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Biomedical subjects

W G Obana

Publications and source records attributed to W G Obana.

14 recordsLinked to original sources
PubMed1992

Resection of dominant opercular gliosis in refractory partial epilepsy. Report of two cases.

Frontal opercular gliosis in the dominant hemisphere caused medically refractory partial epilepsy in two patients. Both patients were aphasic during their seizures, but otherwise had normal speech. Magnetic resonance images showed well-demarcated lesions resembling tumors in each patient; on heavily T2-weighted images, the lesions were hyperintense compared with normal brain. Cortical mapping with subdural grids localized speech to the area of the lesions; therefore, the resections were performed under local anesthesia and speech was tested throughout the procedure. Postoperatively, both patients were seizure-free and had no new neurological deficits. Well-demarcated lesions, even in the dominant operculum, can be safely removed in patients with medically refractory partial epilepsy.

Adolescent↗
PubMed1992

Nonoperative treatment of neurosurgical infections.

The indications for nonsurgical management of CNS infections manifested by collections of pus are very limited. In general, such management is restricted to neurologically intact patients who are unable to undergo the needed surgical procedure and in whom the organism can be identified presumptively from other cultures. In such circumstances, brain abscesses less than 1.5 cm in diameter, small subdural empyemas, some spinal epidural abscesses, and many cases of spinal osteomyelitis can be successfully treated with prolonged intravenous antibiotic therapy. In patients who are unable to tolerate a neurosurgical procedure, the presence of an infectious CNS mass lesion is not hopeless and vigorous medical therapy offers the possibility of cure.

Brain Abscess↗
PubMed1991

Ultrasound-guided aspiration of a neonatal brain abscess.

The authors successfully treated a Serratia marcescens brain abscess in the right parieto-occipital region of a newborn infant born at 27 weeks' gestation and weighing 800 g. Bedside ultrasound-guided aspiration techniques and local anesthesia were used to treat the abscess.

Brain Abscess↗
PubMed1991

A case of Rhodococcus equi brain abscess.

We treated a patient with acquired immunodeficiency syndrome for a brain abscess caused by Rhodococcus equi, an actinomycete that usually infects the lung in immunosuppressed hosts. Rhodococcus equi brain abscess is an extremely rare lesion that has never been reported in a patient with acquired immunodeficiency syndrome. The infection was cured by lengthy therapy with multiple antibiotics after aspiration of the lesion to identify the infective organism and determine its sensitivity to antibiotics.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Epidermoid cysts of the brain stem. Report of three cases.

The authors report the cases of three patients with epidermoid cysts which insinuated themselves into the brain stem. In all three patients, the tumor occupied the pons, although in one it was predominantly located in the medulla. The cyst contents and nonadherent tumor capsule were removed in all three patients, but no attempt was made to remove tumor densely adherent to the brain stem. One patient's cyst was removed in one operation, but maximal resection in the other two required two operations. After surgery, sixth nerve function completely returned in one patient; another patient had a stable pontine gaze palsy but developed new facial weakness; and the third patient had stable cranial nerve deficits with a diminished hemiparesis. The last patient developed a pseudomeningocele and communicating hydrocephalus, and required a lumboperitoneal shunt. In all three patients, computerized tomography scans demonstrated hypodense tumors not enhanced by contrast material. Magnetic resonance imaging was performed on two patients; in both, the tumors showed increased signal intensity relative to brain on T1-weighted images and decreased signal intensity relative to brain on T2-weighted studies. Magnetic resonance imaging, the most accurate modality for localizing these lesions and determining their extent, was also invaluable for postoperative monitoring and follow-up evaluation. Safe and adequate resection includes decompression of cyst contents and removal of nonadherent portions of the cyst capsule. Cyst wall adherent to the brain stem, however, should not be removed.

Adult↗
PubMed1991

Metastatic juvenile pilocytic astrocytoma. Case report.

