Imaging for Cluster Headache
MRI brain without contrast is the imaging modality of choice for patients presenting with cluster headache to exclude structural mimics, though imaging is not routinely required if the presentation is entirely typical with normal neurological examination. 1, 2
When to Image Cluster Headache Patients
Patients presenting with symptoms suggestive of cluster headache warrant at least a brain MRI scan in their work-up to exclude structural pathology. 1 This recommendation exists because:
- Even typical cluster headache with characteristic episodic time patterns and response to standard treatments can be caused by underlying structural pathology such as pituitary tumors 2
- Symptomatic cluster headache or cluster-like syndromes associated with structural lesions have been documented, though establishing causality can be difficult 2
- By definition, primary cluster headache is not caused by structural pathology, but secondary causes must be excluded 2
MRI vs CT for Cluster Headache
MRI (not CT) is the investigation of choice when neuroimaging is considered for cluster headache. 2 The rationale includes:
- MRI provides superior sensitivity for detecting structural mimics including pituitary lesions, vascular malformations, and other intracranial pathology 2
- CT has insufficient sensitivity to adequately exclude structural causes of cluster-like presentations 2
Red Flags Requiring Imaging
Neuroimaging becomes more urgent when cluster headache presentations include:
- Atypical features that deviate from classic cluster headache patterns 3
- Focal neurologic signs or symptoms on examination 3, 4
- New onset in patients over age 50 3
- Progressive or worsening pattern 3
- Abnormal neurological examination findings 5
Common Pitfalls to Avoid
- Do not use CT as the primary imaging modality for cluster headache evaluation, as it lacks sensitivity for detecting structural mimics like pituitary adenomas 2
- Do not skip imaging entirely even when the presentation appears typical, as structural lesions can present with classic cluster headache features and respond to standard treatments 2
- Do not assume causality between an identified lesion and cluster headache without careful clinical correlation, as incidental findings are common 2