The underlying problems resulting in controversies in the clinical management of transient ischemic attacks: an overview.

Of all the controversial topics in the management of cerebrovascular diseases the subject of transient ischemic attacks is perhaps the most controversial. A preponderance of literature related to the subject, reflecting a remarkable degree of interest in the topic, is a result of this controversy. Each conclusion serves to stimulate more interest, more evaluation, and more controversy. We will attempt to give an overview of the controversies in the management of transient ischemic attacks.

Progression of a dural arteriovenous malformation resulting in an intracerebral hematoma. A case report.

A progressing, essentially extracranial arteriovenous malformation with purely external carotid feeders can involve the intracranial vasculature by enlargement of its drainage area. Thus it can cause cerebral dysfunction by an intracranial bleed or raised intracranial pressure due to venous engorgement. A case is described to support this possibility.

The histochemical demonstration of guanase: observations in the human central nervous system.

1. A method is described for the histochemical demonstration of the purine catabolizing enzyme guanase, employing glutaraldehyde fixation and Nitro blue tetrazolium (NBT). Parallel biochemical studies confirm that enzyme activity is not significantly inhibited by exposure to glutaraldehyde. 2. By this procedure guanase activity has been visualized in neurons and glial elements of the human central nervous system (CNS). 3. Controls consisted of direct incubation of cryostat sections with a specific inhibitor of guanase (5-amino-4-imidazole carboxamide) and omission successively of the substrate guanine, of xanthine oxidase and of NBT. Enzyme activity was completely inhibited by the above procedures, and by boiling of tissues for 10 min prior to fixation. 4. Levels of enzyme activity in spinal cord and brain were assessed by a subjective scoring method, and showed close comparability with biochemical assay data in brainstem and cerebral hemispheres; whereas a low correlation for enzyme activity was observed in spinal cord and cerebellum. Differences between biochemical and histochemical assessments of CNS guanase activity are discussed.