Extraction of angiogenesis factor from chronic subdural haematomas. Significance in capsule formation and haematoma growth.

The extraction of angiogenesis factor (AGF) from the contents of chronic subdural haematomas was attempted in order to explain the angiogenesis in the capsule. AGF was extracted from eight patients using the modified Phillip's method, which has previously been used for the extraction of tumour angiogenesis factor. The thickness of the haematoma capsule was measured immediately after removal. The Hounsfield units were evaluated as the average value of three areas in the haematoma on CT scans. Chromatographic separation of the treated contents gave five fractions. The highest activity was observed in the fourth fraction on bioassay by the air sac method. The intensities of AGF activity varied from patient to patient. Although no correlation existed between the degree of AGF activity and thickness of the capsule, a positive correlation was seen between the activity and the density of the contents as indicated by Hounsfield's units on a CT scan. This may indicate the existence of a sequence of cause and effect between increase in the AGF activity and haemorrhage in the capsule of the haematoma. AGF activity increases after haemorrhage in the haematoma capsule, leading to acceleration of angiogenesis in the capsule, which promotes the haemorrhagic cause in the haematoma. Thus, a vicious circle between AGF in the haematoma, angiogenesis in the capsule and haemorrhage in the haematoma is established. It is considered that this gives rise to growth of the haematoma.