The trigeminocervical complex and migraine: current concepts and synthesis

Neurones in the trigeminocervical complex are the major relay neurones for nociceptive afferent input from the meninges and cervical structures; therefore, they are the neural substrates of head pain. This review highlights the importance of two basic mechanisms in headache physiology: convergence of nociceptive afferents and sensitization of trigeminocervical neurones. These physiologic findings have clinical correlates such as hypersensitivity and spread and referral of pain frequently seen in patients with primary headache, such as migraine. Special reference is made to the influence of structures from the upper cervical spine in generating and contributing to migraine headaches. The pathophysiology and functional relevance of these basic mechanisms to headaches is discussed in the context of recent experimental findings with regard to pain processing.