[Symptomatic cluster headache. Expression of multiple sclerosis relapse with magnetic resonance tomography detection of pontomedullary lesion in the ipsilateral trigeminal nucleus area].

We describe a 25-year-old male who developed, in the course of an acute exacerbation of his multiple sclerosis, cluster headache-like attacks which responded to oxygen therapy. Magnetic resonance imaging revealed a lesion in the area of the ipsilateral pontomedullary trigeminal nuclei. This symptomatic case and other published cases are most probably explained by an activation of the trigeminovascular system as it is assumed for primary headache syndromes.