Secondary cluster headache due to a contralateral demyelinating periaqueductal gray matter lesion.

Objectives/background Tension-type headache and migraine without aura are the most common primary headaches occurring in people with demyelinating diseases, whereas cluster headache (CH) can be considered exceptional. The location of demyelinating lesions could be strategic in these cases, involving areas interacting with the trigeminovascular system. Methods and results We report a case of a 54-year-old woman with right-sided CH as the initial manifestation of multiple sclerosis and showing a left dorsal brainstem lesion on magnetic resonance imaging, in the region of the dorsal longitudinal fasciculus (DLF). Conclusion Our case seems to suggest a possible role of the DLF in the process that leads to CH attacks. Because neuroimaging clearly showed a lesion contralateral to CH pain, we hypothesize that some fibers from periaqueductal gray matter project to the contralateral side, besides the known ipsilateral connections.