Movement disorders : official journal of the Movement Disorder Society
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Former studies suggest an additional involvement of the sensory nervous system, beside the involuntary contractions of antagonist muscles, in idiopathic hand dystonia. We studied contact heat-evoked potentials and quantitative sensory testing (QST) in 10 patients suffering from idiopathic hand dystonia and 10 age-matched healthy controls. Cortical potentials recorded from the vertex (Pz) after contact heat stimulation of the volar forearm and the dorsum of the hand at a temperature of 51°C showed significantly reduced A-δ-amplitudes. ⋯ QST results showed an impairment of the thermal detection thresholds, the mechanical pain sensitivity and the mechanical pain threshold at the affected body side of the patients. Our results suggest a loss of distinct sensory functions of the affected hand in comparison with the contralateral hand and to matched healthy subjects in patients suffering from idiopathic hand dystonia. For the first time, an extended loss of sensory function could be shown in patients suffering from idiopathic hand dystonia.
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The clinical heterogeneity of Parkinson's disease (PD) may point at the existence of subtypes. Because subtypes likely reflect distinct underlying etiologies, their identification may facilitate future genetic and pharmacotherapeutic studies. Aim of this study was to identify subtypes by a data-driven approach applied to a broad spectrum of motor and nonmotor features of PD. ⋯ Four similar PD subtypes were identified in two different populations and are largely characterized by differences in the severity of nondopaminergic features and motor complications: Subtype 1 was mildly affected in all domains, Subtype 2 was predominantly characterized by severe motor complications, Subtype 3 was affected mainly on nondopaminergic domains without prominent motor complications, while Subtype 4 was severely affected on all domains. The subtypes had largely similar mean disease durations (nonsignificant differences between three clusters) but showed considerable differences with respect to their association with demographic and clinical variables. In prevalent disease, PD subtypes are largely characterized by the severity of nondopaminergic features and motor complications and likely reflect complex interactions between disease mechanisms, treatment, aging, and gender.