Sensitization and pain.

Migraine is often accompanied with signs of increased intracranial and extracranial mechanical sensitivities. The prevailing view today is that migraine headache is a neurovascular disorder with intracranial origin and involvement of meningeal blood vessels and their pain nerve fibers. Allodynia, defined as perception of pain following not painful stimulation, is a common clinical feature in various pain syndromes, and as part of migraine pain, it can be considered an indicator of trigeminal neural network sensitization. The cutaneous allodynia that accompanies the migraine headache in a large percentage of patients may be considered the clinical expression of central nervous system sensitization and is characterized by pain provoked by stimulation of the skin that would ordinarily not produce pain. An altered codification process of sensory impulses in the brainstem, in particular by the nucleus caudalis trigeminalis, may justify the temporal aspects and symptoms in the course of migraine attack.