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Biomedical subjects

G A Gates

Publications and source records attributed to G A Gates.

At least 37 records · Page 2Linked to original sources
PubMed1997

Parosteal osteogenic sarcoma of the mastoid bone.

Parosteal osteogenic sarcoma (POS) is an uncommon surface bone tumor, most often arising from the metaphyseal end of long bones. Involvement of the cranial bones is rare, with only 1 case of mastoid bone POS previously reported in the literature. Two patients with POS of the mastoid are presented, 1 followed up for 25 years after surgical treatment. The presenting signs and symptoms, as well as distinctive radiographic findings, are discussed. Histologic features are also described. Typically, cranial POS appears as a sessile, densely ossified surface growth with radiating bone spicules that blend with surrounding soft tissue. Treatment is en bloc resection, which is curative in most cases.

Adult↗
PubMed1997

Functional MR spectroscopy of the auditory cortex in healthy subjects and patients with sudden hearing loss.

PURPOSE: To use MR spectroscopy to study the biochemical changes produced by auditory stimuli in patients with sudden sensorineural hearing loss and to compare these findings with the biochemical changes seen in healthy volunteers. METHODS: Single-voxel MR spectroscopy was used to study biochemical changes in the auditory cortex in 11 control subjects and 19 patients with sudden sensorineural hearing loss. MR spectroscopic signals were measured during three different sound conditions (scanner noise, music, and sirens). RESULTS: A lower MR spectroscopic lactate signal was observed in control subjects during the music stimulus than during the other sound conditions. This music-induced lactate change was not observed in patients with hearing loss. The other proton metabolites (choline, creatine, N-acetylaspartate [NAA]) remained stable during the different auditory stimuli. However, the NAA/creatine ratio was higher in the auditory cortex of patients than in the control subjects, and was not dependent on the sound condition. CONCLUSION: The detection of stimulus-induced and stable biochemical MR spectroscopic changes in patients with hearing loss may be useful in assessing disease activity.

Acoustic Stimulation↗
PubMed1997

Hear ye? Hear ye! Successful auditory aging.

Age-related hearing loss (presbycusis) is a multifactorial process that affects nearly all people in their senior years. Most cases are due to a loss of cochlear hair cell function and are well mediated by communication courtesy and modern amplification technology. Severe hearing loss is generally due to cochlear problems or age-related diseases and may require speech reading, assistive listening devices, and cochlear implants, depending on the degree of loss. Presbycusis may seriously impair communication and contribute to isolation, depression, and possibly dementia. Accurate diagnosis and prompt remediation are widely available but are frequently underused. Geriatric health care and well-being is enhanced by the detection and remediation of communication disorders.

Aged↗
PubMed1996

Central auditory dysfunction, cognitive dysfunction, and dementia in older people.

OBJECTIVES: To determine in older people the relation between auditory dysfunction and cognitive dysfunction, and if central auditory test abnormalities predict the onset of clinical dementia or cognitive decline. DESIGN: Prospective population-based cohort study. SETTING: Framingham Heart Study outpatient biennial examinations 18 and 21. PARTICIPANTS: Members of the Framingham Heart Study cohort with normal findings from cognitive screening tests at biennial examination 18. MEASUREMENTS: Peripheral audiometric thresholds and word recognition in quiet; Synthetic Sentence Identification with Ipsilateral Competing Message (SSI-ICM); Mini-Mental State Examination; and detailed neuropsychological testing of subjects with abnormal findings from the Mini-Mental State Examination. Relative risk of dementia was determined using age-adjusted Cox proportional hazards regression models. RESULTS: Hearing loss significantly lowered performance on the verbal parts of the Mini-Mental State Examination. The relative risk of subsequent clinical dementia or cognitive decline was 6 in subjects with very poor scores (< 50%) in one ear on the SSI-ICM (P = .02); the relative risk was 12.5 if the poor scores were present in both ears (P = .001). CONCLUSIONS: Central auditory dysfunction precedes senile dementia in a significant number of cases and may be an early marker for senile dementia. Hearing tests should be included in the evaluation of persons older than 60 years and in those suspected of having cognitive dysfunction.

Aged↗
PubMed1996

Sizing up the adenoid.

In almost any operating room in the country, one is likely to see on the surgical list a procedure entitled something like "bilateral myringotomy and tympanostomy tube insertion with possible adenoidectomy" abbreviated "BMT, poss Ad" or equivalent. In practice, this means that after inserting the tubes, the surgeon will examine the nasopharynx by palpation or mirror inspection, and if the adenoid is deemed to be enlarged, it will be removed.

Adenoidectomy↗
PubMed1996

Cost-effectiveness considerations in otitis media treatment.

