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PubMed1997

Fine structure of extracellular matrix and basal laminae in two types of abnormal collagen production: L-proline analog-treated otocyst cultures and disproportionate micromelia (Dmm/Dmm) mutants.

L-Azetidine-2-carboxylic acid (LACA), a naturally occurring vegetable imino acid, can be incorporated into mammalian proteins in place of proline, thereby eliciting an inhibitory effect on collagen secretion. Exposure of explants of the embryonic mouse inner ear to LACA reduces the number of collagen fibrils in the otic capsule, gives rise to a dose-dependent derangement of the basal lamina, and ultimately results in dysmorphogenesis and retarded differentiation of the inner ear. Disproportionate micromelia (Dmm) is an incomplete dominant form of dwarfism characterized by a reduced quantity of type II collagen in the cartilaginous extracellular matrix (ECM). Abnormal morphogenesis in homozygotic Dmm mice resembles the abnormal morphogenesis observed in LACA-exposed otic explants, resulting in malformed inner ears with a bulky cartilaginous capsule and a lack or reduction of defined perilymphatic spaces (Van De Water and Galinovic-Schwartz, 1987). In this study, we examined by ultrastructural analysis LACA-exposed otic explants and inner ears of Dmm/Dmm mouse embryos for abnormalities in the collagenous constituents of the basal laminae and capsular ECM. We demonstrate, in comparison to normal embryonic mouse inner ears, a reduction in collagen fibrils and irregular cytodifferentiation of chondrocytes in the ECM of LACA-exposed and Dmm/Dmm inner ears as well as in the basal laminae of LACA-exposed specimens. In addition, we provide evidence of dysmorphogenesis of the otic capsule and perilymphatic spaces in LACA-exposed explants. Moreover, while previous studies demonstrated the anomalous development of sensory structures in otocyst explants following LACA exposure, in this study we provide evidence of the normal morphogenesis of otic epithelial-derived sensory structures in homozygotic Dmm/Dmm mouse embryos.

Animals↗
PubMed2000

Perinatal toxicology of Ruta chalepensis (Rutaceae) in mice.

Dried leaf infusions of Ruta chalepensis L. (Rutaceae), 'rue', 'ruda', were found to cause perinatal changes in mice, at daily doses of 0.16, 0.80 and 1.60 g/kg, administered p.o. from 1 to 14 days post coitum. Significant decreases in the appearance time of physical signs, righting reflex and cliff avoidance together with minus scores in string test and swimming ability were observed. Moreover, histological studies showed progressive angiogenic development on placenta blood supply and weakness at blood barrier in brain, thymus and pery-lymph vestibule. We found out that the results tend to confirm the embryotoxic effect of the plant and its harmful use.

Animals↗
PubMed1995

[Pressure relations between endocranial and intracochlear fluid spaces in patients with inner ear diseases].

Intracranial pressure is transmitted to the perilymph of the cochlea via the cochlear aquaeduct and via Reissner's membrane to the endolymph. The "Tympanic Membrane Displacement Analyser (TDA)" is a new device that may be a useful non-invasive method to show intracranial and intracochlear pressure changes indirectly measured by tympanic membrane displacement during stapedial reflex contraction. The TDA was utilised in 20 normal persons and in 29 patients with unilateral diseases of the inner ear. No significant differences in the tympanic membrane displacement were found between patients with sensorineural hearing loss, patients with Ménière's disease, and normal persons.

Adolescent↗
PubMed1995

[Noninvasive assessment of intracochlear pressure. III. Case reports of patients with intracochlear hyper- and hypotension].

It was the scope of two previous papers to outline the basics and possible neurotological applications of the tympanic membrane displacement technique (TMD). The present paper is aimed at briefly reviewing five distinct cases where a sudden sensorineural hearing loss with/without tinnitus could be monitored by the TMD technique. These features include a sudden hearing loss upon lumbar puncture, the audiological manifestation of an internal hydrocephalus, stapes gusher and the round window rupture. All symptoms are based on a change in intracranial and intracochlear pressure which in turn leads to the manifestation of the previously unknown sensorineural hearing loss and/or tinnitus.

Adult↗
PubMed2004

Effect of acute inner ear pressure changes on low-level distortion product otoacoustic emissions in the guinea pig.

