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PubMed2006

Could vestibular evoked myogenic potentials (VEMPs) also be useful in the diagnosis of perilymphatic fistula?

The role of vestibular evoked myogenic potentials (VEMPs) is at this time indisputable in the study of vestibular disorders. Furthermore, VEMPs are widely accepted as a diagnostic tool when a superior semicircular canal dehiscence (SCD) is suspected, presenting in such cases a lowering of threshold values able to raise a recordable response due to increased inner ear immittance. According to the same principle, the possibility of another kind of alteration having the same effect on the inner ear might be considered when high-resolution computed tomography has excluded the presence of an SCD. In this paper four cases are described in which high-resolution computed tomography showed normal features without any labyrinthine dehiscence and VEMP threshold values were lowered; the appropriateness of suspecting a perilymphatic fistula in such cases and resorting to VEMPs in detecting a perilymphatic fistula is discussed.

Adult↗
PubMed1982

Amino acid content of guinea pig perilymph collected under conditions of quiet or sound stimulation.

With the cochlear aqueducts blocked, guinea pig cochleas were perfused with artificial perilymph. The collected perfusates were treated with 5-(dimethylamino)-1-naphthalenesulfonyl chloride (dansyl-Cl). The derivatized constituents were analyzed by high- performance liquid chromatography using fluorometric detection. The concentration of none of the compounds measured, including the putative transmitters glutamate and aspartate, was found to increase in the perfusate in response to sound stimulation. These results do not support the suggestion that one of these compounds might be primary afferent transmitter of audition.

Acoustic Stimulation↗
PubMed1991

Old theme and new reflections: hearing impairment associated with endolymphatic hydrops.

The cause(s) of the hearing impairment associated with Menière's disease are not understood but are undoubtedly associated with the inner ear endolymphatic hydrops. Two major hypotheses have been proposed and widely received: endolymphatic overpressure followed by leaky membranes and subsequently the mixing of high K+ endolymph with perilymph. Our recent data on an experimental model of endolymphatic hydrops have provided grounds for renewed reflections on the pathology. Indeed our data might be interpreted without involving either of the above hypotheses and suggests that the symptoms of Menière's disease might be accounted for by a flow of perilymph from scala vestibuli towards scala tympani with the mixing of the two perilymphs which are similar but not identical in composition. The higher K+ concentration arriving from the scala vestibuli into the scala tympani at the apex of the cochlea via the helicotrema is likely to be toxic to hair cell and auditory nerve fiber function. The mixing of the two perilymphs could result in deterioration of low frequency sensitivity, provoke low frequency tinnitus and in the long term cause spiral ganglion cell degeneration at the apex of the cochlea. The feeling of fullness in the ear might be the result of the decreasing perilymph volume in the scala vestibuli which could give rise to inner ear conductive losses. The patency of the cochlear aqueduct might play a role in determining the high risk group of individuals likely to manifest the symptoms of endolymphatic hydrops.

Ear↗
PubMed1989

Distribution and metabolism of leukotriene C4 after cisternal injection in guinea pigs.

Following cisternal injection of [3H8]LTC4 into guinea pigs, leukotriene metabolites were identified in the brain, cerebellum, perilymph, blood, liver and kidneys. LTC4 was metabolized into LTD4 and LTE4 in the cerebrospinal fluid and LTE4 was transported into the blood for general circulation and uptake into the liver and kidneys. The excretion of LTE4 from CNS to blood seemed to be the rate-limiting step in the elimination of leukotrienes from the body. Leukotrienes were also transported into the perilymph. The conversion of LTC4 into LTD4 and LTE4 was lower in perilymph as compared to the cerebrospinal fluid, suggesting a rate limiting function of the cochlear aqueduct that can be defined as a cerebrospinal fluid-labyrinth barrier.

Animals↗
PubMed2004

An analysis of correlation between the unusual location of the jugular bulb and audiovestibular symptoms.

