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Biomedical subjects

K J Doyle

Publications and source records attributed to K J Doyle.

At least 19 recordsLinked to original sources
PubMed2001

Effects of difluoromethylornithine chemoprevention on audiometry thresholds and otoacoustic emissions.

OBJECTIVES: To determine the effects of long-term, low-dose difluoromethylornithine (DFMO) on audiometric thresholds and distortion product otoacoustic emission (DPOAE) levels in humans. DESIGN: A prospective, randomized, placebo-controlled phase 2 clinical trial of DFMO in participants with a prior adenomatous colonic polyp. SETTING: Academic tertiary care referral center. PARTICIPANTS: One hundred twenty-three volunteer subjects with colorectal polyps and normal hearing for the frequencies 250 through 2000 Hz. INTERVENTIONS: Subjects were randomized to receive placebo or oral DFMO at daily dosages between 0.075 and 0.4 g/m(2) of body surface area for 12 months. OUTCOME MEASURES: Pure-tone audiometric thresholds for the frequencies 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz and DPOAE levels were measured at baseline and 1, 3, 6, 9, and 12 months after starting treatment with DFMO or placebo and 3 months after cessation of treatment if there was a suggestion of possible changes at the 12-month measurement. RESULTS: At these low dosages, there was little evidence for shifts in auditory pure-tone thresholds, and there were no statistically significant shifts in DPOAE levels. For auditory pure-tone thresholds, there was a subtle, approximately 2- to 3-dB hearing level decrease in hearing sensitivity for the 2 higher DFMO dosages, but only at the 2 lowest frequencies, 250 and 500 Hz. CONCLUSIONS: Administration of low-dose DFMO for 12 months did not produce hearing loss, in contrast to prior studies that used higher dosages.

Antineoplastic Agents↗
PubMed2001

Delayed, reversible hearing loss caused by difluoromethylornithine (DFMO).

OBJECTIVES/HYPOTHESIS: Difluoromethylornithine (DFMO) is an anticancer experimental drug that is ototoxic. The objectives of these three experiments were to: 1) determine a dose and dosing schedule of DFMO that produces significant hearing loss (HL) in newborn gerbils; 2) compare the HL level for control and newborn gerbils receiving daily subcutaneous injections of DFMO; and 3) to determine if DFMO-related HL is significantly reversible following discontinuation of DFMO treatment. STUDY DESIGN: Prospective, non-randomized experimental design with placebo controls. METHODS: Click-evoked auditory brainstem response (ABR) testing was performed for 21-day-old Mongolian gerbils following daily subcutaneous injections of DFMO or saline. Three experiments were carried out using different injection schedules and doses of DFMO. In experiment 3, animals were retested at 42 days of age following a 3-week recovery from DFMO. RESULTS: Animals administered an 18-day regimen of DFMO at 1 g/kg per day (from day 3 to day 20) had click thresholds of 25 to 65 dB nHL, whereas animals receiving daily injections of saline had thresholds of 5 to 20 dB nHL. Animals retested after 3 weeks of recovery from DFMO treatment had thresholds ranging from 5 to 20 dB nHL. Differences were statistically significant. CONCLUSIONS: DFMO causes mild to moderate HL in neonatal gerbils that recovers after discontinuation of the drug.

Animals↗
PubMed2001

Choristoma of the middle ear: a component of a new syndrome?

CASE REPORT: Salivary choristoma of the middle ear is a rare entity. The authors report the 26th known case, which is unique in several respects: the patient had abnormalities of the first and second branchial arches, as well as the otic capsule and facial nerve in ways not yet reported. Our patient presented with bilateral preauricular pits, conchal bands, an ipsilateral facial palsy, and bilateral Mondini-type deformities. A review of the literature revealed salivary choristomas of the middle ear to be frequently associated with branchial arch abnormalities, most commonly the second, as well as abnormalities of the facial nerve. REVIEW OF THE LITERATURE: All 25 cases were reviewed and the results reported with respect to clinical presentation, associated abnormalities, operative findings, and hearing results. It has been proposed that choristoma of the middle ear may represent a component of a syndrome along with unilateral hearing loss, abnormalities of the incus and/or stapes, and anomalies of the facial nerve. CONCLUSION: Eighty-six percent of the reported patients with choristoma have three or four of the four criteria listed to designate middle ear salivary choristoma as part of a syndrome. In the remaining four patients, all of the structures were not assessed.

Child↗
PubMed2000

Neurotologic follow-up after radiation of posterior fossa tumors.

