Disease Information for Labyrinth fistula

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Clinical Manifestations
Signs & Symptoms
Relentless vomiting/retching/purging
Vomiting
Ataxia
Dizziness/Dizzy
Nystagmus
Spatial orientation/perception difficulty
Unable to tandem walk/straight line
Vertigo
Vertigo/relentless
Balance problems
Collapse/Prostration
Falling
Vasovagal activation/parasympathetic tone/Signs
Acute Hearing Loss
Ear fullness/Aural pressure
Head Movement Vertigo
Hearing loss
Hearing problems
Henneberts/eye deviation/pneumatic otoscopy/sign
Sound distortion
Sudden deafness
Tinnitus
True Vertigo Sign Confirmed
Unilateral sudden deafness
Vertigo in Elderly
Vertigo triggered by exertion/valsalva/defecation
Vertigo triggered/positional change
Vertigo triggered/Tragus pressure sign
Diagnostic Test Results
Other Tests & Procedures
TEST/Caloric/nystagmus/challenge abnormal
CT Scan
CT Scan/Acoustic Cochlear Abnormalities
MRI/Acoustic high resolution/cochlea abnormal
Associated Diseases & Rule outs
Rule Outs
Labyrinthitis
Meniere's disease
Associated Disease & Complications
Deafness
Deafness, sensorineural
Labyrinthe fistula
Syncope/Fainting
Ataxia Disorder
Deafness Acquired
Disease Mechanism & Classification
Class
CLASS/Cochlear lesion/disorder (ex)
CLASS/Ears/accessory (category)
CLASS/Labyrinth involvement/disorder (ex)
CLASS/Vestibular/labyrinth disorder (ex)
Process
PROCESS/Fistula disorder (ex)
PROCESS/Structural/anatomic/foreign body (category)
Synonyms
Synonym
fistula inner ear, fistula labyrinth, inner ear fistula, labyrinth fistula, Labyrinthine fistula, Labyrinthine fistula (disorder), Labyrinthine fistula unspec, Labyrinthine fistula unspecified, Perilymph fistula, Unspecified labyrinthine fistula, Unspecified labyrinthine fistula (disorder), Synonym/Superior Semicircular Canal dehiscence
Treatment
Surgical Procedures or Treatments
SX/Surgery
Other Treatments
TX/Expectant/supportive treatment.
Definition

Perilymphatic or labyrinthine fistula is a condition in which an abnormal communication is present between the perilymphatic space of the inner ear and the middle ear or mastoid; The manifestations of this disease vary in severity and complexity, commonly ranging from very mild to incapacitating; Perilymphatic fistulas (PLFs) may induce hearing loss, tinnitus, aural fullness, vertigo, disequilibrium, or a combination of these complaints; The vagueness of symptoms caused by PLF and the overlapping symptoms of other disease processes make the diagnoses elusive; History of the Procedure: Sustained interest in PLF began in the mid 1960s; The initial focus was on PLFs that developed following stapedectomy procedures; The recognition that loss of perilymph following stapedectomy could produce hearing loss, disequilibrium, and tinnitus led to the recognition that these same symptoms could arise from perilymph loss caused by other types of trauma; In the early 1970s, Victor Goodhill first distinguished between implosive and explosive forces as potential causes for rupture of the round or oval window membrane leading to

PLF; Problem: General agreement exists that PLF occurs and that leakage of perilymph from the inner ear into the middle ear can cause acute hearing loss, paroxysmal vertigo, disequilibrium, and tinnitus; Virtually no consensus exists regarding how frequently PLF occurs, how it should be diagnosed, or how it should be treated when suspected; A high degree of controversy surrounds the appropriate indications for surgical exploration and operative repair of PLF; Frequency: Frequency is unknown;

Etiology: PLF occurs when perilymph leaks from the perilymphatic spaces of the bony labyrinth into the middle ear space; The loss of perilymph alters the balance between perilymph and endolymph within the membranous labyrinth; PLF is thus a form of inner ear fluid imbalance; Ménière disease, another form of inner ear fluid imbalance, occurs when endolymph is present in overabundance; Both disease entities alter the endolymph-to-perilymph ratio in the same direction, which may account for the difficulty involved with separating their clinical presentations;

Pathophysiology: Inner ear fluids are almost completely contained within a rigid bony framework. However, the perilymphatic space is connected to the subarachnoid space via the cochlear aqueduct; The size of the cochlear aqueduct varies dramatically between subjects; Even when it is relatively large, the cochlear aqueduct is often completely obstructed with arachnoid tissue; Evidence exists that the arachnoid becomes denser with increasing age; Thus, the patency of the cochlear aqueduct varies among persons; Establishing whether the cochlear aqueduct is patent in any particular individual is impossible;

