Porth's Essentials of Pathophysiology, 4e

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Somatosensory Function, Pain, and Headache

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before prophylactic agents will be effective. Most of the medications used for prevention of CDH have not been examined in well-designed, double-blind studies.

the potential for addiction to opioids, another obstacle to adequate pain management in children and the elderly is the myth that patients in these age groups feel less pain than other patients, and even if they feel significant pain, they do not remember it. Moreover, it can be extremely difficult to accurately assess the location and intensity of pain in very young children, who are cognitively imma- ture, or in cognitively impaired elderly. Research during the past few decades has added a great deal to the body of knowledge about pain in children and the elderly.  Pain in Children Human responsiveness to painful stimuli begins in the neonatal period and continues through the life span. Although the specific and localized behavioral reactions are less marked in newborns, they clearly perceive and remember pain, as demonstrated by their integrated physiologic responses, including protective or with- drawal reflexes, to nociceptive stimuli. 57–59 For example, newborns in the neonatal intensive care unit (NICU) demonstrate protective withdrawal responses to a heel stick after repeated episodes. In fact, a newborn’s pain may be accentuated because descending inhibitory path- ways to the dorsal horn are not as well developed at birth. 58 Furthermore, the newborn’s dorsal horn neu- rons have a wider receptive field and lower excitatory threshold than those of older children. The recognition that untreated pain can lead to serious consequences has resulted in a more liberal use of opioids for treatment of pain in the newborn, particularly in the NICU. 59 As infants and children mature cognitively and developmentally, their responses to pain become more complex. Children do feel pain and have been shown to reliably and accurately report pain at as young as 3 years of age. 59 Like newborns, they also remember pain, as evidenced in studies of children with cancer, whose distress during painful procedures increases over time To manage pain adequately, ongoing assessment of the presence of pain and response to treatment is essen- tial. 58,59 Behavior is a useful sign, but can be mislead- ing. A toddler may scream during an ear examination because of fear rather than pain, and a child with inad- equately relieved cancer pain may withdraw from his or her surroundings. Some physiologic measures, such as heart rate, are convenient to measure and respond rapidly to brief nociceptive stimuli, but they are nonspe- cific. Investigators have devised a range of behavioral distress scales for infants and young children, mostly emphasizing the child’s facial expressions, crying, and bodily movements. Children 3 to 7 years of age become more articu- late in describing the intensity, location, and severity of the pain. There are self-report measures for children of this age, including scales with faces of actual children or cartoon faces. With children 8 years of age or older, without intervention. Pain Assessment

Temporomandibular Joint Pain A common cause of head pain is temporomandibular joint (TMJ) syndrome. It usually is caused by an imbal- ance in joint movement because of poor bite, bruxism (i.e., teeth grinding), or joint problems such as inflam- mation, trauma, and degenerative changes. 56 The pain almost always is referred and commonly presents as facial muscle pain, headache, neck ache, or earache. Referred pain is aggravated by jaw function. Headache associated with this syndrome is common in adults and children and can cause chronic pain problems. Treatment of TMJ pain is aimed at correcting the prob- lem, and in some cases this may be difficult. The initial therapy for TMJ pain should be directed toward relief of pain and improvement in function. Pain relief often can be achieved with use of the NSAIDs. Muscle relaxants may be used when muscle spasm is a problem. In some cases, the selected application of heat or cold, or both, may provide relief. Referral to a dentist who is associated with a team of therapists, such as a psychologist, physical therapist, or pain specialist, may be indicated. ■■ Headache is a common disorder that is caused by a number of conditions. Some headaches represent primary disorders and others occur secondary to another disease state in which head pain is a symptom. ■■ Primary headache disorders include migraine ■■ Although most causes of secondary headache are benign, some are indications of serious disorders such as meningitis, brain tumor, or ruptured cerebral aneurysm. ■■ Temporomandibular joint (TMJ) syndrome is one of the major causes of headaches. It usually is caused by an imbalance in joint movement because of poor bite, teeth grinding, or joint problems such as inflammation, trauma, and degenerative changes. headache, tension-type headache, cluster headache, and chronic daily headache. SUMMARY CONCEPTS

Pain in Children and Older Adults

Pain frequently is under-recognized and undertreated in both children and the elderly. In addition to the concern about the effects of analgesia on respiratory status and