Superior canal dehiscence syndrome

Superior canal dehiscence syndrome
Superior canal dehiscence syndrome
Other names	SCDS
Specialty	Neurotology, neurology, ENT

Last updated April 07, 2024

The semicircular canal dehiscence (SCD) is a category of rare neurotological diseases/disorders affecting the inner ears, which gathers the superior SCD, lateral SCD and posterior SCD. These SCDs induce SCD syndromes (SCDSs), which define specific sets of hearing and balance symptoms.^[1]^[2] This entry mainly deals with the superior SCDS.

The superior semicircular canal dehiscence syndrome (SSCDS) is a set of hearing and balance symptoms that a rare disease/disorder of the inner ear's superior semicircular canal/duct induces.^[3]^[4]^[5] The symptoms are caused by a thinning or complete absence of the part of the temporal bone overlying the superior semicircular canal of the vestibular system. There is evidence that this rare defect, or susceptibility, is congenital.^[6]^[7] There are also numerous cases of symptoms arising after physical trauma to the head. It was first described in 1998 by Lloyd B. Minor of Johns Hopkins University in Baltimore.^[8]

Symptoms

The superior canal dehiscence can affect both hearing and balance to different extents in different people.^{[ citation needed ]}

Symptoms of the SCDS include:

Autophony – person's own speech or other self-generated noises (e.g. heartbeat, eye movements, creaking joints, chewing) are heard unusually loudly in the affected ear
Dizziness/vertigo – chronic disequilibrium caused by the dysfunction of the superior semicircular canal
Tullio phenomenon – sound-induced vertigo, disequilibrium or dizziness, nystagmus and oscillopsia
Pulse-synchronous oscillopsia
Hyperacusis – the over-sensitivity to sound
Low-frequency conductive hearing loss
A feeling of fullness in the affected ear
Brain fog
Fatigue
Headache/migraine
Tinnitus – high pitched ringing in the ear

Symptoms in detail

SCDS-related autophony differs greatly in quality and range from the more common form which results from an open, or patulous Eustachian tube through which sufferers of this disorder hear the sound of their own voice and breathing. In contrast, patients with SCDS-related autophony report hearing their own voice as a disturbingly loud and distorted "kazoo-like" sound deep inside the head as if relayed through "a cracked loudspeaker." 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.^[9]
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 patient's own voice are typical examples of sounds that can cause a loss of balance when this condition is present, although there are countless others. The presence of Tullio may also mean that involuntary eye movements (nystagmus), sometimes rotational, are set off by sound, giving the sufferer the impression that the world is tipping, clockwise or anticlockwise, depending on the site of the dehiscence. Some patients report this tilt as being as much as 15°. For such persons, a visit to the concert hall or to a noisy playground may seem like being at the epicenter of an earthquake. A change of pressure within the middle ear (for example when flying or nose-blowing) may equally set off a bout of disequilibrium or nystagmus.^{[ citation needed ]}
Low-frequency conductive hearing loss is present in many patients with SCDS and is explained by the dehiscence acting as a "third window." Vibrations entering the ear canal and middle ear are then abnormally diverted through the superior semicircular canal and up into the intracranial space where they become absorbed instead of being registered as sound in the hearing center, the cochlea. Due to the difference in resistance between the normal round window and the pathological dehiscence window this hearing loss is more serious in the lower frequencies and may initially be mistaken for otosclerosis. In some patients there is true enhancement of low frequency hearing via bone conducted sound. A clinical sign of this phenomenon is the ability of the patient to hear (not feel) a tuning fork placed upon the ankle bone.
Pulsatile tinnitus is yet another of the typical symptoms of SCDS and is caused by the gap in the dehiscent bone allowing the normal pulse-related pressure changes within the cranial cavity to enter the inner ear abnormally. These pressure changes affect the sound of the tinnitus which will be perceived as containing a pulse-synchronized "wave" or "blip" which patients describe as a "swooshing" sound or as being like the chirrup of a cricket or grasshopper.
Brain fog and fatigue are both common SCDS symptoms and are caused by the brain having to spend an unusual amount of its energy on the simple act of keeping the body in a state of equilibrium when it is constantly receiving confusing signals from the dysfunctional semicircular canal.
Headache and migraine are also often mentioned by patients showing other symptoms of SCDS due to the body overcompensating for poor hearing in the affected ear by tensing up nearby parts of the face, head, and neck and using them as almost a secondary eardrum.

