Time course of the haemodynamic response to visual stimulation in migraine, measured using near-infrared spectroscopy
Coutts LV et al. – The time course of the functional response as measured by near–infrared spectroscopy (NIRS) may be an effective tool to track therapy with precision spectral filters (PSF) and explore the mechanisms of visual stress in migraine.Methods
- The present study used near–infrared spectroscopy (NIRS) to characterise the haemodynamic response to a range of visual stimuli in 20 patients with migraine (15 with aura and 5 without) and paired controls in order to assess the effect of ophthalmic treatment.
- In an initial study, the response to three stimuli (chequerboard, and two gratings of different spatial frequency) was measured.
- In a second study, using the mid–spatial frequency grating as stimulus, the response was compared when precision spectral filters (PSF), grey filters or filters of control colour were worn as ophthalmic lenses.
- In the first study the time course of the response differed between the groups.
- The difference was most distinct for the grating with mid–spatial frequency.
- In the second study the PSF broadened (normalised) the haemodynamic response in migraineurs relative to controls, consistent with fMRI BOLD findings and suggesting a physiological mechanism for their reported efficacy.
- In neither study were there differences in the amplitude of the response between migraine and control groups or indeed between filters.