Proprioceptive sensitivity in Ehlers–Danlos syndrome patients
Reaching movements are rapidly adapted following training with rotated visual feedback of the hand. Our laboratory has also found that this visuomotor adaptation results in changes in estimates of felt hand position (proprioceptive recalibration) in the direction of the visuomotor distortion (Cressman and Henriques in J Neurophysiol 102:3505–3518, 2009; Cressman et al. in Exp Brain Res 205:533–544, 2010). In the current study, we investigated proprioceptive acuity and proprioceptive recalibration in a group of individuals with Ehlers–Danlos syndrome (EDS), a degenerative condition associated with collagen malformation. Some studies have suggested that these patients may have proprioceptive impairments, but the exact nature of the impairment is unclear (Rombaut et al. in Clin Rheumatol 29:289–295, 2010a). In this study, we measured the ability of EDS patients to estimate their felt hand position and tested whether these estimates changed following visuomotor adaptation. We found EDS patients were less precise in estimating their felt hand position in the peripheral workspace compared to healthy controls. Despite this poorer sensitivity, they recalibrated hand proprioception to the same extent as healthy controls. This is consistent with other populations who experience proprioceptive deficits (e.g. the elderly, Parkinson’s disease patients), suggesting that sensory noise does not influence the extent of either motor or sensory plasticity.