Piovesan Elcio J, Kowacs Pedro A, Oshinsky Michael L
Jorge Manços do Nascimento Teixeira 868, São José dos Pinhais, 83005-500 Brazil.
Curr Pain Headache Rep. 2003 Oct;7(5):377-83. doi: 10.1007/s11916-003-0037-x.
Cranial nociceptive perception shows a distinct topographic distribution, with the trigeminal nerve receiving sensory information from the anterior portions of the head, the greater occipital nerve, and branches of the upper cervical roots in the posterior regions. However, this distribution is not respected during headache attacks, even if the etiology of the headache is specific for only one nerve. Nociceptive information from the trigeminal and cervical territories activates the neurons in the trigeminal nucleus caudalis that extend to the C2 spinal segment and lateral cervical nucleus in the dorsolateral cervical area. These neurons are classified as multimodal because they receive sensory information from more than one afferent type. Clinically, trigeminal activation produces symptoms in the trigeminal and cervical territory and cervical activation produces symptoms in the cervical and trigeminal territory. The overlap between the trigeminal nerve and cervical is known as a convergence mechanism. For some time, convergence mechanisms were thought to be secondary to clinical observations. However, animal studies and clinical evidence have expanded our knowledge of convergence mechanisms. In this paper, the role of convergence mechanisms in nociceptive physiology, physiopathology of the headaches, clinical diagnosis, and therapeutic conduct are reviewed.
颅部伤害性感受呈现出独特的拓扑分布，三叉神经接收来自头部前部的感觉信息，枕大神经以及后颅区域上颈神经根的分支也接收相应信息。然而，在头痛发作期间，即便头痛的病因仅特定于某一条神经，这种分布规律也并不遵循。来自三叉神经和颈部区域的伤害性信息会激活三叉神经尾侧核中的神经元，这些神经元延伸至C2脊髓节段以及颈背外侧区域的外侧颈核。这些神经元被归类为多模式神经元，因为它们接收来自不止一种传入类型的感觉信息。临床上，三叉神经激活会在三叉神经和颈部区域产生症状，而颈部激活则会在颈部和三叉神经区域产生症状。三叉神经与颈部之间的重叠被称为汇聚机制。有一段时间，汇聚机制被认为是临床观察的次要结果。然而，动物研究和临床证据扩展了我们对汇聚机制的认识。本文将对汇聚机制在伤害性生理、头痛的病理生理、临床诊断及治疗行为中的作用进行综述。
