Yield of head computed tomography in patients with new onset of transient headaches.

Background: Headache is a common patient complaint. The threshold for brain imaging in headache is debated, especially when the headache is transient, although even if the headache has resolved at presentation, a sentinel bleed heralding a subarachnoid haemorrhage (SAH) often remains a concern.

Objective: To assess the yield of computed tomography (CT) head scan referrals for patients with transient headache symptoms.

Methods: This study looked at 6 months of CT results in order to assess for brain pathology, with a particular focus on subarachnoid haemorrhage. Where any pathology was identified, detailed chart review looked for potential high-risk indicators.

Results: Between January and July 2015, 531 undifferentiated headache patients were referred for head CT. Of these, 177 (33.3%) presented with a transient or episodic pattern. None of these cases had SAH on imaging nor re-presented with SAH within 3 months of initial CT. However, 7.3% (13/177) had other significant intracranial pathologies. The only significant risk factor for CT abnormality in this setting was focal neurology on presentation (odds ratio 3.1 (95% confidence interval (CI) 1.2-11.0); P = 0.044). All identified cases of SAH over the 6-month study period occurred in patients with persistent headache, and their clinical presentations showed a similar cluster of symptoms to previous literature (including thunderclap headache, vomiting and loss of consciousness).

Conclusions: This study suggests that patients with transient headache are at a low risk of SAH; however, further study is needed to quantify this, and other serious pathologies remains a concern, especially in the setting of focal neurology at presentation.