The costs of treatment of children with otitis media with effusion comprise a substantial part of the total health care expenditure. However, there is little information about the value of therapy expressed in cost-effectiveness terms, and disagreement still exists about optimal therapy. This article considers the elements of cost-effectiveness analysis as they pertain to treatment of young children with otitis media with effusion and develops a first approximation model using data from several sources. The assumptions on which this model is based need to be validated by additional research. Otitis media with effusion treatment costs are high because of the large, and apparently increasing, number of symptomatic cases. Medical therapy, which is the primary treatment modality, consumes two thirds of the expenditures for otitis media with effusion. Surgical therapy is a cost-effective treatment for children in whom medical therapy for otitis media with effusion fails. Medical and surgical therapy are complementary, and each should be included in the analysis of cost-effectiveness.

Adenoidectomy↗
PubMed1995

Auditory dysfunction in aging and senile dementia of the Alzheimer's type.

OBJECTIVE: To determine the prevalence and type of auditory dysfunction in older volunteer subjects with mild probable Alzheimer's disease (pAD). METHODS: Pure-tone thresholds, word recognition in quiet, Synthetic Sentence Identification with Ipsilateral Competing Message or Contralateral Competing Message, distortion-product otoacoustic emissions, and auditory brain-stem responses were done in 82 elderly volunteer subjects whose cognitive, psychologic, and neurologic status had been determined through annual testing in a research center. Based on clinical criteria and the Clinical Dementia Rating (CDR) scale, 40 subjects had been judged to be nondemented (CDR score, 0), and 42 had a clinical diagnosis of pAD, with 22 in the questionable (CDR score, 0.5) and 20 in the mild (CDR score, 1) categories. RESULTS: The mean age-adjusted pure-tone average thresholds (0.5, 1.0, and 2.0 kHz) were poorer in the subjects with pAD by 5.1 dB in the right ears and 6.1 dB in the left ears; these differences were not statistically significant. Word recognition in quiet did not differ by CDR category. The age-adjusted scores on the Synthetic Sentence Identification with Ipsilateral Competing Message or Contralateral Competing Message were significantly reduced in the subjects with mild pAD. Distortion-product otoacoustic emission amplitudes and auditory brain-stem response thresholds and latencies paralleled the pure-tone threshold results and did not differ across the CDR groups. CONCLUSIONS: Central auditory dysfunction was evident in subjects with even mild cases of pAD, whereas peripheral auditory function was not different from that in age-matched control subjects. Additional research is needed to delineate the mechanisms of central auditory dysfunction and to establish the sensitivity and specificity of auditory testing in subjects with Alzheimer's disease. We recommend auditory assessment, including Synthetic Sentence Identification with Ipsilateral Competing Message or Contralateral Competing Message, for older patients in general and in particular for those in whom dementia is suspected.

Aged↗
PubMed1995

Ototoxicity of topical otomicrobial agents.

Topical antimicrobial solutions are used commonly for prevention or treatment of purulent otorrhea even though most solutions contain ototoxic agents. This study compares the cochlear and middle ear toxicity of cortisporin otic solution (COS), 0.3% gentamicin ophthalmic solution (GOS), benzalkonium chloride (0.026% and 0.05%), and 1.0% Ofloxacin, a new quinolone antibiotic. Saline 0.9% was used as a control. The agent was instilled daily for 7 days into the bulla of juvenile guinea pigs. The animals were sacrificed on the 14th day. The organ of Corti was examined using surface preparation light microscopy and scanning electron microscopy. The tympanic membrane (TM) and adjacent middle ear mucosa were examined with light microscopy. The average cochlear hair cell damage was 66% for COS, 6.5% for GOS, and 1% for Ofloxacin, benzalkonium and saline. COS and benzalkonium 0.05% produced moderate mucosal thickening and inflammation. However, this was not statistically different from the mild mucosal thickening produced by saline, GOS, Ofloxacin and 0.026% benzalkonium. There was statistically significant mild to moderate thickening of the TM for all agents compared to the saline control.

Animals↗
PubMed1994

Closure of clival cerebrospinal fluid fistula with biocompatible osteoconductive polymer.

Cerebrospinal fluid fistula into the upper airway often results in meningitis. Closure of fistulas is usually effective using conventional surgical techniques to reconstruct the defect. We report a case of cerebrospinal fluid fistula into the sphenoid sinus and nasopharynx secondary to resection of a clivus chordoma that resisted conventional attempts at closure, including a rectus abdominus free flap. Closure of the fistula was accomplished with the use of a novel alloplast, biocompatible osteoconductive polymer. Follow-up for more than 1 year shows no evidence of rejection, infection, or recurrent cerebrospinal fluid rhinorrhea.

