Cerebral hypoxia

Etiology 1. Disturbances in auto regulation of blood supply to the brain 2. Conditions affecting cerebral blood vessels

Disturbances in auto regulation of blood supply to the brain Auto regulations fails at 60 mmHg blood pressure. If sustained for MT few seconds leads to irreversible brain damage. The neurons are affecting first, then neuroglia cells and later than meninges and blood vessels.

Conditions Cardiorespiratory arrest Sudden severe hypotension Carbon monoxide poisoning Hypercapnia Drug over dosage with opioid analgesics,

Conditions affecting cerebral blood vessels Occlusion of cerebral artery Arterial stenosis occurs in arteritis If the individual survives the initial episode of ischemia then infarction, necrosis and loss of function of the affected area of brain may occur

Stroke (cerebrovascular disease)

Predisposing factors Hypertension Atheroma Cigarette smoking Diabetes mellitus It occurs when blood flow to brain is suddenly intruppted causing hypoxia Effects are- paralysis, distrubences in vision, speech

Causes are- 1.cerebral infarction (85%): atheroma or thrombosis Transient ischemic attack (TIA) Recurrence attack may follow permanent damage 2. Spontaneous intracranial haemorrhage (15 %): – Intracerebral haemorrhage : mircroaneurysm in prolonged hypertension, A. severe haemorrhage: causes destruction and compression of tissue sudden increase in ICP. Death due to damage in vital centres of MO. B. Less severe haemorrhage: causes paralysis and disorganized speech and vision may be reversed after normal ICP – Subarachnoid haemorrhage : Aneurysm In subarachnoid space, associated with hypertension, blood may spread around brain and spinal cord causing incrasese in ICP but no brain damage