OBJECTIVE: Case reports indicate that abnormal location of the jugular bulb (JB) may result with some vestibular and audiological symptoms. The aim of this study is to analyze the correlation between the radiological view of the JB and audiovestibular findings and to clarify its possible role for Meniere-like problems. METHOD: Fifty-six patients, who had abnormal view of the JB on computerized tomography (CT) were selected to the study in this prospective case review. They were classified in three groups (Group-I; Lateral, Group-II; Intermediate and Group-III; Medial), according to the location of the JB. Patients were subjected to audiogram and vestibular tests (Dix-Hallpike maneuver, fistula test, vestibulospinal tests, electronystagmography (ENG)). RESULTS: JB was compressing on the cochlear aqueduct (CA) in two patients in group-II. Seventeen out of 25 patients in group-III had radiological evidence of obstruction of vestibular aqueduct (VA). 19 patients had neurosensorial and four patients had conductive hearing loss. All of the patients in group-I and nine of the patients in group-II gave normal caloric response to stimulation. Twelve of 19 patients in group-III demonstrated canal paresis ranging from 22 to 80%. CONCLUSION: Present study points out that there is a high correlation between HJB and vestibular problems in symptomatic cases. In patients who have HJB without classic vertigo attacks subclinical involvement of the vestibular system has been observed on ENG recordings. These findings imply that radiological existence of HJB may be a predisposing factor for Meniere-like complaints.

Electronystagmography↗
PubMed2003

Contamination of perilymph sampled from the basal cochlear turn with cerebrospinal fluid.

Our understanding of the perilymph kinetics of drugs depends largely on data obtained by the analysis of perilymph samples. Although a number of studies have demonstrated qualitatively that perilymph samples may be contaminated by cerebrospinal fluid (CSF), and some investigations adopt specific methods to minimize CSF contamination of their samples, many other studies fail to consider the influence of this potential artifact on their measurements. In the present study we have attempted to quantify the degree of CSF contamination of perilymph samples taken from the basal turn of the guinea pig cochlea using the ionic marker trimethylphenylammonium (TMPA). TMPA solution was irrigated across the round window membrane while a TMPA-selective electrode sealed into the perilymphatic space continuously monitored perilymph TMPA concentration. After a period of TMPA loading, a perilymph sample was aspirated and its TMPA content determined. Differences between the sample concentration and the measured TMPA time course during perilymph loading and sampling were analyzed using a finite element computer model for simulation of solute movements in the inner ear fluids. The experimental results were consistent with the aspirated fluid sample from the cochlea being replaced by CSF drawn into the perilymphatic space through the cochlear aqueduct. The dependence of perilymph sample purity on the location of sampling and on the volume withdrawn was quantified. These relationships are of value in the design and interpretation of experiments that utilize perilymph sampling.

Animals↗
PubMed2004

Perilymphatic application of alpha-melanocyte stimulating hormone ameliorates hearing loss caused by systemic administration of cisplatin.

It has previously been demonstrated that ototoxicity induced by systemic administration of cisplatin is reduced by concomitant systemic administration of alpha-melanocyte stimulating hormone (alpha-MSH). In this study we investigated the effects of cochlear, perilymphatic application of alpha-MSH during intraperitoneal administration of cisplatin. Guinea pigs, implanted with a round-window electrode, allowing daily monitoring of the compound action potential (CAP), and also implanted with a mini-osmotic pump, pumping at a rate of 0.25 microl/h either physiological saline or alpha-MSH solution (0.02, 2, and 20 microg/ml), were treated daily with a bolus injection of cisplatin (2 mg/kg) until the electrocochleogram showed a persistent decrease in CAP amplitude (> or = 40 dB threshold shift at 8 kHz). Then, cisplatin treatment was stopped, but intracochlear perfusion of alpha-MSH or physiological saline was continued for 10 days to evaluate possible effects of alpha-MSH on the expected recovery. On day 10, the animals were killed and the cochleas were fixed and processed for histological analysis. All groups required 6-7 days of cisplatin to reach the criterion CAP threshold shift. Ten days after cessation of the cisplatin treatment, recovery of the CAP was observed in all groups and at all frequencies, although it was more pronounced at the lower frequencies. With respect to recovery, small statistically significant differences were found between the saline and the alpha-MSH co-treated groups. Histological results showed significantly less outer hair cell (OHC) loss in the group co-treated with 2 microg/ml alpha-MSH as compared to the group co-treated with saline. Since alpha-MSH was directly delivered to the cochlea, the ameliorating effect of alpha-MSH on OHC survival is likely to involve a cochlear target.