OBJECTIVE: Stereotactic radiation treatment, also known as gamma knife surgery or radiosurgery, has come into acceptance as a treatment alternative to surgical removal for posterior fossa tumors. The purpose of this article is to describe the role of the neurotologist in the optimal management of neurotologic complications after stereotactic radiation, as illustrated by five patients. STUDY DESIGN: Retrospective chart review. PATIENTS: Five patients who underwent stereotactic radiation of posterior fossa tumors. MAIN OUTCOME MEASURES: Presence or absence of neurotologic complications (tumor growth, hearing loss, imbalance/ataxia, vertigo, and facial paralysis) or neurosurgical complaints (facial numbness, motor weakness, headache, hydrocephalus, and subarachnoid cysts). RESULTS: Postradiation neurotologic complaints included vertigo, imbalance/ataxia, and progressive hearing loss in four of the five patients. Continued tumor growth occurred in two patients; two patients had no growth; in one patient the tumor became smaller. The complications of facial nerve paralysis, facial numbness, motor weakness, headache, hydrocephalus, cerebellar edema, and posterior fossa arachnoid cyst formation occurred less frequently. CONCLUSIONS: Stereotactic radiation of posterior fossa tumors can produce significant neurotologic problems. It is imperative that neurotologists remain involved in the follow-up care of patients with posterior fossa tumors to offer optimal treatment alternatives for the neurotologic disorders.

Aged↗
PubMed2000

External and middle ear effects on infant hearing screening test results.

This study investigated the relationship between external and middle ear factors and hearing screening results by automated auditory brain stem response (ABR) and transient-evoked otoacoustic emissions (EOAEs). The ears of 200 healthy newborns aged 5 to 48 hours underwent screening by ABR and EOAE, followed by otoscopic examination. The pass rates for ABR and EOAE were 91% and 58.5%, respectively. On otoscopic examination, 28% (112/400) ears had occluding vernix obscuring the view of the tympanic membrane. Cleaning of vernix was successfully performed in all but 2 ears that had occluding vernix. Cleaning of vernix significantly increased the pass rates of all 400 ears for ABR and EOAE to 96% and 69%. Decreased tympanic membrane mobility was found in 22.7% (90/396) of ears that were evaluated otoscopically. Decreased tympanic membrane mobility had a significant effect on EOAE screening; only 33.4% of ears passed EOAE testing. Decreased tympanic membrane mobility did not significantly affect pass rates for ABR screening; 95% of these ears passed the automated ABR screen. Implications for newborn hearing screening are discussed.

Cerumen↗
PubMed1999

Prevalence of external auditory canal exostoses in surfers.

OBJECTIVE: To determine (1) the prevalence of external auditory exostoses in a population of surfers and (2) the relationship between the length of time spent surfing and the prevalence, severity, and location of the exostoses. DESIGN: Cross-sectional epidemiological study. SETTING: General community. PATIENTS: Three hundred seven avid surfers (93.5% males and 6.5% females; age distributions: 11.2% were < or =20, 67.9% were 21 to 40, 17.5% were 41 to 50, and 3.3% were >50 years). MAIN OUTCOME MEASURES: Questionnaires focusing on surfing habits (number of years, geographic region, and number of days per year of surfing) were correlated with otoscopic findings. A simple grading system was devised, based on the degree of external auditory canal stenosis. Grades of normal, mild, moderate, and severe corresponded to 100%, 99% to 66%, 65% to 33%, and less than 33% effective patent surface area, respectively. RESULTS: There was a 73.5% overall prevalence of external auditory exostoses and a 19.2% overall prevalence of osteomas in the group studied. Of 441 ears with exostoses, 54.2% were mild, 23.6% were moderate, and 22.2% were severe. Of individuals who had surfed for 10 years or less, 44.7% had normal ear canals and only 6% had severely obstructed auditory canals. In comparison, in the group that had surfed for longer than 20 years, only 9.1% had normal auditory canals and 16.2% were severely affected. Of surfers with no exostoses, 61.1% had surfed for 10 years or less. In contrast, of surfers with severe exostoses, 82.4% had surfed for more than 10 years. Finally, the lesions seemed to affect all external auditory canal quadrants equally. CONCLUSION: A positive association exists between the amount of time individuals spend surfing and the presence and severity of exostoses of the external auditory canal.

Adult↗
PubMed1999

The case for early identification of hearing loss in children. Auditory system development, experimental auditory deprivation, and development of speech perception and hearing.

Human infants spend the first year of life learning about their environment through experience. Although it is not visible to observers, infants with hearing are learning to process speech and understand language and are quite linguistically sophisticated by 1 year of age. At this same time, the neurons in the auditory brain stem are maturing, and billions of major neural connections are being formed. During this time, the auditory brain stem and thalamus are just beginning to connect to the auditory cortex. When sensory input to the auditory nervous system is interrupted, especially during early development, the morphology and functional properties of neurons in the central auditory system can break down. In some instances, these deleterious effects of lack of sound input can be ameliorated by reintroduction of stimulation, but critical periods may exist for intervention. Hearing loss in newborn infants can go undetected until as late as 2 years of age without specialized testing. When hearing loss is detected in the newborn period, infants can benefit from amplification (hearing aids) and intervention to facilitate speech and language development. All evidence regarding neural development supports such early intervention for maximum development of communication ability and hearing in infants.

