Energy consumption of locomotion with orthosis versus Parastep-assisted gait: a single case study.

STUDY DESIGN: Single case study. OBJECTIVES: To evaluate the energy expenditure during ambulation with the Advanced Reciprocating Gait Orthosis (ARGO), with and without functional electrical stimulation (FES), and with the Parastep system in a single subject, in order to avoid the effect of inter-subject variability. SETTING: The Centre of Sport Medicine and Bioengineering Centre 'Don C Gnocchi' Foundation ONLUS IRCCS, Milano, Italy. METHODS: A single patient (lesion level T5-T6) was trained specifically for each walking system and was evaluated after each training period. The effects of FES on muscle conditioning, spasticity and bone density were also evaluated. The HR/VO2 relationship and the energy cost of locomotion were measured during wheelchair (WHCH) use, during locomotion with ARGO (with and without FES) and Parastep system at different speeds. RESULTS: The following was observed at the end of the whole training: (a) circumferences of both lower limbs and quadriceps forces were increased, whereas fatigue index was slightly decreased, spasticity and bone density were unchanged; (b) compared to WHCH locomotion, the slope of HR/VO2 curves with ARGO was higher (slope difference=51.1 b 1O2(-1)), with ARGO+FES was similar (slope difference=-5.3 b 1O2(-1)) and with Parastep was smaller (slope difference=-55.6 b 1O2(-1)); (c) HR increased linearly with all locomotion systems, but did not rise above 125 bpm with Parastep; (d) the cost of locomotion was higher with Parastep than with ARGO (with and without FES), tested at each velocity; (e) Parastep appears to be easier to use for the subject. CONCLUSIONS: (a) FES can improve ambulation with orthosis, but the cost of locomotion remains very high; (b) the Parastep assisted gait elicits a higher energy expenditure than other orthoses, probably due to the lower speed of locomotion and to the high isometric effort of the stimulated muscles. SPONSORSHIP: This work has been partially supported by the Italian Minister of Public Health (Ricerca Finalizzata IRCCS no ICS030.7/RF97.25).

Standing-up exerciser based on functional electrical stimulation and body weight relief.

The goal of the present work was to develop and test an innovative system for the training of paraplegic patients when they are standing up. The system consisted of a computer-controlled stimulator, surface electrodes for quadricep muscle stimulation, two knee angle sensors, a digital proportional-integrative-derivative (PID) controller and a mechanical device to support, partially, the body weight (weight reliever (WR)). A biomechanical model of the combined WR and patient was developed to find an optimum reference trajectory for the PID controller. The system was tested on three paraplegic patients and was shown to be reliable and safe. One patient completed a 30-session training period. Initially he was able to stand up only with 62% body weight relief, whereas, after the training period, he performed a series of 30 standing-up/sitting-down cycles with 45% body weight relief. The closed-loop controller was able to keep the patient standing upright with minimum stimulation current, to compensate automatically for muscle fatigue and to smooth the sitting-down movement. The limitations of the controller in connection with a highly non-linear system are considered.

Touch-screen system for assessing visuo-motor exploratory skills in neuropsychological disorders of spatial cognition.

A new computerised test adopting touch-screen technology has been developed to assess the visuo-motor exploration of extra-personal space. The test was derived from well-known paper-and-pencil cancellation tasks used widely in the diagnosis and quantitative assessment of unilateral spatial neglect (USN), a neuropsychological syndrome that is more frequent and severe after damage to the right cerebral hemisphere. A main component deficit of USN is the defective visuo-motor exploration of the side of space contralateral to the side of the lesion (contralesional), namely, in right-sided brain-damaged patients it occurs on the left side and vice versa. The computer-based paradigm consisted of a visuo-motor spatial exploratory task: the subjects were instructed to touch, in any order they wished, all the targets they detected on a computer touch-screen. This measured the time of occurrence and the spatial co-ordinates of each touch event and forwarded the data to the computer for storage; the computer provided feedback to the subject by 'tagging' the touched target. The paradigm allowed the calculation of accuracy and latency indexes and recorded the exploratory pathway taken by each subject. A pilot study was performed in ten normal subjects and 15 brain-damaged patients, with and without psychometric evidence of USN; the results showed that the equipment was able to provide quantitative indexes related to the spatial-temporal aspects of exploratory ability, which are useful for diagnostic purposes, and revealed significant differences between the controls and patients with USN: the overall average values of latency and crossing indexes increased in patients with USN, compared with the controls (latency from 0.77 to 1.90s; path crossing index from 7.0% to 59.5%), and the significantly negative USN patient latency gradient (-2.79 against a null control value) evidenced a worsening of performance towards the left side.

A pilot study of myoelectrically controlled FES of upper extremity.

Functional electrical stimulation (FES) of upper limbs can be used for the recovery of some hand functions on patients with CNS lesions. This study deals with the control of FES by means of myoelectrical activity detected from voluntarily activated paretic muscles. The specific aim of this paper is to evaluate the accuracy of myoelectrical control in terms of produced force and movement. For this purpose, a specific device called myoelectrical controlled functional electrical stimulator (MeCFES) has been developed and applied to six tetraplegic patients with a spinal cord lesion and one stroke hemiplegic patient. Residual myoelectric signals from the paretic wrist extensor (m. extensor carpi radialis, ECR) have been used to control stimulation of either the wrist extension (i.e., the same muscle) or thumb flexion. A tracking test based on a visual feedback of the produced force or movement compared to a reference target trajectory was used to quantify control accuracy. A comparison was made between the tracking performances of each subject with and without the MeCFES and the learning process for two of the subjects were observed during consecutive sessions. Results showed that the wrist extension was improved in three out of five C5 SCI patients and the thumb flexion was largely increased in one incomplete C3 SCI patient. The hemiplegic patient showed limited thumb control with the MeCFES but indicated the possibility of a carry over effect. It was found that a low residual natural force resulted in a less accurate movement but also with a large increase (up to ten times) of the muscle output. On the contrary, persons with a medium residual force obtained a smaller amplification of muscle force with a higher tracking accuracy.

Functional control of the hand in tetraplegics based on residual synergistic EMG activity.

A microprocessor controlled device (MeCFES) was used for the investigation of the possibility of restoring hand function in C5 tetraplegics with paralysis of the hand. To date, 3 tetraplegics have been testing the system. The myoelectric signals from wrist extension were recorded and used as control signals for functional electrical stimulation (FES) of thumb adduction/flexion. The results have shown that the device can improve the hand function of tetraplegics. In this part of the work, a hand function test was designed and used to assess the results.

Internal-external control and temporal orientation among southeast Asians and white Americans.

This study examined ethnic group differences with the use of the Model of Human Occupation (Kielhofner, 1985b). Three groups--immigrants from Thailand, immigrants from Cambodia, and white Americans--were contrasted on two constructs--internal versus external control and temporal orientation. The study attempted to identify whether nonpatient subjects have an internal locus of control and a strong future orientation, as the Model of Human Occupation would predict. No differences were found with the use of the Internal-External Scale (Rotter, 1966). The Thai and white Americans differed significantly on the Time Reference Inventory (Roos & Albers, 1965b). The Thai selected more items referring to the past, and the white Americans chose more statements applying to the present. There were no differences for past or future time extensions between groups. All the groups had a greater past extension than future extension. It was proposed that a larger future time perspective was not a requisite for functional temporal adaptation.