Dominant A1: angiographic and clinical correlations with anterior communicating artery aneurysms.

It has been observed but never proven that anomalies of the anterior communicating artery complex are associated with anterior communicating artery aneurysms (ACAA). Therefore, in an effort to understand the significance of haemodynamic factors in the genesis, as well as the clinical course of ACAA, we evaluated the correlation between certain angiographic patterns of flow in the anterior circulation and the clinical findings of 51 patients with ACAA compared with 50 matched controls. Four significant associations which have never been validated were identified: 1) a dominant A1 (filling both A2's) was found in 57% of ACAA patients versus 14% of controls (p less than 0.001). 2) Unilateral hypoplasia of the opposite A1 was present in 24% of ACAA patients versus 6% of controls (p = 0.01). 3) Exclusive filling of the ACAA from one A1 occurred in 78%. 4) No statistically significant relationship was found between the anatomic flow patterns studied and the patients clinical presentation including age, sex, or grade. We conclude that anterior communicating artery aneurysms are significantly related in a majority of patients with the presence of a dominant A1, probably as the result of enhanced haemodynamic stress caused by this anatomic abnormality in the circulation. However, this association is not constant, and a dominant pattern of flow did not correlate with the clinical course. This is probably a reflection of the differences between factors initiating aneurysm formation and those influencing its growth, as well as of the relative limitations of angiography when pathophysiological extrapolations are attempted.     

Brain tissue oxygenation in patients with cerebral occlusive disease and arteriovenous malformations

It is not clear if ventilation with oxygen increases brain tissue oxygen pressure (PO2) during ischaemia. We have measured brain tissue PO2, carbon dioxide pressure (PCO2) and pH during baseline anaesthesia and oxygen ventilation in non-ischaemic control patients (n = 9), patients with cerebral occlusive disease (n = 11) and patients with arteriovenous malformations (AVM, n = 12). The same anaesthetic treatment was given to all groups and anaesthesia was constant during the study. Arterial pressure, brain temperature and arterial blood-gas tensions were similar between groups. Under baseline conditions, brain tissue PO2 was mean 4.2 (SD 1.4) kPa in the controls and was 70% lower in patients with ischaemia and AVM. Patients with occlusive disease also had elevated tissue PCO2 and acidosis. During oxygen ventilation, PO2 increased to 7.5 (2.9) kPa in controls and this was 50% greater than the increase in the ischaemia and AVM patients. The results showed that baseline tissue oxygenation and increases in PO2 during hyperoxia were attenuated in patients with ischaemia or AVM.      

Transcranial cerebral oximetry and carotid cavernous fistula occlusion

Summary Different methods have been used in the evaluation and monitoring of the cerebral oxygen supply during neuro-interventional therapies. Attenuation of near-infrared light by the chromophores oxyhemoglobin and deoxyhemoglobin have shown to be useful in the study of the cellular oxygen metabolism and oxygen delivery to the brain. Transcranial cerebral oximetry (TCCO) has the advantage of providing real-time information regarding regional brain oxygen saturation (rSO₂) by using wavelengths in the near-infrared range.We present a patient with a carotid cavernous fistula who underwent balloon occulusion and concurrent continuous TCCO monitoring. TCCO was found to be a useful tool providing immediate rSO₂ values during the angiographic and interventional procedures. Initial balloon occlusion of a carotid cavernous fistula resulted in partial occlusion of the internal carotid artery lumen causing an immediate decrease in rSO₂ which correlated with angiographic findings. Subsequent reocclusion of the fistula produced a slower and smaller degree of decrease in rSO₂ with clinical improvement in the patient. Changes in rSO₂ were detected before any adverse clinical event was observed. TCCO was reliable, safe, sensitive, and provided a real-time assessment tool for the monitoring of brain oxygen supply in a patient undergoing a neuroendovascular procedure.     

The management of arteriovenous malformations in children

Between January 1941 and June 1989, 46 children below the age of 18 with an arteriovenous malformation (AVM) were managed. There were 7 patients with AVM diagnosed before the age of 2; 10 patients were diagnosed between the ages of 3 and 10; and 29 patients were diagnosed between 11 and 18. There were equal numbers of male and female patients. Twenty-five of the AVMs were large (>5 cm longest diameter). All 7 AVMs diagnosed before the age of 2 were large. The usual clinical presentation was congestive heart failure, bruit and an enlarging head. Three patients underwent excision with 2 deaths and 1 excellent result. In 11 patients (aged 3–18) with AVM without history of hemorrhage, 3 had excision with 2 excellent and 1 fair result. Four remained stable. Four developed progressive deficits or hemorrhage. In 10 patients (aged 3–18) with AVM and hemorrhage who were treated medically, 7 (70%) had an episode of re-hemorrhage. Three patients had excision of AVM after re-hemorrhage, but before the age of 18 with an excellent result. Eighteen patients (aged 3–18) with AVM and a single episode of hemorrhage underwent excision with 17 excellent or good results and 1 fair result. The overall mortality was 7%. Eighty-five percent of the children with excision of AVM had an excellent or good result. The best treatment for AVM in children is surgical excision.Presented at the XVII Annual Meeting of the International Society for Pediatric Neurosurgery, Bombay 1989     

Image-directed percutaneous biopsies with a biopsy gun

Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.     

Nano-C60 cytotoxicity is due to lipid peroxidation

This study examines the biological effects of water-soluble fullerene aggregates in an effort to evaluate the fundamental mechanisms that contribute to the cytotoxicity of a classic engineered nanomaterial. For this work we used a water-soluble fullerene species, nano-C₆₀, a fullerene aggregate that readily forms when pristine C₆₀ is added to water. Nano-C₆₀ was cytotoxic to human dermal fibroblasts, human liver carcinoma cells (HepG2), and neuronal human astrocytes at doses 50 ppb (LC₅₀=2–50 ppb, depending on cell type) after 48 h exposure. This water-soluble nano-C₆₀ colloidal suspension disrupts normal cellular function through lipid peroxidation; reactive oxygen species are responsible for the membrane damage. Cellular viability was determined through live/dead staining and LDH release. DNA concentration and mitochondrial activity were not affected by the nano-C₆₀ inoculations to cells in culture. The integrity of cellular membrane was examined by monitoring the peroxy-radicals on the lipid bilayer. Subsequently, glutathione production was measured to assess the cell's reaction to membrane oxidation. The damage to cell membranes was observed both with chemical assays, and confirmed physically by visualizing membrane permeability with high molecular weight dyes. With the addition of an antioxidant, l-ascorbic acid, the oxidative damage and resultant toxicity of nano-C₆₀ was completely prevented.