Acoustic Stimulation↗
PubMed1998

Comparison of newborn hearing screening by transient otoacoustic emissions and auditory brainstem response using ALGO-2.

The aim of this study is to compare pass rates for two different hearing screening methods in well newborns as a function of age. A previous study by this group compared click evoked otoacoustic emissions (EOAE) and automated auditory brainstem response (ABR) using the ALGO-1 infant hearing screener (Natus Medical, Foster City, CA). Since that study, a new generation automated ABR screener, the ALGO-2, has been developed. In this study, 232 ears in 116 healthy newborn infants aged 5-48 h were tested using the ALGO-2 screener and EOAE. Overall, 92% of ears passed the ABR, while 57% passed the EOAE screen. The ABR pass rate was higher than in the previous study, where 88.5% of ears passed the ABR screen using ALGO-1. The EOAE pass rate in the present study was lower than in the previous study, in which 79% passed the EOAE screen. Pass rates for both EOAE and ABR improved significantly with increasing infant age. There was no significant difference in the test time required for ALGO-2 (5.7 min) compared with EOAE (5.2 min). The results are compared with earlier studies and implications for universal hearing screening are discussed.

Acoustic Stimulation↗
PubMed1998

Auditory neuropathy in childhood.

OBJECTIVES: Auditory neuropathy is a recently described disorder in which patients demonstrate hearing loss for pure tones, impaired word discrimination out of proportion to pure tone loss, absent or abnormal auditory brainstem responses, and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We have identified eight pediatric patients having hearing deficits that are most likely due to a neuropathy of the eighth nerve. In this study, the results of audiologic testing performed with these eight children are described. STUDY DESIGN: Retrospective review of audiologic findings in eight children with auditory neuropathy. METHODS: Each subject was tested with pure tone and speech audiologic testing, auditory brainstem response, and click-evoked otoacoustic emissions. Results of these tests were tabulated and summarized. RESULTS: Pure tone audiologic testing revealed five children with upsloping sensorineural hearing loss, two with high frequency loss, and one with a mild, flat configuration. Six children demonstrated poor word discrimination scores, and the other two had fair to good word discrimination. All eight subjects had normal distortion product and transient otoacoustic emissions. All eight children demonstrated absent or marked abnormalities of brainstem auditory evoked potentials. These findings suggest that while cochlear outer hair cell function is normal, the lesion is located at the eighth nerve. CONCLUSIONS: Recent advances in otoacoustic emissions testing permit differentiation of neural deafness from sensory deafness. This paper describes the clinical presentation and audiologic findings in pediatric auditory neuropathy, as well as the recommended management of these patients. Otolaryngologists should be aware of this disorder and implications for its management, which differs from treatment of sensorineural hearing loss.

Adolescent↗
PubMed1997

Newborn hearing screening by otoacoustic emissions and automated auditory brainstem response.

The aim of this study is to compare pass rates for two different hearing screening methods in well newborns as a function of age. Hearing screening tests were performed on 400 ears in 200 healthy newborn infants at the University of california-Irvine Medical Center. The screening methods used were automated auditory brainstem response (ABR) and click evoked otoacoustic emissions (EOAE). The infants' ages ranged from 5 to 120 h, with an average age of 24 h. Overall, 88.5% of ears passed the ABR screen, and 79% passed the EOAE screen. There was no significant difference in the ABR pass rate for infants aged 0-24 h of age as compared with infants aged > 24 h compared with the group aged 0-24 h (P < 0.01). Results are compared with earlier studies and implications for universal hearing screening are discussed.

Age Factors↗
PubMed1997

Neonatal hearing screening with otoscopy, auditory brain stem response, and otoacoustic emissions.

A study was performed to investigate the relationship between external and middle ear factors and hearing screening results by auditory brain stem response (ABR) and transient evoked otoacoustic emissions (EOAEs). The ears of 200 well newborns aged 5 hours to 48 hours underwent screening by ABR and EOAEs, followed by otoscopic examination. The pass rates for ABR and EOAE screening were 88.5% and 79%, respectively. On otoscopic examination, 13% (53 of 400) ears had occluding vernix obscuring the view of the tympanic membrane. Cleaning of vernix was attempted in ears that failed ABR or EOAE screening. Seventeen ears that failed ABR were cleaned, and 12 (71%) of them passed repeat ABR. Thirty-three ears that failed EOAE screening were cleaned, and 22 (67%) of them passed repeat emissions testing. Cleaning vernix increased the pass rates for ABR and EOAE screening to 91.5% and 84%, respectively. Decreased tympanic membrane mobility was found in 9% of ears that could be evaluated otoscopically. Increased failure rates for both ABR and EOAE screening were found in infant ears with decreased tympanic membrane mobility, but significance testing could not be performed because of inadequate sample size. Prevalence of occluding external canal vernix and middle ear effusion as a function of increasing infant age were studied. Implications for newborn hearing screening are discussed.