Action Potentials↗
PubMed1995

Experimental observation of particulate flow along cranial nerves.

The purpose of this study was to investigate the communicative routes via the cranial nerves among the middle ear, the auditory tube, the inner ear, and the subarachnoid space under nearly physiological conditions. Various volumes of Indian ink were slowly injected into the facial nerve trunk of rabbits at the stylomastoid foramen, then serial sections of the heads were observed under the light microscope. This study yielded the following results: (i) Indian ink penetrated into the subarachnoid space through the internal auditory canal and/or the jugular foramen along the nerve sheaths of the VIIth, IXth, and/or Xth cranial nerves. (ii) Indian ink penetrated through the nerve sheaths of the cochlear, superior vestibular, and inferior vestibular nerves to the fundus of the internal auditory canal. (iii) Indian ink reached the scala tympani and the scala vestibuli via the cochlear aqueduct. (iv) Indian ink penetrated to the nerve sheaths of the tensor tympani and/or tensor palati nerves from the subarachnoid space of the trigeminal ganglion. In conclusion, it was shown that certain small particles are able to penetrate from the facial nerve sheath at the entrance of the stylomastoid foramen to the VIIIth, IXth, and Xth nerve trunks, the middle ear, the area around the auditory tube, the inner ear, and the subarachnoid space.

Animals↗
PubMed1990

Temporal bone findings in two cases of head injury.

Temporal bone findings in two cases of head injury are reported. In one patient, longitudinal fractures occurred in both temporal bones, and extended to the middle ear bilaterally. Bleeding was seen in the tympanic cavity, mastoid air cells, internal auditory meatus and facial nerve canal. Bleeding was observed in the scala tympani, cochlear aqueduct and endolymphatic sac, but there were no fractures. In the other patient, bleeding was seen in the internal auditory meatus and facial nerve canal. In the right ear, endolymphatic hydrops was observed in all turns of the cochlea.

Adult↗
PubMed2001

[Magnetic resonance tomography imaging of the inner ear of patients with sensorineural hearing loss or vertigo].

BACKGROUND: Progress in surgical techniques in the temporal bone has lead to the demand of exact delineation of this complex anatomical region for preoperative planning. The aim of this study was to assess the potential of a three-dimensional T2 weighted turbo-spin-echo-sequence to depict anatomical details and pathological changes of the inner ear. METHODS: Twenty-five patients presenting with sensori-neural hearing loss and/or vertigo were included in this study. A T2 weighted turbo-spin-echo-sequence was carried out on a 1.5 T imager, employing a surface coil with a diameter of 8 cm. The scan parameters were set as follows: TR 2000, TE 500, scan matrix 128 x 128, field of view 90 mm, slice thickness 0.66 mm, NSA 4. In addition, 3D maximum-intensity-projections (MIP) were created, using these data as source images. RESULTS: Image quality was excellent in all 25 cases. The 2.5 cochlear windings, modiolus, vestibule with saccule and utricle all three semicircular canals, crus commune and the facial nerve and vestibulocochlear nerve in the inner auditory canal were clearly delineated in all patients. The cochlear aqueduct was seen in 32% (8 cases), while the vestibular aqueduct was delineated in 16% (4 cases) in this series. In MIP, the entire labyrinth was shown in a single view. In 22 patients regular morphology was found, while in three cases pathological changes were detected (an enlarged vestibular aqueduct and saccus in one patient, partial fibrous obliteration of the labyrinth in two patients). CONCLUSIONS: The introduced TSE sequence can be used to delineate the anatomy of the inner ear as well as pathological changes. The technique appears to be useful for preoperative planning.

Adolescent↗
PubMed1993

[Effect of myelography on the curve of the auditory evoked early brain stem potentials].

In 50 patients auditory threshold and brain stem evoked potential studies were carried out before and after myelography. Due to the analysis of amplitudes and latencies of auditory brain stem measurements, significant functional disorders of the hearing organ and the auditory pathway could be demonstrated. In most of the patients these functional disorders were found to be subclinical, whereas 12 patients showed alterations extending from a subjectively slight hearing loss to an audiometrically objectified acute hearing loss depending on its intensity in each case. The reasons of these functional disorders could not be clarified. An open cochlear aqueduct through which perilymph enters the subarachnoidal space leading to a secondary endolymphatic hydrops can be considered as the cause in cases where manifest symptoms develop. The changes in brain stem audiometry can be additionally explained by changes in osmolality of the inner ear fluids which may lead to the development of an endolymphatic hydrops.

