Subarachnoid Haemorrhage Quiz

See Presentation. Option A is correct because subarachnoid haemorrhage classically causes a sudden, severe thunderclap headache, one that reaches its maximum intensity within seconds. Patients often describe it as the worst headache of their life. It happens because arterial blood floods the subarachnoid space and the pressure inside the skull suddenly rises. Other features are vomiting, neck stiffness (from irritation of the meninges, the membranes around the brain), sensitivity to light, seizures and a reduced level of consciousness, which may be lost at once or hours later. Most people with a thunderclap headache do not have a subarachnoid haemorrhage, but NICE says this should not deter further investigation when the diagnosis is suspected, because the condition is an emergency. A suspected case needs an urgent CT scan. The key is the pattern of onset: a headache that is sudden and severe from the start points to a bleed, whereas headaches that build up over hours or days point elsewhere. A helpful memory aid is the word thunderclap, which means instant onset at maximum severity, like a clap of thunder.

• Onset: a sudden, severe thunderclap headache that reaches maximum intensity within seconds.
• Description: patients often call it the worst headache of their life.
• Cause: arterial blood floods the subarachnoid space and the pressure inside the skull suddenly rises.
• Action: a suspected case needs an urgent CT scan.