A variety of indirect evidence suggests that pressure changes within the subarachnoid space can be communicated to the inner ear; Such pressure changes may be communicated through the cochlear aqueduct or alternatively through a patent lamina cribrosa, cochlear modiolus, or vestibular aqueduct; At least in some patients, stapes gushers appear to arise from a defective modiolus, allowing free communication between the spinal fluid and perilymphatic space;The length of the cochlear aqueduct and the presence of arachnoid within its lumen tend to dampen the effects of sudden pressure changes in the subarachnoid space, thereby protecting the inner ear from rapid pressure changes; Simultaneous increases in pressure on the endolymphatic sac also protect the intracochlear membranes by equalizing endolymphatic and perilymphatic pressure; Even so, sudden increases in subarachnoid pressure can be transferred from inner ear fluids; At the round window membrane and the annulus of the oval window, the middle ear space is separated from the perilymphatic space by a soft tissue membrane; These areas permit pressure change between the middle ear and perilymphatic space; Excess pressure generated on either side of these membranes can result in tear or rupture leading to the egress of perilymphatic fluid from the membranous labyrinth; In addition to the oval window annulus and round window membrane, which are present in every person with normal hearing, a number of other sites for PLF are possible in some individuals;

The fistula ante fenestram lies anterior to the anterior portion of the stapes footplate and is an embryonic residua formed by the resorption of precartilage in the fetus;

Microfissures have been noted with regularity extending from the ampulla of the posterior semicircular canal to the round window; Congenital anomalies of the inner ear are associated with a much higher incidence of PLF; Incomplete partitioning (Mondini dysplasia) often is accompanied by incomplete formation of the stapedial footplate and a high incidence of PLF; The Hyrtl fissure and other congenital anomalies are other potential sites of perilymph loss;

Goodhill separated the hydrodynamic forces that could potentially produce PLF into implosive and explosive forces; Everyday activities, such as lifting, straining, coughing, and sneezing, are associated with increases in cerebrospinal fluid (CSF) pressure; Such pressure increases then can be transmitted to the inner ear via a patent cochlear aqueduct or through the lamina cribrosa of the internal auditory canal; A precipitous increase in pressure within inner ear fluids can result in tears of the oval window annulus or round window membrane; Vulnerability to such tears may depend on the inherent strength of these tissues, which may vary among individuals; Goodhill termed tears produced by increased pressure within the inner ear fluid compartment as explosive; Conversely, pressure can increase rapidly within the middle ear space as a result of barometric pressure change, compression trauma of the ear, Valsalva maneuver, and pinched-nose sneezing; Ruptures or tears of the round window membrane, oval window annulus, or membranes protecting a fistula ante fenestram, microfissure, or the Hyrtl fissure that result from increased middle ear pressure also are termed explosive forces by Goodhill; In addition to changes related to hydrodynamic pressure, head injury may produce rupture of the membranes that seal the inner ear and prevent escape of perilymphatic fluid into the middle ear space; The precise mechanism by which perilymph loss produces hearing loss is unclear; Decompression of the perilymphatic space may create secondary endolymphatic hydrops; Consequently, the usual symptoms of endolymphatic hydrops (Ménière disease) arise; Secondary endolymphatic hydrops has been histologically identified in experimental animals with PLF; Compelling indirect evidence exists that hearing loss in this circumstance is the result of loss of perilymphatic pressure; A large number of reports describe hearing loss associated with decreased subarachnoid pressure secondary to spinal anesthesia; Hardy demonstrated that such hearing loss can be reversed by injecting 20 mL of isotonic sodium chloride solution into the subarachnoid space;

In 1974, Robertson demonstrated changes in the tuning curves of single spiral ganglion cells from the basal membrane after removal of perilymph from the tympanic scala of the guinea pig; Flint et al showed an increase in auditory brainstem response (ABR) thresholds of 10-15 dB in guinea pigs with artificially created PLF; however, the etiology remains controversial; Bohmer demonstrated no change in auditory thresholds measured in guinea pigs with simple round window membrane perforation, even though a decrease was noted in the normal positive hydrostatic pressure within the cochlea; Evidence of auditory change also has been provided by measuring electrocochleographic changes after the creation of PLF; Ackley demonstrated consistent increase in the ratio of the summating potential (SP) to the action potential (AP) in guinea pigs with obstructed cochlear aqueducts after the creation of PLF; Others have subsequently confirmed these results;

