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Up to date, the treatment of arteriovenous racemose angiomas of the brain remains unsatisfactory. Intraoperative hemorrhages, post-embolizational or postoperative deficits depending on the site and size of the A VM as well as inoperability of rare angioma types have promoted the technical improvement of diagnostic and therapeutic approaches. Nevertheless, some pathophysiological problems of A VM hemodynamics have not been solved. Many angiographical studies, observations during embolization and operation, dopplersonographical and other perfusion measurements provided some insight. Sufficient animal models have yet to be developed in order to elucidate the pathophysiological mechanisms. This monograph describes A V fistula models in cats and rats, both conventional and newly developed, which allow a better comparison with human cerebral angiomas than previous ones. The most important result is that the model of the breakthrough of arterial pressure waves into the capillaries following a failure of cerebrovascular regulation cannot be confirmed. Rather, according to the findings in precapillary vessels presented here, the regulation functions normally so that a breakdown of regulation cannot be responsible for global brain edema often seen after removal of angiomas. The regulation was demonstrated using different methods, most important of which being the CO response of 2 brain vessels to varying CO contents of the inhaled air. Angiographical, dopplersonographical and 2 perioperative dopplersonographical as well as intraoperative measurements of flow and pressure have been applied.
List of contents
I. Introduction.- 1. History.- 2. Aim of the Study.- 3. Hemodynamic Principles of Cerebral Perfusion.- 4. Hemodynamics in Cerebral Angiomas.- II. Animal Experiments.- 1. Experimental Arteriovenous Fistulae.- 2. Materials and Methods.- 3. Results of the Fistula Models in Rats.- 4. Results of Fistula Models in Cats.- 5. Discussion and Summary of Animal Experiments.- III. Angiography in Angioma Patients Before and After Surgery.- 1. Materials and Methods.- 2. Results.- 3. Discussion.- 4. Summary and Conclusion.- IV. Transcranial Doppler Sonography in Angioma Patients.- 1. Introduction, Methods and Normal Values.- 2. Transcranial Doppler Sonography in Angioma Patients (Normocapnia).- 3. CO2 Reactivity, Normal Values and Findings in Angioma Patients.- V. Intraoperative Studies in Angioma Patients.- 1. Intraoperative Methods (History).- 2. Topics of Our Intraoperative Measurements.- 3. Methods Used in This Study.- 4. Operative Strategy and Preparation of Vessels to Be Measured.- 5. Measurements Before AVM Removal.- 6. Measurements After AVM Removal.- 7. CO2 Reactivity of Vessels Supplying Angioma and Brain Before and After AVM Exclusion.- 8. Discussion.- 9. Summary of Intraoperative Measurements.- VI. Final Conclusions.- References.