Causes

According to current research, in approximately 2.5% of the general population the bones of the head develop to only 60–70% of their normal thickness in the months following birth. This genetic predisposition may explain why the section of temporal bone separating the superior semicircular canal from the cranial cavity, normally 0.8 mm thick, shows a thickness of only 0.5 mm, making it more fragile and susceptible to damage through physical head trauma or from slow erosion. An explanation for this erosion of the bone has not yet been found.^{[ citation needed ]}

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 Ménière's disease, perilymphatic fistula and cochlea-facial nerve dehiscence.^[10]^[11] 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 Ménière's disease, sometimes causing the one illness to be confused with the other. There are reported cases of patients being affected by both Ménière's disease and SCDS concurrently.^{[ citation needed ]}

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.^[12]

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.^[13]^{[ unreliable source? ]}^[14] 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. Bone cement has been the material most often used, in spite of its tendency to slippage and resorption, and a consequent high failure rate; recently, soft tissue grafts have been substituted.^[15]

Eponym

Occasionally this disorder has been referred to as Minor's syndrome, after its discoverer, Lloyd B. Minor. However, that eponym has also been given to an unrelated condition, the paralysis and anaesthesia following a spinal injury, which is named after the Russian neurologist, Lazar Minor (1855–1942). In the latter case this term is now nearly obsolete.^[16]

Known cases

Sean McDonough, ESPN sportscaster

Related Research Articles

The inner ear is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the temporal bone of the skull with a system of passages comprising two main functional parts:

<span class="mw-page-title-main">Ménière's disease</span> Disorder of the inner ear

Ménière's disease (MD) is a disease of the inner ear that is characterized by potentially severe and incapacitating episodes of vertigo, tinnitus, hearing loss, and a feeling of fullness in the ear. Typically, only one ear is affected initially, but over time, both ears may become involved. Episodes generally last from 20 minutes to a few hours. The time between episodes varies. The hearing loss and ringing in the ears can become constant over time.

The vestibulocochlear nerve or auditory vestibular nerve, also known as the eighth cranial nerve, cranial nerve VIII, or simply CN VIII, is a cranial nerve that transmits sound and equilibrium (balance) information from the inner ear to the brain. Through olivocochlear fibers, it also transmits motor and modulatory information from the superior olivary complex in the brainstem to the cochlea.

The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most mammals.

Ototoxicity is the property of being toxic to the ear (oto-), specifically the cochlea or auditory nerve and sometimes the vestibular system, for example, as a side effect of a drug. The effects of ototoxicity can be reversible and temporary, or irreversible and permanent. It has been recognized since the 19th century. There are many well-known ototoxic drugs used in clinical situations, and they are prescribed, despite the risk of hearing disorders, for very serious health conditions. Ototoxic drugs include antibiotics, loop diuretics, and platinum-based chemotherapy agents. A number of nonsteroidal anti-inflammatory drugs (NSAIDS) have also been shown to be ototoxic. This can result in sensorineural hearing loss, dysequilibrium, or both. Some environmental and occupational chemicals have also been shown to affect the auditory system and interact with noise.

An ear is the organ that enables hearing and body balance using the vestibular system. In mammals, the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.

<span class="mw-page-title-main">Labyrinthitis</span> Medical condition

Labyrinthitis is inflammation of the labyrinth, a maze of fluid-filled channels in the inner ear. Vestibular neuritis is inflammation of the vestibular nerve. Both conditions involve inflammation of the inner ear. Labyrinths that house the vestibular system sense changes in the head's position or the head's motion. Inflammation of these inner ear parts results in a sensation of the world spinning and also possible hearing loss or ringing in the ears. It can occur as a single attack, a series of attacks, or a persistent condition that diminishes over three to six weeks. It may be associated with nausea, vomiting, and eye nystagmus.

<span class="mw-page-title-main">Endolymph</span> Inner ear fluid

Endolymph is the fluid contained in the membranous labyrinth of the inner ear. The major cation in endolymph is potassium, with the values of sodium and potassium concentration in the endolymph being 0.91 mM and 154 mM, respectively. It is also called Scarpa's fluid, after Antonio Scarpa.

