Systematic review of outcome measures of walking training using electromechanical and robotic devices in patients with stroke.

OBJECTIVE: The aim of this systematic review was to identify appropriate selection criteria of clinical scales for future trials, starting from those most commonly reported in the literature, according to their psychometric properties and International Classification of Functioning, Disability and Health (ICF) domains. DATA SOURCES: A computerized literature research of articles was conducted in MEDLINE, EMBASE, CINALH, PubMed, PsychINFO and Scopus databases. STUDY SELECTION: Clinical trials evaluating the effects of electromechanical and robot-assisted gait training trials in stroke survivors. DATA EXTRACTION: Fifteen independent authors performed an extensive literature review. DATA SYNTHESIS: A total of 45 scales was identified from 27 studies involving 966 subjects. The most commonly used outcome measures were: Functional Ambulation Category (18 studies), 10-Meter Walking Test (13 studies), Motricity Index (12 studies), 6-Minute Walking Test (11 studies), Rivermead Mobility Index (8 studies) and Berg Balance Scale (8 studies). According to the ICF domains 1 outcome measure was categorized into Body Function and Structure, 5 into Activity and none into Participation. CONCLUSION: The most commonly used scales evaluated the basic components of walking. Future studies should also include instrumental evaluation. Criteria for scale selection should be based on the ICF framework, psychometric properties and patient characteristics.

Corticospinal drive during painful voluntary contractions at constant force output.

In the voluntary contractions, output force can be maintained constant although the inhibitory influences exerted by pain on muscle activity. We investigated changes in the spontaneous and evoked activity of the abductor digiti minimi muscle (ADM) and the biceps brachii muscle (BIC) in healthy volunteers during constant force noxious contraction, resulting from chemically activated nociceptive afferents. EMG-force relationship, motor-evoked response (MEP) to transcranial magnetic stimulation and determinism (DET) of surface EMG signals during constant force contraction was analyzed before, during and after chemically induced tonic activation of their nociceptive afferents. Under constant force contraction, amplitude of surface EMG signal decreased in BIC and increased in ADM during pain with respect to control condition. In both muscles, the size of motor-evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) of the primary motor cortex was significantly higher during pain than in control. Level of determinism extracted from surface EMG signal by non-linear method was similarly and significantly increased in both muscles during pain stimulation. Finally, nociceptive stimulation caused a decline in steadiness of the force exerted by ADM and BIC. These results are interpreted in terms of increased corticospinal synchronizing inputs. The possibility that it may play a role in governing force production to counteract pain inhibitory influences on motor system is considered.

Influences of chemically-induced muscle pain on power output of ballistic upper limb movements.

OBJECTIVE: To analyse the conditioning effects of localised acute muscle pain on power output during ipsi- and contra-lateral ballistic arm extensions. METHODS: Eight male subjects performed right arm (ipsilateral) and left arm (contra-lateral) bench press movements. The power output (and force and velocity) of the concentric phase of movement was measured before and during muscle pain induced by a standardised intramuscular injection of levo-ascorbic acid in the right pectoralis major muscle (prime mover muscle) and in the lateral head of the right triceps brachii muscle (synergist). RESULTS: The power output of ipsi- and contra-lateral arm bench press movements was significantly decreased during pain of the right pectoralis major muscle, but not during pain of the right lateral triceps muscle. The velocity and force were both affected and contributed to the decrease in power output. CONCLUSIONS: Acute muscle pain of a prime mover muscle reduces ipsi- and contra-lateral motor performance of ballistic upper limb extension. This is not a generalised or non-specific inhibitory effect on the motor system, since pain failed to modify motor performance when applied to a synergist, non-prime mover, muscle. A basically bilateral executive cortical plan for ballistic upper limb extension could explain the conditioning effect of muscle pain on both ipsi- and contra-lateral arm. SIGNIFICANCE: The results presented here contributes to the understanding of the conditioning effects of muscle pain on movement performance.

Early somatosensory processing during tonic muscle pain in humans: relation to loss of proprioception and motor 'defensive' strategies.

OBJECTIVE: It is known that tonic muscle pain induced by a Levo-Ascorbic (L-AS) solution injected in a foot muscle can transiently modify both regional proprioception and stimulus perception. These findings are paralleled by changes of middle-latency lower-limb somatosensory evoked potentials (SEPs). However, little is known on the behaviourally relevant aspect whether eventual SEP pain-induced changes could be partly due to a sort of 'motor strategy' of subjects in the frame of a self-protective reaction towards the noxious stimulus. Movement and imagery of movements are in fact known to reduce mainly pre-central SEP amplitude (i.e. gating effect). METHODS: Low-threshold afferents ulnar SEPs, psychophysical pain ratings and fingers' position sense were monitored in the time-course during L-AS injection in the right first dorsal interosseous muscle. Control experiments included SEPs (either following prevalent ulnar nerve low-threshold afferent stimulation or more conventional mixed nerve stimulation) during actual movements execution and imagery of movements of the right hand. RESULTS: Tonic pain induced a significant reduction of the post-central N(20)-P(25)-N(33) complex and a significant increase of the N(18) wave. These changes, that were paralleled by distortion of the finger position sense, were delayed 2-5 min with respect to the maximal subjective pain sensation. Conversely, movement imagery tasks lead to a significant, selective, reduction of the pre-central N(30) complex. This wave was even more reduced during actual movements, in combination with a reduction of those post-central components peaking after the first activation of the primary sensory cortex. CONCLUSIONS: Early sensory processing at cortical level is changed during tonic muscle pain, mainly for those components which may be theoretically involved in proprioceptive afferent elaboration. These changes are likely not due to subconscious or voluntary motor strategies of the subjects in the frame of a self-protective aversive reaction towards the noxious stimulus.