Adult↗
PubMed1994

Does topical antibiotic prophylaxis reduce post-tympanostomy tube otorrhea?

Purulent otorrhea is the most common complication of tympanostomy tube (TT) insertion. It may occur in the postoperative period or at any time during the sojourn of the tube. The efficacy of topical antimicrobial prophylaxis against purulent postoperative otorrhea (PPO) has been examined in 5 prospective, randomized studies; all demonstrated a reduction in PPO from topical antimicrobial prophylaxis, but in only 1 study was the difference statistically significant. Because the 5 studies used 2 different experimental designs--by-patient, and by-ear--a single meta-analysis could not be done. However, the by-patient studies met the criteria for meta-analysis, which demonstrated a combined odds ratio of 0.12 (95% confidence interval 0.04 to 0.37, p = .0002). This represents an 85% reduction in otorrhea, which is judged to be clinically as well as statistically significant. We conclude from the available evidence that prophylactic use of topical antimicrobial agents following TT insertion consistently reduces the rate of PPO. However, the low incidence of PPO and the heterogeneity of the published studies prevent making a final judgment for or against the continued use of these agents. Therefore, given that these potentially ototoxic agents are frequently administered to prevent postoperative otorrhea, further study of this subject is warranted. In the meantime, we recommend judicious use of these agents following TT insertion in those cases at higher risk for PPO, namely those with mucoid or purulent effusion.

Administration, Topical↗
PubMed1994

Adenoidectomy for otitis media with effusion.

The efficacy of adenoidectomy in the surgical treatment of children with otitis media with effusion (OME) persisting after adequate medical therapy has been established in three independent randomized clinical trials. Although each of these studies used a different experimental design, all showed significant reductions in morbidity from OME after adenoidectomy as compared to the control groups. Subsequent application of these findings in formulating clinical guidelines for the use of adenoidectomy has yet to be realized, and recommendations to parents for or against the procedure appear to vary more with the surgeon's philosophy than with the condition of the child. This discussion examines the effectiveness and cost of adenoidectomy for the treatment of children with chronic OME and addresses the question of whether adenoidectomy should be used as a primary or a secondary surgical therapy. The argument is made to use adenoidectomy as a primary therapy in selected cases on the basis of patient age, type of OME, and patient preference, and to base the decision not on the size of the adenoid, but on its known pathophysiology.

Adenoidectomy↗
PubMed1994

Anatomic considerations in botulinum toxin type A therapy for spasmodic dysphonia.

Chemodenervation by injection of botulinum toxin type A into the vocal fold(s) has become the preferred treatment for patients with adductor spasmodic dysphonia. Injection may be done either perorally or transcutaneously; each method has its advocates and advantages. The authors have used the transcutaneous transcricothyroid membrane route exclusively with satisfactory results in more than 50 patients. Temporary breathliness and aspiration are common. The preferred injection site should be as close as possible to the motor end plates of the affected muscle. The thyroarytenoid muscle end plates are distributed throughout the muscle, whereas in the lateral cricoarytenoid muscle they are located in band in the center of the muscle. The transcutaneous injection site is below and posterior to the midpoint of the vibrating vocal fold as visualized by indirect laryngoscopy. The proximity of this site to the lateral cricoarytenoid muscle suggests that postinjection breathiness and aspiration may be related to spread of botulinum toxin type A to the lateral cricoarytenoid muscle. However, it is likely that thyroarytenoid muscle paresis is mainly responsible for this side effect and that the rapid clearing of the breathy dysphonia in the face of prolonged relief of spasmodic dysphonia symptoms suggests the action of an adaptive neural response, such as axonal sprouting. Further research of this subject is warranted.

Botulinum Toxins↗
PubMed1994

Distortion product otoacoustic emissions in the elderly.

Clinical interest in otoacoustic emissions (OAEs) is increasing. These can be elicited rapidly in a number of test paradigms that reflect the functional status of the outer hair cells of the organ of Corti. Distortion product otoacoustic emissions (DPOEs) have been well described in infants, and adults, but not in the elderly. The value of DPOE testing as a means of objective assessment of cochlear function is still being studied. The authors obtained DPOEs in 129 ears of 71 elderly volunteer subjects (age 56-93 yr) and in 16 ears of eight young adults (age 19-26 yr) with normal pure-tone thresholds (PTTs). The relation between DPOEs and PTTs, as expressed by the r2 statistic, was 0.18, 0.46, and 0.30 at 1, 2, and 4 kHz, respectively. Amplitudes of DPOEs did not decrease significantly with age, when adjusted for PTTs. Sensitivity and specificity, receiver operating characteristic curves, as well as posterior probabilities were analyzed to elucidate the relation between DPOEs and PTTs. At 2 kHz 90 percent of ears with PTTs 40 dB HL or less exhibited DPOEs of -4 dB SPL or greater, and all ears with PTTs greater than 40 dB HL had either no measurable DPOEs or DPOE amplitude less than 4 dB SPL.