Auditory Pathways↗
PubMed2001

Unpredictable hearing loss after intratympanic gentamicin treatment for vertigo. A new theory.

A new hypothesis is advanced suggesting that unpredictable cases of profound hearing loss after intratympanic gentamicin treatment (IGT) may be caused by decreased patency of the communication routes between the inner ear and the cerebrospinal fluid, primarily of the cochlear aqueduct. A tympanic displacement analyzer, which can indirectly analyze inner ear and intracranial pressure changes and can also evaluate the efficiency of communication between these two compartments, was used. Two cases are presented: in the first, a patient who became deaf after IGT showed signs of decreased patency of the communication routes with the tympanic membrane displacement (TMD) test; in the second, a patient without hearing damage after IGT had efficient communication evaluated by the TMD test. These preliminary findings are in accordance with the proposed pathophysiology. If future clinical studies confirm the present theory and findings, it may prove possible to predict and prevent deafness after IGT and possibly also after systemic aminoglycoside treatment.

Adult↗
PubMed1992

The perilymphatic hypertension syndrome.

Perilymphatic hypertension is usually related to gushers which occur in the operating room when the stapes footplate is punctured or removed. These patients present defects in the modiolus, or enlarged cochlear aqueducts, which allow easy access of spinal fluid to the perilymphatic space. This syndrome was detected in children and appears to present consistent audiological patterns. They present a mixed hearing loss and in spite of the presence of an air-bone gap the stapedial reflexes are present. These children benefit from the use of hearing aids but show very little insertion gain in the low frequencies when tested with real-ear measurements.

Cerebrospinal Fluid Pressure↗
PubMed2001

Hearing loss after surgery of ruptured cerebral aneurysm.

Only a few cases have been reported of hearing impairment after various procedures that result in loss of cerebrospinal fluid (CSF). We experienced eight cases of hearing loss following surgery for ruptured cerebral aneurysm. Angiography revealed that the aneurysm was located at the middle cerebral artery bifurcation in two cases, anterior communicating artery in four cases, posterior communicating artery in one case, and superior hypophyseal artery in one case. All of them were relatively far from the hearing structures. The aneurysm was clipped easily after drainage of CSF for slack brain. Pure-tone audiometry revealed unilateral or bilateral hearing loss that not only affected the low, but all frequencies. Completely normalized hearing was found in five patients at 3-6 months follow-up, whereas two cases noticed a partial loss and one made no recovery. We speculate that the explanation of hearing loss following aneurysm surgery results directly from diminished CSF pressure by the loss of CSF during operation. This decrease is transmitted to the perilymph via a patent cochlear aqueduct (CA) producing the release of perilymphatic fluid in the subarachnoid space. It is possible that a haemolabyrinth caused by an inflow of subarachnoid haemorrhage through CA could be an additional factor in the induced impaired hearing.

Aged↗
PubMed2002

Intraoperative assessment of perilymphatic fistulas with intrathecal administration of fluorescein.

OBJECTIVES: Assessment of perilymphatic fistulas remains a diagnostic problem. Because of a lack of reliable clinical tests, exploratory tympanotomy is necessary to detect membrane leaks in the middle ear. To improve objectivity in the intraoperative visualization of perilymphatic fistulas, we used intrathecal fluorescein for perilymph staining to increase the sensitivity and specificity of diagnosis of perilymphatic fistulas. STUDY DESIGN: Prospective study in the setting of a tertiary, referral, and academic center. METHODS: Twenty-eight patients with suspected traumatic, idiopathic, iatrogenic, or inflammatory perilymphatic fistulas were admitted for exploratory tympanoendoscopy for perilymphatic fistula detection. Twenty-five to 100 mg sodium fluorescein 10%, diluted with cerebrospinal fluid, was administered by lumbar puncture 2.5 to 23.5 hours before tympanoendoscopy. The oval and round window niches were microscopically and endoscopically observed with white and blue light, using specific filters. RESULTS: In two patients (7%), obvious fluorescence was detected behind the round window membrane with blue light. Direct observation of perilymph in stapedectomy and in semicircular canal fistula revealed no staining. Neurological complications of intrathecal fluorescein, as reported by other authors, were not observed. CONCLUSIONS: Probably because of a different patency of the cochlear aqueduct, intrathecal fluorescein for intraoperative detection of perilymphatic fistula resulted in a significant perilymph staining in only a few patients. Considering the possible complications of this method, we would not recommend it for routine evaluation of perilymphatic fistula.

