The Use of Computerised Dynamometry to Quantify Functional Grip and Release in People Post Stroke: A Pilot Study

ABSTRACT

To present a theoretical construct and pilot data from an analytic technique to simultaneously quantify positive and negative upper motor neuron (UMN) features.

Computerised hand dynamometry was used to measure hand contraction-relaxation cycles during a repetitive grasp and release task. Measurements of force, time, force velocity and ‘grip work’ were collected on a pilot sample of 5 post-stroke subjects and 5 matched controls. Within and between group differences were analysed.

Force, time and velocity dependent aspects of hand performance did not differ between the dominant and nondominant upper-limbs of control subjects. In contrast, the post-stroke group generated less grip force over longer cycle times with their affected limb, consistent with negative UMN features. In controls, 97% of grip work was task specific, with 3% associated with involuntary, non-task grip work. Conversely, the post-stroke group generated high levels of involuntary, non-task grip work (39%), a feature consistent with positive UMN features of muscle overactivity. Force velocity and maximal force were lower in the non-affected limbs of the stroke group than matched dominant limbs of the control group, supporting functional Magnetic Resonance Imaging data that the function of non-affected cerebral hemisphere is abnormal following stroke.

The computerised dynamometry analysis paradigm was able to simultaneously quantitate aspects of hand performance affected by positive and negative UMN features within an individual and between groups. This approach uses a clinically relevant, functionally based assessment technique that appears to have greater ecological validity and fewer limitations than current measures of spasticity.

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