Correlation of cerebral microvascular circulation with vital signs in cerebral compression and the validity of three concepts: vasodilation, autoregulation, and terminal rise in arterial pressure.

Background: Vasodilation, autoregulation, and rising arterial pressure are three common concepts in cerebral compression, believed to improve cerebral blood flow to maintain the brain's nutrition. However, these concepts are unclear, unproven, and based on assumptions. This study aimed to correlate cerebral circulation with alterations of vital signs and to evaluate the above concepts based on physics and hemodynamics. Methods: Without new animal experiments, a large amount of data: recording of vital signs, long movies of cerebral circulation, and numerous photos of histological examination and microvessels obstruction in cerebral compression in cats was studied, and only partial and preliminary results were reported in 1970. The experiments were supported by an NIH grant for head injury, done before the 1985 Institutional Animal Care and Use Committee requirement. The advent of digital technology facilitated digitizing and stepwise correlating them and evaluating the validity of the above concepts. Results: As cerebral compression increased intracranial pressure (ICP), veins dilated, not arteries, and arterial microvessels obstructed, diminished, and stopped cerebral circulation. Simultaneously, vital signs deteriorated, and pupils became fixed and dilated. There was no evidence for what is believed as autoregulation. Conclusion: In cerebral compression, rising ICP obstructs cerebral arterial microvessels while simultaneously deteriorating vital signs. There is no evidence for dilatation of the arteries; only veins dilate, best-called venodilation. There is no evidence of autoregulation; what occurs is a cerebral compartmental syndrome. The terminal rise of arterial pressure is the hemodynamic result of cerebral circulation cessation, overloading the aorta. None of the concepts benefit the brain's nutrition.

Evidence-based treatment of cavernous sinus meningioma.

BACKGROUND: Cavernous sinus meningioma (CSM) causes gradual ophthalmoplegia and may eventually cause compression of the chiasma. The tumor is often histologically benign, slow growing, and seldom life threatening. Besides visual limitation, ophthalmoplegia causes emotional stress and disability. The tumor is commonly treated by operation, radiation, or both. While effective in varied degrees, the treatments, especially radical operation, are associated with unacceptable mortality and morbidity. The question remains as to what treatment approach is most conducive to longest survival with minimum disability. METHODS: In five patients, operation, radiotherapy, or both were based on presenting symptoms or delayed based on a doctor-patient decision, seeking the most desirable and suitable option that potentially offers longer life with less disability. RESULTS: Five patients were followed from over 2 to almost 5 decades: two patients are still alive, 25 and 28 years after craniotomy and radiation. One was treated conservatively for 15 years before requiring craniotomy and radiation. One was followed for 45 years without needing craniotomy or radiation, despite enlargement of the tumor. One was followed for 36 years after craniotomy. Patient did not have radiation. Craniotomy consisted of removing enough tumor to diminish symptoms without causing complications. There were no mortalities or complications. CONCLUSION: The patient number is not large enough to make a broad conclusion. However, the individualized treatments and long follow-ups, together with detailed literature review, suggest that CSM requires individualized staged treatments based on each patient's condition. A period of "wait and see" before starting with either surgery or radiation treatment can benefit the patient.

Cerebral microvessel perfusion and pathologic alteration of the brain during drowsiness and coma caused by brain tumor: a laboratory study on rats.

BACKGROUND: In cerebral compression, deterioration of consciousness and coma are traditionally thought to be caused by compression, shift, hemorrhage, or herniation of the brain stem. The objective of this study was to evaluate vascular perfusion and pathologic alteration in the entire brain during drowsiness and coma. METHODS: Brain tumors were developed in 3 newborn rat litters by inoculation of KSV (a murine erythroblastosis virus) into their brain. Within several weeks, brain tumors developed. When the animals became drowsy or comatose, their brains were perfused with microbarium, India ink, or paraformaldehyde solution. In 2 animals, the brain vasculature was casted with plastic materials. The brains were either fixed for magnification radiography or prepared for histologic examination. RESULTS: The brains of control animals showed an abundance of microvessels and penetrating capillaries located perpendicular to the cortex and deep within the brain. The latter entities cannot be detected even in the best routine cerebral angiography in human beings. Microvessels were obstructed, in a patchy and dispersed fashion, during drowsiness, especially in the ipsilateral hemisphere. Obstruction of microvessels was present not only in the brain stem but also in the rest of the brain and in the cerebellum of comatose animals; larger vessels appeared to be markedly narrowed. The study also revealed evidence of diffuse infarcts, cellular ischemia, swelling, and periventricular damage throughout the brain. CONCLUSIONS: During drowsiness and coma caused by cerebral compression, cerebral capillaries progressively obstruct not only in the brain stem but also throughout the brain, considerably in a more severe pattern during coma than during drowsiness. These likely cause the diffuse neurologic disabilities and behavioral changes often seen after recovery from coma caused by cerebral compression.

Randomized, pilot study of intermittent pneumatic compression devices plus dalteparin versus intermittent pneumatic compression devices plus heparin for prevention of venous thromboembolism in patients undergoing craniotomy.

BACKGROUND: Unfractionated heparin and the low molecular weight heparin, dalteparin, are used for prophylaxis against venous thromboembolism in patients undergoing craniotomy. These drugs were compared in a randomized, prospective pilot study comparing intermittent pneumatic compression devices plus dalteparin to intermittent pneumatic compression devices plus heparin. METHODS: One hundred patients undergoing craniotomy were randomly allocated to receive perioperative prophylaxis with subcutaneous (SC heparin, 5000 units every 12 hours, or dalteparin, 2,500 units once a day, begun at induction of anesthesia and continued for 7 days or until the patient was ambulating. Entry criteria were age over 18 years, no deep vein thrombosis (DVT) preoperatively as judged by lower limb duplex ultrasound and no clinical evidence of pulmonary embolism preoperatively. Patients with hypersensitivity to heparin, penetrating head injury or who refused informed consent were excluded. Patients underwent a duplex study 1 week after surgery and 1 month clinical follow-up. All patients were treated with lower limb intermittent pneumatic compression devices. RESULTS: There were no differences between groups in age, gender, and risk factors for venous thromboembolism. There were no differences between groups in intraoperative blood loss, transfusion requirements or postoperative platelet counts. Two patients receiving dalteparin developed DVT (one symptomatic and one asymptomatic). No patient treated with heparin developed DVT and no patient in either group developed pulmonary embolism. There were two hemorrhages that did not require repeat craniotomy in patients receiving dalteparin and one that did require surgical evacuation in a patient treated with heparin. Drug was stopped in two patients treated with dalteparin because of thrombocytopenia. None of these differences were statistically significant. CONCLUSION: There was no significant difference in postoperative hemorrhage, venous thromboembolism or thrombocytopenia between heparin and dalteparin. The results suggest that, given the small sample size of this trial, both drugs appear to be safe and the incidence of venous thromboembolism by postoperative screening duplex ultrasound appears to be low when these agents are used in combination with intermittent pneumatic compression devices.