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Biomedical subjects

V S Dayal

Publications and source records attributed to V S Dayal.

At least 19 recordsLinked to original sources
PubMed1998

Auditory brain stem response in young and old guinea pigs.

OBJECTIVE: To characterize age-related auditory changes in genetically similar guinea pigs. BACKGROUND: In humans and animals, changes in hearing are known to occur with age. METHODS: Brain stem-evoked responses were measured in genetically similar guinea pigs that ranged 6-36 months in age. Changes in hearing and the input/output function curve were determined. RESULTS: Threshold shift with increase in age was seen. Marked reduction in amplitude of response with increasing age was also demonstrated. No change was seen in latency or interpeak interval. CONCLUSIONS: In genetically similar guinea pigs, age-related changes in threshold occurred. Latency and interpeak intervals remained unchanged. Amplitude of response decreased substantially after 12 months of age to a greater extent than predicted by threshold shifts alone. This phenomenon appears important in understanding the pathophysiology of age-related hearing loss.

Age Factors↗
PubMed1995

Labyrinthectomy in the elderly.

This study involved elderly patients with Meniere's disease with incapacitating vertigo. Several of these patients underwent surgery for relief of symptoms that was tailored to the individual's general health and degree of physical activity. Factors that might affect postoperative rehabilitation and recovery were considered, including vision, vertebrobasilar ischemia, proprioception (such as neuropathy resulting from diabetes), and basal ganglia disease. The postoperative results of this tailored approach have been completely satisfactory.

Age Factors↗
PubMed1992

Luetic endolymphatic hydrops: diagnosis and treatment.

Luetic endolymphatic hydrops (LEH) is an effectively treatable disorder that requires astute clinical judgment to suspect, confirm, and treat. We provide a review of the literature as well as recommendations regarding the clinical management of LEH with discussion of several illustrative cases. We also give an overview of laboratory testing for the diagnosis and monitoring of the infectious process. Ultimately, the control of the otologic symptoms in LEH requires acumen on the part of the clinician.

Aged↗
PubMed1991

Potentiation of cochlear hair cell loss by acoustic stimulus and gentamicin in the guinea pig.

We explored the possibility of synergism between a pure-tone stimulus and gentamicin in causing cochlear injury by analyzing hair cell loss. Guinea pigs receiving daily injections of gentamicin (200 mg/kg body wt.) for 1 week were exposed to a 2 kHz tone (95 dB SPL, 2 hours daily). Surface preparations of the spiral organ were studied by phase contrast microscopy, and the extent of hair cell loss in the entire organ of Corti was recorded in cytocochleograms. Gentamicin by itself was slightly ototoxic, damaging the innermost row of outer hair cells, whereas exposure to sound alone caused no hair cell loss. Combined antibiotic and acoustic exposure produced extensive cochlear damage. A few animals showed massive hair cell degeneration and collapse of the organ of Corti, except in the apical turn. The site of damage was possibly determined by the frequency of the sound stimulus. Thus, an intermittent tonal stimulus such as that used in the present experiment can be harmless by itself, but causes injury to cochlear hair cells in guinea pigs when administered in combination with gentamicin.

Acoustic Stimulation↗
PubMed1990

Surgical inferences from study of temporal bones with glomus jugulare tumor.

Over the past few years, considerable advances have been made in the surgical treatment of glomus jugulare tumors. The long-term results of such surgery for cure of these tumors has yet to be established, however. We have reviewed the temporal bones of two patients who had glomus jugulare tumors. Such study provides a special opportunity to evaluate the major critical areas of involvement of these tumors, which bears on the long-term results of surgery, and is important in developing treatment to cure these benign, though aggressive, tumors.

Carotid Artery, Internal↗
PubMed1989

Influence of age on hair cell loss in the rabbit cochlea.

The surface preparation technique was used for a study of cochlear hair cell loss as a function of age in rabbits 1 week, 6 months, 1 year, and 4 years old. Cytocochleograms from these animals were prepared which indicated damaged or missing hair cells over the entire spiral organ from the apical to the basal coil. The loss in the mean percentage of total outer hair cells (OHC) and inner hair cells (IHC) appeared to increase linearly with increasing age, with a statistically significant correlation. The cell loss was similar in all three rows of OHC in each of the age groups. In animals up to 1 year of age, areas of OHC loss were localized in the apical and basal coils. In 4-year-old rabbits, OHC degeneration had become progressively accentuated and widespread. The pattern of IHC loss was somewhat similar to that of OHC. Age-related hair cell loss in the rabbit is comparable to that in the rat, monkey, and human cochlea.

Aging↗
PubMed1988

Phaeomycotic cyst (chromoblastomycosis) of the neck.

An unusual fungal infection of the neck caused by Phialophora verrucosa (chromoblastomycosis) is presented. The patient acquired this fungus by cutting his chin on a wooden floor. Surgical and medical therapy of this unusual disease is discussed.

