Table 1 Main aspects of neurorehabilitation and outcome, and their implications for rehabilitation technology

UL

stroke

damaged CST

little recovery, esp. chronic impairment of hand/finger extension

prox. arm muscle activation; avoidance of muscle contractures; use of impaired limb for  support/holding function

prox. arm muscle strengthening; continuous passive limb motion; training of compensatory strategies

therapy: passive mobilization (position control) or weight support for self-initiated proximal movements; active/passive hand module with extension bias

assistance: supported arm/hand motion (admittance control) vial intention detection (e.g. force, EMG, gaze)

intact CST

spontaneous recovery of approx. 70–80% of intial arm/hand impairment

arm reaching and simple grasping function; uni−/bimanual ADL functions

functional reach/grasp and bimanual (cooperative) hand movements; strengthening of wrist/finger extensors; simple movement training with transfer to ADL; limited dose-dependent training effects: subacute > chronic stage

therapy: proximal gravity support during reach/grasp; training of individual joints using dedicated devices, including hand/fingers, as well as (cooperative) bimanual training (Fig. 2)

assistance: passive proximal gravity support combined with active wrist/finger support via residual function amplification (force/EMG control)

SCI (incomplete)

typical lesion level C6/7

spastic forearm flexor muscle tone impeding the development of tenodesis grasp

tenodesis grasp; bimanual grasp

assistance: active exoskeleton/glove to facilitate wrist and finger flexion/extension triggered by proximal arm motion (e.g. joint angle sensor)

LL

stroke

hemiparesis

spontaneous recovery; spastic muscle support; reduced level of stepping movement ability

non-assisted ambulation

generation of appropriate afferent input from load (body un/reloading) and hip receptors (hip extension) during stepping; importance of stepping velocity and hip extension (initiation of swing); dose-dependent training effects

therapy: body-weight support according to paresis; adapted movement support (position/admittance control for severe impairment and variable impedance control for mild/moderate impairment; Fig. 3); leg flexor activation through robotically assisted hip extension

SCI (incomplete)

paraparesis

some prox. leg muscle function and spastic muscle tone required for stepping ability

assisted/independent ambulation