OBJECTIVE: To determine a relation between acute inner ear pressure changes and cochlear function as measured by low-level 2f(1)-f(2) distortion product otoacoustic emissions (DPOAEs). MATERIAL AND METHODS: During and after a change in inner ear pressure induced by injection or aspiration of perilymph, the 2f(1)-f(2) DPOAE at 4.5 kHz generated by low-level primaries was recorded in the guinea pig. RESULTS: Large changes in overall inner ear pressure produced only small changes in the 2f(1)-f(2) amplitude and phase. During injection of 0.5 microl of artificial perilymph into the scala tympani over a 10-s period, the mean inner ear pressure increased by approximately 500 Pa, with an accompanying mean increase in the 2f(1)-f(2) amplitude of 0.7 dB. During aspiration of 0.5 microl of perilymph over a 10-s period, the mean inner ear pressure decreased by approximately 700 Pa, with an accompanying mean decrease in the 2f(1)-f(2) amplitude of 0.9 dB. Changes in DPOAE amplitude followed inner ear pressure changes with a delay of 1-2 s. The magnitude and sign of the amplitude changes can (partly) be explained by a change in oval window stiffness. No explanation was found for the measured delay. CONCLUSION: Clinically, these experiments can be of value in gaining insight into the pathophysiological mechanisms of pathological pressure changes as seen in Meniere's disease and perilymphatic fistulae.

Animals↗
PubMed1984

History taking in dizziness. The most important diagnostic step.

When faced with a complaint of dizziness, the primary care physician may be tempted to assume that the cause is inner ear dysfunction and that the patient needs to be referred to an otologist. According to Dr Hybels, however, most dizzy patients do not have an ear problem and a carefully executed history is likely to pinpoint the correct diagnosis. The following article delineates the fine points of history taking and discusses some of the most common causes of dizziness.

Aging↗
PubMed1986

The dizzy child.

Dizziness in childhood may be the result of significant vestibular or central nervous system pathology. It is the responsibility of otolaryngologists and neurologists to provide appropriate diagnosis and treatment of these disorders.

Child↗
PubMed1993

Spontaneous perilymphatic fistula: myth or fact.

Controversy exists surrounding the diagnosis of spontaneous perilymphatic fistula. In an effort to help resolve this controversy the author conducted a review of the literature as well as a review of 212 of his patients who underwent surgical exploration for suspected perilymphatic fistula. Interpretation of the literature reviewed was hampered by the lack of a uniformly accepted definition for the word spontaneous. Dorland's Medical Dictionary defines spontaneous as that which occurs without external influence. Webster's Dictionary, on the other hand, provides a much more confining definition of the word by stating that a spontaneous event is one that occurs or is produced by its own energy. Only 58 percent of the author's 212 patients had an antecedent history of an external event that may have precipitated the suspected perilymphatic fistula (trauma, flying, diving) while almost 41 percent recalled an antecedent event of internal origin (lifting, straining, sneezing, nose blowing). If one were to support the definition of spontaneous provided by Dorland's Medical Dictionary, then the 41 percent of patients who had no antecedent history of external event would have to be considered as having spontaneous perilymphatic fistula. If, on the other hand, one were to endorse the definition of spontaneous provided by Webster's then less than 2 percent of the author's patients would have to be considered as having spontaneous perilymphatic fistula.

Adolescent↗
PubMed2001

Endoscope-guided round window fistula repair.

OBJECTIVE: Endoscope-guided round window membrane repair was performed to evaluate whether the approach is feasible in the treatment of a round window fistula. STUDY DESIGN: Retrospective case review. SETTING: Tertiary care academic center. PATIENT: A 27-year-old man had been scuba diving 6 days previously in the Australian Great Barrier Reefs. He had poor hearing with tinnitus in the left ear and a vertiginous sensation. INTERVENTION: A myringotomy was incised, and a tympanoscope was introduced into the middle ear cavity. With the patient under general anesthesia, the middle ear and the oval and round window areas were examined with a tympanoscope. In endoscopic visualization, a round perforation could be seen in the round window membrane. After detection of the round window perforation, a small piece of temporal fascia was obtained to seal the membrane perforation. RESULTS: One month after the operation, the patient's hearing was significantly better. The myringotomy had healed. CONCLUSION: A transmyringeal endoscopic procedure for round window fistula repair is feasible and combines the best features of minimally invasive surgery and aural endoscopy.

Adult↗
PubMed2002

Causes of conductive hearing loss after stapedectomy or stapedotomy: a prospective study of 279 consecutive surgical revisions.

