Clinical features

Typically, the patient afflicted by subarachnoid haemorrhage is over 40 years. The nature and severity of the symptoms depend upon the severity of the bleed.

These include:

• sudden severe headache ("my worst headache ever") - worse and different in character to previous migraine; may bring the patient to their knees
• premonitory headaches occur in the preceding weeks in 25 to 50% of cases; overlooked as often by the patient as by the physician
• loss of consciousness or epileptic seizure occurs in 50% of cases; usually transient, sometimes prolonged
• with less severe bleeding, the patient tends to present with a mild headache or delirium
• bigger bleeds may cause nausea, vomiting and convulsions
• meningism often develops with 3-12 hours
• coma or a depressed level of consciousness may result from the direct effect of the haemorrhage or from the mass effect of an associated intracerebral haematoma
• focal signs, e.g. limb weakness, dysphasia may result from a haematoma
• a "reactive hypertension" is common - the patient undergoes a rise in blood pressure with no evidence of pre-existing hypertension which may last for several days
• presence of a III nerve palsy indicates direct nerve damage from a posterior communicating artery or basilar artery aneurysm, or transtentorial herniation
• fundus examination may reveal subhyaloid or vitreous haemorrhages, or papilloedema
• plantar responses are usually extensor
• back pain may arise from blood in the spinal theca