Neurological and Systemic Pitfalls in the Diagnosis of Cluster Headaches: A Case-Based Review

To describe different pitfalls in the diagnosis of primary cluster headaches (CHs) with the guidance of seven case vignettes.

The question of whether primary CHs and migraines are totally different entities has been long debated. Autonomic features can be detected in as many as 60% of migraine patients. Although some genetic similarities have been found, CACNA1A mutations have not been detected among CH patients with hemimotor aura in contrast to hemiplegic migraine. Recently, functional MRI studies have shown that the left thalamic network was the most discriminative MRI feature in distinguishing migraine from CH patients. Compared to migraine, CH patients showed decreased functional interaction between the left thalamus and cortical areas mediating interception and sensory integration. However, clinically the most significant feature had been the restlessness and agitation seen during headache attacks patients with CHs. This feature is also important in distinguishing cluster patients from other patients having other trigeminal autonomic cephalalgias except for a subset of patients with hemicrania continua. CH is an important member of the group of headache disorders characterized by their association with one or more autonomic features in the trigeminal nerve distribution and termed Trigeminal Autonomic Cephalalgias (TACs). Although CH is a relatively rare condition, judged by the distress it generally causes to the affected individual, early diagnosis and institution of appropriate therapy seem mandatory. Correct diagnosis of CHs needs avoidance of pitfalls. Such pitfalls generally include differentiation from migraine, differentiation from other side locked headache disorders, from other trigeminal autonomic cephalalgias (TACs), and lastly, recognition of rare presentations of cluster-like manifestations with hemiplegic aura and simulating trigeminal and glossopharyngeal neuralgias. Differentiation between primary and symptomatic CHs related to sellar pathologies and systemic medical conditions is of equal importance. In the present review such issues are discussed with the assistance of seven case vignettes.