<span class="mw-page-title-main">Benign paroxysmal positional vertigo</span> Medical condition

Benign paroxysmal positional vertigo (BPPV) is a disorder arising from a problem in the inner ear. Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head. This can occur with turning in bed or changing position. Each episode of vertigo typically lasts less than one minute. Nausea is commonly associated. BPPV is one of the most common causes of vertigo.

<span class="mw-page-title-main">Vertigo</span> Type of dizziness where a person has the sensation of moving or surrounding objects moving

Vertigo is a condition in which a person has the sensation of movement or of surrounding objects moving when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspiration, or difficulties walking. It is typically worse when the head is moved. Vertigo is the most common type of dizziness.

The vestibular nerve is one of the two branches of the vestibulocochlear nerve. In humans the vestibular nerve transmits sensory information transmitted by vestibular hair cells located in the two otolith organs and the three semicircular canals via the vestibular ganglion of Scarpa. Information from the otolith organs reflects gravity and linear accelerations of the head. Information from the semicircular canals reflects rotational movement of the head. Both are necessary for the sensation of body position and gaze stability in relation to a moving environment.

The Dix–Hallpike or Nylén–Bárány test is a diagnostic maneuver from the group of rotation tests used to identify benign paroxysmal positional vertigo (BPPV).

Tullio phenomenon, sound-induced vertigo, dizziness, nausea or eye movement (nystagmus) was first described in 1929 by the Italian biologist Prof. Pietro Tullio. (1881–1941) During his experiments on pigeons, Tullio discovered that by drilling tiny holes in the semicircular canals of his subjects, he could subsequently cause them balance problems when exposed to sound.

<span class="mw-page-title-main">Labyrinthine fistula</span> Medical condition

A labyrinthine fistula is an abnormal opening in the inner ear. This can result in leakage of the perilymph into the middle ear. This includes specifically a perilymph fistula (PLF), an abnormal connection between the fluid of the inner ear and the air-filled middle ear. This is caused by a rupture of the round window or oval window ligaments separating the inner and middle ear.

<span class="mw-page-title-main">Nystagmus</span> Dysfunction of eye movement

Nystagmus is a condition of involuntary eye movement. People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision.

The vestibular evoked myogenic potential is a neurophysiological assessment technique used to determine the function of the otolithic organs of the inner ear. It complements the information provided by caloric testing and other forms of inner ear testing. There are two different types of VEMPs. One is the oVEMP and another is the cVEMP. The oVEMP measures integrity of the utricule and superior vestibular nerve and the cVemp measures the saccule and the inferior vestibular nerve.

Lloyd Brooks Minor is an American surgeon, researcher, educator, and academic administrator. Since December 2012, he has served as the Carl and Elizabeth Naumann Dean of Stanford University School of Medicine at Stanford University. Previously, he was the provost of Johns Hopkins University.

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Vestibulocochlear dysfunction progressive familial, known also as familial progressive vestibulocochlear dysfunction is an autosomal dominant disease that results in sensorineural hearing loss and vestibular areflexia. Patients report feelings of vague dizziness, blurred vision, dysequilibrium in the dark, and progressive hearing impairment.

Cochlear hydrops is a condition of the inner ear involving a pathological increase of fluid affecting the cochlea. This results in swelling that can lead to hearing loss or changes in hearing perception. It is a form of endolymphatic hydrops and related to Ménière's disease. Cochlear hydrops refers to a case of inner-ear hydrops that only involves auditory symptoms and does not cause vestibular issues.

