Raised intracranial pressure is due to the tumour mass, surrounding cerebral oedema and hydrocephalus due to blockage of the CSF pathways. The features of raised intracranial pressure are described in detail in Chapter 3. The major symptoms are headache, nausea and vomiting, and drowsiness. Headache is the most common symptom in patients with cerebral astrocytoma and occurs in nearly three-quarters of patients; vomiting
occurs in about one-third. The headaches are usually gradually progressive and although frequently worse on the side of the tumours, they may be bitemporal and diffuse. Characteristically, the headache is worse on waking and improves during the day. Nausea and vomiting occur as the intracranial pressure increases, and
the patient frequently indicates that vomiting may temporarily relieve the severe headache. Drowsiness, that is, a deterioration of conscious state, is the most important symptom and sign of raised intracranial pressure. The extent of impairment of conscious state will be related to the severity of raised intracranial pressure. An alert
patient with severely raised intracranial pressure may rapidly deteriorate and become deeply unconscious when there is only a very small further rise in the pressure within the cranial cavity.
