Biomedical subjects

A J Fishman

Publications and source records attributed to A J Fishman.

9 recordsLinked to original sources

PubMed2000

Electrode to modiolus proximity: a fluoroscopic and histologic analysis.

HYPOTHESIS: This study was conducted to evaluate the electrode to modiolus proximity of two commonly used electrodes (Nucleus and Clarion) and a new prototype electrode. BACKGROUND: Theoretical advantages of modiolus-hugging cochlear implant electrodes include reduced stimulus energy requirements, more efficient power management and longer battery life, more discreet ganglion cell population stimulation, and reduced facial nerve stimulation. METHODS: Fluoroscopic analysis and histologic surface preparation analysis of electrode position and trauma. RESULTS: The Nucleus straight electrode occupied an outer wall position in the scala tympani. The Clarion electrode occupied a more intermediate position. The actively coiling prototype electrode was modiolus hugging but caused more trauma than the other two electrodes tested. CONCLUSIONS: The optimal modiolus-hugging atraumatic intracochlear electrode does not currently exist.

Cochlear Implantation↗

PubMed2000

Shaw scalpel in revision cochlear implant surgery.

The use of traditional electrocautery is prohibited in revision or replacement cochlear implant surgery because of the concern for end organ tissue damage. Additionally, electrical current spread to the malfunctioning device could interfere with an accurate cause-of-failure analysis. Clinical reports have confirmed the utility of the Shaw scalpel for dermatologic, ophthalmic, and head and neck surgery. The Shaw scalpel is a thermally activated cutting blade that provides a bloodless field through immediate capillary and small vessel hemostasis. Avoidance of wound and flap complications is of primary concern in cochlear implant surgery. The long-term wound healing compared favorably to that of other surgical cutting instruments in several experimental reports. We have routinely used the Shaw scalpel in revision cochlear implant surgery and in primary surgery whenever electrocautery was contraindicated. We have retrospectively evaluated 22 cases in which the Shaw scalpel was used for cochlear implant revision and primary surgery. The chart review included patient demographics, the indication for surgery, the contraindication for electrocautery, intraoperative surgical notes, the wound healing evaluation, the evaluation for alopecia, and postoperative speech understanding. No significant complications occurred intraoperatively, and the long-term wound healing results were no different from those obtained with conventional surgical techniques. The explanted devices were undamaged, and valuable diagnostic information could be obtained. All patients performed at or better than their preoperative levels on speech recognition testing. Our results indicate that the Shaw scalpel is a relatively safe, easy-to-use, and effective instrument.

Adult↗

PubMed1998

Stability of the cochlear implant array in children.

OBJECTIVE: To determine cochlear implant electrode stability in the young patient. Electrode migration due to future skull growth was a concern that led to prohibiting implantation in children less than 2 years of age. Recently, the high level of performance achieved by young implantees has led to a re-evaluation of this lower age limit, requiring an assessment of the effects of skull growth over time. STUDY DESIGN: Prospective radiographic analysis of electrode position of cochlear implants in young children. METHODS: Twenty-seven children implanted with the Nucleus (Cochlear Corp., Denver, CO) or Clarion (Advanced Bionics Inc., Sylmar, CA) multi-channel cochlear prostheses were subjects for this study. Follow-up radiographic studies were obtained for a period of 1 month to 5 years after implantation. The age at time of implantation ranged from 14 months to 5 years. An intraoperative modified Stenver's view plain radiograph was obtained as a baseline. After implantation, on a yearly basis transorbital Stenver's and base views were obtained for comparative purposes. Additional radiographs were obtained whenever a change in performance or electrode map caused suspicion for extrusion. Electrode position was determined using a computer graphics enhancement technique whereby image contrast filters enhanced the visibility of the electrode array and surrounding bony structures. RESULTS: An analysis of the data revealed no migration of the electrode array over time. CONCLUSIONS: The confirmation of the stability of the electrode array alleviates the concern of the effects of skull growth on cochlear implantation in young children.

Child, Preschool↗

PubMed1996

Database for sensorineural hearing loss.

We are creating a bank of EBV immortalized lymphoblast cells and extracted DNA taken from the blood of deaf children and their relatives, in order to study the molecular basis of hereditary deafness. We have established a corresponding database for sensorineural hearing loss that records clinical data for each entered specimen. The purpose of this paper is to present the content and design of the computerized relational database. The data model is designed first to identify known etiologies of deafness, either acquired or syndromic, and then to characterize the clinical features of the deaf individual, and both their affected and non-affected family members. The application operates in a graphical environment of visual prompts and message panels. The database is organized by sections which record demographic data, presenting complaints, otologic history, birth and perinatal history, developmental history, symptoms of chronic airway obstruction, family history, neurologic history, congenital infections, hospitalizations and surgical history, medication history, vestibular findings, audiometry, radiology, medical conditions and syndromes and physical examination. The database was developed on a commercially available software product. Our database is presented as a model for use by other clinicians and investigators.

Airway Obstruction↗

PubMed1996

Cerebrospinal fluid drainage in the management of CSF leak following acoustic neuroma surgery.