References

↑ Chien W, Carey J, Minor L (2011). "Canal dehiscence". Current Opinion in Neurology. 24 (1): 25–31. doi:10.1097/WCO.0b013e328341ef88. PMID 21124219.
↑ Ward B, van de Berg R, van Rompaey V, Bisdorff A, Hullar T, Welgampola M, Carey J (2021). "Superior semicircular canal dehiscence syndrome: diagnostic criteria consensus document of the committee for the classification of vestibular disorders of the Bárány Society". Journal of Vestibular Research. 31 (3): 131–141. doi:10.3233/VES-200004. PMC 9249274 . PMID 33522990.
↑ Minor LB (January 2000). "Superior canal dehiscence syndrome". The American Journal of Otology. 21 (1): 9–19. doi:10.1016/s0196-0709(00)80105-2. PMID 10651428.
↑ Minor, Lloyd B.; Cremer, Phillip D.; Carey, John P.; Santina, Charles C. Della; Streubel, Sven-Olrik; Weg, Noah (2001). "Symptoms and Signs in Superior Canal Dehiscence Syndrome". Annals of the New York Academy of Sciences. 942 (1): 259–273. Bibcode:2001NYASA.942..259M. doi:10.1111/j.1749-6632.2001.tb03751.x. PMID 11710468. S2CID 42255809.
↑ Minor LB (October 2005). "Clinical manifestations of superior semicircular canal dehiscence". The Laryngoscope. 115 (10): 1717–27. doi: 10.1097/01.mlg.0000178324.55729.b7 . PMID 16222184. S2CID 16760670.
↑ Murray, Melissa (March 8, 1999). "Old Bone Collection Reveals Basis for Some Dizziness". The Johns Hopkins Gazette. 28 (25).
↑ Duffy, Jim (1999). "The Clue in the Old Bones". Hopkins Medical News. Archived from the original on 2016-06-05. Retrieved 2008-01-20.
↑ Minor, Lloyd B.; Solomon, David; Zinreich, James S.; Zee, David S. (1 March 1998). "Sound- and/or Pressure-Induced Vertigo Due to Bone Dehiscence of the Superior Semicircular Canal". Archives of Otolaryngology–Head & Neck Surgery. 124 (3): 249–58. doi: 10.1001/archotol.124.3.249 . PMID 9525507.
↑ Albuquerque W, Bronstein AM (September 2004). "'Doctor, I can hear my eyes': report of two cases with different mechanisms". Journal of Neurology, Neurosurgery, and Psychiatry. 75 (9): 1363–4. doi:10.1136/jnnp.2003.030577. PMC 1739236 . PMID 15314139.
↑ "Symptoms of Superior Canal Dehiscence Syndrome". Johns Hopkins Medicine. 16 October 2021.
↑ Wackym, P. Ashley; Balaban, Carey D.; Zhang, Pengfei; Siker, David A.; Hundal, Jasdeep S. (13 December 2019). "Third Window Syndrome: Surgical Management of Cochlea-Facial Nerve Dehiscence". Frontiers in Neurology. 10: 1281. doi: 10.3389/fneur.2019.01281 . PMC 6923767 . PMID 31920911.
↑ Öhman, Jenny; Forssén, Annika; Sörlin, Anette; Tano, Krister (2018-11-02). "Patients' experiences of living with superior canal dehiscence syndrome". International Journal of Audiology. 57 (11): 825–830. doi: 10.1080/14992027.2018.1487086 . ISSN 1499-2027. PMID 30178689. S2CID 52147006.
↑ "superior semicircular canal dehiscence - superior canal dehiscence syndrome". www.otosurgery.org. Archived from the original on 2017-08-24. Retrieved 2008-01-20.
↑ Kertesz, Thomas R; Shelton, Clough; Wiggins, Richard; Galstonbury, Christine; Layton, Bryan J.; Worthington, Don W.; Harnsberger, H. Ric (October 2001). "Superior semi-circular canal dehiscence: Resurfacing with calcium phosphate bone cement". Australian Journal of Otolaryngology. 4 (3): 167–173.
↑ Teixido, Michael; Seymour, Peter E.; Kung, Brian; Sabra, Omar (July 2011). "Transmastoid Middle Fossa Craniotomy Repair of Superior Semicircular Canal Dehiscence Using a Soft Tissue Graft". Otology & Neurotology. 32 (5): 877–881. doi:10.1097/MAO.0b013e3182170e39. PMID 21659938. S2CID 8313147.
↑ synd/1691 at Who Named It?

External links

Ward, Bryan K.; Carey, John P.; Minor, Lloyd B. (28 April 2017). "Superior Canal Dehiscence Syndrome: Lessons from the First 20 Years". Frontiers in Neurology. 8: 177. doi: 10.3389/fneur.2017.00177 . PMC 5408023 . PMID 28503164.

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[Chien_et_al._(2011)-1] Chien W, Carey J, Minor L (2011). "Canal dehiscence". Current Opinion in Neurology. 24 (1): 25–31. doi:10.1097/WCO.0b013e328341ef88. PMID 21124219.

