Handbook of clinical neurology
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Noninvasive brain stimulation (NIBS) is a unique method for studying cognitive function. For the study of cognition, NIBS has gained popularity as a complementary method to functional neuroimaging. By bypassing the correlative approaches of standard imaging techniques, it is possible to establish a putative relationship between brain cognition. ⋯ Moreover, an important factor is the possible interactions between these factors and the physiological and cognitive state of the subject. To use NIBS in cognition, it is important to understand not only how NIBS functions but also the brain mechanisms being studied and the features of the area of interest. To describe better the advanced knowledge provided by NIBS in cognition, we will treat each NIBS technique separately and underline the related hypotheses beyond applications.
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Disorders of cognition are a major societal burden. As the population grows and ages, these conditions demand urgent attention, as healthcare resources stretch to accommodate the growing number of patients. ⋯ By targeting specific structures within known circuits, deep brain stimulation (DBS) can have effects across memory and cognitive networks, and is therefore a potentially promising avenue for novel dementia treatments. This chapter reviews the literature on DBS for AD and dementia associated with Parkinson's disease, and highlight some of the neuroanatomical targets that offer the most promise in modulating the underlying pathological activity in brain circuitry.
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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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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.
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Skin biopsy with a 3mm disposable circular punch is easy to perform and allows, after proper processing, the visualization of epidermal, dermal, and sweat gland nerve fibers. A technique of sampling the epidermis alone by applying a suction capsule, the "blister" technique, has also been developed. It is most common to stain immunohistochemically for the pan-axonal marker protein gene product 9.5 (PGP 9.5), an ubiquitin C-terminal hydroxylase. ⋯ In several hereditary neuropathies intraepidermal nerve fiber density may be reduced but other abnormalities can also be demonstrated in dermal myelinated fibers. Some small swellings and varicosities may be present in the distal leg skin biopsy of healthy individuals but large axonal swellings are considered as evidence of a pathological process affecting the normal structure of nerves. The indirect immunofluorescence technique with confocal microscopy provides the opportunity to study the complex structure of sensory receptors and cutaneous myelinated fibers and the innervation of sweat glands, arrector pilorum muscles, and vessels.