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Biomedical subjects

D B Hawkins

Publications and source records attributed to D B Hawkins.

At least 55 records · Page 3Linked to original sources
PubMed1985

Pilomatrixoma of the head and neck in children.

Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a benign tumor of hair cell origin. It is an unusual, but not particularly rare, tumor. Fifty percent or more of pilomatrixomas occur in the head and neck, and 40% occur in patients under 10 years of age. Pilomatrixomas may be mistaken for cysts, calcified lymph nodes, calcified hematomas or hemangiomas, or parotid gland tumors. We describe our experience with 15 children, 1 1/2-12 years of age, in whom we have excised pilomatrixomas from the head and neck.

Child↗
PubMed1985

Some effects of FM-system coupling on hearing aid characteristics.

A variety of electroacoustic characteristics was measured on four hearing aids and then repeated with the hearing aids connected to two different FM systems via three coupling methods: direct input, neck loop, and silhouette inductor. The measurements included frequency response, harmonic distortion, noise levels, input-output functions, and FM receiver volume control wheel taper curves. Omnidirectional and directional FM microphones were compared in a classroom environment, and minor changes in hearing aid-silhouette coupling were investigated. Large differences were found in some frequency response comparisons, with no single coupling method providing consistently better agreement with the hearing aid alone response. With the exception of the silhouette inductor, distortion and noise levels were similar for the hearing aids and FM-hearing aid combinations. Differences in the input-output functions between the hearing aids and the FM systems were observed. Some FM-hearing aid combinations produced very nonlinear FM receiver volume control wheel taper curves. The output level of a broadband noise in a classroom was reduced when a directional FM microphone was compared to the omnidirectional version. The results indicate that it cannot be assumed that the electroacoustic characteristics of a personal hearing aid are preserved when it is connected to an FM system.

Acoustics↗
PubMed1985

Lateral sinus thrombosis: a sometimes unexpected diagnosis.

Lateral sinus thrombosis, a frequent complication of ear infections in preantibiotic days, is seldom seen today. When it does occur, it is usually in a patient with a known history of a chronic ear infection. Two patients are described with septic pulmonary emboli from inapparent lateral sinus thrombosis. Lateral sinus thrombosis should be suspected in any patient with chills, fever, neck pain, and septic pulmonary emboli.

Adolescent↗
PubMed1985

An unusual case of laryngeal scleroma.

An unusual case of nasal and laryngeal scleroma is presented. Laryngeal scleroma should be included in the differential diagnosis of obstructing lesions of the supraglottic airway. The immunoperoxidase staining method is useful in establishing the diagnosis in cases of equivocal culture and histopathologic appearance. It can further be used as an objective test to determine the effectiveness and duration of antibiotic therapy.

Adolescent↗
PubMed1984

Signal-to-noise ratio advantage of binaural hearing aids and directional microphones under different levels of reverberation.

The signal-to-noise ratio necessary for a constant performance level was determined for normally hearing and hearing-impaired subjects under three levels of reverberation (0.3, 0.6, and 1.2 s) with monaural and binaural hearing aids having directional and omnidirectional microphones. Results indicated (a) a significant binaural advantage (2-3 dB) which was independent of microphone type and reverberation time, (b) a significant directional microphone advantage (3-4 dB) which was independent of hearing aid arrangement (monaural or binaural) but dependent on level of reverberation, (c) a significant reverberation effect which was larger than either the binaural or directional microphone effect, and (d) additive binaural and directional microphone advantages. The results suggest that the signal-to-noise ratio is optimized when binaural hearing aids with directional microphones are used in rooms with short reverberation times.

Acoustics↗
PubMed1984

Comparisons of speech recognition in noise by mildly-to-moderately hearing-impaired children using hearing aids and FM systems.

Four hearing aid arrangements (monaural-omnidirectional, monaural-directional, binaural-omnidirectional, binaural-directional) and a number of FM system-personal hearing aid combinations (including direct input, neck loop, and silhouette inductor--monaural and binaural--and environmental microphone on and off) were evaluated in a school classroom on nine children with mild-to-moderate sensorineural hearing losses. Two measures of speech recognition in noise were employed. First, the signal-to-noise ratio (S/N) yielding 50% identification of spondees was determined using a simple up-down adaptive procedure. Second, word recognition scores were obtained for three amplification arrangements at two different S/Ns (+6 and +15 dB). The average FM advantage over a personal hearing aid was equivalent to a 15-dB improvement in S/N. Activation of the hearing aid microphone caused most of the FM advantage to disappear. The benefit offered by the FM system decreased as the environmental S/N increased but remained significant even at +15 dB. Significant improvement also was found with the use of directional as compared to omnidirectional microphones, both in the hearing aids and FM teacher microphone.

Acoustics↗
PubMed1984

Corticosteroid management of airway hemangiomas: long-term follow-up.

Nine children with airway obstructing hemangiomas were managed with corticosteroid therapy for durations of 6 weeks to 17 months. One patient required a tracheotomy. Steroid therapy improved the airways of the other 8 patients. Therapy was continued for 8 months or longer in 6 patients, none of whom developed life-threatening infections. Examinations 1 1/2 to 7 1/2 years after therapy revealed all of the patients to be within normal range for height and weight, but 3 of the 6 patients treated for 8 months or longer were in the lower range of normal. Steroid therapy is an effective method of protecting the airway in some patients with hemangiomas. Its disadvantage is that therapy may be necessary for several months. The risk of infections and growth suppression is minimized by using small maintenance dosage and alternate day therapy.

