Abstract
Dear sir We thank colleague Boudreau for his comments. We could not prove botulinum toxin (BTX) to be effective in patients with chronic tension-type headache (CTTH). There are a number of possible reasons for our negative outcome as stated in our Discussion. Whether normal levels of neuropeptides [such as calicitonin gene-related protein (CGRP)] in patients with CTTH (1) play a role in our negative outcome is uncertain. It suggests central sensitization of nociceptive input, with a state of spinal hypersensivity. There is, however, evidence for an antinociceptive effect of botulinum toxin, as found in a rat model with formalin-induced inflammatory pain (2). These findings suggest that BTX blocks peripheral sensitization and, indirectly, reduces central sensitization. Boudreau hypothesizes that if CGRP levels are elevated in migraine patients than BTX might be effective in these patients. However, clinical benefit of botulinum toxin in treatment of migraine is still unproven (3).