Handbook of clinical neurology
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Review
Peripheral nerve involvement in hereditary cerebellar and multisystem degenerative disorders.
Hereditary ataxias (HA) encompass an increasing number of degenerative disorders characterized by progressive cerebellar ataxia usually accompanied by extracerebellar semeiology including peripheral nerve involvement. Classically, HA were classified according to their pathological hallmark comprising three main forms: (1) spinal form predominantly with degeneration of spinocerebellar tracts, posterior columns, and pyramidal tracts (Friedreich's ataxia, FA); (2) olivopontocerebellar atrophy (OPCA); and (3) cortical cerebellar atrophy (CCA). In the 1980s Harding proposed a clinico-genetic classification based upon age of onset, modality of transmission, and clinical semeiology. ⋯ In this chapter we will review peripheral nerve involvement in classical pathological entities (OPCA and CCA), ARCA, ADCA, and ILOCA paying special attention to the most prevalent syndromes in each category. As a general rule, nerve involvement is relatively common in any form of ataxia except ILOCA, the most common pattern being either sensory or sensorimotor neuronopathy with a dying-back process. An exception to this rule is AR spastic ataxia of Charlevoix-Saguenay where nerve conduction studies show the characteristic pattern of intermediate neuropathy implying that sacsin mutation causes both axonal and Schwann cell dysfunction.
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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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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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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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Tinnitus is a common disorder and traditional treatment approaches such as medication, active or passive sound enhancement, and cognitive behavioral therapy have limited efficacy. Thus, there is an urgent need for more effective treatment approaches. Functional imaging studies in patients with tinnitus have revealed alterations in neuronal activity of central auditory pathways, probably resulting as a consequence of sensory deafferentation. ⋯ Transcranial direct current stimulation (tDCS) has also shown potential for the treatment of tinnitus. Both auditory and frontal tDCS have shown tinnitus reduction in a subgroup of patients. In spite of the promising results of the different brain stimulation approaches, further research is needed before these techniques can be recommended for routine clinical use.