Clinical: Seltzer and McCabe gathered clinical data from 91 patients with surgically confirmed PLF; Most patients (90%) had auditory symptoms, generally hearing loss; The character of the loss varied from sudden and profound to mild and fluctuating; Tinnitus was noted in 63% of patients, and aural fullness was noted in 25%; Glasscock et al reported that 83% of their patients with traumatic PLF had complaints of sudden or fluctuating sensorineural loss;

Vestibular symptoms occur in most patients. Balance disturbance can be described as true rotational vertigo, lightheadedness, disequilibrium, intolerance to motion, or any combination of these symptoms; Seltzer and McCabe reported such symptoms in 80% of patients with PLF, and Glasscock et al reported 77% incidence of true vertigo or disequilibrium; In obvious cases, membrane rupture is accompanied (or followed within a few minutes) by rapid severe hearing loss, loud roaring tinnitus, and severe rotational vertigo; Vertigo often is incapacitating and accompanied by visceral symptoms (eg, sweating, pallor, nausea, vomiting); Even cursory examination demonstrates marked instability and nystagmus; Audiometric evaluation reveals sensorineural hearing loss; Platform posturography confirms disequilibrium with a vestibular pattern, and platform fistula test results are positive; Vertigo and, to a lesser degree, tinnitus and hearing loss are sometimes exacerbated by straining (the Valsalva maneuver);

Unfortunately, many PLFs do not manifest in a straightforward fashion; A combination of otologic symptoms may result, and symptoms may fluctuate in complex ways that are difficult for the patient to explain; Onset of symptoms may be delayed by several days, or the acute phase may be masked by more serious injuries in other areas; Rotational vertigo may be entirely absent, and disequilibrium may be mild, vague, and episodic; Hearing loss, tinnitus, and aural fullness may come and go unpredictably; Such elusive symptomatology is partially responsible for the controversy surrounding this disorder; The diagnosis of PLF often depends on the antecedent history of otologic surgery, trauma, diving, or congenital ear malformation; Fluctuating or sudden hearing loss with or without vestibular symptoms in a patient with a previous stapedectomy, for example, is highly suggestive of PLF; Trauma frequently is cited as the cause of a PLF; Changes in the middle ear pressure sufficient enough to implode the round window membrane can occur during descent while flying, forced Valsalva maneuver, or suppressed sneezing; Pullen reported that 48 of 62 patients with suggested PLF following scuba diving had round window membrane rupture; Pressure sufficient to rupture the round window membrane can develop at a depth of water as shallow as 4 ft; Explosive PLFs can arise from CSF pressure increases caused by physical exertion, coughing, and straining; Klokker and Vesterhauge have reported on 4 cases of perilymph fistula that occurred in flight attendants who flew with upper respiratory infections during a 6-month period; All 4 flight attendants work for a major Scandinavian airline that employs approximately 3,000 flight attendants; PLF may be the ultimate etiology of progressive neurosensory hearing loss in some children; Its frequency remains unknown and is contested; Grundfast and Bluestone reported that 66% of 33 children with progressive neurosensory hearing loss had PLF at exploratory tympanotomy; Reilly and Kenna prospectively evaluated 244 children with sensorineural hearing loss of unknown etiology; of the 54 ears that were surgically explored, 42% demonstrated active PLF; Weber et al, in a follow-up article, confirmed that surgical repair of perilymph fistula does not result in a significant risk of postoperative hearing loss and that fistula repair may prevent further hearing loss, even in patients in whom a perilymph fistula was not identified at the time of surgery; The indications for exploratory tympanotomy are controversial; Accurate diagnosis is difficult; If the patient"s history is suggestive of PLF, objective testing should be used to reinforce or reject the initial assessment; The signs and symptoms of PLF are relatively nonspecific and overlap greatly with those seen in other otolaryngologic and neurologic diseases; PLF can be particularly difficult to differentiate from Ménière disease; Histologically, the 2 diseases are similar; However, the final diagnosis of PLF requires integration of all available information; Because PLFs can be difficult to diagnose, some surgeons believe that patients should be given the opportunity to choose surgical exploration even when PLF is unlikely; Such an approach leads to many explorations with negative findings and many patients who do not benefit from the procedure; Conversely, a few patients benefit who would otherwise have had undiagnosed PLF; Other surgeons prefer to use fairly rigid criteria for the diagnosis of PLF; These surgeons explore fewer individuals and have a much higher rate of positive intraoperative findings; A high percentage of their operative cases improve following surgery; however, some cases of PLF are missed; These patients may have lost an opportunity for clinical improvement or cure; Objective testing becomes especially important when the history of antecedent trauma is vague or remote; A PLF test or elevated SP/AP ratio on electrocochleography (ECoG) significantly raises the likelihood of PLF; Treatment is surgical using high resolution CT scan to document

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