Transcallosal, interfornicial approaches for lesions affecting the third ventricle: surgical considerations and consequences.

A group of 11 patients with a variety of lesions affecting the 3rd ventricle have been treated using a direct transcallosal interfornicial approach to the region. In 3 patients, no attendant hydrocephalus was present. In an effort to minimize potential cortical injury related to the approach, we studied the venous anatomy in the region of the coronal suture. Based on this study, appropriate flap placement and interhemispheric entry points were defined. Although no lasting, clinically apparent morbidity was observed in any of the 11 cases, we performed more sophisticated studies of the interhemispheric transfer of somesthetic and perceptual motor tasks, as well as psychometric testing related to parameters of intelligence and memory, 3 to 8 months postoperatively in 6 cases. The results and clinical material indicate that this surgical technique is a safe, feasible alternative in the management of a wide spectrum of pathological lesions within this region. A transcallosal, interfornicial approach offers excellent visualization of the entire 3rd ventricle without the dependence on hydrocephalus or an extensive extra-axial mass to enhance the exposure. With proper planning and technique, it may be accomplished with a minimum of physiological consequence.

Ischemic brain edema following middle cerebral artery occlusion in baboons: relationship between regional cerebral water content and blood flow at 1 to 2 hours.

The relationship between increase in water content in ischemic brain and levels of regional blood flow has been studied in 11 primates. Flows were recorded using the method of hydrogen (2-minute) clearance, from a total of 128 electrodes in cortex and white matter, and a gradation of ischemia was produced by middle cerebral occlusion transorbitally. The flows were reduced in the area of densest ischemia from control levels of 12.0 +/- 12.0 ml/100g/min to 7.0 +/- 5.4 ml/100g/min, with lesser decreases over the remainder of the ischemic hemisphere. Water content was measured in cortex and white matter, in regions topographically related to those of flow measurements, by densitometric assessment using precalibrated kerosene/bromobenzine columns. The average water content of cortex in regions remote from ischemia was 797.4 +/- 5.8 mg/gm and in white matter 708.5 +/- 8.2 mg/gm. Significant increases in water content (comparing corresponding regions of the two hemispheres) of up to 11.4 +/- 7.5 mg/gm were demonstrated in the most ischemic cortical areas. A gradient of water increase was evident in the ischemic hemisphere, increases water content being greatest in the opercular zone and least in the parasagittal area. Significant differences in white matter water content between the 2 hemispheres were demonstrated only in the most densely ischemic areas in the current experiments where ischemia was limited to 93 +/- 20 mins in the 11 animals without reperfusion. The relationship between ischemic density and water content increase showed that significant increases in water content occurred in regions where terminal flows had been below 20 ml/100g/min, indicating that accumulation of water in ischemic brain begins at flow values comparable to those associated with the failure of synaptic transmission, higher than those associated with failure of the ionic pump of the cell. Possible pathophysiological mechanisms are discussed.

[Analysis of the hemodynamics in patients with artificial mitral valve insufficiency]. / Analiz gemodinamiki u bol'nykh s artifitsial'noi nedostatochnost'iu mitral'nogo klapana.

Hemodynamic disorders which developed in 12 patients with artificial mitral incompetence were studied. A method developed in the clinic of analysing the findings of catheterization and cine-angiocardiography was used. The method of analysis of single-plane ventriculograms makes it possible to estimate the volume of blood regurgitated into the left atrium to an accuracy of several millilitres. The degree of artificial incompetence is determined from the relative regurgitation which is estimated by dividing the volume of returned blood flow by the total volume of ventricular ejection. It is concluded that the "malignancy" of the course of artificial incompetence is determined by a sharp reduction of the effective cardiac output (to 33--50% of the normal volume) against the background of rapid rapid exhaustion of the left ventricular myocardum.

Effect on canine cerebral blood flow of two common pressor agents during prolonged halothane anesthesia.

Inasmuch as prolonged halothane anesthesia is often associated with hypotension, the effects of pressor agents possibly employed to adjust this hypotension on cerebral blood flow are of interest. In dogs, after prolonged halothane anesthesia, there was a marked difference in the effects of phenylephrine and angiotensin on cerebral blood flow at dosages which promote moderate rises in blood pressure. Phenylephrine had no effect whereas angiotensin had a significantly enhancing effect on cerebral blood flow.

Timing of pentobarbital administration for brain protection in experimental stroke.

Significant reduction of experimentally induced cerebral infarction was associated in the canine model with the administration of pentobarbital at one hour postocclusion but not thereafter.