OBJECTIVE: To analyze the causes for residual or recurrent conductive hearing loss following stapedectomy or stapedotomy and then propose surgical techniques to avoid these complications. STUDY DESIGN: Prospective study of 279 consecutive stapedectomy or stapedotomy revisions performed by the author. SETTING: Tertiary referral center. PATIENTS: The study included 260 patients who presented with a 20 dB or greater average air-bone gap in the speech frequencies 1 month to 35 years following stapedectomy or stapedotomy (19 patients were explored for possible oval window perilymph fistula). INTERVENTION: Stapedectomy (stapedotomy) surgical revision. MAIN OUTCOME MEASURES: Microscopic inspection and palpation assessed the mobility and continuity of the malleus, incus, and prosthesis. Infrared laser vaporization thinned the oval window neomembrane to identify the precise depth and margins of the oval window, the presence of residual stapes footplate, and finally, the relationship of the prosthesis to the fenestra into the vestibule. RESULTS: Prosthesis displacement out of the oval window fenestration with fixation of the prosthesis against the residual stapes footplate or otic capsule margin was demonstrated in 81% (211/260) of the patients. Of these patients, 31% had complete incus erosion, and an additional 60% demonstrated partial incus erosion, usually on the undersurface of the incus. Residual fixed stapes footplate was found in 14%, and malleus fixation in 4%. Incus dislocation was found in 4%, and incus fixation in 2%. CONCLUSIONS: Prosthesis migration and subsequent fixation caused the majority of stapedectomy failures. Collagen contracture of the oval window neomembrane lifts the prosthesis out of the oval window fenestration. Prosthesis displacement then results from adhesions pulling the prosthesis or mechanical forces further tilting the prosthesis. Incus erosion results from vibration against the fixed prosthesis. Six specific stapedotomy recommendations are made to minimize postoperative prosthesis migration.

Adolescent↗
PubMed2006

Recurrent diving-related inner ear barotrauma.

OBJECTIVE: To present two cases of recurrent diving-related inner ear barotrauma (IEB) and to discuss the possible cause and pathogenesis of the increased inner ear vulnerability. STUDY DESIGN: Case series. SETTING: Tertiary referral center. PATIENTS: Two scuba divers suffering from repeated cochleovestibular barotrauma. INTERVENTIONS: Neurotological evaluation, perilymphatic fistulae repair, and conservative treatment. MAIN OUTCOME MEASURE: The increasing popularity of scuba diving expose the individuals involved in this sport to unique pathologies that are not common under terrestrial conditions. The otolaryngologist who is involved in the care of these patients is required to diagnose and treat diving-related ear injuries and to consider the risk for recurrent inner ear injury when diving is resumed. CONCLUSION: IEB carries a risk for permanent hearing loss and chronic vestibulopathy. We recommend complete neurotological evaluation including high-resolution CT of the temporal bones as a routine workup for IEB. The presence of a significant residual sensorineural hearing loss, evidence for noncompensated vestibular damage, and CT findings of possible enhanced cerebrospinal fluid-perilymph connection should be considered when a return to diving activity is considered.

Adult↗
PubMed2005

Persistence of perilymph fistula mechanism in a completely paretic posterior semicircular canal.

The three dimensional eye movements (search coil technique) of a patient with a completely paretic left posterior semicircular canal as a result of a perilymph fistula (PLF) were studied. The patient still exhibited pressure induced nystagmus that obeyed Ewald's first law. This finding cannot be explained by otolith stimulation, but might indicate that PLF mechanisms either persist in canal plugging or act on the ampulla by directly deflecting the cupula.

Adult↗
PubMed1983

Response of cat semicircular canal afferents to sinusoidal polarizing currents: implications for input-output properties of second-order neurons.

1. We studied the response of cat vestibular afferents, most likely innervating the semicircular canals, to sinusoidal polarizing currents applied to an electrode implanted near the horizontal ampulla. 2. Electrode implantation abolished responses to natural stimulation and reduced the level of resting activity compared to a population of afferents from unimplanted animals. The distribution of coefficients of variation of resting activity was, however, similar to that seen when the labyrinth is intact. 3. Many fibers were modulated sinusoidally by polarizing currents in the frequency range 0.175-4 Hz. Phase was mainly constant and typically led stimulus negativity by approximately 14 degrees, although about half the regular fibers had a phase lead that increased with frequency. Mean sensitivity (spikes X s-1 X microA-1) of regular and irregular fibers increased by a factor of about 1.5 over the frequency studied. Absolute sensitivity was about 7 times higher for irregular than for regular fibers. The overall behavior of the afferents could be well described by a transfer function in the form, sk, with 0 less than k less than 1. 4. We compared the response of afferent fibers to sinusoidal current with the response of second-order neurons studied under similar conditions in earlier experiments (15, 23). While the slopes of the sensitivities were similar, second-order neurons developed a phase advance over afferents at frequencies around 1 Hz. This difference in dynamics can be described by a transfer function in the form tau S + 1, with tau = 12 ms. This predicts that second-order neurons can develop a phase lead of about 25 degrees with respect to afferents at 6 Hz, a frequency still in the physiological range. It remains to be determined whether this applies to a particular subset of second-order neurons contributing to vestibulocollic reflexes.

Afferent Pathways↗