Accidents, Home↗
PubMed1988

Vestibulo-ocular (VOR) abnormalities at high rotational frequencies in patients with Menière's disease.

Although visual feedback is required to maintain gaze stability during low-frequency rotations (below 1 Hz) because of suboptimal VOR gain in this frequency range, such behavior is not as evident at higher frequencies. Benson and Hydén et al. noted a steady increase in VOR gain in the higher-frequency range (2 to 5 Hz), where visual feedback has little effect. Similar behavior has also been reported in the monkey models. Eleven patients with diagnoses of Meniere's disease had tests of VOR and VOR cancellations performed with the use of pseudorandom oscillations as high as 5 Hz. The responses at various frequencies were compared with normal data from 17 subjects. The VOR gain in patients exhibited a more rapid rise at high frequencies than that observed in normal subjects. For example, at 3.5 Hz the normal gain was 1.09, whereas patients exhibited a gain of 1.35 (mean of 11 subjects). When the performance during VOR cancellation tasks was compared, Meniere's patients appeared to be less able to perform these tasks; however, when the values were compared by use of a cancellation index that compensates for any difference in VOR gain, this apparent difference disappeared.

Adult↗
PubMed1987

AIDS, otolaryngology and a case of adenoid cystic carcinoma of the parotid arising in a patient with the AIDS-related complex.

The incidence of acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) is increasing, and as head and neck manifestations of this entity are common it is important that otolaryngologists have an up-to-date knowledge of this condition. In this paper the epidemiological aspects of the disease are reviewed and the head and neck manifestations discussed. An interesting case of adenoid cystic carcinoma of the parotid arising in a patient with ARC is presented.

AIDS-Related Complex↗
PubMed1987

Orbital complications of acute sinusitis.

Although the association of sinusitis and inflammation of the orbits has been known for centuries, and the incidence widespread until the introduction of antibiotics, there has been a marked decline in the number of case reports in the medical literature since the 1940s. In this paper three recent cases are presented, with a review of the anatomy, clinical features and the authors' approach to the management of the problem, along with a literature search of this topic.

Acute Disease↗
PubMed1986

Study of pursuit and vestibulo-ocular cancellation.

This present study, a follow-up of our earlier investigation, further examines the time courses of recovery of oculomotor and vestibular function while patients are under the sedative effect of a single dose of secobarbital (Seconal). The assessment included tests for saccade and smooth pursuit, and the vestibulo-ocular reflex and its cancellation, as evaluated by sinusoidal and pseudorandom rotation in a high-frequency hydraulic chair (up to 5 Hz). Analysis of results showed that the vestibulo-ocular reflex (VOR) gain, depressed soon after drug intake, recovered substantially after a few hours. Changes in VOR gain were more pronounced with higher frequencies of rotation at 2 and 3 Hz, and greater with pseudorandom than sinusoidal stimulation. Under barbiturate influence, pursuit and VOR cancellation followed distinctly different time courses of recovery. This dissociation between VOR cancellation and pursuit supports the theory that these two systems are subserved by different mechanisms. Saccadic hypermetria was also observed after drug intake.

Adult↗
PubMed1986

Tracheostomy in intensive care setting.

A detailed analysis of early complications resulting from tracheostomy in 50 consecutive patients, admitted to the Intensive Care Unit, who had required ototracheal intubation, is presented. The very low incidence of complications seen in this study supports the contention that a carefully performed tracheostomy is a safe procedure in the management of these critically ill patients. In view of this and the greater incidence of laryngeal and tracheal stenosis associated with longer periods of orotracheal intubation followed by tracheostomy, early tracheostomy should be considered in patients intubated for five days in whom further prolonged respiratory assistance is anticipated.

Adult↗
PubMed1986

Age related cochlear toxicity from noise and antibiotics--a review.

Laboratory experimental evidence indicates that there is an age related susceptibility to cochlear damage from noise exposure and ototoxic antibiotics. In some rodents there is a critical period of auditory development during which there is greater vulnerability to such damage and, in some species, noise induced damage is influenced by genotype. Available data from patients are inconclusive in this regard. Further careful studies are indicated in this area. All available evidence emphasizes that caution should be exercised in the use of ototoxic drugs during pregnancy, in neonates, young children, and older people.

Acoustic Stimulation↗
PubMed1984

Vestibular compensation and nystagmus.

In healthy young subjects barbiturate induced vestibular nystagmus was sequentially studied with repeated electronystagmographic recordings. The analysed data together with our earlier studies indicated that, except for vertical nystagmus, spontaneous and different types of positional nystagmus by themselves are not diagnostic of site of lesion. The transition from spontaneous to positional to paroxysmal nystagmus observed in follow up studies of several of these cases indicates that these various types of vestibular nystagmus are likely a measure and reflection of different degrees of vestibular decompensation.

Adult↗