Reviews for Primary Care - Fall 2007 - (Page 48) Insomnia and Neurological Disorders continued high-acceleration movements compared with age-matched controls.95 No increase in sleep-related breathing disorders has been demonstrated in HD, also in contrast with findings in other neurodegenerative dementias.96 Circadian-rhythm sleep disturbances, however, are an important pathological feature of HD and may arise from a disruption of the expression of the circadian clock genes mPer2 and mBmal1 in the SCN, the principal circadian pacemaker in the brain.97 the hypersomnia in MD may be attributed to these morphological abnormalities and appear to be central in nature.104 Fatal Familial Insomnia Fatal familial insomnia (FFI) is a very rare prion disease that leads to loss of neuroendocrine regulation, loss of vegetative circadian rhythmicity, and ultimately the demise of the patient. In patients with FFI, severe progressive insomnia, loss of orthostatic stability, increased salivation, increased body temperature, and daytime stupor alternating with wakefulness develop. In the final stage of the disease, patients may become very agitated, confused, and disoriented. Eventually, progressive stupor and coma develop, and the patient dies. The genotypic localization of patients with FFI is on the short arm of the human chromosome 20. Neuropathologically one finds severe degeneration and gliosis of the anterior and dorsomedial nucleus of the thalamus.105 Myotonic Dystrophy Sleep abnormalities in patients with myotonic dystrophy (MD) include hypersomnia, sharing with narcolepsy a short sleep latency and the presence of sleep-onset REM periods during the mean sleep latency test.98 Hypersomnia is found in almost one third of patients with MD, and the severity of daytime sleepiness correlates with the severity of muscular impairment.99 Corpus callosum atrophy might occur in MD patients, and the size of the corpus callosum anterior area might be associated with the hypersomnia.100 Patients with MD report a longer sleep period, a less restorative sleep, difficulties with sleep initiation, and hypersomnia comparable with those in idiopathic hypersomnia.99 Patients with MD were found to have an increased risk of obstructive sleep apnea, central sleep apnea, and excessive daytime sleepiness.82,84,101 These patients are also thought to have a centrally mediated impairment in breathing, probably related to a brainstem respiratory center disorder rather than respiratory muscle weakness. 102,103 Neuropathological findings in patients with MD consist of severe neuronal loss and gliosis in the midbrain and pontine raphe, particularly in the dorsal raphe nucleus and superior central nucleus, pontine, and medullary reticular formation.104 Alveolar hypoventilation and Laboratory Assessment Laboratory investigations for insomnia may be undertaken if traditional therapy for insomnia fails or if other underlying sleep disturbances, such as sleep apnea or periodic leg movements, are suspected. Polysomnography should be performed in patients suffering from insomnia who, during the course of their evaluation, are suspected of having a comorbid sleep disorder, such as sleep apnea.106-109 Unfortunately, the diagnosis and treatment of sleep disturbances may be problematic in neurodegenerative diseases with severe functional impairment given the difficulties in ascertaining the clinical history from the patient. Actigraphy is a recently developed technique that uses a motion detector to record activities during sleep and waking and may be useful in the diagnosis of insomnia and circadian rhythm sleep disorders in patients with neurodegenerative diseases. Diagnostic Approaches to Insomnia in Dementia Clinical Assessment The first and most important step in the work-up of insomnia presenting in patients with dementia is a detailed inventory of sleep complaints. The history should consist of sleep history, family history, medication and substance use (such as caffeine, nicotine, and alcohol), and information about underlying medical or psychiatric pathologies. The history should also be specifically directed at possible respiratory disturbances during sleep. It is important to perform physical examination for the diagnosis of the primary or associated medical conditions, including neurological disorders, that may be responsible for the sleep disturbances. Treatment of Insomnia in Neurological and Neurodegenerative Disorders Treatment of sleep disturbances in patients with underlying dementias should begin with the treatment of the primary underlying condition. The goal of therapy is to improve the quality of life. The general measures are directed at reducing the risk factors that may exacerbate the sleep disruption. An attempt should be made to reduce or eliminate medications that could potentially disrupt sleep. Associated conditions such as depression, anxiety, or pain need to be treated with appropriate medications. The patients should be encouraged to develop good sleep habits, maintain a regular sleep-wake cycle, and refrain from taking extensive daytime naps. Substances that may disrupt sleep, such as caffeine, alcohol, and nicotine, should be prohibited. 48 VOL. 1 NO. 1 2007 REVIEWS FOR PRIMARY CARE
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