A robotic test of proprioception within the hemiparetic arm post-stroke

It's nice to know they are on working on objective validation of such loss. Now we just need that great stroke association  to put out a request for proposal to come up with a solution to bring back proprioception.  This is so f*cking simple, you hire researchers to solve the problem you want solved. By following the strategy you have been working on for the last 50 years.
http://www.jneuroengrehab.com/content/11/1/77/abstract

Lucia Simo, Lior Botzer, Claude Ghez and Robert A Scheidt

Author Affiliations

For all author emails, please log on.

Journal of NeuroEngineering and Rehabilitation 2014, 11:77  doi:10.1186/1743-0003-11-77
Published: 30 April 2014

Abstract (provisional)

Background

Proprioception plays important roles in planning and control of limb posture and movement. The impact of proprioceptive deficits on motor function post-stroke has been difficult to elucidate due to limitations in current tests of arm proprioception. Common clinical tests only provide ordinal assessment of proprioceptive integrity (eg. intact, impaired or absent). We introduce a standardized, quantitative method for evaluating proprioception within the arm on a continuous, ratio scale. We demonstrate the approach, which is based on signal detection theory of sensory psychophysics, in two tasks used to characterize motor function after stroke.

Methods

Hemiparetic stroke survivors and neurologically intact participants attempted to detect displacement- or force-perturbations robotically applied to their arm in a two-interval, two-alternative forced-choice test. A logistic psychometric function parameterized detection of limb perturbations. The shape of this function is determined by two parameters: one corresponds to a signal detection threshold and the other to variability of responses about that threshold. These two parameters define a space in which proprioceptive sensation post-stroke can be compared to that of neurologically-intact people. We used an auditory tone discrimination task to control for potential comprehension, attention and memory deficits.

Results

All but one stroke survivor demonstrated competence in performing two-alternative discrimination in the auditory training test. For the remaining stroke survivors, those with clinically identified proprioceptive deficits in the hemiparetic arm or hand had higher detection thresholds and exhibited greater response variability than individuals without proprioceptive deficits. We then identified a normative parameter space determined by the threshold and response variability data collected from neurologically intact participants. By plotting displacement detection performance within this normative space, stroke survivors with and without intact proprioception could be discriminated on a continuous scale that was sensitive to small performance variations, e.g. practice effects across days.

Conclusions

The proposed method uses robotic perturbations similar to those used in ongoing studies of motor function post-stroke. The approach is sensitive to small changes in the proprioceptive detection of hand motions. We expect this new robotic assessment will empower future studies to characterize how proprioceptive deficits compromise limb posture and movement control in stroke survivors.

The complete article is available as a provisional PDF. The fully formatted PDF and HTML versions are in production.