Pain in Down's syndrome.

Pain is a homeostatic mechanism that intervenes to protect the organism from harmful stimuli that could damage its integrity. It is made up of two components: the sensory-discriminative component, which identifies the provenance and characteristics of the type of pain; and the affective-motivational component, on which emotional reflexes, following the painful sensation, depend. There is a system for pain control at an encephalic and spinal level, principally made up of the periaqueductal grey matter, the periventricular area, the nucleus raphe magnus, and the pain-inhibition complex situated in the posterior horns of the spinal cord. Through the activation of these pain-control systems, the nervous system suppresses the afference of pain signals. Endogenous opioids represent another analgesic system. In the course of various studies on pain transmission in Down patients, the reduced tolerance of pain and the incapacity to give a qualitative and quantitative description emerged in a powerful way. All of these aspects cause difficulty in evaluating pain. This is linked to several learning difficulties. However, it cannot be excluded that in these anomalies of pain perception, both the anatomical and the neurotransmitter alteration, typical of this syndrome, may hold a certain importance. This fact may have important clinical repercussions that could affect the choice of therapeutic and rehabilitative schemes for treatment of pathologies in which pain is the dominant symptom, such as postoperative pain. It could influence research on analgesics that are more suitable for these patients, the evaluation of the depth of analgesia during surgical operation, and ultimately, absence of obvious pain manifestations. In conclusion, alterations of the central nervous system, neurotransmitters, pain transmission, and all related problems should be considered in the management of pain in patients with Down's syndrome, especially by algologists and anesthesiologists.