Endophenotyping in idiopathic adult onset cervical dystonia

Publication date: Available online 23 April 2017
Source:Clinical Neurophysiology
Author(s): Georg Kägi, Diane Ruge, Florian Brugger, Petra Katschnig, Rafael Sauter, Mirta Fiorio, Michele Tinazzi, John Rothwell, Kailash P Bhatia
ObjectiveIdiopathic adult onset cervical dystonia (IAOCD) is considered to be a partially penetrant autosomal dominant genetic condition. Dystonia may result from genetic and environmental factors. In this view, part of the physiology should be an endophenotype stemming from the genetic background. We assessed the most discriminative test to separate patients with IAOCD and healthy controls for further endophenotyping in non-affected 1^st degree relatives.MethodsWe included patients with IAOCD, their 1^st degree relatives and healthy controls. Tests performed: 1) Sensory temporal discrimination (visual, tactile, visuo-tactile), 2) Paired pulse paradigms using transcranial magnetic stimulation (TMS), 3) Mental rotation paradigms. Results: 45 patients with IAOCD, 23 healthy controls and 14 non-affected 1^st degree relatives were recruited. Visuo-tactile temporal discrimination separated best between controls and patients as well as between controls and 1^st degree relatives. 36% of the latter had an abnormal visuo-tactile temporal discrimination. No difference between patients and healthy controls was found for the other paradigms.ConclusionsVisuo-tactile temporal discrimination separates controls from patients with IAOCD and its 1^st degree relatives. 36% of the latter had abnormal visuo-tactile thresholds supporting the role of visuo-tactile temporal discrimination as an endophenotype for IAOCD.SignificanceEven though the study was of exploratory design, our findings expand the understanding of endophenotypes in IAOCD.



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