Acute regional cerebral ischemia was produced in the middle cerebral artery (MCA) territory in monkeys (Macaca mulatta) by selective embolization of the internal carotid (ICA) bifurcation with minimum surgical intervention in the neck under sedated conditions. Two of five hours after embolization, brain water (measurement of dry weight) and tissue concentration of sodium and potassium were determined in the tissues of the sylvian cortex, putamen and subcortical white matter in the affected MCA territory. As early as three hours, initial increase in brain water was detected in the samples of the putament without noticeable change in tissue electrolytes in two of three animals. Gross ischemic swelling of the gray matter, in both the sylvian cortex and putamen, became obvious in six of eight animals after four to five hours. This swollen gray matter showed marked increase in brain water (up to 36% swelling), increase in tissue sodium (up to 100% of the control value), and decrease in tissue potassium (down to 55%). On the other hand, edema in the white matter, if present at all, was minimal without detectable change in tissue electrolytes and was always accompanied by much greater ( greater than two to seven times) edema in the gray matter. Thus, the gray matter edema, in both the deep subcortical structures and the cortex, appeared to play the major role in the development of hemispheric swelling of the brain which may begin within hours of the onset of the MCA stroke in monkeys. Microscopically, the swollen gray matter which showed more than 10% swelling with a definite shift of tissue sodium and potassium content appeared to be dead tissue. However, early edema in the gray matter which showed less than 10% swelling without detectable change in electrolytes might be caused by simple diffusion of water through the dysfunctional capillary wall or cell membrane with or without a permeability gradient between the intravascular cerebrospinal fluid and cerebral tissue compartment and might possibly be reversible.

SUMMARY Selective embolization of the internal carotid artery bifurcation (ICA bifurcation) was performed in monkeys (Macaca mulatto) to study acute regional cerebral ischemia in the middle cerebral artery (MCA) territory with minimum surgical intervention in the neck under sedated conditions.The anthropomorphic similarity in angio-anatomy of the carotid system of monkeys and the use of silastic spheres, as artificial emboli, of the critical diameter of 1.2 to 1.4 mm resulted in the overall success rate of 87% in localizing the site of embolization to the ICA bifurcation, producing ischemia in the whole middle cerebral artery territory.All the animals with ICA-bifurcation embolization had contralateral deep motor weakness and conjugate eye deviation with nystagmus toward the site of embolization. Simultaneous EEC recording showed flattening of the basic background activities over the affected MCA area and cerebral arteriograms showed definite retrograde filling of the proximally occluded MCA. Clinical recovery was observed in a few animals within two to five hours of embolization. Gross ischemic swelling in the affected MCA territory, particularly in the gray matter, became obvious in six of eight animals which were exposed to four to five hours of ischemia.The angio-anatomical study of the carotid system of this experimental animal as a background for this MCA stroke model confirmed the previous observations of other investigators that the extremely abundant leptomeningeal anastomoses would be one of the major factors leading to the variability in the clinicopathological pictures seen in the models of proximal MCA occlusion. In addition, the prc-parenchy mal anastomoses in the base of brain between the medial striate arteries from the proximal anterior cerebral (ACA) and lateral lenticulostriate arteries from the MCA were observed and described as a possible functional collateral to the basal ganglia in case of proximal MCA occlusion.

This report presents our experience with the use of autogeneic fat patch grafts to protect the exposed dura mater during lumbar spine operations. A total of 44 consecutive surgical procedures was performed primarily for discogenic or spondylotic disease from 1979 to 1982. Prophylactic antibiotics were used in 21 (48%) cases. The autogeneic fat transplants were well accepted by all recipients during 10.4 (1 to 32) months of follow-up. Fat grafts, greater than 1 cm in thickness, were easily identified on subsequent computed tomographic (CT) scans. There were no postoperative wound infections. However, 1 patient developed a large subcutaneous sterile fluid accumulation at the fat donor site, which required surgical intervention. Our results, both short and long term, indicate that autogeneic fat transplants may be well tolerated in the lumbar spine area. The fat graft viability as demonstrated by CT scanning and histological examination supports the contention that autogeneic fat interposed between dura mater and overlying musculature may serve as a barrier limiting the growth of cicatrix into the spinal canal.

This report illustrates three cases of symptomatic tension pneumocephalus developing after evacuation of chronic subdural hematoma (SDH) by burr holes. Review of the literature revealed that tension pneumocephalus is seldom recognized as a reason for neurological deterioration after the surgical treatment of chronic SDH.