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Biomedical subjects

B L Hershey

Publications and source records attributed to B L Hershey.

10 recordsLinked to original sources
PubMed2000

Complex vertebral arteriovenous fistula and ruptured aneurysm in neurofibromatosis: a therapeutically challenging case.

The objective and importance of this study was to describe the challenges encountered with treating a high-flow vertebral arteriovenous fistula (AVF) and ruptured aneurysm in a patient with life-threatening hemorrhage. A 36-year-old female with Neurofibromatosis type 1 (NF1) presented 2 weeks after uneventful cesarean section with a rapidly expanding pulsatile neck mass. Angiography demonstrated a complex left vertebral AVF and multiple associated vertebral artery aneurysms. Emergent endovascular coil embolization was performed using a retrograde and antegrade approach to occlude the fistulas and trap the ruptured aneurysm, successfully treating the acute hemorrhage. Subsequent definitive therapy was accomplished utilizing a combined neurointerventional and neurosurgical strategy of direct-puncture acrylic embolization and ligation of the vertebral artery. Recent advances in neurointerventional technology allow novel approaches in the primary and/or preoperative treatment of complex vascular lesions such as those seen in NF1.

Case Reports↗
PubMed1997

Orbital infections.

Orbital infections account for the majority of primary intraorbital disease processes. Sinusitis is the most common etiology. Five stages of cellulitis secondary to sinusitis have been described. Systemic conditions which predispose to orbital infection include diabetes, septicemia, malignancy, and immunosuppresion. Clinical signs and symptoms include superficial inflammatory changes, as well as proptosis, limitation of extraocular motility, and visual loss. Causative agents are most commonly bacteria, with fungus, viruses, and parasites seen less frequently. Imaging is performed by CT and/or MRI which are complementary in certain cases. Differential diagnosis of imaging abnormalities includes inflammatory and granulomatous diseases, as well as neoplasm.

Eye Infections↗
PubMed1995

Use of ex vivo magnetic resonance imaging to detect onset of vigabatrin-induced intramyelinic edema in canine brain.

Vigabatrin (VGB) causes intramyelinic edema (microvacuolation) in brain of dogs and rodent, which has encouraged development of noninvasive methods to monitor for this effect during clinical trials. We report the qualitative ex vivo magnetic resonance imaging (MRI) changes observed in a neuropathology study in dogs to detect time of onset and regression of VGB-induced intramyelinic edema. Beagles were randomly assigned to 18 groups of 6 dogs per group and administered vigabatrin orally (p.o.) at a dose of 300 mg/kg/day (2 males, 2 females) or placebo (1 male, 1 female). Animals were killed and examined at weekly intervals during the 12 weeks of treatment and at 1, 2, 4, 8, 12, and 16 weeks after discontinuation of drug treatment. Myelin microvacuolation in thalamus, hypothalamus, and fornix were noted histologically after 4-5 weeks of treatment. Increases in MRI T2 intensity were observed in hypothalamus after 4 weeks and in thalamus and columns of the fornix after 7 weeks. Both MRI T2 intensity and microvacuolation continued to increase during 12-week VGB treatment. When VGB treatment was discontinued after 12 weeks, both MRI T2 intensity and microvacuolation began to decrease. Sixteen weeks after VGB discontinuation, histopathology had returned to normal and MRI examination demonstrated a marked trend toward reversal of the increased T2 signal intensity. MRI thus has potential as a noninvasive surveillance technique in certain experimental and clinical conditions associated with intramyelinic edema.

Animals↗
PubMed1993

Suprasellar masses: diagnosis and differential diagnosis.

Suprasellar masses are neoplastic, vascular, congenital, or infectious/inflammatory in origin. Magnetic resonance imaging (MRI) is the study of choice for evaluating suprasellar masses, although computed tomography (CT) may provide complementary information. Suprasellar masses present with a variety of neurologic or endocrine dysfunctions depending on their site of origin and mass effect on adjacent structures. Imaging characteristics of the most common suprasellar lesions are described with particular emphasis on MR findings.

Adenoma↗
PubMed1989

Initial experience with SPECT imaging of the brain using I-123 p-iodoamphetamine in focal epilepsy.

Nineteen patients with complex partial seizures refractory to medical treatment were examined with routine electroencephalography (EEG), video EEG monitoring, computed tomography or magnetic resonance imaging, neuropsychological tests and interictal single photon emission computed tomography (SPECT) with I-123 iodoamphetamine (INT). In 18 patients, SPECT identified areas of focal reduction in tracer uptake that correlated with the epileptogenic focus identified on the EEG. In addition, SPECT disclosed other areas of neurologic dysfunction as elicited on neuropsychological tests. Thus, IMP SPECT is a useful tool for localizing epileptogenic foci and their associated dynamic deficits.

Adolescent↗
PubMed1988

Intraocular tumors: evaluation with MR imaging.

Sixty-seven ocular tumors were studied with magnetic resonance (MR) imaging and computed tomography (CT). These tumors included primary uveal melanoma (n = 55), circumscribed choroidal hemangioma (n = 3), diffuse choroidal hemangioma (n = 1), retinal capillary hemangioma (n = 1), medulloepithelioma (n = 1), choroidal nevus (n = 1), retinoblastoma (n = 1), and choroidal metastases (n = 4). MR imaging demonstrated all these lesions, while CT demonstrated 88%. Associated retinal detachment was more easily distinguished from the neoplasms with MR imaging. Extrascleral extension of melanoma and hemorrhagic cystic necrosis within the melanoma were clearly demonstrated with MR imaging, but not with CT. Ninety-three percent of melanomas were markedly hyperintense, compared with the intensity of the vitreous body, on T1-weighted images and hypointense on T2-weighted images. All metastatic lesions were isointense on T1-weighted images and hypointense on T2-weighted images. The circumscribed choroidal hemangiomas were hyperintense on T1-weighted images and isointense on T2-weighted images. MR imaging is superior to CT in detection of intraocular tumors and may be more specific in diagnosis.

Choroid Neoplasms↗
PubMed1986

Magnetic resonance imaging of the child's brain.

The most significant difference between magnetic resonance imaging (MRI) and computed tomography (CT) is that the former graphic representation of the cerebrospinal axis and its structures does not use ionizing radiation or the injection of contrast material. The physical principles of MRI and the very characteristic appearances of some pathological processes common in children require special study. Low-proton density areas are generally dark; the short T1 value is responsible for white matter appearing clear; inversion recovery sequences permit study of the progression of myelination.

Brain↗
PubMed1985

Pediatric brain computed tomography.

Computed tomography today provides good anatomic depiction of the brain and its gross disease processes that have as a manifestation alteration of brain density, disturbance in blood-brain barrier, or mass effect. As such, computed tomography often provides valuable diagnostic information in the appropriate clinical setting. This article reviews many of the more common pediatric central nervous system disease states that have been demonstrated more easily as a result of computed tomography.

Adolescent↗
PubMed1983

High-resolution CT of lesions of the optic nerve.

The optic nerves are well demonstrated by high-resolution computed tomography. Involvement of the optic nerve by optic gliomas and optic nerve sheath meningiomas is well known. However, nonneoplastic processes such as increased intracranial pressure, optic neuritis, Grave ophthalmopathy, and orbital pseudotumor may also alter the appearance of the optic nerve/sheath on computed tomography. Certain clinical and computed tomographic features permit distinction of these nonneoplastic tumefactions from tumors.

Cranial Nerve Neoplasms↗