Biomedical subjects

R R Marsh

Publications and source records attributed to R R Marsh.

At least 19 recordsLinked to original sources

PubMed1992

Usefulness of computed tomographic scan in the evaluation of sensorineural hearing loss in children.

A retrospective chart study was conducted to determine the diagnostic yield of temporal bone imaging for children with sensorineural hearing loss of unknown cause. Seventy consecutive cases, spanning 4.5 years, were identified and individual computed tomography films reviewed. Cases were analyzed with respect to patients' age, duration of hearing loss, sudden onset vs progressive loss, unilateral vs bilateral, and other symptoms. Of the 70 computed tomographic scans, nine showed temporal bone or other intracranial abnormalities. The majority of these findings were localized to structures in the posterior and middle cranial fossae. No eight nerve tumors were identified. Congenital hearing loss and hearing loss secondary to viral infections are the most common cause of sensorineural hearing loss when discovered in early childhood and, often, have no radiographic abnormality. The decision to explore an ear for a presumed perilymph fistula is based almost exclusively on the history and physical examination, and not on the demonstration of any radiographic findings. For the children presenting with stable hearing impairment in the absence of other findings, computed tomographic scans were either negative or did not contribute to diagnosis. Since tumors of the eighth nerve are rare in children under 16 years of age (without neurofibromatosis), and radiologic studies have a low yield in identifying perilymph fistulas, the routine use of computed tomographic imaging in such children may be unjustified.

Adolescent↗

PubMed1992

Signal to noise constraints on maximum length sequence auditory brain stem responses.

In conventional auditory brain stem response (ABR) testing, the stimulus rate must be low enough that the responses do not overlap. By using stimulus patterns derived from the pseudorandom binary series known as maximum length sequences (MLSs), it is possible to stimulate at mean rates of hundreds of clicks per second, and extract the responses. It has been suggested that this could reduce test time appreciably, but there is reason to believe that the MLS ABR is intrinsically noisier than conventional averaging. To test this premise, 10 ears were tested with conventional ABR procedures and with MLS ABRs having 2, 4, and 8 times as many stimuli per second as the conventional condition. Noise levels in control runs were in agreement with predictions. With a 40 dB nHL stimulus, wave V amplitude decreased in the MLS ABRs to the extent that none of the MLS conditions was as efficient as the conventional ABR. Any assessment of the value of MLS ABRs in reducing test time must take into consideration the higher noise levels inherent in this procedure.

Acoustic Stimulation↗

PubMed1991

The auditory brain stem response recorded with 60 Hz notch filters.

Line-frequency (60 Hz in the USA) interference is a common source of contamination during recording of the auditory brain stem response (ABR). Notch filters are undeniably effective in eliminating this artifact, but concerns have been expressed as to their effect on the ABR itself. Theoretical considerations suggest that the degree of distortion should be minimal if the filter is sufficiently sharp and the stimulus rate has no multiples very close to 60 Hz. Responses simultaneously recorded through three notch filters of varying sharpness confirmed this: Latency was virtually unaffected with any filter or stimulus rate, and distortion was minimal when a sharply tuned filter was used in conjunction with a stimulus rate of 23.3 Hz, whose nearest harmonic to 60 is 69.9 Hz.

Acoustics↗

PubMed1991

Developmental patterns of normal nutritive sucking in infants.

The purpose of this investigation was to quantify normal nutritive sucking, using a microcomputer-based instrument which replicated the infant's customary bottle-feeding routine. 86 feeding sessions were recorded from infants ranging between 1.5 and 11.5 months of age. Suck height, suck area and percentage of time spent sucking were unrelated to age. Volume per suck declined with age, as did intersuck interval, which corresponded to a more rapid sucking rate. This meant that volume per minute of sucking time was fairly constant. The apparatus provided an objective description of the patterns of normal nutritive sucking in infants to which abnormal sucking patterns may be compared.

Age Factors↗

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↗