Tracking disease progression in Huntington’s Disease using electrophysiology of the sensorimotor system

Abstract

Huntington’s Disease (HD) is a hereditary progressive neurodegenerative disorder with pathologies occurring on structural, functional and behavioral levels in the course of the disease. Since visible symptoms only begin to occur in mid-adulthood, being able to predict motor symptom onset would be valuable for clinical use. We found that over the 24-month observation period, our HD gene carrier groups had a stronger deterioration in somatosensory evoked potential (SEP) amplitude than healthy controls. Within the HD gene carriers, the converter group, experiencing motor symptom onset during the study, showed a steeper deterioration than the early manifest group and tended towards having a steeper decline than premanifest group. Groups were similar in regards to their latencies, motor thresholds and motor evoked potentials (MEPs). When comparing slopes intraindividually in the converter group, we were able to show that SEP deterioration was steeper around symptom onset than it was in a comparable timeframe before or after onset. Even though these results indicate that SEPs are sensitive for tracking disease progression inter- and intraindividually, we were unable to predict motor symptom onset from the N20 slope. This indicates that sensory afferent pathways might be more precise to track development than motor efferent pathways.