Spontaneous subarachnoid hemorrhage is bad: Fifty percept mortality rate with half the survivors suffering from significant chronic disability. A whole one quarter of patients die in the field. Of those who make it to the ED, a few will be crashing in our resuscitation rooms, but most will just have a headache. So, the problem we face in the ED with SAH is two-fold: First, the clinical manifestations range from just a headache alone – maybe a sentinel leak, to comatose and death. The second problem is that once we identify a subarachnoid bleed, secondary bleeding and ischemia snowball fast leading to delayed badness. It follows that our job in the ED is two-fold: We need to find the needle in the haystack of headache-alone patients who have a SAH. That sentinel leak, that if you pick up now, can prevent a giant bleed and death later. And the literature suggests we’re not great at this – rates of misdiagnosis have been estimated to be as high as 7%. In this part 1 of our 2-part podcast series on subarachnoid hemorrhage, world-renowned EM researcher Dr. Jeff Perry and EM-stroke team clinician Dr. Katie Lin join Anton in a deep dive on SAH decision tools, key clinical clues, indications for CT/CTA, indications for LP, CSF interpretation so that we can safely improve our diagnostic accuracy and save lives...



Podcast production, sound design & editing by Anton Helman; Voice editing by Braedon Paul

Written Summary and blog post by Sara Brade, edited by Anton Helman May, 2024

Cite this podcast as: Helman, A. Lin, K. Perry, J. Episode 194 Subarachnoid Hemorrhage Recognition, Workup and Diagnosis. Emergency Medicine Cases. May, 2024. https://emergencymedicinecases.com/subarachnoid-hemorrhage-recognition-workup-diagnosis. Accessed November 19, 2024

Résumés EM Cases 

Go to part 2 of this 2-part podcast on subarachnoid hemorrhage

Traumatic vs atraumatic/spontaneous subarachnoid hemorrhage

The most common cause of SAH is head trauma. Trauma can cause SAH, but SAH can also cause trauma (ie. SAH causes syncope and patient falls or crashes their car, etc). Etiology (traumatic or atraumatic) dictates the work-up and management. Features to help distinguish the two:

Spontaneous subarachnoid hemorrhage is missed up to 7% of the time - why?

In 73% of cases of missed spontaneous SAH, the most common mistake was not considering the diagnosis and not ordering a non-contrast CT head (NCCTH). Spontaneous SAH has a spectrum of disease presentation. We can’t rely on the “classic presentation” as our only trigger for ordering imaging. We also have to understand the limitations of NCCTH and pursue additional follow-up testing when appropriate (ie. LP and/or CTA). More on work-up below.

“Thunderclap” headache - is it accurate for subarachnoid hemorrhage diagnosis?

“Thunderclap” headache can mean different things to different people. In the Ottawa SAH Rule for headache evaluation, “thunderclap” headache is defined as abrupt onset severe headache that peaks instantly at onset. While most patients with SAH experience headaches that peak in far less than 1 hour, in order to capture all patients with SAH we should still be concerned about SAH in patients with a severe headache peaking up to 1 hour after onset.