convulsions or stiff neck. Spinal puncture is done only for diagnostic purposes. Repeated lumbar punctures may give rise to a new leakage. (d) Symptom

Arteriovenous malformations (AVMs) - are congenital abnormalities which may affect any part of the brain, including cerebellum and brain stem. Clinical presentation: 1 Intracranial bleeding - more commonly intracerebral. 2 Epilepsy - AVMs responsible are usually large parietal lesions. 3. Progressive neurological deficits - such as slowly evolving hemiparesis. 4.Headache - may be the only presenting symptom. Investigations - CT scan can demonstrate large AVMs. Angiography for small AVMs when surgical excision is being considered. Treatment - Surgery indicated if hemorrhage has occurred and the malformation is easily accessible and can be excised without neurological deficit (b) Embolization of feeding arteries of large lesions with multiple feeders. (c) Stereotoxic radiosurgery may be used to obliterate small AVMs. 12. COMA AND BRAIN DEATH Definition - A state of unarousable unresponsiveness or absence of any psychologically understandable response to external stimuli or inner need Consciousness depends on the interaction of cerebral hemispheres and the reticular activating system of the upper brain stem. Any process interfering with the function of these structures may result in coma. Causes: 1. Structural brain damage - Infarction Hemorrhage Tumour Hematoma Infection: Meningitis, cerebral malaria, encephalitis, abscess Trauma 2. Systemic causes: (a) Metabolic - Anoxia-ischemia. Respiratory, cardiac, hepatic or renal failure.