Robot-assisted arm assessments in spinal cord injured patients: a consideration of concept study.

Robotic assistance is increasingly used in neurological rehabilitation for enhanced training. Furthermore, therapy robots have the potential for accurate assessment of motor function in order to diagnose the patient status, to measure therapy progress or to feedback the movement performance to the patient and therapist in real time. We investigated whether a set of robot-based assessments that encompasses kinematic, kinetic and timing metrics is applicable, safe, reliable and comparable to clinical metrics for measurement of arm motor function. Twenty-four healthy subjects and five patients after spinal cord injury underwent robot-based assessments using the exoskeleton robot ARMin. Five different tasks were performed with aid of a visual display. Ten kinematic, kinetic and timing assessment parameters were extracted on joint- and end-effector level (active and passive range of motion, cubic reaching volume, movement time, distance-path ratio, precision, smoothness, reaction time, joint torques and joint stiffness). For cubic volume, joint torques and the range of motion for most joints, good inter- and intra-rater reliability were found whereas precision, movement time, distance-path ratio and smoothness showed weak to moderate reliability. A comparison with clinical scores revealed good correlations between robot-based joint torques and the Manual Muscle Test. Reaction time and distance-path ratio showed good correlation with the "Graded and Redefined Assessment of Strength, Sensibility and Prehension" (GRASSP) and the Van Lieshout Test (VLT) for movements towards a predefined position in the center of the frontal plane. In conclusion, the therapy robot ARMin provides a comprehensive set of assessments that are applicable and safe. The first results with spinal cord injured patients and healthy subjects suggest that the measurements are widely reliable and comparable to clinical scales for arm motor function. The methods applied and results can serve as a basis for the future development of end-effector and exoskeleton-based robotic assessments.

Defining the role of sensation, strength, and prehension for upper limb function in cervical spinal cord injury.

BACKGROUND: Upper limb function plays a significant role in enhancing independence for individuals with tetraplegia. However, there is limited knowledge about the specific input of sensorimotor deficits on upper limb function. Thus the theoretical framework designed to develop the Graded Redefined Assessment of Strength Sensibility and Prehension (GRASSP) was used as a hypothetical model to analyze the impact of impairment on function. OBJECTIVE: To define the association of impairment (sensation, strength, and prehension measured by the GRASSP) to upper limb function as defined by functional measures (Capabilities of Upper Extremity Questionnaire, Spinal Cord Independence Measure). METHODS: A hypothetical model representing relationships by applying structural equation modeling was used to estimate the effect of the impairment domains in GRASSP on upper limb function. Data collected on 72 chronic individuals with tetraplegia was used to test the hypothetical model. RESULTS: Structural equation modeling confirmed strong associations between sensation, strength, and prehension with upper limb function, and determined 72% of the variance in "sensorimotor upper limb function" was explained by the model. Statistics of fit showed the data did fit the hypothesized model. Sensation and strength influence upper limb function directly and indirectly with prehension as the mediator. CONCLUSIONS: The GRASSP is a sensitive diagnostic tool in distinguishing the relative contribution of strength, sensation and prehension to function. Thus, the impact of interventions on specific domains of impairment and related contribution on clinical recovery of the upper limb can be detailed to optimize rehabilitation programs.

Reliability of movement workspace measurements in a passive arm orthosis used in spinal cord injury rehabilitation.

