Biomedical subjects

R R Marsh

Publications and source records attributed to R R Marsh.

At least 37 records · Page 2Linked to original sources

PubMed1990

Hearing impairment in ventilator-dependent infants and children.

Bronchopulmonary dysplasia is a complication of prematurity that can require months or years of ventilatory support. Among a cohort of 12 such ventilator-dependent patients, half had auditory brainstem response thresholds of 40 dB nHL or worse in the better ear. In 10 of 23 ears the threshold was 50 dB or worse. This incidence of hearing impairment is much greater than for other high-risk premature infants. Although conductive impairment was implicated in many cases, the degree of impairment is greater than that ordinarily seen with middle ear effusion.

Audiometry, Evoked Response↗

PubMed1990

Recovery of the basilar papilla following intense sound exposure in the chick.

Newly hatched chicks were exposed to a 900-Hz tone at 120 dB SPL for 48 hours, then sacrificed, along with unexposed controls, at intervals of 0-15 days following exposure. Examination of the basilar papilla by scanning electron microscopy demonstrated a 32% loss of hair cells within the lesion area with substantial shrinkage of the apical surfaces of the survivors. Within days, the papilla returned to a nearly normal appearance, and new hair cells were seen, but the number of new cells was only a fraction--approximately 22%--of the number lost. Expansion of the apical surfaces of the surviving cells to larger than normal size was a major factor in the recovery of the papilla.

Animals↗

PubMed1989

Reliability of sleep sonography in detecting upper airway obstruction in children.

In children, lymphoid hyperplasia is by far the most common cause of airway obstruction during sleep, but the determination as to presence or degree of obstruction is seldom made objectively, because of the expense and stress of polysomnography. If audio recordings are made by parents at home with standardized equipment, however, obstruction can be recognized readily. Such recordings obtained from 50 patients were computer processed and the resulting displays were independently rated by two judges. Interobserver correlation was 0.87 and split-half reliability was 0.83, demonstrating very good reliability of the processing and scoring procedures. Recordings made on successive nights were highly consistent as well (test-retest reliabilities of 0.78 and 0.86 for the two raters). This recording method, which is well accepted by parents and children, has both clinical and research value in the assessment of airway obstruction.

Adenoidectomy↗

PubMed1989

Ototoxicity of antimycotics.

Neither otomycoses nor defects of the tympanic membrane are rare. In cases of fungal infection when the tympanic membrane is not intact, the possibility exists that antimycotic medication could enter the middle ear and diffuse into the cochlea via the round window. Five antimycotic preparations were tested for acute ototoxic potential in guinea pigs. Those containing acetic acid or propylene glycol caused appreciable elevation of brainstem response thresholds, while little or no impairment resulted from tolnaftate or clotrimazole solutions in polyethylene glycol 400.

Animals↗

PubMed1988

A prospective study of titanium ventilation tubes.

A prospective controlled study was undertaken in which in 100 children a titanium ventilation tube was inserted in one ear, and a Paparella silicone tube was inserted in the contralateral ear as a control. The tubes were evaluated with respect to length of time of intubation, episodes of otorrhea, and early occlusion. Sixty-five patients were followed for at least one year, or until both tubes had extruded. Long-term follow-up of these patients has revealed little difference in the incidence of tube occlusion, early extrusion, or infection with otorrhea. Since the titanium tube is more than twice as expensive and has no proven advantages over a silicone tube of similar design, we have no reason to recommend its use over the less costly, standard silicon ventilation tube.

Child, Preschool↗

PubMed1988

Digital filtering of auditory evoked potentials.

Digital filters have been proposed by many authors for analysis and enhancement of the auditory brain stem response and related potentials. Because these techniques are unfamiliar to many, and require attention to underlying assumptions, an overview of the field is presented, with emphasis on limitations and risks of each method. Topics include Fourier transforms, finite impulse response (convolutional) filters, and infinite impulse response (recursive) filters.

Brain Stem↗

PubMed1986

Auditory brainstem responses in young children with Down's syndrome.

Auditory brainstem evoked responses (ABRs) were studied in 37 Japanese infants and children with Down's syndrome to determine the level of the lesion causing their unresponsiveness to sound stimuli. ABR thresholds, peak latencies of waves I and the peak interval latency of wave I-V were measured. For comparison with ABR thresholds, behavioral audiometry was performed. Thirty-two percent of the patients (12 cases) with Down's syndrome showed no responses by ABR as well as behavioral audiometry. The other ABR abnormalities with respect to age-matched controls were classified into 6 types: shorter wave I latencies (2 cases, 5%), shorter wave V latencies (7 cases, 19%), shorter wave I-V intervals (8 cases, 22%), wave I prolongation (13 cases, 35%), wave V prolongation (5 cases, 14%) and prolongation of wave I-V peak interval (no case, 0%). Our results demonstrate a high incidence of hearing loss at middle and inner ear levels, and suggest some anomaly within the auditory brainstem in Japanese cases of Down's syndrome.

