Neurosurgery
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A clinical entity called roof disc is described. It is a centrally located disc extruction found posterior to the posterior borders of the vertebrae that is enclosed by the intact posterior longitudinal ligament; the roof disc exerts pressure against the dorsally lying thecal sac and its enclosed cauda equina roots, causing symptoms and signs incident to this pressure. ⋯ Three varieties are described and examples are presented. Its concealed location makes the conventional surgical approaches ineffective, including foraminotomy and laminotomy or laminectomy with standard discectomy.
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Radiation therapy provides the most effective adjuvant treatment for patients with malignant brain tumors, but brain intolerance to potentially curative doses of radiation is limiting. Solid tumors are thought to contain a substantial population of cells that are hypoxic; because much of the cell kill caused by ionizing radiation is the result of an oxygen-dependent, free radical-mediated attack on deoxyribonucleic acid, hypoxic tumor cells are known to be radioresistant and are therefore a barrier to cure. With the hope of improving the therapeutic ratio of brain tumor radiation therapy, hypoxic cell radiosensitizers are being evaluated. ⋯ Clinical trials ae providing considerable information about the pharmacokinetics and toxicities of these agents. The preliminary results obtained in clinical trials with brain tumor patients are somewhat discouraging; drug toxicity limits the number of radiation treatments with which a sensitizer may be given. The results of ongoing clinical trials with metronidazole and misonidazole and the identificiation of new, less toxic hypoxic cells sensitizers may improve the potential for this modality of therapy.
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The relationship of the anterior inferior cerebellar artery (AICA) to the facial (7th) and vestibulocochlear (8th) nerves was studied using 3x to 20x magnification in 50 cerebellopontine angles (CPAs) from 25 adult cadavers. The AICA originated from the basilar artery as a single (72% of the CPAs), duplicate (26%), or triplicate (2%) artery. Each of the 50 CPAs had one or more arterial trunks that coursed in close proximity to the 7th and 8th cranial nerves and thus were said to be nerve-related. ⋯ The internal auditory and recurrent perforating arteries arose most commonly from the premeatal segment, and the subarcuate artery arose most commonly from the postmeatal segment. There were one to four internal auditory arteries per CPA, zero to three recurrent perforating arteries, and zero or one subarcuate artery. The effects of occlusion of the nerve-related arteries and their involvement in conditions treated by neurosurgeons are reviewed.