Body Fluids↗
PubMed1996

Cerebellopontine angle epidermoids: results of surgical treatment.

Epidermoids, or congenital cholesteatomas, constitute about 0.2% to 1.5% of intracranial tumors, and 3% to 5% of tumors of the cerebellopontine angle (CPA). We review the surgical management of CPA epidermoids in 13 patients at the House Ear Clinic for the years 1978 to 1993. There were seven male and six female patients, ranging in age from 27 to 59 years (average, 40 years). Tumors ranged in size from 3.5 cm to 7.0 cm, and the surgical approach was tailored to the tumor extent and location. All patients complained at presentation of unilateral hearing loss, and nine had poor speech discrimination (less than 50%) preoperatively. Serviceable hearing was preserved in two patients. Two patients presented with facial nerve symptoms, and four cases had postoperative permanent facial nerve paralysis (House-Brackmann Grade V or VI). There were no surgical deaths. Four patients required second surgeries to remove residual cholesteatoma. Compared with prior series, we describe a higher rate of total tumor removed, as well as a higher rate of second operations, indicating a more aggressive approach to these lesions.

Journal Article↗
PubMed1996

Reporting operative hearing results in stapes surgery: does choice of outcome measure make a difference?

In a prior study, findings indicated that when reporting results of chronic ear surgery, neither choice of pre-versus postoperative bone-conduction scores nor choice of frequencies to include a averaging makes a substantial difference in reported outcome. In this study, audiologic data from 240 stapes-surgery patients at three different institutions were used to generate a variety of outcome measures. Use of preoperative rather than postoperative bone-conduction values in computing postoperative air-bone gap resulted in an approximately 5-dB smaller mean gap and a 2% higher success rate. Frequencies included in averaging made little difference in mean computed air-bone gap, although success rate (gap < 10 dB) was lower by 6% when 4 kHz was used in a four-frequency average rather than 3 kHz. Results for air conduction were similar to those for air-bone gap regarding choice of frequencies to include in averaging. When using air-conduction pure-tone average (PTA) as the outcome measure, those with normal preoperative sensorineural hearing had a > 20% higher success rate than the general population of stapes-surgery patients. The greatest differences in success rate were based on definition of and criteria for success. Success rate was higher when based on air-bone gap than when based on air-conduction PTA. As in the prior chronic ear study, differences in outcome were more drastically affected by criteria for "success" than by frequencies included. Unlike similar data from chronic ear surgery, however, success rate differed depending on choice of air-bone gap or air-conduction PTA as the definition for success. Further, air and bone scores from the same test interval must be used to accurately reflect air-bone gap in stapes surgery.

Adolescent↗
PubMed1996

Reporting operative hearing results in stapes surgery: does choice of outcome measure make a difference?

PURPOSE: Findings of a prior study indicated that neither choice of pre- versus postoperative bone-conduction scores nor choice of frequencies to include in averaging makes a substantial difference in reported outcomes of chronic ear surgery. METHODS: In this study, audiologic data from 240 stapes surgery patients at three different institutions were used to generate a variety of outcome measures. RESULTS: Use of preoperative rather than postoperative bone-conduction values in computing postoperative air-bone gap resulted in an approximately 5-dB smaller mean gap and a 2% higher success rate. Frequencies included in averaging made little difference in mean computed air-bone gap, although success rate (gap < or = 10 dB) was lower by 6% when 4 kHz was used in a four-frequency average rather than 3 kHz. Results for air conduction were similar to those for air-bone gap regarding choice of frequencies to include in averaging. When we used air-conduction pure-tone average (PTA) as the outcome measure, those with normal preoperative sensorineural hearing had a > 20% higher success rate than the general population of patients with stapes surgery. CONCLUSIONS: The greatest differences in success rate were based on definition of and criteria for success. Success rate was higher when based on air-bone gap than when based on air-conduction PTA. As in the prior chronic ear study, differences in outcome were more drastically affected by criteria for "success" than by frequencies included. Unlike similar data from chronic ear surgery, however, success rate differed depending on choice of air-bone gap or air-conduction PTA as the definition for success. Further, air and bone scores from the same test interval must be used accurately to reflect air-bone gap in stapes surgery.

Adolescent↗