Jacob Ben-David

Drug-induced tinnitus and other hearing disorders.

SummaryTinnitus and hearing loss, both reversible and irreversible, are associated both with acute intoxication and long term administration of a large range of drugs. The mechanism causing drug-induced ototoxicity is unclear, but may involve biochemical and consequent electrophysiological changes in the inner ear and eighth cranial nerve impulse transmission. Over 130 drugs and chemicals have been reported to be potentially ototoxic. The major classes are the aminoglycosides and other antimicrobials, anti-inflammatory agents, diuretics, antimalarial drugs, antineoplastic agents and some topically administered agents.Prevention of drug-induced ototoxicity is generally based upon consideration and avoidance of appropriate risk factors, as well as on monitoring of renal function, serum drug concentrations, and cochlear and auditory functions before and during drug therapy. Ototoxicity, although not life-threatening, may cause considerable discomfort to patients taking ototoxic drugs, and in some cases drug discontinuation may be necessary to prevent permanent damage.Much research has been performed to investigate the causes and mechanisms of ototoxicity, to try to prevent this complication. Despite these efforts, ototoxicity still occurs, and there is much work to be done in order to understand the mechanism of ototoxicity of different drugs and to prevent hearing loss and tinnitus in the future.

Mal de Debarquement and Posture: Reduced Reliance on Vestibular and Visual Cues

Objective The neural mismatch theory assumes that the intersensory conflicts leading to motion sickness are resolved by changes in the relative weighting of the various senses that contribute to orientation. If this sensory rearrangement persists after disembarkment, it might result in mal de debarquement (MD): ataxia and a rocking sensation sometimes felt after landing. The objective of the present study was to examine possible changes in sensory organization in naval crew members with differing susceptibility to MD with computerized dynamic posturography (CDP).

ENDOTHELIAL INJURY OF CAPILLARIES IN THE STRIA VASCULARIS OF GUINEA PIGS TREATED WITH CISPLATIN AND GENTAMICIN

The drugs cisplatin and gentamicin are used for treatment of various cancer patients suffering from infection. The authors report a detailed electron microscopic study of blood vessels in stria vascularis of guinea pigs after treatment with cisplatin alone and in combination with gentamicin. The most distinctive features expressing endothelial cellular injury were mitochondrial, including occasional paracrystalline inclusions; electron-lucent foci with depleted organelles; intracytoplasmic vacuole formations; lipid bodies; cytoplasmic extrusions located on the luminal surface; and severe luminal constriction of part of the vessels from animals treated with the combined drugs. The study suggests that the damage to strial capillaries due to treatment with cisplatin alone and in combination with gentamicin may contribute to the injurious effects of these drugs on the strial tissue. Furthermore, the results of this study may enlarge the awareness of the potential vascular damage and vascular complications in additional body systems after medical use of cisplatin alone or in combination with gentamicin.

Computerized Dynamic Posturography and Seasickness Susceptibility

Objective/Hypothesis: The neural mismatch theory emphasizes the role of conflicting multimodal sensory interactions in producing both motion sickness and the rearrangement process that finally leads to habituation to the adverse motion conditions. If this theory is, indeed, correct, the patterns of the response to the integrated signal from simultaneous multisensory stimulation, characterized by unusual relationships between the senses responsible for spatial orientation, should differ according to motion sickness susceptibility. Computerized dynamic posturography (CDP) provides the opportunity to simultaneously change the interactions between visual, somatosensory, and vestibular inputs, thus giving an indication of the relative importance of these senses in maintaining balance. The objective was to investigate balance strategies in naval crew members with differing susceptibility to sea conditions using CDP.

