摘要:

The audiograms of some patients suffering from Meniere's disease show an unexplained conductive component, or air-bone gap (ABC), predominantly in the low frequencies. Neither the history nor physical findings support poor eustachian tube function, ossicular chain abnormalities, chronic ear disease, physical trauma, or otosclerosis as a cause of this audiometric finding. In the present study, 40 patients diagnosed as suffering from classical Meniere's disease were evaluated audiometri-cally. Thirteen (32.5%) of these patients demonstrated a low frequency ABC. An otologic evaluation was performed on each patient who exhibited the abnormal finding, but no middle ear pathology was discovered. An otherwise unexplained low frequency ABC in patients with Meniere's disease suggests the possibility of an “inner ear” conductive hearing loss. This conductive component may result from endolymphatic hydrops or perilymphatic hypertension (i.e., an inner ear hyperpressure exerted against the medial surface of the stapedial footplate) rather than from middle ear pathology. “Inner ear” conductive hearing loss is thought to be caused by an increase in inner ear fluid volume (endolymphatic hydrops) and pressure (endolymphatic or perilymphatic hypertension), which dampens footplate mobility medially and which is directly related to a relative inner ear or labyrinthine hyperpressure. Since the footplate mobility is only dampened and not fixed, a stapedial reflex may still be elicited.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

In five cases of labyrinthine fistulae caused by extensive cholesteatoma, more than 30-dB improvement in bone conduction was observed in four postoperative cases and in one case after preoperative administration of antibiotics. In each case, a fistula of more than 2 mm in length was present at the lateral semicircular canal, and membranous labyrinthine wall was exposed when the cholesteatoma membrane was removed. These five cases were considered to be in the stage of serous labyrinthitis. The experience with these cases shows that emergent antibiotic treatment and surgery are appropriate for cases with reduced bone conduction in which labyrinthine fistula caused by cholesteatoma is suspected. In addition, as the reduction of bone conduction does not necessarily preclude the possibility of good postoperative hearing, tympanoplasty may be appropriate even for cases with markedly reduced bone conduction due to labyrinthine fistulae.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

The possible role of vitamin D in hearing impairment was investigated by the measurement of three metabolites of vitamin D in 28 patients with bilateral sensorineural hearing loss (BSNHL). Twenty-three of 28 patients showed a significantly decreased level of 1,25-dihydroxyvitamin D3, with a normal value of 25-hydroxy-vitamin D3. In addition to experimental and clinical reports regarding vitamin D deficiency, the present study suggests that vitamin D deficiency is one of the etiologies of BSNHL, through the calcium metabolism and microcirculation in the cochlea.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Electrical testing of the facial nerve has evolved into an important means of assessing neural injury. However, the inability to stimulate the intratemporal facial nerve electrically results in a delay in diagnosis, because axonal degeneration must progress distal to the stylomastoid foramen before testing can be meaningful. To circumvent this problem, we began an investigation of magnetic stimulation of the facial nerve, because pulsed magnetic fields can pass unattenuated through all body structures, including bone. Normal volunteers and one patient with acute facial paralysis were studied with both magnetic and electric stimulation of the facial nerve. The results indicate that (1) magnetic stimulation was more comfortable because high current levels were not required atthe skin surface to assure indepth stimulation, (2) magnetic and electric stimulation of the extratemporal facial nerve resulted in nearly identical compound muscle action potentials, indicating that the sites and mechanisms of neural depolarization are similar, and (3) transtemporal magnetic stimulation appears to allow depolarization of the proximal intratemporal nerve. These preliminary results are encouraging and indicate that magnetic stimulation of the facial nerve warrants further investigation.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

The effect of sodium fluoride treatment in patients with otospongiosis has been evaluated in a prospective clinical double-blind, placebo-controlled study of 95 patients. The results showed a statistically significant greater deterioration of hearing loss in the placebo group than in the group actively treated with 40 mg of sodium fluoride daily. These results support the view that sodium fluoride can change otospongiotic, active lesions to more dense, inactive otosclerotic lesions.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

