Chapter 28 Brainstem reflexes and their relevance to pain

Publisher Summary This chapter describes the physiology of the brainstem reflexes and their application to the main craniofacial pain syndromes. The brainstem reflexes that are most commonly used in clinical neurophysiology are classified as non-nociceptive because, although exerting a defense action, they are not selectively mediated by nociceptive afferents. The chapter reviews that the brainstem is involved in nociception and pain in several respects. It discusses that the excitability of the trigeminal brainstem net of sensory neurons and interneurons is strongly modulated by the reticular formation. The trigeminal system is involved because it primarily generates, contributes to pathophysiological mechanisms, or conveys some of the most important chronic pain syndromes, from trigeminal neuralgia to migraine to temporomandibular dysfunction. Brainstem reflexes are the best tool for assessing trigeminal and brainstem function, and have been and are being widely used both in diagnostic and pathophysiological studies of craniofacial pain syndromes.