Olfactory and Trigeminal Event - Related Potentials in Migraine
Konrad Grosser 1, 4 MRCP; Rieke Oelkers 1 MD; Thomas Hummel 2 MD; Gerd Geisslinger 1, 3 MD, PhD; Kay Brune 1 MD; Gerd Kobal 1 MD; Jörn Lötsch 1, 3 MD
1 Department of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen - Nürnberg,
Universitätsstrasse 22, D - 91054 Erlangen, Germany
2 Department of Otorhinolaryngology; University of Dresden Medical School; Fetscherstr. 74, D - 01307 Dresden, Germany
3 Center of Pharmacology, Johann - Wolfgang - Goethe University, Theodor - Stern - Kai 7, D - 60590 Frankfurt / Main, Germany
4 Department of Medicine, University Hospital Wales; Heath Park, Cardiff CF4 4XW, United Kingdom
Background: Trigeminal / neuronal hyperexcitability and spreading depression activating the trigemino-vascular system are discussed in migraine - pathophysiology. This study investigated trigeminal and olfactory event related potentials in migraineurs.
Methods: Nasal chemosensitivity was assessed in nineteen female migraineurs with or without aura >72h before or after an attack and in 19 healthy females employing event-related cortical potentials (ERPs) after specific trigeminal stimulation of nasal nociceptors with short pulses of CO2, and specific olfactory stimulation with H2S. Odor thresholds and odor identification performance were also tested.
Results: Migraineurs exhibited greater responses to trigeminal stimulation, indicated by significantly larger ERP amplitudes N1. In contrast, olfactory ERP amplitudes P1N1 were significantly smaller in migraineurs. A leave - one - out classification procedure on the basis of these two parameters assigned 76.3% cases correctly. The olfactory ERP amplitude discriminated better between groups than trigeminal ERPs (71.1vs. 68.4% correct classification).
Conclusions: Our data suggest trigeminal hyperexcitability in migraineurs. A general increase of nasal chemosensitivity is not supported because of smaller olfactory ERP amplitudes in migraineurs. Olfactory ERPs discriminate better than trigeminal ERPs between migraineurs and controls emphasizing the significance of the olfactory system in migraine.