Handbook of clinical neurology
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This chapter summarizes progress in the evaluation of peripheral nerve (PN) lesions and disorders by imaging techniques encompassing magnetic resonance imaging (MRI) and nerve ultrasound (US). Due to the radiation exposure and limited sensitivity in soft tissue contrast, computed-tomography (CT) plays no significant role in the diagnostic work-up of PN disorders. MRI and US are complementary techniques for the evaluation of peripheral nerves, each having particular advantages and disadvantages. ⋯ In experimental settings, novel molecular and cellular MRI contrast agents allow in-vivo assessment of nerve regeneration as well as monitoring of neuroinflammation. Depending on further clinical development, contrast-enhanced MRI has the potential to follow cellular responses over time in vivo and to overcome the current limitations of histological assessment of nerve afflictions. Further advances in contrast-enhanced US has the potential for developing into a tool for the assessment of nerve blood perfusion, paving the way for better assessments of ischemic neuropathies.
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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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The diagnosis of brain death should be based on a simple premise. If every possible confounder has been excluded and all possible treatments have been tried or considered, irreversible loss of brain function is clinically recognized as the absence of brainstem reflexes, verified apnea, loss of vascular tone, invariant heart rate, and, eventually, cardiac standstill. This condition cannot be reversed - not even partly - by medical or surgical intervention, and thus is final. ⋯ Generally, the concept of brain death has been accepted by all major religions. But patients' families may have different ideas and are mostly influenced by cultural attitudes, traditional customs, and personal beliefs. Suggestions are offered to support these families.
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Tourette syndrome is a neuropsychiatric disorder characterized by motor and vocal tics, often associated with behavioral disorders, with typical onset in early childhood. In most patients, the symptoms decrease spontaneously when adulthood is reached, or can be treated with behavioral therapy or medication. Only a small proportion of patients are candidates for surgical treatment. ⋯ Current knowledge of cortical-basal ganglia-thalamocortical circuits provides explanations for the beneficial effects of DBS on tics. Inclusion and exclusion criteria have been formulated to identify good candidates for DBS. Because of the small number of patients, there is a strong need for multicenter double-blind trials with standard protocols.
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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.