Citations

Abstract The alterations in metabolism and cerebral blood flow that occur following transient focal ischemia were studied in rabbits anesthetized with halothane and subjected to transient occlusion of an M2 segment of the middle cerebral artery (MCA). The parameters measured included intracellular brain pH and focal cortical blood flow (fCBF)—assessed by the umbelliferone technique—electrocorticograms, and cortical microcirculatory changes. A gradient of ischemia developed in the cortex between the patent and occluded vessels. Cortical sites with moderate and severely diminished flow were examined as a function of time before and after occlusion. Mean preocclusion fCBF was 50.8 ± 2.1 ml/100 g/min, and brain pH was 6.99 ± 0.04. Following occlusion, fCBF fell to 14.6 ± 2.3 ml/100 g/min, with an intracellular pH of 6.53 ± 0.03 in sites of severe ischemia in the territory of the occluded vessel. Sites between the patent and occluded branches revealed moderate changes in fCBF and intracellular pH of 26.7 ± 3.6 ml/100 g/min and 6.74 ± 0.03 ml/100 g/min, respectively. Sites adjacent to the patent M2 branch remained similar to baseline. Pretreatment intravenously with nimodipine, a dihydropyridine class of Ca2+ channel antagonist, improved flow in the territory of the occluded segment of the middle cerebral artery to 30.6 ± 2.2 ml/100 g/min, while maintaining the brain pH at 6.83 ± 0.03. Similarly, at sites intermediate between the patent and occluded M2 segments of the MCA, cortical blood flow remained at 53.5 ± 4.0 ml/100 g/min, and the pH at 6.95 ± 0.04, in 10 animals pretreated with nimodopine. This effect was apparently achieved by blocking the secondary, ischemia-induced vasoconstriction known to occur in areas of focal incomplete ischemia. The diphenylalkylamine class Ca2+ channel blockers was examined using verapamil. This was found to be without significant effect. The vehicle carrying nimodopine was also without effect. To authenticate further the reliability of MCA occlusion, a separate group of animals was examined with cautery occlusion of the M2 segment of the MCA. Nimodopine had an effect in this group of animals identical to that caused by occlusion of the vessel with a clip. Visual inspection of the cortex in control and treated animals revealed a marked difference in the development of cortical pallor and microcirculatory changes. We conclude that nimodopine protects the conducting vessels against the secondary vasoconstriction known to occur in areas of focal incomplete ischemia, and thus increases collateral flow. This agent may have the potential for brain protection in areas of incomplete focal ischemia from occlusion of a single major vessel.

Abstract The natural history of postirradiation extracranial cerebrovascular disease is uncertain. Previous reported cases spanning 20 years of carotid surgery are difficult to evaluate, because patients may sometimes have unspecified symptoms, physical examinations, postoperative results, and follow-up. Also, the evolution of carotid surgery over the past two decades makes it impossible to compare earlier operative technique with the state-of-the-art technique of today. Our series of 7 patients underwent 9 carotid endarterectomies with an average follow-up period of 46 months. The number of patients is small, and although technically this is a more difficult operation, we feel the results are favorable and may be comparable with endarterectomy procedures in nonirradiated patients. These patients should be approached as if radiation changes are not a major factor when they are considered for reconstructive arterial surgery.

Abstract We report a case of cerebral abscess due to Haemophilus paraphrophilus in a 51-year-old man who was otherwise healthy and had no cardiac abnormality. A source for the infection was not definitively identified; however, the patient had had dental manipulations 2 weeks before the onset of symptoms, and an oral source is probable. The patient was treated successfully with antibiotics after removal of the abscess. Bacteriological studies are discussed.