Adult↗
PubMed2004

Location and timing of initial osteoid deposition in postmeningitic labyrinthitis ossificans determined by multiple fluorescent labels.

OBJECTIVES/HYPOTHESIS: Variable amounts of fibrosis and neo-ossification fill the cochlea following bacterial meningitis. The purpose of the study was to delineate the timing and location of initial ossification following pneumococcal meningitis, as well as subsequent remodeling and resorption, over the 3-month period after infection. STUDY DESIGN: Randomized, double-blind study. METHODS: Fluorochromes are compounds that specifically incorporate into ossifying bone. Sequential addition of different colored fluorochromes during osteoneogenesis define the timing and location of osteoid deposition and mineralization. Mongolian gerbils were infected by intrathecal injection of Streptococcus pneumoniae type 3, and control gerbils received saline. Both groups were injected with calcein on postoperative day 3, followed by xylenol orange, oxytetracycline, and alizarin red on days 7, 14, and 28 respectively. Ten experimental gerbils were killed 24 hours after each label, and an additional group at 84 days after infection. Two groups of 10 control gerbils were killed at 29 and 84 days after treatment. The temporal bones and tibias were harvested, embedded in plastic, and sliced with a diamond saw. Wafers at a thickness of 200 microm were mounted in sequence and examined. RESULTS: Sixteen of 49 experimental animals (33%) were positive for at least one of the fluorescent labels. Fluorescent labeled osteoid was present at all sampling times. Label extended from the endosteal wall into the lumen of the scala tympani between the vestibule and the round window membrane. Discrete sites of fluorescence varied among specimens and were associated with the opening of the cochlear aqueduct, the scala tympani, organ of Corti, and the stria vascularis and spiral ligament in all turns from base to apex. CONCLUSION: The results indicate that osteoid is deposited and begins mineralization by day 3 after infection, at least, and continues, at least, through the first 28 days after infection. There was no apparent resorption of new bone and remodeling by 84 days after infection.

Animals↗
PubMed2005

Disequilibrium after cochlear implantation caused by a perilymph fistula.

OBJECTIVES: Cochlear implantation has become a safe and effective method for the auditory rehabilitation of the profoundly hearing impaired. Incidence of disequilibrium and vertigo after cochlear implantation ranges from 13% to 74% in the literature. Most patients report resolution of these symptoms with medical therapy and vestibular rehabilitation. We present a case of persistent disequilibrium after cochlear implantation. Further workup of this patient revealed radiographic findings suggestive of a perilymphatic fistula, with immediate and complete resolution of symptoms after exploratory tympanotomy and packing around the cochleostomy. STUDY DESIGN: Case report. METHODS: A retrospective chart review of a patient with postoperative disequilibrium unresponsive to maximal medical and vestibular rehabilitation therapy. RESULTS: Diagnostic workup of the patient included a temporal bone computed tomography (CT) scan, which revealed air in the vestibule and the ampulla of the superior and lateral semicircular canals. After failure of 5 months of conservative therapy, the patient was taken to the operating room for middle ear exploration and repacking of the cochleostomy site. The patient reported immediate and complete resolution of vertigo postoperatively. CONCLUSION: We present a case of disequilibrium as a result of an apparent perilymphatic fistula after cochlear implantation that was refractory to standard therapy. In such cases, appropriate workup should include a temporal bone CT scan to look for air in the vestibule or other abnormalities that may indicate potential etiology. Surprisingly, this patient had immediate and complete resolution of symptoms after surgery. If conservative therapy fails, middle ear exploration by way of an exploratory tympanotomy and packing of the cochleostomy with periosteum and muscle is a viable option and may lead to resolution of symptoms.

Adult↗