Evaluation of lithium response in episodic cluster headache: a retrospective case series.

OBJECTIVE: In this study, we attempted to evaluate the response to lithium treatment and its tolerability in the prevention of episodic cluster headache (CH) and to identify clinical predictors of response.

BACKGROUND: Verapamil and lithium are the most widely used drugs in the prevention of CH attacks. Lithium is considered a second-line treatment in part because of its potentially severe adverse drug reactions (ADRs). Evidence for the efficacy of lithium in CH prevention is greater in chronic than in episodic patients. In addition, because of its narrow therapeutic window and ADRs (which can be significantly reduced with proper periodical monitoring of blood levels), lithium is recommended only in chronic CH, when other drugs are ineffective or potentially harmful.

METHODS: Our primary aim was to determine whether lithium reduced the number of attacks per day (attack frequency). We compared attack frequency in 3 periods: run-in, the first, and the second week of lithium treatment. Responders were defined as patients showing at least a 50% reduction in attack frequency.

RESULTS: Lithium response was evaluated in 26 patients. Treatment led to a significant reduction in attack frequency within 2 weeks in a percentage of 77% of responders and 23% of nonresponders. Responders and nonresponders did not differ in terms of demographic and clinical characteristics. Only 15% of patients experienced mild ADRs.

CONCLUSION: Our study provides additional evidence on the effectiveness of lithium in the prevention of episodic CH. It also shows the tolerability of lithium, given the short duration of treatment and low dosage.