Audiometry, Evoked Response↗

PubMed1986

A controlled study of a 'new' ventilating tube. The gold standard?

A prospective controlled study of a gold ventilation tube was undertaken in which a gold tube was inserted in one ear of 88 children and a Paparella silicone tube was inserted in the contralateral ear as a control. The tubes were evaluated with respect to length of time of intubation, episodes of otorrhea and early occlusion. Sixty-three patients were available for a follow-up of at least 6 months. The gold tube remained in place for a shorter period of time when compared to the control tube. Episodes of otorrhea were infrequent and there was not any significant difference between the two types of tubes. The gold tube became occluded more frequently than the control tube. Since the gold tube is approximately 3 times more expensive and has no proven advantages over our conventional silicone tube, we have no reason to recommend its use in preference to any other available tube.

Acute Disease↗

PubMed1986

Relief of upper airway obstruction by adenotonsillectomy.

Adenotonsillectomy is often performed to relieve upper airway obstruction, even in children who do not present with severe apnea. Although adenotonsillectomy provides dramatic relief from obstructive sleep apnea, little evidence is available as to the efficacy of surgery in the far more prevalent cases of partial airway obstruction. We report the results of a prospective study of 100 children with adenotonsillar obstruction (without severe apnea) and 50 age-matched control children. The majority of patients exhibited appreciable sleep disturbances preoperatively, as compared to controls, and had substantial postoperative improvement, as demonstrated by parental questionnaire and sleep sonography--the computer-aided analysis of respiratory sounds. Mouth breathing and behavior problems were also prevalent preoperatively and were affected positively by adenotonsillectomy. It appears that surgery in such cases can have far-ranging benefits, even for the child whose obstruction does not demonstrate severe apnea.

Adenoidectomy↗

PubMed1986

Auditory brainstem responses and behavioural responses in pre-term infants.

Auditory brainstem responses (ABRs) and behavioural thresholds were studied in 25 pre-term infants with post-conceptional ages of approximately 40 weeks to ascertain whether there were differences in the ABR between normal preterm and full-term new born infants to compare behavioural thresholds around 40 weeks of post-conceptional age and to follow changes of their behavioural thresholds in the first year of life. ABR thresholds, peak latencies of Waves I and V and the I-V peak interwave latency were measured. Behavioural audiometric thresholds to pure tones were determined through behavioural observation audiometry and conditioned orientation-reflex audiometry. The ABR thresholds of the pre-term infants, whether they were small for date (SFD) or appropriate for date (AFD), were in the normal ranges of the controls. Moreover, there were no significant differences between either the SFD or the AFD group and controls, as far as Wave I or V latency or I-V interval are concerned. Thus, the ABR was apparently unaffected by the infant being small-for dates. Behavioural audiometry disclosed that all normal full-term infants responded to pure tone stimuli, with mean thresholds of 85 dB, while only 42% of AFD and 30% of SFD would respond to pure tone stimuli at 90 dB or less. Behavioural thresholds caught up with the normal range by 12 months of age, except for a few infants.

Audiometry↗

PubMed1985

The auditory pathology of brain death as revealed by auditory evoked potentials.

A case of brain death is reported in which the auditory brainstem response, middle latency component, and slow vertex response were recorded before and after the cessation of cortical activity, and in which histological examination of the temporal bone and central auditory pathways was performed post mortem. Brain death of at least 48 hours' duration was demonstrated by neurological examination, flat electroencephalographic recording, and persistent absence of auditory evoked responses. The postmortem examination was performed 3 hours after death. The pathological studies of the whole length of the auditory pathway revealed total autolysis of the organ of Corti, marked cell loss in the dorsal cochlear nucleus, and moderate cell loss in other nuclei of the central auditory pathway. It should be considered that total autolysis of the organ of Corti and severe cell loss of the cochlear nucleus may occur if the auditory brainstem response becomes absent in comatose patients.

Adult↗

PubMed1985

Hearing loss and visco-elasticity of middle ear fluid.

