Lancet neurology
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Cluster headache is a form of primary neurovascular headache with the following features: severe unilateral, commonly retro-orbital, pain accompanied by restlessness or agitation, and cranial (parasympathetic) autonomic symptoms, such as lacrimation or conjunctival injection. It occurs in attacks typically of less than 3 h in length and in bouts (clusters) of a few months during which the patient has one or two attacks per day. ⋯ Observations of circadian biological changes and neuroendocrine disturbances have suggested a pivotal role for the hypothalamus in cluster headache. Functional neuroimaging with PET and anatomical imaging with voxel-based morphometry have identified the posterior hypothalamic grey matter as the key area for the basic defect in cluster headache.
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The contribution of genetic components to the pathology of sleep disorders is increasingly recognised as important. Genetic studies have identified genes that may be important in the regulation of circadian rhythms, which in turn determine the time of sleep onset and waking. ⋯ The contribution of genetic factors to obstructive sleep apnoea syndrome (OSAS) has led to a better understanding of this complex disorder that may be part of a larger syndrome associated with respiratory, cardiovascular, and metabolic dysfunction. The aim of this review is to discuss the current knowledge on the role of genetic factors in sleep disorders, in particular circadian disorders, narcolepsy, restless-legs syndrome, and OSAS.
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Phantom-limb pain is a common sequela of amputation, occurring in up to 80% of people who undergo the procedure. It must be differentiated from non-painful phantom phenomena, residual-limb pain, and non-painful residual-limb phenomena. Central changes seem to be a major determinant of phantom-limb pain; however, peripheral and psychological factors may contribute to it. ⋯ Interventions targeting central changes seem promising. The prevention of phantom-limb pain by peripheral analgesia has not yielded consistent results. Additional measures that reverse or prevent the formation of central memory processes might be more effective.
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Recent evidence suggests that the placebo effect is mediated by the dopaminergic reward mechanisms in the human brain and that it is related to the expectation of clinical benefit. On the basis of this theory, we propose some criteria for the proper investigation of the placebo effect, and review the evidence for a placebo effect in Parkinson's disease, depression, pain, and other neurological disorders. We also discuss the evidence for the use of placebos in long-term substitution programmes for the treatment of drug addiction.