Handbook of clinical neurology
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Multiple system atrophy (MSA) is a sporadic and fatal α-synuclein-linked oligodendrogliopathy manifesting with progressive autonomic failure, poorly levodopa-responsive parkinsonism, and cerebellar ataxia, in any combination. Here we review key aspects of MSA integrating important insights from rapidly emerging fields such as genetics, diagnostic work-up including imaging, and translational therapies aimed at disease modification.
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Anti-NMDA receptor encephalitis is a newly characterized severe neuroautoimmune syndrome with a progressive, clinical course. Most often seen in females, it usually begins with a prodromal phase suggestive of an acute or subclinical upper respiratory tract infection that lasts for up to 2 weeks. This is followed by a psychotic and seizure phase in which the child may rapidly develop seizures, behavioral changes, and, less commonly in children, psychiatric symptoms, resulting in frequent misdiagnoses. ⋯ Relapses in children may be multiple and occur in 20-25% of cases. Recovery is slow and may take 3 years or longer. Even so, the child may not always regain its premorbid level of health.
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This chapter considers the use of central thalamic deep brain stimulation (CT/DBS) to support arousal regulation mechanisms in the minimally conscious state (MCS). CT/DBS for selected patients in a MCS is first placed in the historical context of prior efforts to use thalamic electrical brain stimulation to treat the unconscious clinical conditions of coma and vegetative state. ⋯ The conceptual foundations for CT/DBS in selected patients in a MCS are then presented with consideration of both circuit and cellular mechanisms underlying recovery of consciousness identified from empirical studies. Directions for developing future generalizable criteria for CT/DBS that focus on the integrity of necessary brain systems and behavioral profiles in patients in a MCS that may optimally response to support of arousal regulation mechanisms are proposed.
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Invasive stimulation of the motor (precentral) cortex using surgically implanted epidural electrodes is indicated for the treatment of neuropathic pain that is refractory to medical treatment. Controlled trials have demonstrated the efficacy of epidural motor cortex stimulation (MCS), but MCS outcome remains variable and validated criteria for selecting good candidates for implantation are lacking. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive approach that could be used as a preoperative tool to predict MCS outcome and also could serve as a therapeutic procedure in itself to treat pain disorders. ⋯ The most studied target is the precentral cortex, but other targets, such as the prefrontal and parietal cortices, could be of interest. The analgesic effects of cortical stimulation relate to the activation of various circuits modulating neural activities in remote structures, such as the thalamus, limbic cortex, insula, or descending inhibitory controls. In addition to the treatment of refractory neuropathic pain by epidural MCS, new developments of this type of strategy are ongoing, for other types of pain syndrome and stimulation techniques.
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Stroke is the major cause of long-term disability worldwide, with impaired manual dexterity being a common feature. In the past few years, noninvasive brain stimulation (NIBS) techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), have been investigated as adjuvant strategies to neurorehabilitative interventions. These NIBS techniques can be used to modulate cortical excitability during and for several minutes after the end of the stimulation period. ⋯ Differential modulation of cortical excitability in the affected and unaffected hemisphere of patients with stroke may induce plastic changes within neural networks active during functional recovery. The aims of this chapter are to describe results from these proof-of-principle trials and discuss possible putative mechanisms underlying such effects. Neurophysiological and neuroimaging changes induced by application of NIBS are reviewed briefly.