A Horner-like syndrome and cluster headache. What comes first?

Purpose: To evaluate if an ocular sympathetic lesion may be a prerequisite for cluster headache to occur. Methods: Patients with a permanent Horner-like syndrome at the debut of cluster headache were identified from history and photographs. Results: Among 57 patients with cluster headache, seven patients (5 males and 2 females) exhibited a permanent Horner-like syndrome on the painful side when first seen at the outpatient department. During this study it was possible to get information from six of these patients and five of them had side constant cluster headache. In retrospect, these five patients had had a Horner-like syndrome for years prior to the onset of ipsilateral cluster headache. Conclusion: The findings indicate that a sympathetic lesion or dysfunction may be a prerequisite for the subsequent development of cluster headache.