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Background: Dopa-responsive dystonia is clinically dominated by a combination of dystonia and parkinsonism, both known to be associated with abnormal activity in premotor-motor circuits.Methods: To probe premotor-motor excitability, we used a transcranial magnetic stimulation dual pulse conditioning paradigm in 15 genetically confirmed dopa-responsive dystonia patients and 20 controls under different medication states. We also determined silent periods, short-latency afferent inhibition, interhemispheric inhibition, and short-interval intracortical inhibition and facilitation.Results: In contrast to healthy controls, no motor cortex inhibition was seen after premotor conditioning regardless of the dopaminergic state in patients. The duration of the ipsilateral silent period was increased in the OFF state, and short-latency afferent inhibition was reduced in the ON compared with the OFF state.Conclusion: Premotor-motor circuits appear hyporesponsive in dopa-responsive dystonia. [ABSTRACT FROM AUTHOR]

Abstract: Background: Dopa-responsive dystonia (DRD) is a young-onset neurometabolic disorder often presenting with a combination of parkinsonism and dystonia. The pathophysiology includes an impairment of dopaminergic and serotonergic neurotransmission. Uncontrolled reports suggest an increased frequency of neuropsychiatric abnormalities and sleep impairment. Methods: In 23 GCH1 mutation-positive DRD patients and 26 healthy controls, non-motor features and their effect on the quality of life (QoL) were assessed. Six patients underwent polysomnography (PSG). Results: Depressive and anxiety symptoms were not more common among DRD patients. Average sleep quality was similar across groups. This was also true for self-reported mean sleep onset (27.5 vs. 27.1 min) and total sleep time (6.5 vs. 6.6 h). Upon PSG, the number of spontaneous arousals was increased in four patients. QoL was impaired with respect to physical health. Sleep impairment and depressive but not anxiety symptoms were associated with lower QoL. Conclusion: The present results do not confirm the clinical impression and biologically plausible assumption of an increased frequency of non-motor symptoms in DRD. The impairment of QoL is associated with a decline of the physical condition only but not with other factors. [Copyright &y& Elsevier]

Introduction: GCH1 mutations have been linked to decreased striatal dopamine and development of dopa-responsive dystonia (DRD) and Parkinsonism. Sensory and sensorimotor integration impairments have been documented in various forms of dystonia. DRD patients with confirmed GCH1 mutations have demonstrated normal short-latency afferent inhibition (SAI), a measure of sensorimotor inhibition, under chronic dopaminergic replacement therapy (DRT), but reduced inhibition after a single l-dopa dose following 24 h withdrawal. Studies have revealed normal SAI in other forms of dystonia but reductions with DRT in Parkinson's disease. Longitudinal changes in sensorimotor inhibition are unknown.Methods: We analyzed sensorimotor inhibition using two different measures: SAI and somatosensory-motor inhibition using dual-site transcranial magnetic stimulation (ds-TMS). SAI was measured using digit stimulation 25 ms prior to contralateral primary motor cortex (M1) TMS. DS-TMS was measured using TMS over the somatosensory cortex 1 or 2.5 ms prior to ipsilateral M1 stimulation. A total of 20 GCH1 mutation carriers and 20 age-matched controls were included in the study. SAI and ds-TMS were evaluated in GCH1 mutation carriers both OFF and ON DRT compared to controls. Furthermore, longitudinal changes of SAI were examined in a subset of the same individuals that were measured ∼five years earlier.Results: Neither SAI nor ds-TMS were significantly different in GCH1 mutation carriers relative to controls. No effects of DRT on SAI or ds-TMS were seen but SAI decreased over time in mutation carriers OFF DRT.Conclusion: Our longitudinal results suggest changes in SAI that could be associated with plasticity changes in sensorimotor networks. [ABSTRACT FROM AUTHOR]