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Biomedical subjects

D J Lilly

Publications and source records attributed to D J Lilly.

At least 19 recordsLinked to original sources
PubMed2000

Functional hemispherectomy: radical treatment for Rasmussen's encephalitis.

Rasmussen's encephalitis is a progressive, debilitating disease that usually appears in the pediatric population but also may affect adults. Uncontrolled seizures, cognitive decline, and a progressive hemiparesis accompany this disorder. Treatment options are limited and consist of medical management, which is somewhat experimental and ineffective; the use of either intravenous antiviral agents or steroids; or surgical resection of the affected hemisphere. Patients undergoing hemispherectomy for Rasmussen's encephalitis are complex. Nurses caring for these patients require a high degree of knowledge and specialized skills. Patient outcome is highly affected by the knowledge and skill of the entire team of healthcare professionals needed to manage these patients.

Adult↗
PubMed1992

Tympanic electrocochleography: normal and abnormal patterns of response.

Electrocochleography has been widely used in human and animal studies of endolymphatic hydrops. A variety of response patterns have been reported in normal and hydropic ears. Recent clinical studies have focused almost exclusively on the amplitude ratio of the summating potential (SP) and action potential (AP) derived from alternating polarity click responses. In this report normal response patterns are described with a tympanic membrane electrode employing condensation, rarefaction and alternating polarity clicks and tone burst stimulation. A variety of response abnormalities are described in patients with suspected endolymphatic hydrops. The exclusive use of alternating polarity clicks is not adequate to reveal the nature of these abnormalities.

Acoustic Stimulation↗
PubMed1992

Surgical management of perilymphatic fistulas: a Portland experience.

A comprehensive review of our series of surgical perilymphatic fistula (PLF) repairs, as well as a review of published results from other otologists, suggested an unacceptably high rate of postoperative PLF recurrence. Some recurrences were related to specific events (i.e., coughing, strenuous activity, Valsalva-type maneuvers). However many cases had no apparent cause. Rather, the patients' symptoms recurred spontaneously, and at reoperation the graft was seen to have not "taken," suggesting graft failure rather than "patient failure." After a critical evaluation of current PLF surgical procedures and state-of-the-art concepts of wound healing, we developed a new surgical technique for PLF closure. Combining the use of laser graft-site preparation, an autologous fibrin glue "buttress," and a program of postoperative activity restriction, the new procedure allowed us to achieve statistically significant improvements in graft retention and surgical outcome, with recurrences dropping from 27 percent to 8 percent. In addition, complete resolution or significant symptomatic improvement occurred in 89 percent of patients with vertigo and/or dizziness and in 84 percent with disequilibrium. We conclude that this new surgical technique is an important addition to the otologic surgeon's arsenal for PLF management.

Adolescent↗
PubMed1991

Surgical management of perilymph fistulas. A new technique.

A wide range of recurrence rates (21% to 47%) for perilymph fistula repairs have been reported in the otology literature. An improved surgical technique developed at the Portland (Ore) Good Samaritan Hospital and Medical Center Neurotology Department was used to repair perilymph fistulas in 58 patients from October 1986 to October 1988. Our recurrence rate was reduced from 27% in a 1982-1985 study to 8% in our study. At 1 year postoperatively, improvements in disequillibrium, dizziness, and vertigo were comparable with results of older surgical techniques. Functional outcomes were also good: 83% of patients returned to normal activities of daily living, and 71% also returned to school or resumed gainful employment outside the home.

Adolescent↗
PubMed1990

The dynamic posturographic pressure test for the presumptive diagnosis of perilymph fistulas.

A diagnosis of perilymph fistulas (PLFs) can be made only by identification of repeated accumulation of crystal-clear fluid from an otic capsule defect or labyrinthine window at tympanotomy. It would be highly desirable to base a decision to operate for the diagnosis and management of PLFs on a database that includes quantitative test data, which confirms, with a high probability, a clinical suspicion of PLF. This article reviews progress in the development of a test of the vestibular response to external auditory canal pressure changes as recorded by dynamic posturography. Based on results to date, it appears that a fistula test with dynamic posturography is more sensitive than those based on VOR responses. This may be due to the ability of dynamic posturography to isolate vestibular from both visual and somatosensory influences on motor responses during external canal pressure changes.

Ear Diseases↗
PubMed1987

Quantitative diagnostic test for perilymph fistulas.

Clinically, the definitive diagnosis of perilymph fistulas can only be made by tympanotomy. Results of various fistula tests based upon the vestibulo-ocular reflex have not correlated well with findings during tympanotomy. A new fistula test has been developed based upon vestibulo-spinal responses. By systematic removal of both visual and support-surface orientation references from the subject--leaving only vestibular control of postural reflexes--patients with perilymph fistulas demonstrated an increased (sometimes phase-locked) postural sway in response to sinusoidal changes in external auditory canal pressures. Results from 100 consecutively operated ears (64 patients)--77 of whom underwent preoperative and postoperative moving-platform fistula tests--indicate that the test sensitivity is 97 percent for this highly selective patient population. Absolute specificity could not be determined because, on patients without clinical indications for surgery, tympanotomy is contraindicated.

