title: Phantom hand and wrist movements in upper limb amputees are slow but naturally controlled movements.
abstract: After limb amputation, patients often wake up with a vivid perception of the presence of the missing limb, called "phantom limb". Phantom limbs have mostly been studied with respect to pain sensation. But patients can experience many other phantom sensations, including voluntary movements. The goal of the present study was to quantify phantom movement kinematics and relate these to intact limb kinematics and to the time elapsed since amputation. Six upper arm and two forearm amputees with various delays since amputation (6months to 32years) performed phantom finger, hand and wrist movements at self-chosen comfortable velocities. The kinematics of the phantom movements was indirectly obtained via the intact limb that synchronously mimicked the phantom limb movements, using a Cyberglove® for measuring finger movements and an inertial measurement unit for wrist movements. Results show that the execution of phantom movements is perceived as "natural" but effortful. The types of phantom movements that can be performed are variable between the patients but they could all perform thumb flexion/extension and global hand opening/closure. Finger extension movements appeared to be 24% faster than finger flexion movements. Neither the number of types of phantom movements that can be executed nor the kinematic characteristics were related to the elapsed time since amputation, highlighting the persistence of post-amputation neural adaptation. We hypothesize that the perceived slowness of phantom movements is related to altered proprioceptive feedback that cannot be recalibrated by lack of visual feedback during phantom movement execution.
authors.affiliation: Institute of Movement Sciences (ISM), UMR 7287 - CNRS & Aix-Marseille University, Marseille, France. Electronic address: jozina.de-graaf@univ-amu.fr.
authors.forename: J B
authors.initials: JB
authors.lastname: De Graaf
authors.affiliation: Institute of Intelligent Systems and Robotics (ISIR), UMR 7222, CNRS/INSERM, U1150 Agathe-ISIR, Sorbonne University, UPMC Univ Paris 06, Paris, France.
authors.forename: N
authors.initials: N
authors.lastname: Jarrassé
authors.affiliation: Institute of Movement Sciences (ISM), UMR 7287 - CNRS & Aix-Marseille University, Marseille, France.
authors.forename: C
authors.initials: C
authors.lastname: Nicol
authors.affiliation: Louis Pierquin Centre of the Regional Institute of Rehabilitation, Nancy, France.
authors.forename: A
authors.initials: A
authors.lastname: Touillet
authors.affiliation: Institute of Movement Sciences (ISM), UMR 7287 - CNRS & Aix-Marseille University, Marseille, France.
authors.forename: T
authors.initials: T
authors.lastname: Coyle
authors.affiliation: Centre for Functional Readaptation of Valmante, Marseille, France.
authors.forename: L
authors.initials: L
authors.lastname: Maynard
authors.affiliation: Louis Pierquin Centre of the Regional Institute of Rehabilitation, Nancy, France.
authors.forename: N
authors.initials: N
authors.lastname: Martinet
authors.affiliation: Louis Pierquin Centre of the Regional Institute of Rehabilitation, Nancy, France.
authors.forename: J
authors.initials: J
authors.lastname: Paysant
mesh_terms: D000328:Adult; D000368:Aged; D000674:Amputees; D001696:Biomechanical Phenomena; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D010591:Phantom Limb / Q000503:physiopathology*; D011434:Proprioception / Q000502:physiology*; D013997:Time Factors; D014953:Wrist / Q000503:physiopathology*
keywords: amplitude; evolution over time; movement feedback; neuroplasticity; velocity; voluntary phantom movements