Handbook of clinical neurology
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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.
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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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Several countries have adopted laws that regulate physician assistance in dying. Such assistance may consist of providing a patient with a prescription of lethal medication that is self-administered by the patient, which is usually referred to as (physician) assistance in suicide, or of administering lethal medication to a patient, which is referred to as euthanasia. The main aim of regulating physician assistance in dying is to bring these practices into the open and to provide physicians with legal certainty. ⋯ Arguments against the legal regulation of physician assistance in dying include principled arguments, such as the wrongness of hastening death, and arguments that emphasize the negative consequences of allowing physician assistance in dying, such as a devaluation of the lives of older people, or people with chronic disease or disabilities. Opinion polls show that some form of accepting and regulating euthanasia and physician assistance in suicide is increasingly supported by the general population in most western countries. Studies in countries where physician assistance in dying is regulated suggest that practices have remained rather stable in most jurisdictions and that physicians adhere to the legal criteria in the vast majority of cases.
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A variety of noninvasive brain stimulation techniques have been used to study neuronal plasticity. Mostly, noninvasive techniques have been employed, and the bulk of studies have focused on the motor system, because its physiology is more readily accessible and physiological properties can be studied with greater detail than in other systems. ⋯ Several of the phenomena induced by noninvasive brain stimulation have been mapped on to cellular physiological mechanisms such as synaptic long-term potentiation or long-term depression. Although some parallelisms are intriguing, this approach has also its limitations, and more direct verification of physiological phenomena by animal studies is needed.
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Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. ⋯ These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices.