Biomedical subjects

C D Abernathey

Publications and source records attributed to C D Abernathey.

8 recordsLinked to original sources

PubMed1992

Utilization of image-derived computer-assisted stereotaxis in a community-based practice setting.

The success of a community-based stereotactic program is dependent upon community commitment, technological capability, referral base, patient/family support and, most importantly, proper patient selection. To develop a program of superior quality requires not only a substantial financial commitment, but also a basic philosophical approach which fully supports acquisition and education of support staff, physical plant renovation and an establishment of an expanding referral base. This report details the development of a highly sophisticated stereotactic program in Cedar Rapids, Iowa, a semirural community with a base referral population of approximately 300,000.

Brain Diseases↗

PubMed1989

Microneurosurgical treatment of intracranial dermoid and epidermoid tumors.

Forty-three patients with intracranial, intradural dermoid (8) and epidermoid (35) tumors underwent radical surgical resection utilizing strict microneurosurgical technique. The average age was 37.3 years for the patients with epidermoid tumors and 36.2 years for the patients with dermoid tumors. The male to female ratio was 3:2 for the epidermoid group and 3:1 for the dermoid group. Common clinical presentations included cerebellar dysfunction, cranial nerve impairment, and seizures. Typically, computed tomography scans revealed the epidermoid tumors (30 cases studied) as nonhomogeneous hypodense lesions with irregular borders and without contrast enhancement. The dermoid tumors (7 cases studied) had a similar appearance, but with a wider range of attenuation values. Magnetic resonance imaging findings for the epidermoid tumors (6 cases studied) consisted of increased T1 and increased T2 relaxation times. Supratentorial tumors were excised by the pterional (frontosphenotemporal) approach, mesencephalic tumors by either a supratentorial posterior interhemispheric transtentorial approach or an infratentorial/supracerebellar method, and posterior fossa tumors by either a medially or laterally positioned suboccipital osteoplastic craniotomy. One epidermoid tumor and one dermoid tumor were considered to be subtotally resected because of dense adherences left attached to vital structures; the remaining 41 tumors were completely excised. The most frequent complications were aseptic/chemical meningitis and transient cranial nerve palsies. There were no perioperative deaths. Mean follow-up was 5.2 years. Eighty-six percent of patients reported good to excellent results. No patient had experienced symptomatic or radiographic evidence of recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1989

Colloid cysts: experience with the management of 84 cases since the introduction of computed tomography.

A retrospective review of colloid cysts diagnosed from 1974 to 1986 emphasizes the presenting symptoms of these lesions, their surgical management, and the contribution of modern imaging techniques to their diagnosis and therapy. In this 12-year period, 84 patients (45 men and 39 women) had a colloid cyst diagnosed. The patients' mean age was 46 years (range, 7-82 years). Surgery was performed in 55 patients, 7 of whom had undergone prior surgery elsewhere. The surgical approaches used were transfrontal-transventricular, transcallosal, computer-assisted stereotactic aspiration and resection by stereotactic craniotomy, and shunting of cerebrospinal fluid without removal of the lesion. There was no operative mortality, but complications occurred in 15 patients (27%). Preoperative imaging showed hydrocephalus in 93% of the patients: severe in 43%, moderate in 36%, and mild in 14%. In the surgically treated group, the most common presenting symptoms were headache, change in mental status, ataxia, nausea and vomiting, visual disturbance, emotional lability/inappropriate affect, depersonalization, and hypersomnolence. Twenty-four patients for whom surgery was not recommended are being followed up closely. Most of these patients had normal ventricles. The symptoms in this group included headache, anxiety/nervousness, ataxia, memory impairment, visual disturbance, and seizures. Five autopsy cases of patients with colloid cysts were available during this period and were reviewed. Direct removal of colloid cysts can be accomplished with low morbidity and mortality, avoiding the frequent revisions and complications related to shunt procedures. There is a subgroup of colloid cysts that can be operated upon electively or followed up closely with serial imaging studies.

Adolescent↗

PubMed1989

Stereotaxic suboccipital transcerebellar biopsy of pontine mass lesions.

Twenty-six patients (16 male and 10 female) ranging in age from 5 to 68 years underwent suboccipital transcerebellar stereotaxic biopsy of mass lesions situated in the pons. Stereotaxic computerized tomography, magnetic resonance imaging, and angiographic data were obtained while the patient was positioned in an inverted custom stereotaxic head frame. The patients were then placed under general endotracheal anesthesia and positioned prone. Optimal trajectory planning utilized a transcerebellar route directed through the middle cerebellar peduncle, with target and entry points calculated to avoid vascular structures. No complications were encountered in the perioperative period when this technique was used. Histological diagnosis of the lesions revealed: astrocytomas in 14 patients, oligodendroglioma in one, ependymoma in one, arteriovenous malformations in two, radionecrosis in one, cryptococcal abscess in one, demyelinating disease in three, and infarctions in three. No consistent correlation could be made between radiographic characteristics and histological diagnoses. Empiric treatment of brain-stem lesions without tissue diagnosis based upon the radiological and clinical findings may result in inappropriate therapy administration. Alternatively, open operative procedures to obtain tissue require a visible surface abnormality to guide biopsy, and carry the risks of a major surgical procedure in already compromised patients. For these reasons the authors consider a suboccipital transcerebellar stereotaxic biopsy to be the diagnostic procedure of choice in the assessment of pontine mass lesions.

Adolescent↗

PubMed1989

Treatment of colloid cysts of the third ventricle by stereotaxic microsurgical laser craniotomy.