Vestibular Findings Associated with Chronic Noise Induced Hearing Impairment

Histological and functional derangements of the vestibular system have been reported in laboratory animals exposed to high levels of noise. However, clinical series describe contradictory results with regard to vestibular disturbances in industrial workers and military personnel suffering from noise induced hearing loss (NIHL). The purpose of the present study was to evaluate vestibular function in a group of subjects with documented NIHL, employing electronystagmography (ENG) and the smooth harmonic acceleration (SHA) test. Subjects were 22 men suffering from NIHL and 21 matched controls. Significantly lower vestibulo-ocular reflex gain (p = 0.05), and a tendency towards decreased caloric responses were found in the study group. No differences in the incidence of vertigo symptoms, spontaneous, positional and positioning nystagmus, directional preponderance and canal paresis in the ENG, or the SHA test phase and asymmetry parameters were observed between the groups. These results demonstrated a symmetrical centrally compensated decrease in the vestibular end organ response which is associated with the symmetrical hearing loss measured in the study group. Statistically significant correlations were found between the average hearing loss, the decrement in the average vestibulo-ocular reflex gain (p = 0.01), and ENG caloric lateralization (p = 0.02). These correlations might indicate a single mechanism for both cochlear and vestibular noise-induced injury. The results imply subclinical, well compensated malfunction of the vestibular system associated with NIHL.

Nephrotoxicity of Combined Treatment with Cisplatin and Gentamicin in the Guinea Pig: Glomerular Injury Findings

The drugs cisplatin and gentamicin are given consecutively to various cancer patients suffering from infections. Little information exists about the ultrastructural alterations of kidney glomeruli caused by treatment with these drugs. Renal glomeruli of guinea pigs treated with cisplatin alone and in combination with gentamicin were studied by transmission electron microscopy. The findings revealed foci of damage induced by cisplatin and especially by cisplatin/gentamicin in all glomerular components: glomerular capillaries, including their endothelial cells; basement membrane, epithelial podocytes, mesangial cells, and parietal cells of Bowmans capsule. The damage was expressed by endothelial cytoplasmic extrusions into the vascular lumen, thickening and lamination of capillary basement membrane, focal foot process fusion of podocytes, vacuolization in cytoplasm of endothelial cells of epithelial podocytes and of parietal cells, and the presence of lipid bodies and myeloid bodies in all glomerular cell types. Additionally, injurious effects to cytoplasmic organelles such as mitochondria, nuclei, and endoplasmic reticulum were observed. The results indicate that cisplatin alone and in combination with gentamicin is toxic to renal glomerular tissue. Since these drugs were previously found toxic for strial capillaries in the inner ear and since the main glomerular component is the glomerular capillaries, potential vascular damage and vascular complications in different body systems have to be taken into consideration when these drugs are needed in clinical use.

Eosinophilic granuloma of the temporal bone

Involvement of the temporal bone by eosinophilic granuloma is rare. Four cases are presented here and the pertinant literature is reviewed. This disease must be kept in mind by the otolaryngologist because of the diagnostic and therapeutic problems that may arise. Direct injection of methyl-prednisolone sodium succinate is suggested as a treatment of eosinophilic granuloma in the temporal bone.

Brainstem auditory evoked potentials with increased stimulus rate in patients suffering from systemic lupus erythematosus.

Central nervous system involvement in systemic lupus erythematosus is frequently occult, may be the presenting sign, and is a bad prognostic indicator. At present, there is no reliable, sensitive laboratory test for the evaluation and diagnosis of subclinical central nervous system involvement of the disease. Brainstem auditory evoked potentials with and without increased stimulus rate have been used to diagnose ischemic lesions in the central nervous system.

In vivo measurement of human nasal mucociliary motility using a laser light scattering instrument.

The mucociliary system is one of the most important airway defense mechanisms, and knowledge of the mucociliary wave frequency (MWF) is important in the understanding of this system. Employing a laser light scattering technique and a thin, flexible fiberoptic probe, we developed and tested a simple and practical device for real-time in vivo measurements of mucociliary activity in the human nose. The laser instrument is user-friendly and does not produce any discomfort to the patient. The mean ± SE of MWF of 36 measurements in 16 normal subjects was 7.7 ± 0.5 Hz. The mean MWF of 17 measurements in 7 patients with allergic rhinitis was 5.5 ± 0.2 Hz (p < .005), and the mean MWF of 56 measurements in 17 patients with septum deviation was 5.8 ± 0.2 Hz (p < .001). The instrument presented in this study might provide a new and convenient method of studying the mucociliary activity in the respiratory tract.

Cat-scratch disease of the parotid gland: an often-misdiagnosed entity.

A case of cat-scratch disease involving the parotid area in a young adult is presented. Thanks to meticulous history-taking, the correct diagnosis was suggested and later established, thus preventing unnecessary surgery. The pertinent literature is discussed.