Acute, Severe Headache

Criteria that suggest an acute migraine rather than subarachnoid haemorrhage (SAH):

Rule-in criteria: “P0UND”

• Pulsating
• One-day duration (in practice, 4-72 hours)
• Unilateral location
• Nausea or vomiting
• Disabling intensity

Rule-out criteria: “SUM IT UP”

• Sudden onset
• Unlike previous
• Maximal at onset

Strongly and reliably consistent with subarachnoid haemorrhage:

• > 40 year old with neck pain or neck stiffness and onset with exertion, vomiting, witnessed loss of consciousness, raised BP > 160/100

Note, however, that neck pain is not infrequent, and (in my experience) almost the rule, in migraine but there certainly should not be any meningism with migraine.

Duration of symptoms – the earlier the presentation, the better yield with a non-contrast Head CT, the later the presentation (especially after 5 days), the greater yield with lumbar puncture.

At 12 hours from onset, multi-slice non-contrast head CT scan has a 95% sensitivity and 97% specificity for subarachnoid haemorrhage, while at 2 days the sensitivity drops to 85% and after 5 days to 50%. Conversely, a lumbar puncture is more sensitive a few days after onset of symptoms; where high opening pressures, xanthochromia, > 5 RBCs in last of 4 tubes, is highly suggestive for recent subarachnoid haemorrhage. (see also Czuczman et al, 2013).

Traditionally, a negative CT scan is followed with lumbar puncture (LP). However, non-contrast CT followed by CT angiography (CTA) of the brain can rule out SAH with greater than 99% sensitivity. After the diagnosis of SAH is established, further imaging should be performed to characterize the source of the hemorrhage. This effort can include standard angiography, CT angiography, and magnetic resonance (MR) angiography.¹

Emergent treatment of suspected SAH:

1. control BP
2. nimodipine 60 mg q 4-hr PO/NGT, for 21 days; begin therapy within 96 hours of subarachnoid hemorrhage
3. anti-seizure prophylaxis
4. note any ECG changes:
   1. deep praecordial T-waves
   2. bradycardia
   3. prolonged QT

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Works cited

1. Becske, Tibor and Lutsep, Helmi L. Subarachnoid Hemorrhage Workup: Approach Considerations, Computed Tomography, Lumbar Puncture (medscape.com).