Traumatic perilymph fistulae of the round and oval windows.
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An ultrastructural study of oval and round window changes in otitis media in humans was done. Ten cases were evaluated. In this first ultrastructural study of oval and round windows in otitis media, done at different stages of the disease, the round window membrane changes were similar to those of the mucoperiostium. Morphologic evidence suggests that the round window membrane layers participate in absorption and secretion of substances to and from the inner ear, such that the entire membrane could play a role in a middle and inner ear "defense system." Although the middle ear side of the footplate of the stapes had histopathological changes, the vestibular side remained essentially unchanged.
There are numerous reports on microfissures in the round window niche area, but not many reports have appeared on microfissures in the oval window niche area. In addition, few studies have compared microfissures between the oval and round window niche areas in the same subjects. Hence, the present study investigated the prevalence of microfissures in both areas in human temporal bones. The study was conducted on the 637 ears of 333 cases. Specimens were prepared according to the conventional methods: after fixation, decalcification and dehydration, each specimen was embedded in Celloidin, and the temporal bones were sectioned horizontally at 25-micron intervals. Every 10th section was stained with hematoxylin & eosin, and each section was analyzed under a light microscope. The prevalence of microfissures was analyzed in relation to the sex, left/right differences and age of the subjects. Microfissures were seen in the oval window niche area in 66.2%, and in the round window niche area in 92.0%. When a microfissure was seen in the oval window niche area, it was also detected in the round window niche area in every case. There were no sex or left/right differences in the prevalence of microfissures, and microfissures occurred bilaterally in most cases. The youngest subject with a microfissure in the oval window niche area was a 14-year-old, and the prevalence increased with age up to approximately 60 years. On the other hand, microfissures in the round window niche area were seen in a 3-year-old, and were seen in most cases over the age of ten. These findings suggest that microfissures are more likely to occur in the round window niche area as compared to the oval window niche area. However, the prevalence of microfissures in the oval window niche area was not low either, and it is important to pay attention to both the oval and round niche areas when microfissures are involved in the formation of perilymph fistulae. Given that the prevalence of microfissures in the oval window niche area increased up to about 60 years of age, not only growth, but also mastication, may be involved in the occurrence of microfissures.
Butyl 2-cyanoacrylate was placed on the oval and round window of the ear of the chinchilla and was also used as an adhesive for myringoplasty with autogenous muscle fascia. Butyl 2-cyanoacrylate was found to be difficult to manipulate and moderately toxic to the middle ear; there were occasional significant reactions in the inner ear.
The electrical activity of the inner ear before and after rupture of the round window membrane was monitored in guinea pigs under different pressure conditions with the aid of electrocochleography. Following studies were conducted weekly over a period of 4 weeks. Findings showed that overpressure below the pressure needed to open the Eustachian tube caused strong temporary functional disturbance of the cochlea, especially at high frequencies. Irreversible changes that were pressure-dependent were observed and occurred mainly at high frequencies. Application of low pressure to the round window membrane caused a functional loss comparable to changes after overpressure. Animals with a predamaged cochlea reacted to overpressure that was below opening pressure of the tube and to corresponding low pressure with a longer lasting functional loss than did animals with an undamaged cochlea.
Some patients with sudden hearing loss actually have two membrane breaks, one at the oval or round window and one further inside the cochlea. One may heal spontaneously and the other not, or both, or neither. It is very likely impossible to detect this early from the threshold audiogram, because the intracochlear breaks allows endolymph and perilymph mixing which spreads over much of the anatomically normal clchlea causing diffuse loss of function. This theory is illustrated by three case histories.
The association between diving, barotrauma, and the production of perilymphatic fistula has been known for almost 20 years. Forty-eight cases of round and oval window fistulas following diving have been reviewed and essentially corroborate previous findings. Any patient with a history of diving and subsequent sensorineural hearing loss within 72 hours should be suspected of having a round or oval window perilymphatic fistula and surgical exploration and closure of the fistula should be undertaken. Patients who have a loss of hearing, vertigo, nausea, or vomiting following a decompression dive should be re-compressed and if symptoms do not clear, exploration should be performed. Surgical treatment should be executed as soon as possible after the diagnosis is suspected for the best possible results.
The purpose of this study was to examine potential toxic effects of fibrin tissue adhesive to the middle and inner ears. Using the chinchilla as our experimental model, we placed fibrin sealant on either the footplate or the round window membrane in one ear, and placed similar amounts of normal saline in the same area of the opposite ear. In addition, the fibrin adhesive was used to anchor a fascia lata graft for myringoplasty. Both fibrin adhesive and normal saline produced mild reactions in the middle and inner ears when they were placed on the round window membrane; little reaction occurred when fibrin adhesive was placed on the oval window or when it was used for myringoplasty.
Recently, it has been suggested that otosclerosis represents the host's ongoing immunologic response to measles or other viral antigens. Documentation of past inflammation within the inner ear would serve as further evidence that this mechanism may be at play in the pathogenesis of the disease. Among the characteristic signs of prior inflammation in the inner ear is the presence of lamellar bone at the site of inflammation. This has been described in the temporal bone of a patient with immune-mediated deafness and with the temporal bones of experimental models of immune-mediated inner ear disease. Review of temporal bones with round window otosclerosis from the Eastern Temporal Bone Bank at the Massachusetts Eye and Ear Infirmary show that in four of ten cases there are characteristic signs of a prior severe inflammatory event centered in the scala tympani adjacent to the otosclerotic lesion. Otosclerosis, therefore, may have an inflammatory stage that is the consequence of a host response to an inciting event.