The therapeutic strategies employed in the management of anterior third-ventricular mass lesions remain controversial. Resection by conventional craniotomy, whether via a transcallosal or transcortical approach, carries well-known risks and limitations. Alternatively, in this region traditional stereotaxy has been relegated to use with biopsy only or cyst aspiration procedures. Combining aspects of both conventional and stereotaxic techniques has allowed total removal of 12 colloid cysts in six women and six men ranging in age from 25 to 71 years. No mortality and minimal morbidity have been associated with the procedures. There has been no evidence of recurrence in an average follow-up period of 19 months. By coupling the benefits of stereotaxic precision and localization to the microsurgical management of colloid cysts, several rewards have been realized: 1) only a limited cortical dissection is needed; 2) the hazards of callosal or forniceal injury can be avoided; 3) the lesion is easily localized regardless of ventricular size; 4) hemostasis can be readily achieved with bipolar cautery or defocused laser power; and 5) most importantly, a total resection is possible with little risk to the patient. Stereotaxic microsurgical laser craniotomy provides a new option for the management of colloid cysts and other anterior third-ventricular lesions.

Adult↗

PubMed1988

New xenograft model for assessing experimental therapy of central nervous system tumors: human glioblastoma in the intrathecal compartment of the nude mouse.

Ten congenitally athymic "nude" mice and 10 immunocompetent mice underwent intrathecal inoculation with a human glioblastoma cell line (U87MG) via percutaneous lumbar puncture (5 x 10(5) cells/animal). All of the nude mice developed paraplegia with or without incontinence at 2 weeks and routinely died of inanition 3 weeks postimplantation. Histological examination confirmed extensive proliferation of neoplastic cells within the intrathecal space. A second group of animals was inoculated with 5 x 10(4) cells/animal: 20 nude mice, 10 cyclosporine A-immunosuppressed animals, and 10 immunocompetent control mice. The 20 mice were further divided into four subsets. Subset A did not receive chemotherapy, Subset B received 200 mg of carmustine (BCNU) per m2 by intraperitoneal injection, Subset C received a single dose of 4 mg of methotrexate (MTX) per m2 by intrathecal injection 4 hours after tumor inoculation, and Subset D received 12 mg of intrathecal MTX per m2. Decreasing the concentration of cells per animal by 1 log doubled the time interval required for the development of paralysis and incontinence to 4 weeks. Treatment with intrathecal MTX at a dose of 4 mg/m2 extended the symptom-free period by an additional week (to 5 weeks postinoculation), and a dose of 12 mg/m2 allowed an average of 6 weeks before the onset of neurological impairment. The xenografts did not grow in the immunocompetent control mice, the BCNU-treated group, or the cyclosporine A-immunosuppressed animals. An intrathecal xenograft model of central nervous system malignancies allows a novel approach to the evaluation of experimental chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Activity of phthalocyanine photosensitizers against human glioblastoma in vitro.

In vitro studies utilizing an established human glioblastoma cell line (U87MG) were undertaken to compare the light absorption spectra and photocytotoxicity characteristics of hematoporphyrin derivative (HpD), metal-free phthalocyanine tetrasulfonate (PcS), and aluminum phthalocyanine tetrasulfonate (AlPcS). The peak absorption wavelengths for the compounds studied were: HpD = 630 nm, PcS = 630 nm, AlPcS = 677 nm. Seven different concentrations of each compound (0 to 20 micrograms/ml) were subjected to five different energy levels (40 to 640 joules/cm2) of broad band light (wavelength = 650 +/- 40 nm). Control experiments employing each drug alone and photoactivation alone were also performed. HpD showed a consistent dose-dependent photoactivated cytotoxicity with an abrupt decrease in cell survival when energies of 160 joules/cm2 or more were administered and a drug concentration dependency that resulted in a progressive decline in cell survival beginning at 1.0 microgram/ml. The metal-free PcS had a 10 times greater absorption of light at 675 nm, but only a very weak cytotoxic effect, which occurred at concentrations in excess of 10.0 micrograms/ml and energy levels greater than 320 joules/cm2. AlPcS, however, displayed a 100-fold increase in light absorption at 675 nm when compared to HpD. This was coupled with a decrease in cell survival similar to the HpD curves, but with a much steeper slope of percentage cell kill at lower drug concentrations and energy dosages. The control studies did not result in any appreciable cytotoxic effect. The data suggest that AlPcS holds promise as a second generation photosensitizer in the photodynamic treatment of human gliomas.

Brain Neoplasms↗

PubMed1986

Surgical management of giant sacral schwannomas.

Thirteen cases of giant sacral schwannomas with erosion of the anterior aspect of the sacrum and associated intrapelvic extension are reviewed. These tumors showed no sex predilection; the patients' mean age was 38.6 years at the time of diagnosis, and their symptoms predated the diagnosis by an average of 5.2 years. The most common symptoms were low-back pain and lower-extremity dysesthesiae. Plain roentgenograms, myelography, and computerized tomography constituted essential and complementary studies in the preoperative assessment. Choice of surgical approach (anterior transabdominal vs. posterior transsacral) was dependent upon the amount of sacral destruction, intrapelvic extension, and sacroiliac joint involvement. Microscopic examination revealed classic features of benign schwannoma in all but three cases, which were classified as cellular schwannomas. Patients who presented with pain and dysesthesiae reported immediate and complete relief of symptoms following surgery. In addition, all 13 patients were ambulatory and able to resume their routine daily activities postoperatively. At the last reported follow-up examination, which ranged from 5 months to 33 years and 3 months (mean 9 years) after surgery, two patients had died of unrelated causes, two reported return of preoperative symptoms, and the remainder were asymptomatic. This experience suggests that these histologically benign but neurologically devastating tumors should be aggressively resected with the intent of complete extirpation, and that this goal may be accomplished with minimal risk and an excellent prognosis.

Adolescent↗