Abstract Twenty surgically verified pituitary adenomas were imaged in a systematic comparative fashion with high field strength magnetic resonance imaging (MRI) and computed tomography (CT) before operation. The study group included 11 microadenomas, 4 macroadenomas, 2 recurrent microadenomas, and 3 recurrent macroadenomas. The MRI and CT examinations were evaluated for lesion detection, pituitary stalk displacement, cavernous sinus displacement or invasion, hemorrhage, cystic degeneration within the adenoma, bony erosion, detection of suprasellar extension, and displacement of suprasellar structures. T1 and T2 relaxation characteristics of the adenomas were evaluated on MRI examinations, and contrast enhancement characteristics were evaluated on CT examinations. MRI was superior to CT for detecting the extrasellar extent of tumor. Within the sella turcica, MRI and CT were equivalent with regard to lesion detection, except for 1 patient in whom CT was able to detect a surgically confirmed 3-mm microadenoma that was not visualized on the MRI examination. (Neurosurgery 22:380-385, 1988)

Abstract Six patients with juvenile pilocytic astrocytomas of the thalamus or basal ganglia underwent seven computer-assisted stereotactic laser craniotomies with complete or nearly complete removal of the tumor in all cases. The tumor was located in the right basal ganglia in one patient, the left basal ganglia in one patient, and the left thalamus in four patients. Postoperative assessment of the completeness of tumor removal was confirmed by contrast-enhanced computed tomographic scanning within the first 2 weeks after operation. None of the patients was neurologically worse after the procedure, and five were improved. The duration of follow-up ranged from 6 months to 3.5 years. In this group of patients, the computer-assisted, stereotactically guided resection of these deeply located, benign tumors was accomplished with no morbidity or mortality.

Abstract This report describes a computed tomography-based computer-assisted stereotactic technique for performing 3rd ventriculostomy. The procedure has been performed on seven patients with acquired obstructive hydrocephalus of various etiologies. None of these patients have yet required shunting. (18:791–794, 1986)

Abstract We have developed a computer-resident stereotactic atlas of the human brain that quantitatively defines subcortical structures within anatomical landmarks detected on obliquely reconstructed computed tomography (CT) slices. Horizontal stereotactic atlas sections can be stretched and contracted by polar transformation and labeled by a computer to fit within these CT scan-defined landmarks. The stereotactic coordinates of any substructure on the atlas-labeled CT slice may then be calculated by the computer and expressed in mechanical adjustments on a stereotactic surgical frame located in the operating room. We demonsrate the use of this method in the stereotactic treatment of movement disorders as an augmentation to conventional ventriculography and microelectrode recording.

Abstract Myelography and myelography assisted with computed tomography have been the most commonly used radiographic methods in the study of syringomyelia. These studies have never been entirely reliable in demonstrating the syrinx cavity and its relationship to other intracranial structures. During the 1st year of operation of the magnetic resonance imaging facility, the syringomyelic cavity was demonstrated in 15 patients who all had typical clinical signs and symptoms associated with syringomyelia. Nine cases were syringomyelia with Chiari malformation. One case showed additional hydrocephalus. Four cases were idiopathic, and 1 case was remotely posttraumatic. Magnetic resonance imaging, although it is in its infancy, already promises to be the most important radiographic technique for syringomyelia because it provides an anatomically truthful visualization of the sagittal plane of the cervical cord and can demonstrate the syrinx cavity and its relationship with the cerebellar tonsils, the 4th ventricle, and other related structures.

Abstract Spontaneous cerebrospinal fluid (CSF) rhinorrhea, occurring in the absence of recent trauma, is a distinct clinical entity that can be difficult to diagnose and treat. The case records of 28 patients with this entity were reviewed retrospectively. Pertinent historical data and the results of radiographic evaluation are discussed. The patients were classified into one of three major etiological categories: congenital anomaly, delayed posttraumatic, and tumor groups. The fistulas causing the rhinorrhea were approached extracranially or intracranially, depending on the suspected cause and location. A cure was obtained in 22 of the 27 patients surgically treated (81%). Seventeen patients were cured by a single operation, 5 were cured after multiple operations, and 5 continued to leak despite surgical treatment. Three of the 5 patients who were surgical failures had intracranial tumors, and 2 of them died from complications of persistent fistulas. With the use of a multidisciplinary team approach, an extracranial operation (transethmoidal or transsphenoidal) to repair a spontaneous CSF leak offers a high success rate and is associated with minimal morbidity in appropriately selected patients.

Abstract A simple and reproducible method of quantitating the amount of hematoporphyrin derivative by fluorescence microscopy in biopsies of tumors from patients undergoing photoradiation therapy is presented, substantiated by laboratory studies of experimental central nervous system tumors and normal rat tissues. The literature regarding the quantitation of hematoporphyrin is reviewed, and implications of this study for the future application of photoradiation therapy and the design of laboratory studies are discussed.