Adolescent↗
PubMed1985

Facial electroneurography: clinical and experimental investigations.

Facial electroneurography (ENoG) appears to be a reliable prognostic test for intratemporal facial nerve paralysis. ENoG is objective and allows a permanent record to be maintained. Nonetheless, occasional inconsistencies in clinical correlation may diminish the utility of ENoG. A qualitative study was undertaken to identify the possible reasons for the inaccuracy of ENoG in some patients. Four clinical groups and one experimental group were studied: (1) normal subjects, (2) patients with acute facial palsy, (3) patients with progressive facial palsy, (4) patients with temporal bone tumors and normal facial function, and (5) animals in which one facial nerve was crushed and repaired. The reliability of ENoG is dependent on careful interpretation of data obtained by optimal electrode placement and stimulus duration.

Animals↗
PubMed1984

Otosclerosis in a black child: diagnostic acoustic impedance studies.

Otosclerosis classically describes an osteodystrophic change in the bony labyrinth and stapes footplate, of autosomal dominant inheritance, reported rare under the age of 5, extremely "rare" in the Oriental and Black race, "non-existent" in the American Indian, and with a clinical incidence of 5 per 1000 Caucasians. The differential diagnosis of a non-effusion conductive hearing loss in a child should include otosclerosis, congenital malleus or footplate fixation, tympanosclerotic fixation, congenital cholesteatoma, lysis of the incus long process, Paget's disease, osteogenesis imperfecta, and fibromuscular hyperplasia of the renal artery. Presented is a case report of a 14-year-old black male with bilateral clinical otosclerosis and a persistent stapedial artery. Preoperative multiple-frequency tympanometry and Zwislocki acoustic reactance and resistance analysis demonstrated absence of the "W" resonance pattern on high-frequency tympanometry and the classic friction and stiffness patterns of otosclerotic fixation. Repeat multiple-frequency tympanometry testing post-stapedectomy demonstrated prosthesis articulation. Prosthesis position can be monitored postoperatively by these acoustic impedance studies.

Acoustic Impedance Tests↗
PubMed1984

Fentanyl anesthesia and human brain-stem auditory evoked potentials.

The effect of incremental doses of fentanyl on brain-stem auditory evoked potentials (BAEPs) was studied in 10 patients scheduled for elective surgery. Seven sets of BAEPs were recorded in each patient starting the day before surgery, after premedication and after 10 micrograms/kg increments of fentanyl up to 50 micrograms/kg. No significant effect on either absolute or interpeak latencies of wave I, III, and V of evoked potentials was observed.

Adult↗
PubMed1984

Ototoxic and nephrotoxic effects of combined treatment with cis-diamminedichloroplatinum and kanamycin in the guinea pig.

Ototoxic and nephrotoxic potentiation with concomitant cis-diamminedichloroplatinum, or cis-platinum II (CSP), and aminoglycoside therapy was investigated in the guinea pig. We evaluated possible potentiation of the toxic effects of CSP and kanamycin compared with CSP alone in the inner ear and kidney and quantitatively localized CSP in the cochlea with gamma emission analysis of 195mPt. Kanamycin-treated animals demonstrated cytocochleograms and ABR waveforms, absolute latencies, and interwave latencies for waves I, II, and III similar to control animals at our maximum level of acoustic stimulation. CSP treatment produced 60% to 70% mean outer hair cell (OHC) loss in the basal turn of the cochlea, a reduction in ABR waveform and amplitude, and an increase in latencies of ABR waves I, II, and III. Combined CSP and kanamycin treatment produced 90% to 100% mean OHC loss in all rows of the basal turn of the cochlea, with no discernible ABR waveform corresponding to the region stimulated by a 4500 to 7000 Hz acoustic click. Combined treatment produced the most significant cortical medullary tubular necrosis and interstitial nephritis. Furthermore, this study reports for the first time localization of platinum in the inner ear.

Acute Kidney Injury↗
PubMed1984

Acoustic-reflex adaptation: morphology and half-life data for subjects with normal hearing.

Acoustic-reflex adaptation was studied in 35 subjects with normal hearing using nine pure-tone activators (250-6000 Hz) and a broadband-noise activator. The individual subject data generated by the 31-s activators presented 10 dB above the reflex threshold were digitized, corrected for baseline drift and ear canal volume, and analyzed in terms of the acoustic-admittance change in acoustic mmhos and in terms of the percentage of maximum-reflex magnitude. Reflex adaptation increased as a function of frequency. The adaptation functions for the lower frequencies (less than or equal to 1500 Hz) were essentially linear over the 31-s activator period, whereas the functions for the higher frequencies (greater than or equal to 2000 Hz) were curvilinear over the activator period. The experimental half-life data are compared with a theoretical half-life function that was generated to estimate normal acoustic-reflex adaptation as a function of activator frequency. Finally, the means and standard deviations are reported and discussed for (a) the onset time of adaptation, (b) the half-life time, and (c) the percentage of maximum reflex magnitude at 5-s intervals from 5 to 30 s.

