Neuroimaging in trigeminal autonomic cephalgias: when, how, and of what?

Trigeminal autonomic cephalgias (TACs) are characterized by frequent, short-lasting headache attacks with ipsilateral facial autonomic features. They include cluster headache, paroxysmal hemicrania, and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing. The pathogenesis of TACs is largely unknown, but many case reports in the literature suggest that TACs are secondary to structural lesions. Thus, the question arises whether TAC patients should undergo neuroimaging. Here, we review the recent literature on secondary TACs and attempt to formulate guidelines for neuroimaging.

Recently, we published two reviews of, in total, 33 case reports of patients with a secondary TAC or TAC-like syndrome. Since then, 23 additional cases have been published. Here, we provide a summary of these 56 case reports. TACs were found to be associated with a wide range of both intracranial and extracranial neurovascular and structural lesions. We could not identify a 'typical' clinical warning profile for secondary TACs as these patients could present with clinical features that are entirely characteristic of a TAC, including alternating attack and attack-free periods, and excellent response to TAC-specific treatments.

Even clinically typical TACs can be caused by structural lesions. There are no 'typical' warning signs or symptoms. Neuroimaging should be considered in all patients with TAC or TAC-like syndromes, notably in those with atypical presentation. Depending on the degree of suspicion, additional imaging should be considered assessing intracranial and cervical vasculature, and the sellar and paranasal region.