Adrenal Cortex Hormones↗
PubMed1983

Mastoid subperiosteal abscess.

Subperiosteal abscess was the indication for surgery in every child with acute mastoiditis who underwent mastoidectomy at our institution since 1972. Nineteen such patients are discussed herein. Positive bacteriologic findings included Streptococcus pyogenes in three patients, Streptococcus pneumoniae in three patients, Mycobacterium tuberculosis in two patients, and enterococcus in the one patient with cholesteatoma. Cultures were more often positive for causative bacteria when taken directly from the abscess before or shortly after beginning antibiotic therapy.

Abscess↗
PubMed1983

Acute mastoiditis in children: a review of 54 cases.

Fifty-four children with acute mastoiditis were managed at the Los Angeles County-University of Southern California Medical Center from 1972 through 1982. Our criteria for the diagnosis of acute mastoiditis are acute or subacute otitis media, postauricular swelling and erythema, protrusion of the auricle, and clouding of mastoid air cells on radiographs. Thirty-one (57%) recovered with conservative therapy consisting of early myringotomy and intravenous antibiotic, usually ampicillin. Twenty-three patients were managed surgically. The indication for surgery in each case was the clinical diagnosis of subperiosteal abscess; mastoid radiographs played no part in the decision to operate. Two of the 23 patients managed surgically had only incision and drainage of abscess; simple mastoidectomy was performed on 20 and radical mastoidectomy on one. Etiologic bacteria were cultured in 21 instances, S. pyogenes was cultured in 9, S. pneumoniae was cultured in 6, H. influenzae in 1, enterococci in 1, anaerobes in 2, and M. tuberculosis in 2.

Acute Disease↗
PubMed1983

Corticosteroids in airway management.

Adrenal corticosteroids exert a strong suppressive influence on the basic inflammatory response that leads to tissue swelling. The corticosteroid effect is nonspecific. In upper airway obstruction caused by edema from infection, allergy, or trauma, corticosteroids will exert some degree of suppressive effect. The steroid effect is local and directly proportional to the concentration of steroids in the inflamed tissue. In upper airway obstruction steroids should be delivered to the inflamed tissue in high concentration with the least delay. Dexamethasone and methylprednisolone produce high blood levels within 15 to 30 minutes of intramuscular injection. Recommended initial doses for acute airway obstruction are dexamethasone, 1.0 to 1.5 mg/kg, or methylprednisolone, 5 to 7 mg/kg. The risk of harm from steroid therapy of 24 hours or less is negligible.

Airway Obstruction↗
PubMed1982

A comparison of functional gain and 2 cm3 coupler gain.

The amount by which individual functional gain differed from 2 cm3 coupler gain for a single wide-band hearing aid was determined empirically for 20 hearing-impaired adults. Both occluding and non-occluding earmold fittings were evaluated. The amount of this difference accounted for by known measurement differences, such as coupler, real-ear response differences, earmold differences, and sound field pressure differences between the eardrum and hearing aid microphone location, was also established. While it was found that accounting for the known major measurement differences resulted in a reasonable estimate of median differences between measurements of functional gain and measurements of gain in a 2 cm3 coupler, individual variability was quite high.

Acoustics↗
PubMed1982

Electroacoustic characteristics of personal FM systems.

Electroacoustic characteristics of various personal FM system configurations were obtained through the use of a Zwislocki ear simulator and KEMAR. Saturation Sound Pressure Level 90 and frequency response curves were obtained with different hearing aids in the microphone mode and then compared to the response obtained when the hearing aids were coupled to a FM receiver via neck loops and direct input. In addition, hearing aid orientation to and distance from the loop, clothing effects, internal noise levels, FM receiver volume control taper, and the effect of different FM receivers were investigated. The results indicated substantial microphone-teleloop response differences. Only minor differences were observed in the microphone-direct input comparison. Other variables were found that significantly affect the use of these personal FM systems. The results are discussed in terms of the implications for clinical use.

Acoustics↗
PubMed1982

Overamplification: a well-documented case report.

A well-documented case report is presented in which the use of a high-output hearing aid over a 10-year period resulted in significant threshold shifts in the aided as compared to the unaided ear. At no time did the user experience loudness discomfort and she consistently wanted more gain from the hearing aid, indicating that there is no relationship between loudness discomfort levels and the sound pressure levels at which damage to the auditory system occurs. Difficulties in detecting the cause of the threshold shifts and recommendations for case management are discussed.

Adult↗
PubMed1982

Cysts of the thyroglossal duct.

Experiences with 53 consecutive patients undergoing surgical excision of thyroglossal duct cysts are reported. Four patients (7.5%) developed recurrent cysts after surgery. Analysis of cases revealed the following factors to contribute to an increased risk of recurrence: young age, skin involvement by the cyst, lobulation of the cyst, rupture of the cyst, and failure to follow the second principle advocated by Sistrunk.

Adolescent↗