[Ward_et_al._(2021)-2] Ward B, van de Berg R, van Rompaey V, Bisdorff A, Hullar T, Welgampola M, Carey J (2021). "Superior semicircular canal dehiscence syndrome: diagnostic criteria consensus document of the committee for the classification of vestibular disorders of the Bárány Society". Journal of Vestibular Research. 31 (3): 131–141. doi:10.3233/VES-200004. PMC 9249274 . PMID 33522990.

[3] Minor LB (January 2000). "Superior canal dehiscence syndrome". The American Journal of Otology. 21 (1): 9–19. doi:10.1016/s0196-0709(00)80105-2. PMID 10651428.

[4] Minor, Lloyd B.; Cremer, Phillip D.; Carey, John P.; Santina, Charles C. Della; Streubel, Sven-Olrik; Weg, Noah (2001). "Symptoms and Signs in Superior Canal Dehiscence Syndrome". Annals of the New York Academy of Sciences. 942 (1): 259–273. Bibcode:2001NYASA.942..259M. doi:10.1111/j.1749-6632.2001.tb03751.x. PMID 11710468. S2CID 42255809.

[5] Minor LB (October 2005). "Clinical manifestations of superior semicircular canal dehiscence". The Laryngoscope. 115 (10): 1717–27. doi: 10.1097/01.mlg.0000178324.55729.b7 . PMID 16222184. S2CID 16760670.

[6] Murray, Melissa (March 8, 1999). "Old Bone Collection Reveals Basis for Some Dizziness". The Johns Hopkins Gazette. 28 (25).

[7] Duffy, Jim (1999). "The Clue in the Old Bones". Hopkins Medical News. Archived from the original on 2016-06-05. Retrieved 2008-01-20.

[8] Minor, Lloyd B.; Solomon, David; Zinreich, James S.; Zee, David S. (1 March 1998). "Sound- and/or Pressure-Induced Vertigo Due to Bone Dehiscence of the Superior Semicircular Canal". Archives of Otolaryngology–Head & Neck Surgery. 124 (3): 249–58. doi: 10.1001/archotol.124.3.249 . PMID 9525507.

[9] Albuquerque W, Bronstein AM (September 2004). "'Doctor, I can hear my eyes': report of two cases with different mechanisms". Journal of Neurology, Neurosurgery, and Psychiatry. 75 (9): 1363–4. doi:10.1136/jnnp.2003.030577. PMC 1739236 . PMID 15314139.

[10] "Symptoms of Superior Canal Dehiscence Syndrome". Johns Hopkins Medicine. 16 October 2021.

[11] Wackym, P. Ashley; Balaban, Carey D.; Zhang, Pengfei; Siker, David A.; Hundal, Jasdeep S. (13 December 2019). "Third Window Syndrome: Surgical Management of Cochlea-Facial Nerve Dehiscence". Frontiers in Neurology. 10: 1281. doi: 10.3389/fneur.2019.01281 . PMC 6923767 . PMID 31920911.

[12] Öhman, Jenny; Forssén, Annika; Sörlin, Anette; Tano, Krister (2018-11-02). "Patients' experiences of living with superior canal dehiscence syndrome". International Journal of Audiology. 57 (11): 825–830. doi: 10.1080/14992027.2018.1487086 . ISSN 1499-2027. PMID 30178689. S2CID 52147006.

[13] "superior semicircular canal dehiscence - superior canal dehiscence syndrome". www.otosurgery.org. Archived from the original on 2017-08-24. Retrieved 2008-01-20.

[14] Kertesz, Thomas R; Shelton, Clough; Wiggins, Richard; Galstonbury, Christine; Layton, Bryan J.; Worthington, Don W.; Harnsberger, H. Ric (October 2001). "Superior semi-circular canal dehiscence: Resurfacing with calcium phosphate bone cement". Australian Journal of Otolaryngology. 4 (3): 167–173.

[15] Teixido, Michael; Seymour, Peter E.; Kung, Brian; Sabra, Omar (July 2011). "Transmastoid Middle Fossa Craniotomy Repair of Superior Semicircular Canal Dehiscence Using a Soft Tissue Graft". Otology & Neurotology. 32 (5): 877–881. doi:10.1097/MAO.0b013e3182170e39. PMID 21659938. S2CID 8313147.

[16] synd/1691 at Who Named It?

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Classification	D ICD-10 : H83.8 MeSH : D000084322
External resources	Orphanet : 420402