The effects of laceration of the round window membrane were investigated using the auditory brainstem response in guinea pigs with or without middle ear effusion. Sensorineural hearing impairment occurred in the lower basal turn of the cochlea with middle ear effusion. However, only temporary and mild hearing loss was observed in guinea pigs without middle ear effusion.
Fifteen patients with perilymphatic fistulae were evaluated. Of these patients, three had CSF leaks in addition to the perilymphatic fistulae. Eight patients had fistulae of one or both windows; two had fistulae confined to the lateral semicircular canal; and two had combined fistulae of both round window and lateral semicircular canals. All improved dramatically following surgical repair. In the following study, we have shown that perilymphatic fistulae can occur in the lateral semicircular canal, and we suggest exploration of this area when indicated.
The rupture of the round window membrane with consecutive perilymph fistula has gained in importance in the discussion of the pathogenesis of sudden hearing loss. In a retrospective study, the results of 23 tympanoscopies performed at the ENT Department of the University of Hamburg are reported. Two confirmed perilymph fistulas were seen, whereas in three cases they could not be excluded. After obliteration of the window niches with connective tissue an improvement of the hearing loss was seen in 9 cases. In comparison with our intraoperative findings, the number of perilymphatic fistulas mentioned in literature often seems very high. Nevertheless, tympanoscopy and obliteration of the window niches have their definite place in the therapeutic concept of sudden hearing loss, although the indication must be severely restricted.
The usefulness of endoscopic examination for the diagnosis of idiopathic perilymphatic fistula (IPLF) was investigated. Eight patients presenting with unilateral sensorineural hearing loss and vertigo underwent endoscopic examination by the transtubal or transtympanic approach. In 5 out of the 8 patients, transtubal endoscopy was carried out using a superfine flexible endoscope. With this approach, no abnormal findings were visualized. A perilymphatic leak from the round window was observed in 2 patients by means of transtympanic examination using a needle scope. These findings were confirmed in both patients by microscopic observation during tympanotomy. In one patient who was finally diagnosed with IPLF, the transtympanic endoscopy failed to detect perilymphatic leakage. Although incision of the tympanic membrane is necessary for the examination, transtympanic endoscopy is useful for the diagnosis of IPLF. Further improvement of the superfine flexible fiberscope is necessary before transtubal observation of the tympanic cavity can be effectively conducted.
Perilymphatic fistulas are well documented in the otolaryngologic literature as a cause for both auditory and vestibular symptoms. The anatomic location of fistulas has been clinically confirmed in both the oval and round windows. Furthermore, membranous tears within the cochlea have been described post mortem and may be the cause of the remaining fistulas which are suspected but not confirmed surgically. A fourth source of perilymph fistula has previously been suggested by Okano and Harada. During the past several years, surgical confirmation of perilymph leakage from two microfissure areas has been observed. These cases will be briefly discussed along with their clinical implications. Speculation as to the type of hearing loss caused by fistulas will be offered. Hypotheses concerning the various symptoms encountered in patients and the location of the defect will also be addressed.
Seventy-eight tympanotomies were performed to determine the presence of perilymph fistulas (PLFs); of these, 51% were found. The oval and round windows of all patients were grafted, whether PLFs were present or not. Of those patients with PLFs, 64% had resolution of their major symptom; when no PLF was found, 44% had a similar outcome. We concluded that 1) PLFs often behave as if they are epiphenomena in relation to hearing and balance, 2) PLFs can be intermittent, 3) PLF surgery is disappointing for restoration of hearing in sudden hearing loss when compared to the rate of spontaneous recovery, 4) stabilizing a fluctuating or progressive loss is a more realistic goal, and 5) establishing preoperative criteria for exploration is still a problem.
A case of recurrent meningitis associated with spontaneous cerebrospinal fluid (CSF) rhinorrhea and left sensorineural hearing loss in a 4-year-old boy was found to be due to simultaneous congenital defects. High resolution CT examination clearly showed an anterior fossa defect and an inner ear malformation, including demineralization in the region of the footplate of the stapes, and thus provided clear guidance for the surgeon.
Patients with perilymphatic fistula have been described as having symptoms similar to Meniere's disease and endolymphatic hydrops. Direct clinical or experimental evidence linking the two inner ear disorders has been lacking. An enhancement of the summating potential observed with electrocochleography suggests a diagnosis of ELH in both of these inner ear disorders. In this study, ECoG results of 27 patients with surgically confirmed PLF are reported. Fourteen patients with surgically confirmed spontaneous PLF had abnormal ECoG. Six of these 14 patients had normal hearing. The ECoG changes in patients with Meniere's disease and those with surgically confirmed PLF are identical, indicating the underlying pathologic change in both is hydrops. But there is no specific diagnostic abnormality on ECoG that differentiates these two inner ear disorders. Also, an experimental model of PLF was developed and studied in guinea pigs. "Inactive" PLF is defined as "an opening was made into the cochlea, but if no perilymph moved out through the fistula, it was defined as inactive" An "active" PLF occurs when perilymph actually moves from the inner ear out to the middle ear. ECoGs were recorded before and after creation of an "active" PLF. ECoG abnormalities were seen in "active" PLF and correlated with histologic data demonstrating ELH. An abnormally enhanced summating potential was demonstrated after active removal of perilymph through the experimentally created fistula. Cochlear duct histology showed hydropic distention of Reissner's membrane in the experimental ears and no changes in the membranous labyrinths of the unoperated, control ears.(ABSTRACT TRUNCATED AT 250 WORDS)
After the extensive discussion of the last published literature on the different possibilities of a lesion of the labyrinthine windows, four own cases are discussed. In case of a typical anamnesis of single patients with sudden deafness after sudden exertion or trauma prior to onset the surgical exploration is recommended. It is concluded that spontaneous labyrinthine window ruptures must be added to the etiologic factors in sudden hearing loss.