It has been suggested that the physical properties of middle ear effusion--its viscosity and elasticity--affect the degree of conductive impairment. Exogenous mucus having substantial visco-elasticity was instilled in the bullae of guinea pigs, and the resulting hearing loss was determined by measurements of the cochlear microphonic potential. In this preparation the hearing loss induced by mucus did not differ significantly from that found when the bulla was filled with saline. We find no evidence of a relationship between visco-elasticity of middle ear fluid and amount of conductive impairment.

Animals↗

PubMed1985

The lateral neck radiograph in adenotonsillar hyperplasia.

In this study we have considered whether the lateral neck radiograph is useful in predicting the degree of airway obstruction, and whether supine and erect views are more useful than a single film. We evaluated the supine and erect lateral neck radiographs of 50 patients with upper airway obstruction due to enlarged tonsils and adenoids. Our results show that the supine radiograph, which is technically easier to perform, is entirely satisfactory for appraising the size of the tonsils and adenoids, but that neither view tells us much about the degree of airway obstruction during sleep.

Adenoids↗

PubMed1985

Mucociliary transport of human ear secretions in otitis media with effusion.

Rheologically active mucus glycoproteins (mucins) were isolated from the middle ear effusions of 282 patients (344 ears) presenting with secretory otitis media (SOM). The mucins were pooled according to the pathologic condition associated with the SOM. Pools were reconstituted to the same conditions and tested for ciliary transport rates with the use of the frog palate transport model. Mucin obtained from cleft palate patients showed significant differences in transport behavior in comparison with mucins from other groups of patients with SOM.

Adolescent↗

PubMed1985

Auditory and vestibular function in hyperbaric oxygen.

The therapeutic value of high partial pressures of oxygen is limited by the toxicity of oxygen. Pulmonary damage, visual impairment, and convulsions are known hazards during hyperoxic exposure, but dose-effect relationships have not been quantified for specific organs or functions. As part of an integrated study of organ oxygen tolerance in man (Predictive Study V of the Institute for Environmental Medicine), auditory and vestibular function was evaluated in man before, during, and after exposure to 100% oxygen at 3 atmospheres absolute pressure for 2 to 3.5 hours. No alterations in hearing or equilibrium were detected, suggesting that ototoxicity is not a factor that would limit exposure under these conditions.

Adult↗

PubMed1985

Auditory short, middle, and long latency responses in acutely comatose patients.

For assessing comatose patients, the combination of auditory short, middle, and long latency evoked potentials (auditory brain stem response [ABR], middle latency component [MLC], and slow vertex response [SVR] ) is more comprehensive than auditory brain stem response (ABR) only or ABR with slow vertex response (SVR). Fifty-four acutely comatose patients were studied. Thirty-four of the patients had severe head injury and others had coma of varied etiology. Within two months after admission, 25 patients survived, while 29 patients died. Auditory evoked response measurements were conducted usually within 48 to 72 hours after admission. For patients with normal SVR, MLC, and ABR, there was 100% survival; with absent SVR but normal MLC and ABR, survival was 91%; with absent SVR and MLC and normal ABR, it was 60%; with abnormal ABR, it was 10%; no patient survived whose ABR was absent. It is emphasized that a normal MLC is clearly a predictor of survival of comatose patients, but a normal ABR is not always a reliable indicator of survival.

Adolescent↗

PubMed1985

Auditory testing of dogs with inherited retinal degeneration.

Auditory function was tested by brainstem-evoked response (BSR) audiometry in dogs affected by hereditary retinal degeneration (HRD). Comparison of BSR thresholds and latency-intensity functions revealed no significant difference between progressive rod-cone degeneration (PRCD) affected and unaffected miniature poodles, and no evidence of sensorineural hearing loss in HRD-affected English cocker spaniels and miniature schnauzers. The authors conclude that hearing loss is not a feature of the retinal degenerations in these dogs.

Animals↗

PubMed1984

Auditory brain-stem response and temperature: relationship in the guinea pig.

The neurological applications of the auditory brain-stem response depend largely on the stability of the interval between the peaks of waves I and V. Using guinea pigs, it was demonstrated that hyperthermia and small temperature changes, as well as hypothermia, may affect interpeak latency (IPL) sufficiently to affect its clinical interpretation. The relationship between temperature and IPL is specified by a power function such that there is a 5.3% increase in IPL for a 1 degree C drop. Although the constant for humans may differ from that of guinea pigs, the results of this animal study demonstrate that the relationship between temperature and IPL is invariant from 27 degrees C to 40 degrees C.

Animals↗