Subarachnoid Haemorrhage (SAH)
Hunt and Hess grading system for severity of SAH:
Asymptomatic / minimal headache and mild nuchal rigidity
Moderate / severe headache, nuchal rigidity, no neurological deficit other than cranial nerve palsy
Drowsiness, confusion or mild focal deficit
Stupor, moderate to severe hemiparesis
Deep coma, decerebrate rigidity, moribund appearance
Classically “worst ever” and / or sudden onset ( maximal within one hour often used)
Can be brought on by Valsalva, exercise and coitus; coital headache is an exclusion diagnosis!
May improve over hours, especially if sentinel bleed is small
A good response to analgesia does not exclude SAH
Over half are H&H Grade 1-2 and without classic or severe symptoms or signs, so the biggest risk is not considering the diagnosis
May be completely normal
Focal neurological signs?
Neck stiffness and photophobia may be present
Pupillary signs from raised intracranial pressure
Any change in mentation or level of consciousness
Agitation - can occur with a bleed
Fever - can occur with intracranial haemorrhage
This is where there is current debate and there is value thinking about this issue and discussing with senior doctors in your institution.
Perry et al in a prospective study of 10, 000 patients over 10 years concluded that a CT (new generations) done within 6 hours and negative was sufficient to rule out SAH. (2)
A recent retrospective chart review testing the clinical rule mentioned above suggested that up to 20 % of SAH could be missed by this strategy.
Perry’s prospective look at headaches appears much more robust than the chart review particularly when the chart review used patients with an identified aneurysm on angiography but no xanthochromia as a reason to do an LP (ECI author's opinion).
So, what to do? When the LP is done safely with a small pencil point needle it is very safe. It is more likely you will find an alternative diagnosis for the headache than confirm SAH (in CT negative within 6 hrs) but many clinicians who agree with the Perry paper still do LPs. It is a high stakes miss.
Addendum: This paper published late 2014 supports no LP if CT done within 6 hrs and reported by radiologist
Consider omitting if GCS 15, no focal neurologic deficits, and a negative head CT within 6 hours. A shared decision strategy should be used balanced with LP risks.
Non-contrast CT head within 6 hours - up to 100% sensitive, significantly less sensitive after 6 hours
If normal CT, consider performing an LP but discuss pros and cons with patient
During the process the symptoms may settle, but this has no bearing on the potential diagnosis or the associated risk
Primary survey, ABCDE approach and immediate resuscitation in systems, including oxygen, IV analgesia and fluids via x2 large bore cannulae
Call for help early - senior ED
May be Operating Theatre
Early notification of ICU
If for transfer and retrieval then notify early
Mark, DG et al. (2016) False-negative interpretations of Cranial Computed Tomography in Aneurysmal Subarachnoid Hemorrhage, Academic Emergency Medicine, Vol. 23, No. 5, pp. 591-598.