Glutamate levels in cerebrospinal fluid and triptans overuse in chronic migraine

Objective.-Chronic migraine (CM) is a common disorder, affecting 2% to 3% of the general population. Glutamate is implicated in cortical spreading depression, trigeminovascular activation, central sensitization, and may be linked to migraine chronification. Triptans brought a novel option for the acute migraine treatment. As the development of central sensitization impacts upon the effectiveness of triptan therapy, we hypothesized that glutamate might be related to triptan response mechanisms. Methods.-We studied 19 patients diagnosed with CM according to the International Headache Society (2004) criteria. Patients were divided in those overusing analgesics (NSAIDs); those without overuse, and those overusing triptans. Results.-Cerebrospinal fluid (CSF) glutamate levels were similar in patients overusing acute medications (0.335 +/- 0.225 mu mol) compared to those without overuse (0.354 +/- 0.141 mu mol), P = NS). In contrast, patients overusing triptans had CSF glutamate levels significantly lower than that observed in nonoverusers (0.175 +/- 0.057 vs 0.354 +/- 0.141 mu mol, P = 0.015). and significantly higher than controls (0.175 +/- 0.057 vs 0.109 +/- 0.066 mu mol, P = 0.039). In triptan overusers, CSF glutamate levels, although lower, were not significantly different from patients overusing other types of analgesics. Conclusions.-Our study showed lower glutamate levels in CSF of CM patients overusing triptans. Glutamate may be implicated in triptan response mechanisms, triptans may work in part by reducing extracellular glutamate levels in the brain.