Morbillivirus infections in European seals before 1988.
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Animals↗
Biomedical subjects
J Crowther
Publications and source records attributed to J Crowther.
Anesthesia effects on the electrically evoked middle latency response in guinea pigs.
Recent data indicate that the electrically evoked middle latency response (EMLR) is useful for patient selection for cochlear implantation and may provide a test for determining safe levels of electrical stimulation in cochlear implant recipients. Some anesthetic agents have been reported to alter the auditory evoked middle latency response. The aim of our study was to examine the effects of ketamine and xylazine anesthesia on the EMLR in guinea pigs. A consistent, reproducible, and significant depression in the EMLR was observed after anesthesia. Response latencies were increased and the suprathreshold amplitudes were depressed initially, but later increased above preanesthetic values. Changes followed a predictable time course of depression and overshoot, which allows the investigator to compensate for these effects of anesthesia. No change in threshold was observed. The lack of threshold change and the predictable course of suprathreshold depression indicates that the EMLR may be useful to evaluate responsiveness of the auditory system to electrical stimulation in the anesthetized animal.
Anesthetics↗
The effectiveness of adenoidectomy in the treatment of glue ear: a randomized controlled trial.
One hundred children with glue ear, in whom surgical treatment was indicated, were randomly allocated to 1 of 4 treatment groups. Children in 2 of the groups underwent adenoidectomy plus various combinations of ear operations while in the other 2 groups surgery was confined to the ears. The effect of adenoidectomy was assessed 6 weeks, 6 months and 1 year after surgery by means of audiometry, impedance tympanometry and parental opinion. Improvements in hearing were greater in those children who underwent an adenoidectomy than in those who did not (4.0 dB at 6 weeks; 2.4 dB at 6 months; 0.7 dB at 1 year). However, these differences are of little clinical significance and were only statistically significant (P less than 0.05) 6 weeks after surgery. Middle ear function, measured by tympanometry, revealed a similar pattern of response to treatment. Despite this, 6 months after surgery a higher proportion of parents were satisfied with their child's condition if an adenoidectomy had been performed. Possible explanations of this discrepancy between clinical and parental assessments of outcome are discussed.
Acoustic Impedance Tests↗
Hearing loss in sarcoidosis.
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Adolescent↗
Prospective research with vulnerable children and the risky art of preventive intervention.
The Vermont Vulnerable Child Development Project is presented as an example of community based preventive intervention research employing multiple control groups and prospective epidemiology. Discussion emphasizes both methodological issues and the pragmatics involved in choosing to use community institutions in order to study preventive interventions for very young multi-risk children living with their mentally disturbed parents. Further, a rationale is provided for anticipating and coping with the political, sociological and personality conflicts which are probably inescapable in this type of mental health research.
Child↗
Effect of electrical stimulation on middle latency response in the guinea pig.
A temporary threshold shift (TTS) has been demonstrated in the electrically evoked middle latency response (EMLR) following exposure to moderate levels of continuous electrical stimulation via a cochlear implant. The threshold at which the EMLR was elicited in chronically implanted guinea pigs was elevated by approximately 100% following 30 minutes of moderate intensity (200 microA or more) sinusoidal electrical stimulation of the cochlea. Results obtained under anesthesia varied unacceptably. In awake animals, EMLR thresholds were stable over time and consistent TTSs were observed. The threshold returned to prestimulation levels within 4 hours following termination of the stimulation. The possibility of histopathologic changes and the relevance of these findings in setting safe output levels for cochlear implant processors are discussed.
Animals↗