Journal of neurology, neurosurgery, and psychiatry
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J. Neurol. Neurosurg. Psychiatr. · Aug 2015
ReviewRedefining cerebellar ataxia in degenerative ataxias: lessons from recent research on cerebellar systems.
Recent advances in our understanding of neurophysiological functions in the cerebellar system have revealed that each region involved in degenerative ataxias contributes differently. To regulate voluntary movements, the cerebellum forms internal models within its neural circuits that mimic the behaviour of the sensorimotor system and objects in the external environment. The cerebellum forms two different internal models: forward and inverse. ⋯ Considering the neurophysiological properties of the cerebellar system, we have classified degenerative ataxias into four types depending on which system is involved: Purkinje cells, the corticopontocerebellar system, the spinocerebellar system and the cerebellar deep nuclei. With regard to their respective contributions to the internal models, we speculate that loss of Purkinje cells leads to malformation of the internal models, whereas disturbance of the afferent system, corticopontocerebellar system or spinocerebellar system leads to mis-selection of the proper internal model. An understanding of the pathophysiological properties of ataxias in each degenerative ataxia enables the development of new methods to evaluate ataxias.
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Catatonia is a complex neuropsychiatric syndrome characterised by a broad range of motor, speech and behavioural abnormalities. 'Waxy flexibility', 'posturing' and 'catalepsy' are among the well-recognised motor abnormalities seen in catatonia. However, there are many other motor abnormalities associated with catatonia. ⋯ Electroconvulsive therapy is used in those patients who are resistant to medical therapy. An underlying cause of the catatonia should be identified and treated to ensure early and complete resolution of symptoms.
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J. Neurol. Neurosurg. Psychiatr. · Aug 2015
ReviewStiff-person syndrome: insights into a complex autoimmune disorder.
Stiff-person syndrome (SPS) is characterised by progressive rigidity and muscle spasms affecting the axial and limb muscles. Since its initial description in 1956, marked progress has been made in the clinical characterisation, understanding of pathogenesis and therapy of this disorder. SPS can be classified according to the clinical presentation into classic SPS and SPS variants: focal or segmental-SPS, jerking-SPS and progressive encephalomyelitis with rigidity and myoclonus. ⋯ Paraneoplastic SPS is commonly associated with antiamphiphysin antibodies and breast cancer. Treatment of SPS with drugs that increase the GABAergic tone combined with immunotherapy can improve the neurological manifestations of these patients. The prognosis, however, is unpredictable and spontaneous remissions are unlikely.