Acoustic Stimulation↗
PubMed1981

An evaluation of tympanometric estimates of ear canal volume.

The accuracy of tympanometric estimates of ear canal volume was evaluated by testing the following two assumptions on which the procedure is based: (a) ear canal volume does not change when ear canal pressure is varied, and (b) an ear canal pressure of 200 daPa drives the impedance of the middle ear transmission system to infinity so the immittance measured at 200 daPa can be attributed to the ear canal volume alone. The first assumption was tested by measuring the changes in ear canal volume in eight normal subjects for ear canal pressures between +/- 400 daPa using a manometric procedure based on Boyle's gas law. The data did not support the first assumption. Ear canal volume changed by a mean of .113 ml over the +/- 400 daPa pressure range with slightly larger volume changes occurring for negative ear canal pressures than for positive ear canal pressures. Most of the volume change was attributed to movement of the probe and to movement of the cartilaginous walls of the ear canal. The second assumption was tested by comparing estimates of ear canal volume from susceptance tympanograms with a direct measurement of ear canal volume adjusted for changes in volume due to changes in ear canal pressure between +/- 400 daPa. These data failed to support the second assumption. All tympanometric estimates of ear canal volume were larger than the measured volumes. The largest error (39%) occurred for an ear canal pressure of 200 daPa at 220 Hz, whereas the smallest error (10%) occurred for an ear canal pressure of -400 daPa at 660 Hz. This latter susceptance value (-400 daPa at 660 Hz) divided by three is suggested to correct the 220-Hz tympanogram to the plane of the tympanic membrane. Finally, the effects of errors in estimating ear canal volume on static immittance and on tympanometry are discussed.

Acoustic Impedance Tests↗
PubMed1980

Temporal characteristics of auditory adaptation: a case report.

Auditory-adaptation, or tone-decay, measurements are reported for a patient with an 8th-nerve tumor in the left ear and a sensorineural hearing loss of cochlear origin in the right ear. Data for the patient suggested that the temporal features of auditory adaptation were more effective in differentiating adaptation processes for the two ears and associated lesions than was the magnitude classification of auditory adaptation in dB for the two ears. It is recommended that tests of auditory adaptation include an analysis of the temporal characteristics of the adaptation process.

Audiometry↗
PubMed1980

Magnitude of the acoustic reflex for either homophasic (0 degrees) or antiphasic (180 degrees) binaural activating signals presented in a background of noise.

The threshold of the acoustic reflex (TAR) and the magnitude of middle-ear muscle response were measured for a homophasic (0 degrees) and an antiphasic (183 degrees) 550-Hz tone in a background of in-phase noise. Signal-to-noise ratio ranged from - 20 dB to 5 dB. Whereas previously reported data shows an effect of phase on the percept of loudness, no evidence of a phase effect was measured for acoustic-reflex responses. These results are interpreted as evidence against a relation between loudness and acoustic reflex for binaurally presented signals.

Acoustic Stimulation↗
PubMed1980

Effect of signal bandwidth upon threshold of the acoustic reflex and upon loudness.

The effect of activating-signal bandwidth upon the threshold of the acoustic reflex (TAR) was measured. Subsequently, loudness measurements were made for the same signals at the same intensity levels that were required to elicit an acoustic-reflex response. When loudness and TAR are compared at comparable levels, similar trends emerged. Results from this experiment provide evidence for both qualitative and quantitative similarities between acoustic reflex and the perception of loudness. This, in turn, suggest that signals at TAR may be equally loud for listeners with normal hearing.

Acoustic Stimulation↗
PubMed1976

Time-intensity trade for speech: a temporal speech-Stenger effect.

Time-intensity trade for selected spondaically stressed words was investigated using a centering method for interaural time delays of 0.00, 1.00, 2.00, 2.25, 2.50, and 2.75 msec at five levels of presentation: 0-, 25-, 40-, 55-, AND 70-DB HL (ANSI, 1969). Lateralization effects increased with level of presentation, with a maximum lateralization effect of between 22 and 30 dB occuring with an interaural time delay of 2.25 msec. Multiple images were perceived by all subjects with an interaural time delay of 2.75 msec and by some subjects with an interaural time delay of 2.50 msec at high levels of presentation. No "ear effect" was observed for any of the listeners. A potential clinical application is discussed for this temporal speech-Stenger effect.

Adult↗