seed pod – dehiscence.

Around 1-2% of the general population has a dehiscence (an opening) over the superior semicircular canal, but only a fraction of those people are symptomatic (have the syndrome). Nobody knows the precise number, but experts specialising in inner ear disorders estimate that 0.1% of the general population (one in a 1000) and 15-25% of chronically dizzy patients have the syndrome. Approximately 50% of the patients have SCDS bilaterally, in both ears.

It is now generally recognised that SCDS symptoms tend to first present themselves after a pressure-altering event, such as flying, diving or giving birth, or after physical trauma to the head or another part of the body. For some patients, however, the symptoms seem to build up gradually and may even have been present throughout the person’s whole life. Within the SCDS patient population about 25% have increased intracranial pressure and some doctors have speculated that this pressure may wear down the bone, making the skull thinner. There are several reports of more than one person from a single family with the syndrome. SCDS affects people regardless of age, sex or ethnicity.

presentation of SCDS

SCDS has been described as a great otologic mimicker because of the wide range of other diagnoses with which it can be confused, so a high degree of suspicion is advisable. Treatment of SCDS by surgical intervention has been shown to be effective in the majority of cases.  Successful, well practised surgery methods have been developed. The costs are relatively low but a highly specialised team is required. If an operation is not performed, the brain can learn to compensate to some degree, but this takes its toll in the form of fatigue among other things.

There are reports of some patients who have had spontaneous resolution before a return of symptoms but nobody knows whether the situation can improve permanently without a surgical repair once the SCDS symptoms have set in.  The most likely scenario is that the condition will gradually worsen for the patient, with a downward spiral economically if people are too affected to be able to work. The syndrome has been described as developing in four stages. SCDS is currently often misdiagnosed, and is undoubtedly underdiagnosed.

Most SCDS patients may have been given several tentative but incorrect diagnoses before being informed about SCDS. It is fair to say that the most affected and persistent patients have a higher chance of reaching an accurate SCDS diagnosis as they have many of the symptoms that are considered typical by doctors that have not seen a wide range of patients.

underdiagnosis of SCDS

There are many reasons for the underdiagnosis of SCDS:

  1. The syndrome was first described in the medical literature as recently as 1998 and it still remains little known about amongst the majority of medical professionals.
  2. The diagnostics require a thorough battery of tests that takes time to perform, and involves equipment that is not always readily available; furthermore very few doctors have adequate training for interpreting the results of the tests.
  3. Many SCDS symptoms overlap with those deriving from other medical conditions, and inadequate or inappropriate testing leads to misdiagnosis.
  4. Many SCDS patients will have other concomitant inner ear disorders, such as BPPV, that may confuse the clinical picture.
  5. As fascinating as SCDS may seem, pathology connected to the ears has a relatively low status within the medical world. It’s a curious fact, considering that the brain, whose functions are thoroughly linked in with the inner ear, has top ranking in this respect.
  6. Doctors specialising in balance disorders are a fairly rare breed, prepared to devote copious time to discuss with dizzy patients symptoms that often are diffuse and fluctuating, but may be debilitating nonetheless.

The current situation is unacceptable. Apart from the suffering these circumstances involve, they create a high level of cost. It is expensive for the patients, but is also particularly costly for welfare states that may be called upon to provide abundant benefit payments to those patients since they are unfit for work as a result of their symptoms, as well as health care for the management of symptoms that simply won’t go away without specific and successful surgical repair operations developed specifically for SCDS.

misdiagnosis and concomintant conditions

Recorded misdiagnosis and diagnoses that can be seen concomitantly with SCDS (in alphabetic order):

  • ATTENTION DEFICIT HYPERACTIVITY DISORDER (ADHD)
  • AUTISM
  • CSF LEAK
  • CHIARI MALFORMATION
  • CHRONIC BPPV
  • CHRONIC FATIGUE SYNDROME (CFS)
  • EUSTACHIAN TUBE DYSFUNCTION
  • FIBROMYALGIA
  • HYPOTHYROIDISM
  • INTRACRANIAL HYPERTENSION
  • LYME DISEASE
  • MÉNIÈRE’S DISEASE
  • MIGRAINE ASSOCIATED VERTIGO (MAV)
  • MYALGIC ENCEPALOMYLITIS (ME)
  • PATULOUS EUSTACHIAN TUBE (PET)
  • POST-CONCUSSIVE SYNDROME
  • POST-VIRAL FATIGUE SYNDROME
  • PSYCHOLOGICAL/MENTAL PROBLEMS
  • WHIPLASH

The list is incomplete.  Please note that SCDS can be misdiagnosed as one of the above and/or be present concomitantly with the above.  In fact, some of these diagnoses are suspected to be more commonly present among the SCDS population.

SEE ALSO RELATED DIAGNOSIS.

