Interoceptive sensitivity in patients with cervical dystonia

Introduction Interoceptive sensitivity (IS) is the ability to perceive sensations arising from the inner body. One method used to measure IS is the heartbeat detection task. The aim of this study was to investigate IS in patients with cervical dystonia (CD) and compare the results with those obtained in healthy controls (HC). We also sought possible correlations between IS and demographic, clinical and emotional features in CD. To evaluate the reliability of IS in a subgroup of CD patients and HC, we retested IS 4–6 months after the first evaluation. We also investigated whether dystonic posture affects IS values in HC. Methods Twenty CD patients and 20 HC were investigated. The heartbeat detection task was performed according to a standardized protocol. All the participants underwent a clinical, emotional and psychiatric evaluation. Results IS was lower in CD patients than in HC. The ROC curve analysis showed that an IS value of 0.52 differentiates CD patients from healthy controls. No correlations emerged in CD patients between IS and the demographic, clinical and emotional features. No differences were observed in either CD patients or healthy subjects when IS was retested 4–6 months after the first evaluation. When IS was tested in HC mimicking a dystonic posture, the results were similar to those obtained when they held their heads in a neutral position. Conclusions The study shows that IS is reduced in CD patients possibly due to an altered functional connection between basal ganglia and limbic circuit, including the insula.