Cluster headache and arachnoid cyst

Background: Cluster headache is a primary headache by definition not caused by any known underlying structural pathology. However, symptomatic cases have been described, e.g. tumours, particularly pituitary adenomas, malformations, and infections/inflammations. The evaluation of cluster headache is an issue unresolved. Case description: We present a case of a 43-year-old patient who presented with a 2-month history of side-locked attacks of pain located in the left orbit. He satisfied the revised International Classification of Headache Disorders criteria for cluster headache. His medical and family histories were unremarkable. There was no history of headache. A diagnosis of cluster headache was made. The patient responded to symptomatic treatment. Computer tomography and enhanced magnetic resonance imaging after 1 month displayed a supra- and intrasellar arachnoid cyst with mass effect on adjacent structures. After operation, the headache attacks resolved completely. Discussion and evaluation: Although we cannot exclude an unintentional comorbidity, in our opinion, the co-occurrence of an arachnoid cyst with mass effect with unilateral headache, in a hitherto headache-free man, points toward the fact that in this case the CH was caused or triggered by the AC. The headache attacks resolved completely after the operation and the patient also remained headache free at the follow-up. The response of the headache to sumatriptan and other typical CH medications does not exclude a secondary form. Symptomatic CHs responsive to this therapy have been described. Associated cranial lesions such as tumours have been reported in CH patients and the attacks may be clinically indistinguishable from the primary form. Conclusions: Neuroimaging, preferably contrast-enhanced magnetic resonance imaging should always be considered in patients with cluster headache despite normal neurological examination. Late-onset cluster headache represents a condition that requires careful evaluation. Supra- and intrasellar arachnoid cyst can present as cluster headache.