Chiều dài của lịch sử của bất kỳ của ba tính năng chính của một khối u não là một hướng dẫn với tính chất của khối u, bệnh ác tính. Đây không phải là hết sức rõ ràng, tuy nhiên. Chắc chắn một lịch sử lâu dài cho thấy một khối u ác tính lành tính hoặc cấp thấp. | BRAIN TUMOUR 47 Appetite T or 0 Cranial nerve palsies Wakefulness 0 3-12 depending on Endocrine effects level of tumour Cranial nerves 3 Cerebellar deficit due 4 6 5a to impaired inflow or outflow from the cerebellum Long tract motor and sensory deficits in limbs and trunk Impaired vital functions . respiration thermo-regulation and circulation Fig. Median section through the brain showing the neurological deficits produced by tumours at various sites. The length of history of any of the three main features of a brain tumour is a guide to the nature of the tumour in terms of malignancy. This is not foolproof however. Certainly a long history suggests a benign or low-grade malignancy tumour. A short progressive history obviously implies malignancy but sometimes a benign tumour can be silent for years only to produce a short worrying history when the brain and the intracranial compartments finally become unable to absorb the presence of the enlarging mass lesion. 48 CHAPTER 3 Common brain tumours Gliomas are seen to appear in both the benign and malignant groups of tumours. Astrocytomas are by far the most common glial tumour tumours derived from oligodendrocytes ependyma neurones primitive neuroectodermal or other tissues are much rarer. Unless otherwise specified the words primary brain tumour or glioma refer to an astrocytoma in clinical practice. Gliomas are classified histologically from grade 1 benign to grade 4 the highly malignant glioblastoma multiforme . Benign gliomas are unfortunately much less common than malignant ones and have a tendency to become more malignant with time. Meningiomas are nearly always benign. They may arise from any part of the meninges over the surface of the brain from the falx or from the tentorium. There is a plane of cleavage between tumour and brain tissue which makes total removal a definite possibility so long as the tumour is reasonably accessible and unattached to dural venous sinuses . the sagittal sinus. .
