Challenges for defining minimal clinically important difference (MCID) after spinal cord injury.

STUDY DESIGN: This is a review article. OBJECTIVES: This study discusses the following: (1) concepts and constraints for the determination of minimal clinically important difference (MCID), (2) the contrasts between MCID and minimal detectable difference (MDD), (3) MCID within the different domains of International Classification of Functioning, disability and health, (4) the roles of clinical investigators and clinical participants in defining MCID and (5) the implementation of MCID in acute versus chronic spinal cord injury (SCI) studies. METHODS: The methods include narrative reviews of SCI outcomes, a 2-day meeting of the authors and statistical methods of analysis representing MDD. RESULTS: The data from SCI study outcomes are dependent on many elements, including the following: the level and severity of SCI, the heterogeneity within each study cohort, the therapeutic target, the nature of the therapy, any confounding influences or comorbidities, the assessment times relative to the date of injury, the outcome measurement instrument and the clinical end-point threshold used to determine a treatment effect. Even if statistically significant differences can be established, this finding does not guarantee that the experimental therapeutic provides a person living with SCI an improved capacity for functional independence and/or an increased quality of life. The MDD statistical concept describes the smallest real change in the specified outcome, beyond measurement error, and it should not be confused with the minimum threshold for demonstrating a clinical benefit or MCID. Unfortunately, MCID and MDD are not uncomplicated estimations; nevertheless, any MCID should exceed the expected MDD plus any probable spontaneous recovery. CONCLUSION: Estimation of an MCID for SCI remains elusive. In the interim, if the target of a therapeutic is the injured spinal cord, it is most desirable that any improvement in neurological status be correlated with a functional (meaningful) benefit.

Seated reach distance and trunk excursion accurately reflect dynamic postural control in individuals with motor-incomplete spinal cord injury.

STUDY DESIGN: To determine whether kinematic measures of reach excursion are valid measures of postural control in individuals with motor-incomplete spinal cord injury (MISCI), seated reach test (SRT; obtained from a wrist marker) values and associated trunk excursion values (obtained from a C7 marker) were compared with center of pressure excursion (COPE). Data were obtained from individuals with MISCI and from non-disabled individuals for each of four directions. To assess the reliability of these measures in subjects with MISCI, these values were collected on two separate days. OBJECTIVE: Dynamic seated postural control is essential for individuals who perform their daily activities from a wheelchair. Although seated reach distance is used as a proxy measure for postural control, it is unknown whether this is an accurate and reliable measure of the limits of stability in individuals with MISCI. RESULTS: In subjects with MISCI, the SRT was significantly correlated with the COPE in three directions of reaching (r ≥ 0.71), with the exception being leftward reaching. Trunk excursion was correlated with COPE in all directions (r ≥ 0.93). In non-disabled individuals, both SRT (r ≥ 0.56) and trunk excursion (r ≥ 0.91) were correlated with COPE for all directions. In individuals with MISCI, there was significant intersession agreement for both reach distance (intraclass correlation coefficient (ICC)≥ 0.78) and trunk excursion (ICC ≥ 0.77) measured in all directions. CONCLUSIONS: Although both SRT and trunk excursion are reasonable reflections of COPE, measurement of postural control based on trunk excursion has advantages for individuals who may have difficulty maintaining arm position during reaching. Reach distance is highly reliable in individuals with MISCI in all directions of reaching.

The Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI).

The development and testing of an observational gait assessment instrument, the Spinal Cord Injury Functional Ambulation Inventory (SCI-FAI) is described. To assess validity and reliability, 22 subjects with incomplete spinal cord injury were scored by four raters. Raters scored each subject three times, once live (LS) and twice from videotaped records (VS1, VS2). A moderate-good negative correlation (r = -0.742 and -0.700, for VS1 and VS2, respectively) was found between the gait score and time required to walk a demarcated path. Inter-rater reliability was moderate-good for the live score and the videotaped records (ICC = 0.703, 0.800, and 0.840, respectively). Intra-rater reliability was good (ICC = 0.903, 0.960, 0.942, and 0.850 for Raters 1-4, respectively). To assess sensitivity, another group of 19 subjects with SCI were assessed prior to and following participation in an intensive walking program. A moderate correlation was found between change in gait score and change in lower extremity strength (Pearson r = 0.58). These results indicate that the SCI-FAI is a reliable, valid and sensitive measure of walking ability in individuals with spinal cord injury. In addition, the results suggest that gait analysis using this instrument is equally reliable whether the observation is performed live or from videotaped records.

Combined use of body weight support, functional electric stimulation, and treadmill training to improve walking ability in individuals with chronic incomplete spinal cord injury.

OBJECTIVE: To assess the effect of an intervention combining body weight support (BWS), functional electric stimulation (FES), and treadmill training on overground walking speed (OGWS), treadmill walking speed, speed and distance, and lower extremity motor scores (LEMS). DESIGN: Before and after comparison. SETTING: Miami Project to Cure Paralysis. PARTICIPANTS: Nineteen subjects with American Spinal Injury Association class C injury who were at least 1 year postinjury and had asymmetrical lower extremity function. INTERVENTION: Subjects trained 1.5 hours per day, 3 days per week, for 3 months. The training consisted of body weight-supported treadmill walking assisted by electric stimulation. Stimulation was applied to common peroneal nerve of the weaker lower extremity (LE) and timed to assist with the swing phase of the step cycle. MAIN OUTCOME MEASURES: OGWS in the absence of both BWS and FES; LEMS, and treadmill training parameters of speed and distance. RESULTS: Over the course of training, there was a significant increase in OGWS (from.12 +/- 0.8m/s to .21 +/- .15m/s, p = .0008), treadmill walking speed (from .23 +/- .12m/s to.49 +/- .20m/s, p = .00003), and treadmill walking distance (from 93 +/- 84m to 243 +/- 139m, p = .000001). The median LEMS increased significantly for both the stimulated and nonstimulated leg (from 8 to 11 in the FES-assisted leg, from 15 to 18 in the nonassisted leg, p < .005 for each). CONCLUSIONS: All subjects showed improvement in OGWS and overall LE strength. Further research is required to delineate the essential elements of these particular training strategies.

Spinal cord control of movement: implications for locomotor rehabilitation following spinal cord injury.

In recent years, our understanding of the spinal cord's role in movement control has been greatly advanced. Research suggests that body weight support (BWS) walking and functional electrical stimulation (FES), techniques that are used by physical therapists, have potential to improve walking function in individuals with spinal cord injury (SCI), perhaps long after the stage of spontaneous recovery. Walking is one of the most desired goals of people with SCI; however, we are obligated to be judicious in our claims of locomotor recovery. There are few controlled studies that compare outcomes of BWS training or FES with those of conventional interventions, and access to services using BWS training or FES may be restricted under managed care.

Effect of lower extremity weightbearing load on motoneuron excitability in able-bodied subjects.

Body weight support (BWS) is becoming an increasingly tool popular in rehabilitation settings, but little is known about how weight support effects reflex activity. Lower extremity Hoffman (H) reflex and tendon reflex responses were used to assess motoneuron excitability as a function of static lower extremity weightbearing load in neurologically normal individuals. Factors that are known to affect reflex activity, such as body orientation, movement and task phase were kept constant. Twenty three subjects were studied under three static load conditions (50%, 75% and 100% weightbearing) using four different stimulus conditions (soleus H-reflex, soleus H-reflex with vibration, Achilles tendon reflex, quadriceps tendon reflex). Load had no effect on any of the reflexes studied; we hypothesize that under static conditions, lower extremity reflexes are not affected by superincumbent load.