Meningeal nociception: Electrophysiological studies related to headache and referred pain

Headaches, which are usually referred to characteristic sites of the skull, are believed to involve meningeal nociceptors located in the dura mater en cephali. Animal experiments show that these meningeal nociceptors are polym odal and usually highly sensitive to mechanical stimulation. These properti es are also characteristic for the second order neurons in the spinal trige minal nucleus, most of which receive convergent input from facial receptive sites. Sensitization of primary and secondary neurons by chemical irritant s to mechanical stimuli may be an important mechanism in the generation of headaches. The convergent input from extracranial structures, which seems t o be differentially organized in rodents and man, may explain the typical f eatures of referred headache. Targets for analgesics used in the therapy of headaches (non-steroidal antiinflammatory drugs, 5-HT1 receptor agonists) are probably meningeal nociceptors and different sites of the central trige minal nociceptive and antinociceptive pathways. (C) 2001 Wiiey-Liss, Inc.