Chronic Migraine Is Associated With Sustained Elevation of Somatosensory Temporal Discrimination Thresholds

Background and Objective.-Migraine headache attacks have been shown to be accompanied by significant prolongation of somatosensory temporal discrimination threshold values, supporting signs of disrupted sensorial processing in migraine. Chronic migraine is one of the most debilitating and challenging headache disorders with no available biomarker. We aimed to test the diagnostic value of somatosensory temporal discrimination for chronic migraine in this prospective, controlled study. Methods.-Fifteen chronic migraine patients and 15 healthy controls completed the study. Chronic migraine patients were evaluated twice, during a headache and headache-free period. Somatosensory temporal discrimination threshold values were evaluated in both hands. Duration of migraine and chronic migraine, headache intensity, clinical features accompanying headache such as nausea, photophobia, phonophobia and osmophobia, and pressure pain thresholds were also recorded. Results.-In the chronic migraine group, somatosensory temporal discrimination threshold values on the headache day (138.8 +/- 21.8 ms for the right hand and 141.2 +/- 17.4 ms for the left hand) were significantly higher than somatosensory temporal discrimination threshold values on the headache free day (121.5 +/- 13.8 ms for the right hand and 122.8 +/- 12.6 ms for the left hand, P=.003 and P<.0001, respectively) and somatosensory temporal discrimination thresholds of healthy volunteers (35.4 +/- 5.5 ms for the right hand and 36.4 +/- 5.4 ms for the left hand, P<.0001 and P<.0001, respectively). Somatosensory temporal discrimination threshold values of chronic migraine patients on the headache free day were significantly prolonged compared to somatosensory temporal discrimination threshold values of the control group (121.5 +/- 13.8 ms vs 35.4 +/- 5.5 ms for the right hand, P<.0001 and 122.8 +/- 12.6 ms vs 36.4 +/- 5.4 ms for the left hand, P<.0001). Somatosensory temporal discrimination threshold values of the hand contralateral to the headache lateralization (153.3 +/- 13.7 ms) were significantly higher (P<.0001) than the ipsilateral hand (118.2 +/- 11.9 ms) in chronic migraine patients when headache was lateralized. The headache intensity of chronic migraine patients rated with visual analog score was positively correlated with the contralateral somatosensory temporal discrimination threshold values. Conclusion.-Somatosensory temporal discrimination thresholds persist elevated during the headache-free intervals in patients with chronic migraine. By providing evidence for the first time for unremitting disruption of central sensory processing, somatosensory temporal discrimination test stands out as a promising neurophysiological biomarker for chronic migraine.