The middle components of the auditory evoked response (middle latency response, MLR) were evoked by acoustic clicks from the normal-hearing ear and by charge-balanced biphasic current pulses from the severe-to-profoundly hearing-impaired ears of patients undergoing labyrinthectomy for the management of intractable vertigo. A vertex-positive peak with a latency ranging from 27 msec to 38 msec (Pa) was characteristic of both the electric and the acoustic MLR. In subjects, the electric Pa always preceded the acoustic Pa in latency. In addition, the electric Pa had a sharper appearance than did the acoustic Pa. The electric MLRs were elicited by a range of stimulus intensities and persisted after the completion of labyrinthectomy.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Molecular and cellular biology is the study of cellular ultrastructure and function. Current research in immune regulation, delineation of receptor control function (signal translation at the cellular level), and nucleic acid manipulation (genetic engineering) illustrates fundamental relationships among biochemistry, immunology, and molecular and cellular biology. Our knowledge already includes significant discoveries in membrane permeability, ionic gradients, and mediators of homeostasis. To these are added newer discoveries in bone metabolism, vascular anatomy and physiology, trace element deficiency, and the broader field of nutrition. Biochemical research gradually is unlocking the mysteries of otosclerosis, Paget's disease, endolymphatic hydrops, ototoxicity, acoustic trauma, presbycusis, and other forms of sensorineural hearing loss. This paper presents some of the research topics of current interest. Relationships of molecular and cellular biology, immunology, and nutrition are discussed. Molecular and cellular biology of the inner ear is an exciting “new” frontier.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

In magnesium (Mg)-deficient rats and guinea pigs, noise-induced hearing loss (NIHL) was found to be correlated to the decrease of Mg in serum and perilymph. Also, in noise-exposed humans, NIHL increased with decreasing serum Mg. During the process of mechanoelectrical transduction within the hair cells in the inner ear, membrane permeability of K+and Ca2+will transiently increase. Mg deficiency may additionally increase membrane permeability and, therefore, energy-dependent K+and Ca2+turnover. The increased release of catecholamines in Mg deficiency may affect the hair cells, either directly by increasing the intracellular concentration of free Ca2+and/or indirectly by reducing the blood flow. Also, thromboxane A2, which is increased in Mg deficiency, may reduce the blood flow in the inner ear. By these mechanisms, Mg deficiency may cause energy depletion and irreversible damage to the hair cells.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

A series of Swedish studies has shown that the application of middle ear overpressure may be effective in ameliorating the symptoms associated with Meniere's disease. Other studies have shown that electrocochleography (ECochG) is an effective tool in the identification of Meniere's disease, especially in the presence of active symptoms. Based on the therapeutic potential of middle ear overpressure as a treatment for Meniere's symptoms and on the relationship between these symptoms and ECochG, we investigated the effects of ear canal pressure change on human electrocochleographic components in normally hearing subjects. An experimental system combining an immittance audiometer probe and ear canal electrode was utilized to record extratympanic ECochG when different atmospheric pressures were applied indirectly to the middle ear via the sealed ear canal. All ECochG parameters except for the duration of the whole nerve action potential (AP) of the auditory nerve were significantly affected by pressure changes in the ear canal. Effects included an enlargement of the summating potential (SP) amplitude and of the SP:AP amplitude ratio at pressures above and below 0 decaPa (daPa). An important implication of our findings is that the status of the middle ear must be taken into account in the interpretation of ECochG results.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Forty-eight patients with facial nerve neuromas were treated at the Otologic Medical Group Inc. between 1974 and 1985. The most common presenting symptoms were hearing loss and tinnitus. Facial paralysis occurred in 22 patients (46%). A mass behind the tympanic membrane was seen on otoscopy in 14 patients (29%). These tumors typically involved more than one segment of the nerve and eroded otic capsule bone in 14 patients (29%). High resolution computed tomography (CT) was highly accurate in determining the extent and location of these tumors. Restoration of the continuity of the nerve was undertaken at the time of tumor removal. The major determinant of the ultimate status of facial nerve function was the duration of preoperative paralysis.

ISSN:0192-9763    

出版商:OVID    

年代:1989

数据来源: OVID