Treatment of primary headache disorders with intravenous valproate: initial outpatient experience

To evaluate the effectiveness of intravenous valproate in managing moderate to severe headaches.

Despite major strides in the understanding of primary headache disorders, there have been few additions to acute headache management other than introduction of the triptans. An intravenous antiepileptic preparation, sodium valproate, has been reported to be effective in the management of status epilepticus and acute headache.

Between March 13, 2000 and October 11, 2000, we prospectively treated, in a nonrandomized and open-label study, every patient with a moderate to severe headache (4 or greater on a visual analog scale of head pain from 1 to 10) who wanted treatment with intravenous valproate. Using a verbal visual analog scale for pain (0 = no headache and 10 = most severe headache), we measured head pain before treatment and at time of discharge. The treating nurse monitored vital signs and side effects. A positive response was defined as a 50% or greater reduction at discharge in baseline pain. Information was collected regarding patient demographics, type of headache (according to criteria of the International Headache Society and that recently proposed for chronic headache), observation time in the treatment suite, cumulative dose of valproate, and use of concurrent medications. Univariable and multivariable correlates of response to treatment were identified using logistic regression analysis.

One hundred thirty treatments were given to 89 women and 17 men, aged 17 to 76 years; 92 patients received only one treatment. Valproate doses ranged between 300 and 1200 mg. Thirty-three patients (31%) presented with episodic migraine, with or without aura; 45 patients (42%) presented with chronic daily headache with a history of episodic migraine, with or without aura (transformed migraine); 22 (21%) with unclassifiable chronic headache; 2 (2%) with episodic cluster headache; and 4 (4%) with chronic tension-type headache. For first treatments only, 61 patients (57.5%) responded to treatment, whereas for all treatments, 82 patients (63.1%) responded. Age and gender did not affect likelihood of response, whereas increasing duration of treatment (P=.003) and the additional use of analgesics (P=.021) were each negatively associated with response. Among headache types, unclassifiable chronic headache segregated from all other classified headaches in terms of poor response. Aside from rare dizziness (n = 2) and one spell interpreted as a pseudoseizure, no side effects were noted.

Intravenous valproate is a safe, rapidly effective, abortive headache agent. It appears to be an effective analgesic for identifiable primary headaches, especially episodic headache, and less effective for unclassifiable chronic headache. Randomized, double-blind, controlled studies are warranted.