A retrospective analysis was performed on 174 patients operated on from 1992 to 1995 to evaluate the safety and efficacy of continuous lumbar cerebrospinal fluid drainage (CLCFD) in the management of cerebrospinal fluid (CSF) leaks following acoustic neuroma surgery. There was a 17% incidence of CSF leak. CLCFD stopped the leak in 87% of cases. There were no cases of meningitis associated with CLCFD. One deep vein thrombosis was treated without sequelae. It is concluded that CLCFD is safe and efficacious. The authors recommend that CLCFD be implemented immediately when indicated, foregoing a trial of conservative therapy. Indications and precautions are discussed.

Cerebrospinal Fluid↗

PubMed1992

Regional perfusion, oxygen metabolism, blood volume and immunoglobulin G accumulation at focal sites of infection in rabbits.

Infection causes remarkable changes in extracellular fluid volume, blood flow and oxygen consumption in the region of the lesion. To determine the sequence and magnitude of these changes, we performed serial scintigraphic measurements in 10 rabbits with experimental Escherichia coli abscesses. Positron emission tomography with C15O2, 15O2 and 11CO was used to measure regional blood flow, oxygen extraction (OEF) and blood volume; extracellular fluid volume was evaluated by single photon scintigraphy with indium-111 immunoglobulin G (IgG). Images were recorded following tracer administration at 1 and 7-10 days after infection. At the first imaging time, blood flow to infected muscle had increased by 40% compared with control sites (7.4 +/- 0.6 to 10.8 +/- 3.8 ml/min.100 g), OEF had decreased from 55% +/- 34% to 45% +/- 14%, and the infected-to-contralateral (I/C) ratio of IgG had increased to 3.34 +/- 1.85. At the later imaging time, flow had increased by almost threefold compared with day 1 (29.4 +/- 9.8 ml/min.100 g), OEF had decreased to 29% +/- 14%, and the I/C ratio for IgG had remained constant. Although OEF fell, oxygen delivery (OEF x flow) increased from 4.07 ml/min (control value) to 4.86 ml/min on day 1 and 8.64 ml/min on days 7-9. The infected-to-contralateral (IC) ratio of 15O2/C15O2 was 0.74 +/- 0.15 on day 1 and 0.77 +/- 0.10 at 7-9 days. These studies indicate that expansion of the extracellular fluid volume increases early in the evolution of the infection and exceeds changes in regional perfusion and oxygen delivery.

Animals↗

PubMed1992

Comparison of technetium-99m-glucarate and thallium-201 for the identification of acute myocardial infarction in rats.

The scintigraphic identification of acute severe ischemic myocardial injury requires a marker that localizes rapidly and specifically in zones of damaged myocardium. Technetium-99m-glucarate, a six-carbon dicarboxylic acid, which behaves in vivo somewhat like fructose, was recently described as a marker of severe acute ischemic injury with necrosis. This study was performed to determine the interval between the onset of myocardial ischemia and initial uptake and the duration of a positive scan in experimental animals. Serial injections and images were recorded over 10 days following ligation of the left anterior descending coronary artery of the rat. The distribution of 99mTc-glucarate was compared to that of regional myocardial perfusion monitored with 201TI. The findings on radionuclide imaging were compared to histologic changes in the myocardium. Sequential pinhole images of both radionuclides were collected at 3 hr, 24 hr, 72 hr and 7-10 days following ligation. Ten rats had normal 201TI distributions, no uptake of glucarate and no evidence of infarction by TTC staining at autopsy. Twenty-one rats had either 201TI lesions or evidence of infarction at autopsy. In 17 of these rats, significant acute 99mTc-glucarate uptake was noted, decreasing at 24 hr, and was not seen at 72 hr or 7-10 days. The extent of perfusion abnormality was greatest at 3 hr in most animals; the lesion decreased in four (33%), increased in one (8%) and remained stable in the remainder. These data suggest that 99mTc-glucarate may be a useful marker of acute myocardial injury.

Animals↗

PubMed1983

Perfusion lung scans vs pulmonary angiography in evaluation of suspected primary pulmonary hypertension.

A retrospective review of 15 patients with angiographically- or biopsy-documented primary pulmonary hypertension was performed to assess the value of pulmonary perfusion scanning in noninvasively differentiating these patients from those with potentially operable, chronic (large-vessel) thromboembolic pulmonary hypertension. None of the 15 patients with primary pulmonary hypertension demonstrated a segmental or larger perfusion defect whereas such defects have been uniformly present in previous reports of patients with large-vessel thromboembolic pulmonary hypertension. While perfusion scans in primary pulmonary hypertension may show certain abnormalities, the presence of segmental or larger perfusion defects should suggest the diagnosis of potentially correctable, large-vessel thromboembolic pulmonary hypertension rather than small-vessel, obliterative (primary, idiopathic) pulmonary hypertension.

Adolescent↗

PubMed1982

Cornea plana: a case report.

A case of cornea plana with its typical clinical findings has been presented along with ultrasonographic documentation confirming the axial length of the globe to be normal in this condition. It is presented to draw attention to the clinician that although cornea plana is rare, it should be considered in the differential diagnosis of a patient with small eyes or suspected microcornea.

Aged↗