Adult↗
PubMed1994

Determination of the position of nucleus cochlear implant electrodes in the inner ear.

Accurate determination of intracochlear electrode position in patients with cochlear implants could provide a basis for detecting migration of the implant and could aid in the selection of stimulation parameters for sound processor programming. New computer algorithms for submillimeter resolution and 3-D reconstruction from spiral computed tomographic (CT) scans now make it possible to accurately determine the position of implanted electrodes within the cochlear canal. The accuracy of these algorithms was tested using an electrode array placed in a phantom model. Measurements of electrode length and interelectrode distance from spiral CT scan reconstructions were in close agreement with those from stereo microscopy. Although apparent electrode width was increased on CT scans due to partial volume averaging, a correction factor was developed for measurements from conventional radiographs and an expanded CT absorption value scale added to detect the presence of platinum electrodes and wires. The length of the cochlear canal was calculated from preoperative spiral CT scans for one patient, and the length of insertion of the electrode array was calculated from her postoperative spiral CT scans. The cross-sectional position of electrodes in relation to the outer bony wall and modiolus was measured and plotted as a function of distance with the electrode width correction applied.

Adult↗
PubMed1993

The relation of hearing in the elderly to the presence of cardiovascular disease and cardiovascular risk factors.

Hearing loss with age (presbycusis) is a substantial problem for the elderly. To investigate the possible relation of presbycusis to cardiovascular disease (CVD), the hearing status of a cohort of 1662 elderly men and women was determined and compared with their 30-year prevalence of cardiovascular disease. Age-adjusted multivariate logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) to describe the relation of hearing to cardiovascular disease events, cardiovascular disease risk factors, and both events and risk factors separately for the 676 men and for the 996 women. Cardiovascular disease events were the sum of coronary heart disease, stroke, and intermittent claudication. Five groups of risk factors were studied: hypertension and blood pressure; diabetes, glucose intolerance, and blood glucose level; smoking status and number of pack-years of cigarettes; relative weight; and serum lipid levels, including cholesterol, triglycerides, and lipoprotein fractions. Low-frequency hearing (low pure-tone average, 0.25 to 1.0 kHz) was related to cardiovascular disease events in both genders but more in the women. For women, the OR of having any cardiovascular disease event for a low pure-tone average of 40 dB hearing level was 3.06 (95% CI, 1.84 to 5.10); for a high pure-tone average (average of 4 to 8 kHz) of 40-dB hearing level, the OR for any cardiovascular disease event was 1.75 (95% CI, 1.28 to 2.40). In men with a low pure tone average of 40-dB hearing level, the OR for stroke was 3.46 (95% CI, 1.60 to 7.45) and for coronary heart disease the OR was 1.68 (95% CI, 1.10 to 2.57).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Nerve excitability testing: technical pitfalls and threshold norms using absolute values.

Percutaneous stimulation of the facial nerve is used widely in tests to judge the severity and prognosis of facial paralysis. Several test paradigms are used including nerve excitability threshold (NET), the maximum stimulation test (MST), and electroneuronography (EnoG). Consistent technique and careful control of variables are essential to achieve accurate test results. The sources of variability examined in this study were age, gender, body weight, and the use of electrode paste; the NET was used as the test method. The facial NET in 120 adults without a history of facial paralysis increased linearly with age (P = .0004) and with body weight (P < .0001) and was higher in men than in women adjusted for age and weight (P = .0001). The mean NET +/- SD was 0.7 +/- 0.27 mA in the upper division using the eyelid twitch as an end point, and 1.2 +/- 0.40 mA in the lower division. There was no statistically significant difference in the results between sides. The NET was falsely elevated by the use of electrode paste, presumably due to current shunting away from the nerve. Based on the technique described herein, an absolute NET of > or = 1.25 mA in the upper division or an absolute NET > or = 2.0 mA in the lower division of the human facial nerve is statistically abnormal. These norms are not applicable to grossly obese patients or patients with facial edema or inflammation. Statistical norms allow the NET results to be reported on a continuous scale rather than the dichotomous scale used in the past. The predictive power of the NET will be greatly enhanced by basing test interpretation on both statistical and clinical significance.

Adult↗