Background Certain patterns can induce perceptual illusions/distortions and visual discomfort in most people, headaches in patients with migraine, and seizures in patients with photosensitive epilepsy. Visual stimuli are common triggers for migraine attacks, possibly because of a hyperexcitability of the visual cortex shown in patients with migraine. Precision ophthalmic tints (POTs) are claimed to reduce perceptual distortions and visual discomfort and to prevent migraine headaches in some patients. We report an fMRI visual cortical activation study designed to investigate neurological mechanisms for the beneficial effects of POTs in migraine. Methods Eleven migraineurs and 11 age- and sex-matched non-headache controls participated in the study using non-stressful and stressful striped patterns viewed through gray, POT, and control coloured lenses. Results For all lenses, controls and migraineurs did not differ in their response to the non-stressful patterns. When the migraineurs wore gray lenses or control coloured lenses, the stressful pattern resulted in activation that was greater than in the controls. There was also an absence of the characteristic low-pass spatial frequency (SF) tuning in extrastriate visual areas. When POTs were worn, however, both cortical activation and SF tuning were normalized. Both when observing the stressful pattern and under more typical viewing conditions, the POTs reduced visual discomfort more than either of the other two lenses. Conclusion The normalization of cortical activation and SF tuning in the migraineurs by POTs suggests a neurological basis for the therapeutic effect of these lenses in reducing visual cortical hyperactivation in migraine.

Neurostimulation for primary headaches is being increasingly utilized as a treatment modality. Use of neuromoduation has generated multiple case reports as well as some controlled studies. This article is the first of 2 systematic reviews of available data regarding neurostimulation for primary headache conditions. The pathophysiology, relative anatomy, theoretical mechanisms, and history of neurostimulation for primary headache are covered in this section, Part 1 of 2. The literature regarding peripheral neurostimulatory targets is also reviewed in Part 1. These peripheral targets include: percutaneous nerves, transcranial holocephalic, occipital nerves, auriculotemporal nerves, supraorbital nerves, cervical epidural, and sphenopalatine ganglia. Part 2 will focus on central stimulation, covering vagus nerve, and deep brain stimulation. Part 2 also contains an overall analysis of efficacy, safety, cost, patient selection, and suggestions for further study based on available evidence.

This article is the second of 2 articles reviewing neurostimulation for primary headaches. In Part 1, we described methods, pathophysiology and anatomy, and history of neuromodulation in the treatment of headache, as well as reviewing the literature on peripheral neuromodulation for primary headaches. Peripheral targets for stimulation include percutaneous nerves, transcranial holocephalic, occipital nerves, auriculotemporal nerves, supraorbital nerves, cervical epidural, and sphenopalatine ganglia. In Part 2, we describe available literature on central neuromodulation in primary headaches. Central stimulation targets include vagus nerve and deep brain structures. Part 2 also analyzes overall therapeutic efficacy, safety, cost, patient selection, and recommendations for further research of neurostimulation modalities based on available data.