Patients with cluster headache can show clinical signs of olfactory dysfunction

Introduction: We recently described microstructural changes in the olfactory system of patients with cluster headache. A possible clinical correlate has not been investigated so far. The aim of the present study was to evaluate a possible olfactory dysfunction related to the neuroimaging findings in patients with cluster headache.

Methods: Olfactory function was evaluated in 9 patients with cluster headache and 9 control subjects using standardized Sniffin' sticks. Odour threshold, discrimination threshold and odour identification as well as a sum score (TDI) representing the sum of these three subtests were evaluated.

Results: Odour identification was decreased in patients with cluster headache ((patients: 11.2±2.2, control subjects: 13.6±1.3, p<0.05). Also, patients had a lower TDI score as compared to control subjects (31.2±5.1 vs. 36.3±1.8, p<0.05). Four patients and no control subjects suffered from mild hyposmia as diagnosed by results of the olfactory test conducted in our study.

Discussion: This is the first study describing olfactory dysfunction in patients with cluster headache. Results are in agreement with a previous study describing microstructural changes in the olfactory system of patients with cluster headache and might be related to an interaction between the trigeminal and olfactory system and the involvement of the trigeminal system in the pathophysiology of the disease.