Spontaneous intracerebral haemorrhages are the most dangerous complication of cerebral vascular disease. Because of their frequency and the fact that they lead to serious injuries, prolonged disabilities and, often, death, they have acquired an enormous significance, both medically and socially. Their precise diagnosis, location, wide extent and accomp ying manifestations were for a very long time uncertain and, in small and deeply situated haematomas, these factors were impossible to determine. Diagnosis was confirmed by the clinical picture, by angiography and sometimes by ventriculography and included, in the main, both lobar and more extensive haematomas. The results of operative treatment following the first attempt of H. Cushing in 1903 were poor and remained unsatisfactory in spite of the endeavours of numerous authors (Guillaume et al. 1956; Lazorthes 1956; McKissock et al. 1959; Luessenhop 1967 and many others). Especially for the most frequent and typically hypertensive haematomas in the region of the internal, capsule, the opinion was often expressed that operative treatment was useless.

The rapid development of diagnostic and therapeutic procedures in the management of spinal angiomas has opened up new possibilities and provided better chances for the patients concerned. The greatest impetus to this pro gress was given by the introduction of selective and superselective spinal angiography, microsurgical technique, and embolization. These sophisticated techniques and the skill required for their use are far from being routine in the neurosurgical and neuroradiologic departments. In spite of the rarity of spinal angiomas, the application of the above-mentioned procedures is the prerequisite for improving early diagnosis and giving timely adequate treat ment. Delay in diagnosis and treatment are still the main cause of unsatisfac tory results. In the last 10 -20 years, several groups in Europe and the USA have done important and fundamental work in introducing and developing the diganos tic and therapeutic armamentarium. Based on the pioneering work of their teachers and the classic contribution of Wyburn - Mason in 1943, they simultaneously improved the morphologic, physiologic, and clinical basis of our knowledge. Although progress is going on and many problems have to be solved, the general principles of clinical diagnosis, operative treatment, and embolization have been laid down and are to be published in a special monograph on this topic."

Microsurgery has brought about important changes and progress in the treatment of cere bral aneurysms in recent years. Only 12 years ago McKissock, one of the most experienced surgeons in the treatment of aneurysms pompared the results of operative and nonoperative treatment. He found that mortality and morbidity of cerebral aneurysms was not significantly affected by whether the patients have been operated upon or not. This view is held by many neursurgeons, and was confirmed by results of the Co-operative Study in 1969. In the review on treatment of aneurysms in Progress in Neurological Surgery in 1969, techniques such as encasement with plastic compounds, piloinjection, stereotactic copper or electric thrombosis and metallic thrombosis and profound hypothermia in anaesthesia were listed. In general, these techniques now seem to be of little more than historical interest. Progress in recent yeats has been so enormous that one may perhaps gain the impreSSion that the main problems in the treatment of aneurysms have been solved and that there are no more to be surmounted. This is dangerous and complacent thinking, such as Lord Moynihan indulged in during the thirties. For this reason we thought that the time had come to assemble a group of experts who could discuss the various unsolved and contro versial problems of aneurysm surgery in the friendly and relaxed atmosphere of a "work shop.""

The basic principles of the management of cerebral arteriovenous mal- formations were established during the first phase of the neurological attack on these problems between 1930 and 1960. The leaders were CUSHING, BAILEY and DANDY, but principally OUVECRONA, and in Ger- many TONNIS. The experience gained showed that complete excision of the arteriovenous angioma was the only certain cure, and therefore was the procedure of choice. In the present second phase important advances should be made and indeed are occurring. New diagnostic techniques such as total angio- graphy, selective and superselective angiography, intraoperative and fluorescein angiography, and the EMI-scanner have been developed. The pathophysiological aspects have been further investigated by indirect and direct measurement of local and general cerebral blood flow. Parallel with these developments operative technique itself has been improved and modified by new methods. A more aggressive attitude has been stimulated towards those angiomas, which had to be regarded as inoperable only a few years ago. Among these many im- provements and technical advances include microsurgical techniques, combined stereotactic and microsurgical procedures, artificial emboliza- tion of different kinds and the cryosurgical management. Multiple variables such as the age of the patient, the type, localization, and size of the angioma, its clinical picture and the possible complica- tions, such as hemorrhage have been analysed and are understood better. These factors influence the indication for, and choice of, the appropriate procedure to a great extent.