Seminars in neurology
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Seminars in neurology · Jun 2005
ReviewEvaluation and treatment of painful peripheral polyneuropathy.
Pain is a common component of sensory peripheral polyneuropathy and occurs primarily as a consequence of injury to small, unmyelinated C-fiber nerve axons. This class of fibers is particularly vulnerable to metabolic injury, and the neuropathy manifests in a length-dependent pattern. ⋯ Treatment of painful neuropathy should be directed at removing the offending metabolic injury, if possible. Antiepileptic drugs, tricyclic antidepressants, opiates, and other treatments have shown efficacy in clinical trials for symptomatic relief of neuropathic pain.
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The discovery of the close association between rapid eye movement (REM) sleep and dreaming and development of sleep laboratory techniques ushered in a new era in the study of dreams. For the first time, direct and systematic investigation could be made of such topics as the occurrence, qualities, recollection, and childhood development of dreaming. Experimental methodologies permitted investigation of the responsiveness of dreams to external stimulation and the effects of deprivation of REM sleep. ⋯ Further developments in neurobiological research, including lesion and brain imaging studies, have established a clearer view of the functional neuroanatomy of REM sleep and dreaming. To what degree, and in what way, implications can be drawn from these findings for the psychology of dreaming is controversial. Some more recent theories of dreaming emphasize an adaptive function related to emotion and a role in learning and memory consolidation.
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Disturbed sleep is a key complaint of people experiencing acute and chronic pain. These two vital functions, sleep and pain, interact in complex ways that ultimately impact the biological and behavioral capacity of the individual. Polysomnographic studies of patients experiencing acute pain during postoperative recovery show shortened and fragmented sleep with reduced amounts of slow wave and rapid eye movement (REM) sleep, and the recovery is accompanied by normalization of sleep. ⋯ The pain-sleep nexus has been modeled in healthy pain-free subjects and the studies have demonstrated the bidirectionality of the sleep-pain relation. Given this bidirectionality, treatment must focus on alleviation of both the pain and sleep disturbance. Few of the treatment studies have done such, and as a result no clear consensus on treatment approaches, much less on differential etiology-based treatment strategies, has emerged.
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Breathing is the most important executive function of sleep. Compromise of the ventilatory mechanism is the principal consequence of a neuromuscular dysfunction in the individual who is asleep. This includes alterations of the lower motor neuron, the neuromuscular junction, and muscle. ⋯ Any dysfunction of the diaphragm, whether neurogenic or neuromuscular, will interfere with breathing during REM sleep. So prevalent are sleep respiratory difficulties in patients with neuromuscular disorders that there should be a low threshold to obtain nocturnal polysomnography in these patients with sleep complaints. In patients with a neuromuscular disorder and nocturnal ventilatory compromise, positive airway pressure ventilation improves the quality of sleep and in doing so improves the overall quality of life.