When a Headache Can be Deadly Serious

A minor brain bleed prior to major aneurysmal rupture is a common occurrence and, if unrecognized, is associated with a high mortality. The correct diagnosis of a minor aneurysm leak is important because early diagnosis and management can improve the overall outcome of this disastrous disease.

The Signs and Symptoms of a Brain Bleed

The primary symptom of subarachnoid hemorrhage (aka brain bleed) is a very severe headache of sudden onset. Sentinel, or “warning” leaks that produce minor blood leakage are reported to occur in 30-50% of cases involving a subarachnoid hemorrhage.  Sentinel bleeds produce sudden focal or generalized head pain that may be severe. They also result in nausea, vomiting, photophobia, malaise or less commonly, neck pain.

Sentinel headache is characterized as a severe headache with features different from the usual headache. Sentinel headache is a kind of secondary headache and is characterized as sudden, intense, and persistent, preceding spontaneous subarachnoid hemorrhage by days or weeks. It can occur in 15-60% of patients with spontaneous subarachnoid hemorrhage.

Sentinel headache may be due to bleeding, distention or dissection of the aneurysmal wall in the brain. Sentinel headache is an important warning sign that remains under-estimated when patients are seen at emergency departments, but it should always be considered. A minor bleed prior to major aneurysmal rupture is a common occurrence and, if unrecognized, is associated with a high mortality.

Imaging Studies to Detect a Brain Bleed

In patients presenting with thunderclap headache and normal neurological examination, normal brain CT within 6 hours of headache is very sensitive in ruling out aneurysmal subarachnoid hemorrhage.

At the onset of the bleed, subarachnoid blood is the most readily visible on CT, but it becomes more difficult to appreciate as red blood cell degradation progresses. A non-contrast CT completed within 6 hours of headache onset had a sensitivity of 98.7% with confidence intervals 97.1%–99.4%.” The CT imager must be a third generation or newer.

All patients presenting with a clear history of a thunderclap headache should have an urgent non-contrast CT head scan, followed by a lumbar puncture and vascular imaging (CTA/MRA) to rule out subarachnoid hemorrhage and other mimics as a delay may have lethal consequences. In patients presenting with a thunderclap headache and normal neurological examination, a normal brain CT within 6 hours of headache is extremely sensitive in ruling out aneurysmal SAH.

The Sensitivity of a CT Scan of the Brain in Detecting a Brain Bleed

Treatment of the aneurysm within 24 hours of the bleed reduces the risk of rebleeding. Lumbar puncture has the highest sensitivity in ruling out a subarachnoid hemorrhage but only 12 hours after the onset of the headache. The sensitivity of lumbar puncture for subarachnoid hemorrhage approaches 100%.

The sensitivity of modern CT scanners for subarachnoid approaches 100% when performed within 6 hours of headache onset. In this early presenting population, a lumbar puncture is not necessary to rule out subarachnoid hemorrhage and an initial negative CT scan can be considered a rule out test.

CT scan of the brain will miss about 5% of subarachnoid hemorrhage during the first 24 hours after the ictus increasing to 25% by day 3 and 50% by one week. The sensitivity of a head CT in subarachnoid hemorrhage decreases over time to 86% on day 2, 76% after 2 days, and 58% after 5 days.

Overall, the combination of CT and lumbar puncture is sufficient to rule out a subarachnoid hemorrhage. With modern CT scanners, more than 90% of patients with a subarachnoid hemorrhage will demonstrate evidence of blood in the cerebral subarachnoid space.