It is possible that RCVS is a more frequent cause of thunderclap headache than is recognized, he said, referring to a study conducted by Chen et al. Eighty-three patients with recurrent thunderclap headache were administered CSF examinations and CT. Fifty-six of the patients had thunderclap headache of unknown etiology. When these patients underwent magnetic resonance angiography (MRA), 39% were found to have reversible cerebral vasoconstriction. Dr. Dodick noted that the mean time to the first MRA was 11 days, and some patients did not have an MRA until up to 32 days, “indicating the possibility that 39% is likely a conservative estimate since resolution of vasoconstriction may have occurred by the time the MRA was done in some patients.” This notion was reinforced by a recent study by Ducros et al in 67 patients with RCVS, in which 21% of patients who ultimately demonstrated vasoconstriction on noninvasive angiography initially had normal angiographic studies; in other words, there was a lag between the onset of symptoms and the presence of vasoconstriction on noninvasive angiography. This suggests that cerebral vasoconstriction may begin in smaller distal vessels that extend beyond the resolution of MRA before involving larger proximal cerebral blood vessels.
“I think all patients with thunderclap headache require angiography, at least noninvasive; some probably require catheter angiography, after initial CSF and brain imaging are done and are found to be normal,” Dr. Dodick continued. He speculated that RCVS is a common cause of angiographic thunderclap headache, “no matter what clinical circumstance it occurs under, whether it’s during just a routine Valsalva maneuver, whether it’s spontaneous, or whether it occurs with orgasm.”
Treatment of RCVS
Treatment of RCVS is based on anecdotal evidence. Differentiating between true CNS vasculitis and RCVS is important, as treatment for the two conditions differs. “We felt there was enough in the literature to suggest that patients with [RCVS], particularly if they had transient neurologic symptoms, should be treated with nimodipine or verapamil,” said Dr. Dodick. “I’ve now since changed that recommendation, suggesting that all patients with RCVS be treated with nimodipine or verapamil until angiographic resolution occurs, even if neurologic symptoms are not present.
“The only downside to using a calcium channel blocker in this group of patients would be that if their vasospasm is so severe and you precipitously drop their blood pressure, you could compromise cerebral diffuse pressure to an area of the brain that’s already compromised,” he concluded.
—Karen L. Spittler