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Symptoms

variable symptoms

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).

The majority of SCDS symptoms fall into two main categories; balance and auditory. Secondary symptoms also occur, such as headache, nausea and panic attacks triggered by dizziness. SCDS is commonly referred to as a balance disorder, but it is essential to emphasise that there are people who have SCDS who have hearing loss only, and no vestibular symptoms.

To summarise, a person with a dehiscence or thinning around the labyrinth can:

  1. be completely asymptomatic
  2. have vestibular symptoms only
  3. have hearing loss only
  4. have autophony or tinnitus only
  5. have any combination of 2) to 4)

Here follows a list of the most commonly reported symptoms, first the auditory and balance ones, then others, listed in alphabetical order.

Auditory symptoms
balance issues
other common symptoms

The list is incomplete

A worsening of symptoms is fairly typical if pressure within the head and body becomes elevated (when bending and straining), or if there are external pressure changes, for example in the form of sound waves, barometric pressure (certain types of weather) or when flying. A sudden drop of pressure on descending in a plane can be particularly challenging for the ears.

In the long run, the brain can learn to compensate to some degree, but this takes its toll in the form of fatigue and brain fog among other things.

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Diagnosis

How to find out if you have scds?

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.

Diagnosis requires:

  1. Compatible history
  2. Objective verification on diagnostic testing
  3. CT scan confirmation
  4. Evaluation for other concomitant problems

Ideally things should be done in this chronological order, but insufficient knowledge amongst health professionals and lack of equipment has resulted in the scan often being undertaken before sufficient testing is done. This is unfortunate because people who don’t have SCDS could be saved from unnecessary and potentially harmful radiation from the mainstream CT scanners.
The triad of vertigo, tinnitus and deafness is a familiar presentation in a primary care clinic, but the accurate diagnosis related to these symptoms can be hard to reach. ‘Difficulty with everything in General Practice is spotting the unusual from the commonplace, and continuity of care is really important’, says the National Guardian for the NHS in the UK.  ‘If a patient comes back to see several different people, they might all try something to fix the immediate problem rather than seeing the whole picture.’

“so stoned”

Dizziness can be the presentation for a wide range of diagnoses, and taking the history of a dizzy patient is essential in order to differentiate the possible etiologies of vertigo. The mnemonic “SO STONED” has been proposed, summarising the key factors that allow a first approximation of diagnosis identification: Symptoms, Often (Frequency), Since, Trigger, Otology, Neurology, Evolution and Duration. The most common vestibular diseases have different fingerprints when all these factors are examined.  When considering Ménière’s syndrome, for example, there is a long list of possible causes, including hypothyroidism, tumours (most notably acoustic neuromas), infections, metabolic or immune disorders, perilymphatic fistula, genetic mutations, superior semicircular canal dehiscence syndrome (SCDS), and many more.

The diagnosis should come from a Neuro-otologist or an ENT specialist with a specific focus on vestibular disorders.  If the period of assessment takes less than a day, it is possible that there isn’t enough data to give an accurate SCDS diagnosis.

See the list of equipment in a high end test lab for vestibular testing.

Thicker sliced CT scans are inadequate. To minimise unnecessary radiation, it is important to check that the resolution is high enough at the outset. One millimetre slices are too thick, 0.24 millimetre is the golden standard.

Thinning of bone (without a dehiscence) may also result in the symptoms of SCDS.

related conditions

Alongside SCDS, diagnostic considerations need to include other dehiscences around the labyrinth, and perilymph fistulae (PLF): In between the air-filled middle ear and the fluid-filled space of the inner ear, very small, thin membranes act as little dividers. They are called the oval and round windows. A PLF is a tear in one, or both, of these windows. This allows fluid to leak from the inner ear to the middle ear (which should be dry if everything is normal).  Patients with SCDS are susceptible to PLFs. They can occur in normal hearing subjects, or varying types of hearing loss may be found.

PERILYMPH FISTULA (PLF)
MÉNIÈRE’S
MAV
BPPV
EUSTACHIAN TUBE DYSFUNCTION
INTRACRANIAL HYPERTENSION
CSF LEAK
HYPOTHYROIDISM

 

The list is not complete

See also a list of recorded misdiagnosis and diagnoses that can be seen concomitantly with SCDS.

Treatment

This section is currently a challenge because the doctors performing SCDS surgeries undertake their operations in different ways.  Surgeons with extensive and successful SCDS experience are few and far between. It is therefore important for the patient to do their homework, educate themselves, and carefully evaluate information from the surgeon about his or her track record and success rate, in order to stand a good chance of restoring their health.

The SCDS Society does not advocate bilateral plugging repairs as an SCDS treatment, since studies have shown that a permanent loss of vestibular function ensues. On the contrary, a good number of people have had bilateral resurfacing repairs with bone graft which have restored their vestibular health.

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