Researchers determined that migraineurs exhibit unique responses to tactile stimuli compared with controls, according to a study published in Cephalalgia.
Many migraineurs experience habituation deficits and sensory abnormalities as migraine symptoms, including hypersensitivity to light, sound, and smell. To further understand how migraine influences sensory functioning, researchers conducted experiments stimulating the skin of migraineurs and controls with slow brushing movements.
“Slow brushing over the skin activates C-tactile nerve fibers, which mediate pleasant touch and analgesic effects in healthy subjects,” researchers explained. Because this function is altered under painful conditions, researchers aimed to test whether C-tactile processing is disrupted in migraineurs.
Researchers applied C-tactile stroking stimuli on the dorsal forearm (functioning as a body reference area) and the trigeminally inverted skin (cheek) of 52 migraineurs and 52 controls. Participants’ right cheeks represented the headache area, as it is the location of the second branch of the trigeminal nerve. In addition, “for habituation testing, 60 repeated C-tactile optimal stimuli were presented in both test areas,” researchers said. Participants then rated stimuli by intensity, pleasantness, and painfulness on a visual analogue scale.
Results showed no significantly different pleasantness ratings among migraineurs and controls in response to individual stimulis. However, “during repeated stimulation, controls showed stable pleasantness ratings wile migraineurs’ ratings decreased, especially in those experiencing tactile allodynia during headaches,” authors said. In particular, migraineurs’ pleasantness ratings in the trigeminal area decreased significantly over time, but remained constant on the body reference area.
Individually, 14 migraineurs and 8 controls experienced unpleasant testing on the arm, while 16 migraineurs and 8 controls experienced unpleasant testing on the cheek. For pain ratings, migraineurs experienced “a significantly higher rating than controls in both test areas (P <.02 in the reference area and P ?.031 in the trigeminal area).”
The frequency of triptan intake had a significant effect on pleasantness perception, “with frequent triptan intake resulting in stable rating patterns and no or little triptan intake resulting in decreasing pleasantness ratings,” researchers said. They believe these findings may indicate a potential role of allodynia as a biomarker for altered C-tactile processing, due to the fact that triptan intake is associated with transient allodynia.