The authors report the case of a metastatic juvenile pilocytic astrocytoma of the hypothalamic region in a 10-year-old boy. Eight years after craniotomy and radiation therapy, the tumor spread via cerebrospinal fluid pathways to the left cerebellar tonsil and the lumbosacral region. Histological evaluation of both the original hypothalamic and the new lumbosacral masses showed features of a slow-growing juvenile pilocytic astrocytoma with no evidence of malignant transformation. The clinical implications and possible mechanisms of metastatic spread are discussed.

Astrocytoma↗
PubMed1990

Antimigraine treatment for slit ventricle syndrome.

Slit ventricle syndrome is characterized by chronic or recurring headaches associated with subnormal ventricular volume in patients who have undergone shunt treatment for hydrocephalus. There appear to be at least three pathophysiological mechanisms that cause this syndrome: 1) intermittent shunt malfunction; 2) intracranial hypotension; and 3) paroxysms of increased intracranial pressure in the presence of normal shunt function. To treat seven patients with slit ventricle syndrome caused by paroxysms of elevated intracranial pressure, we successfully used antimigraine therapy rather than standard calvarial expansion procedures. None of these patients has required shunt revision or calvarial expansion during a mean follow-up period of 2 years. The symptoms of slit ventricle syndrome may be a form of "acquired" migraine in shunt patients. We suggest that, in clinically stable patients with normal shunt function, treatment against migraine may stabilize symptoms resulting from paroxysms of increased intracranial pressure. Such treatment may prevent unnecessary shunt revisions and/or calvarial expansion procedures.

Adult↗
PubMed1989

Stroke associated with cocaine use.

We describe eight patients in whom cocaine use was related to stroke and review 39 cases from the literature. Among these 47 patients the mean (+/- SD) age was 32.5 +/- 12.1 years; 76% (34/45) were men. Stroke followed cocaine use by inhalation, intranasal, intravenous, and intramuscular routes. Intracranial aneurysms or arteriovenous malformations were present in 17 of 32 patients studied angiographically or at autopsy; cerebral vasculitis was present in two patients. Cerebral infarction occurred in 10 patients (22%), intracerebral hemorrhage in 22 (49%), and subarachnoid hemorrhage in 13 (29%). These data indicate that (1) the apparent incidence of stroke related to cocaine use is increasing; (2) cocaine-associated stroke occurs primarily in young adults; (3) stroke may follow any route of cocaine administration; (4) stroke after cocaine use is frequently associated with intracranial aneurysms and arteriovenous malformations; and (5) in cocaine-associated stroke, the frequency of intracranial hemorrhage exceeds that of cerebral infarction.

Adult↗
PubMed1988

Effect of opiate antagonists on middle cerebral artery occlusion infarct in the rat.

The authors examined the effect of the opiate antagonists naloxone and thyrotropin-releasing hormone (TRH) on neurological outcome and the size of areas of cerebral infarction in a rat model of focal cerebral ischemia. The middle cerebral artery (MCA) was permanently occluded in 66 adult Sprague-Dawley rats. The rats were randomly divided into three groups. In 20 Group I rats, TRH in normal saline was administered initially as a 2-mg/kg bolus followed by continuous infusion of 2 mg/kg/hr for 4 hours. In 20 Group II rats, naloxone in normal saline was administered initially as a 2-mg/kg bolus followed by continuous infusion of 2-mg/kg/hr for 4 hours. In 26 Group III rats, physiological saline was administered as an initial 0.5-cc bolus followed by continuous infusion of 0.5 cc/hr for 4 hours. All solutions were given in volumes of 0.5 cc for the bolus and 0.5 cc/hr for continuous infusion, and all infusions were begun within 10 minutes of MCA occlusion. Twenty-four hours after treatment, the rats underwent a careful neurological examination and were then sacrificed immediately. The size of areas of cerebral infarction was evaluated using 2,3,5-triphenyltetrazolium chloride staining techniques. The neurological grade of the rats correlated with the size of infarcted areas among all grades, irrespective of treatment (p less than 0.01). Neither naloxone nor TRH improved neurological function or reduced the size of infarction compared to saline-treated control rats. Treatment with TRH caused a significant increase in mean arterial blood pressure during infusion, but naloxone had no effect. These results suggest that neither TRH nor naloxone are effective in the treatment of acute focal cerebral ischemia.

