According to the US Brain Aneurysm Foundation, “Despite widespread neuroimaging availability, misdiagnosis or delays in diagnosis occurs in up to 25 per cent of patients with subarachnoid hemorrhage when initially presenting for medical treatment. Failure to do a scan results in 73 per cent of these misdiagnoses.”
Macquarie University Hospital neurosurgeon, Dr Andrew Davidson, says in rare cases, failure to do a CT scan does result in misdiagnosis of aneurysms in Australia, especially when the severity of a headache is not appreciated by medical staff. To address the problem, his team is educating emergency departments and GPs in regional areas about the importance of accurate diagnosis.
“One of the greatest difficulties is emergency departments are very busy places, with a lot of people presenting with seemingly more important problems,” says Davidson. “Someone with a headache might be pushed to the bottom of the priority list. Only with education of emergency doctors on the importance of a CT scan will we improve this.
“The other problem is if a patient presents a week after the headache, the CT scan can be normal. We impress upon emergency doctors that if the description of the headache sounds worrying, even if the scan is normal, they often need a lumbar puncture [a procedure where a needle is inserted into the lower part of the spine to collect a sample of cerebrospinal fluid] because the residual red blood cells hang around.
Even if the scan is normal, we can detect if they’ve had a haemorrhage on the basis of a lumbar puncture.
“We often get a call from an emergency department and our advice is clear: if there is a suspicious history, they should have a lumbar puncture. Sometimes a lumbar puncture can be inconclusive and a combination of a lumbar puncture and a CT scan is very good at diagnosing a subarachnoid haemorrhage and very good at ruling one out.”