BACKGROUND: Robotic and non-robotic training devices are increasingly being used in the rehabilitation of upper limb function in subjects with neurological disorders. As well as being used for training such devices can also provide ongoing assessments during the training sessions. Therefore, it is mandatory to understand the reliability and validity of such measurements when used in a clinical setting. The aim of this study was to evaluate the reliability of movement measures as assessed in the Armeo Spring system for the eventual application to the rehabilitation of patients suffering from cervical spinal cord injury (SCI). METHODS: Reliability (intra- and inter-rater reliability) of the movement workspace (representing multiple ranges of movement) and the influence of varying seating conditions (5 different chair conditions) was assessed in twenty control subjects. In eight patients with cervical SCI the test-retest reliability (tested twice on the same day by the same rater) was assessed as well as a correlation of the movement workspace to retrieve self-care items as scored by the spinal cord independence measure (SCIM 3). RESULTS: Analysis of workspace measures in control subjects revealed intra-class correlation coefficients (ICC) ranging from 0.747 to 0.837 for the intra-rater reliability and from 0.661 to 0.855 for the inter-rater reliability. Test-retest analysis in SCI patients showed a similar high reliability with ICC = 0.858. Also the reliability of the movement workspace between different seating conditions was good with ICCs ranging from 0.844 to 0.915. The movement workspace correlated significantly with the SCIM3 self-care items (p < 0.05, rho = 0.72). CONCLUSION: The upper limb movement workspace measures assessed in the Armeo Spring device revealed fair to good clinical reliability. These findings suggest that measures retrieved from such a training device can be used to monitor changes in upper limb function over time. The correlation between the workspace measures and SCIM3 self-care items indicates that such measures might also be valuable to document the progress of clinical rehabilitation, however further detailed studies are required.

The Graded Redefined Assessment of Strength Sensibility and Prehension: reliability and validity.

With the advent of new interventions targeted at both acute and chronic spinal cord injury (SCI), it is critical that techniques and protocols are developed that reliably evaluate changes in upper limb impairment/function. The Graded Redefined Assessment of Strength Sensibility and Prehension (GRASSP) protocol, which includes five subtests, is a quantitative clinical upper limb impairment measure designed for use in acute and chronic cervical SCI. The objectives of this study were to: (1) establish the inter-rater and test-retest reliability, and (2) establish the construct and concurrent validity with the International Standards of Neurological Classification of Spinal Cord Injury (ISNCSCI), Spinal Cord Independence Measure II (SCIM), and the Capabilities of Upper Extremity Questionnaire (CUE). The study protocol included repeated administration of the GRASSP to a cross-section of individuals with tetraplegia who were neurologically stable (n=72). ISNCSCI, CUE, and SCIM assessments were also administered. Two assessors examined the individuals over a 7-day period. Reliability was tested with intra-class correlation coefficients; construct validity was established with agreement/discordance analysis between the GRASSP and ISNCSCI sensory and motor items; and concurrent validity was tested with Spearman correlation coefficients. Inter-rater and test-retest reliability for all subtests within the GRASSP were above the hypothesized value of 0.80 (0.84-0.96 and 0.86-0.98, respectively). The GRASSP is about 50% more sensitive (construct validity) than the ISNCSCI when defining sensory and motor integrity of the upper limb; the subtests showed concurrence with the SCIM, SCIM self-care subscale, and CUE. The strongest concurrence to impairment was with self-perception of function (CUE) (0.57-0.83, p<0.0001). The GRASSP was found to demonstrate reliability, construct validity, and concurrent validity for use as a standardized upper limb impairment measure for individuals with tetraplegia.

Upper extremity function in persons with tetraplegia: relationships between strength, capacity, and the spinal cord independence measure.

OBJECTIVE: To quantify the relationship between the Spinal Cord Independence Measure III (SCIM III), arm and hand muscle strength, and hand function tests in persons with tetraplegia. METHODS: A total of 29 individuals with tetraplegia (motor level between cervical 4 and thoracic 1; sensory-motor complete and incomplete) participated. The total score, category scores, and separate items of the SCIM III were compared to the upper extremity motor score (UEMS), an extended manual muscle test (MMT) for 11 upper extremity muscles, and 6 functional capacity tests of the hand. Spearman's correlation coefficients (r(s)) and regression analyses were performed. RESULTS: The SCIM III sum score correlated well with the sum scores of the 3 tests (r(s) > or = .76). The SCIM III self-care category correlated better with the tests ( r(s) > or = .80) compared to the other categories (r( s) < or = .72). The SCIM III self-care item "grooming" highly correlated with muscle strength and hand capacity items (r(s) > or = .80). A combination of hand muscle tests and the key grasping task explained over 90% of the variability in the self-care category scores. CONCLUSIONS: The SCIM III self-care category reflects upper extremity performance as it contains especially useful and valid items that relate to upper extremity function and capacity tests.