Animals↗
PubMed1986

Experimental brain abscess development in the chronically immunosuppressed host. Computerized tomographic and neuropathological correlations.

The neuropathological progression of brain abscess formation was studied experimentally in paired immunosuppressed and control dogs. The immunosuppressed animals received azathioprine and prednisone beginning 7 days prior to intracerebral inoculation with alpha streptococcus. Histological findings were correlated with computerized tomography (CT) brain scans. The evolution of brain abscess in the immunosuppressed animals could be divided into three stages based on histological evaluation: cerebritis stage (1 to 11 days), early-capsule stage (12 to 17 days), and late-capsule stage (18 days and later). There was a significant delay in the evolution of alpha streptococcus brain abscess compared to the authors' previous studies. Histologically, abscesses in immunosuppressed dogs were characterized by a decrease and delay in collagen formation, a reduction in polymorphonuclear leukocytes and macrophages, longer persistence of bacterial organisms, and an increase in gliosis. During the cerebritis stage, abscesses in control animals were consistently larger and more edematous than those in immunosuppressed animals and reached their maximum size by Day 8, whereas abscesses in immunocompromised animals reached their maximum size around Day 12. In the late-capsule stage, abscesses in immunosuppressed animals remained larger than those of control animals and continued to show signs of delayed development. This was evidenced by diffusion of contrast medium into the lucent center of ring-enhancing lesions on delayed CT scans. The results suggest that the decreased inflammatory response and edema formation in the immunosuppressed host resulted in less initial mass effect from brain abscess, but that the eventual size and area of the abscess may have become larger due to the less effective host response.

Animals↗
PubMed1986

Chronic histological effects of ultrasonic hyperthermia on normal feline brain tissue.

The histopathological changes associated with ultrasonic heating of normal cat brain have been correlated with thermal distributions. Ultrasound energy was applied for 50 min at different intensities to generate tissue temperatures from 42 to 48 degrees C. Animals were sacrificed at various intervals from 1 to 56 days. The organization and resolution of thermal damage was characterized by three stages of histopathological changes within the nervous tissue. The acute stage (Days 1-3) was defined by (1) extensive coagulation necrosis, (2) pyknosis of neuronal elements in the gray matter, (3) edema and vacuolation in the white matter, and (4) polymorphonuclear leukocytes. The subacute stage (Days 3-21) was characterized by (1) the appearance of lipid-laden macrophages, (2) liquefaction of the necrotic regions, (3) fibroblastic proliferation, and (4) vascular proliferation with some perivascular inflammatory infiltration (lymphocytes). Lastly, the chronic stage (Days 21-56) was defined by (1) fibrosis (reticulin and collagen formation) and (2) gliosis (reactive astrocytic proliferation) occurring around the fluid-filled necrotic center. Analysis of these data has also included a study of the lesion size versus the dose (temperature for 50 min) of heating. The results demonstrate a significant linear dose-response correlation. The results of this study indicate that the histological appearance and time course of repair of thermal injury in the normal brain tissue are analogous to acute brain necrosis resulting from cerebral infarction, except the thermal damage does not result in significant hemorrhage.

Animals↗
PubMedDate not supplied

Experimental Staphylococcus aureus brain abscess.

The virulent organism Staphylococcus aureus produced brain abscesses that were quantitatively and qualitatively different from those caused by less virulent organisms. S. aureus abscesses created larger lesions, as earlier ependymitis, delayed progress toward healing, and caused areas of inflammatory escape outside the collagen capsule. Imaging tests revealed similar findings: the abscesses were larger, had more extensive central necrosis, and showed earlier evidence of ependymitis. This virulent organism also demonstrated that white matter is more susceptible than overlying gray matter to destruction by infection. The pattern of spread and other histologic findings suggest that collagen capsule formation has less of an infection "containment" function than was previously thought.

Animals↗