Locomotor Training After Human Spinal Cord Injury: A Series of Case Studies

Locomotor disability.

As recommended by the ASIA standards for neurological and functional classification,³⁸ we used the locomotion subscales of the FIM to reflect disability (Tab. 3),³⁹ although this instrument was not developed for use with people with SCI or for measuring functional locomotion.

Walking speed and distance covered in 2 minutes.

We recorded gait speed for subjects who could walk overground independently (n=3). Subjects walked at a self-selected, comfortable speed (instructed as “walk at your natural pace”) and at a fast speed (instructed as “walk as fast as you safely can”) over a 7.3-m distance, and we recorded the time for the middle 3.6 m. We also measured the distance subjects (n=2) could walk in 2 minutes at a comfortable pace and covering as much ground as possible.⁴¹

Balance.

We evaluated balance in one subject using the Berg Balance Test^42,43 and the Falls Efficacy Scale⁴⁴ because tests for balance have not been tested for validity for people with SCI.⁴⁵ The Berg Balance Test is used to assess balance performance during 14 sitting and standing tasks. An examiner scores each test item on a scale from 0 to 4 based on the time or distance requirements, supervision required, need for external support, or need for assistance from the examiner. The highest attainable score of balance function is 56. For the Falls Efficacy Scale, the subject self-rates the confidence with which he or she can perform 10 daily activities (eg, get dressed or undressed, hurry to answer the telephone) without falling on a scale of 1 to 10. The lower the percentage (10%), the greater the individual's confidence that the activities can be performed without falling.

Handicap.

We assessed the degree of handicap using the physical function component of the Medical Outcomes Study (MOS) 36-Item Short-Form Health Survey (SF-36)⁴⁶ and the Craig Handicap Assessment and Reporting Technique (CHART)⁴⁷ in one subject. For the SF-36, the subject rates the degree to which his or her health currently limits the performance of certain daily activities (eg, climbing one flight of stairs, lifting or carrying groceries). The scores range from 0% to 100%, with the high percentage indicating that an individual's health does not at all limit performance of the activities. The CHART is an interview of 27 questions evaluating physical dependence, mobility, occupation, social integration, and economic self-sufficiency as a measure of a person's degree of handicap. In addition to these 2 assessments of handicap, this subject was also asked to identify 3 activities that he perceived as the most difficult to perform because of his SCI. The subject then rated each activity on a Likert-type 10-point scale, with a score of 10 representing the most difficult activity to perform.

Step training on a treadmill.

If a subject could not independently balance or maintain his or her full body weight load while stepping and executing appropriate limb kinematics, body weight support (BWS) was used in an effort to provide a safe and effective environment for locomotor training. A harness (Medical Harness*) worn by the subject and connected to an overhead-motorized or pneumatic lift (Neuro II^†) suspended over the treadmill provided the BWS. The level of weight support was adjusted to maximize bilateral limb loading without the knee buckling during stance. If the subject, while step training with BWST, could not generate the appropriate limb and trunk kinematics associated with locomotion, manual assistance was provided. One trainer assisted each lower extremity. One hand of the trainer was placed on the anterior surface of the leg just below the patella to assist with knee extension during stance. The other hand was placed at the ankle or foot to assist with toe clearance during swing and heel-strike at initial stance. A third trainer stabilized the pelvis in order to maintain an upright trunk. The subjects were not permitted to support themselves by holding on to the treadmill side rails. Elastic side supports were attached diagonally to the subject and to side bars for balance when necessary but still allowed arm swing. Each subject was encouraged to swing his or her arms reciprocally with the lower extremities. When assistance for arm swing was necessary, one trainer manipulated 2 poles positioned horizontal to the ground and held by the subject. The trainers moved the poles forward and backward so that the contralateral arm moved forward with the ipsilateral leg, thereby producing a reciprocating arm swing (Fig. 1). Arm swing assistance was provided intermittently to achieve interlimb coordination, then removed when the subject could perform independently.

Figure 1.

Step training using body weight support on the treadmill with manual assistance.

To initiate stepping on the treadmill, subjects stood with their feet in a position simulating a stride, with one leg in an extended position near the mid-stance phase of the step cycle and bearing the majority of the body weight. As the treadmill speed was increased and carried the leg back to a position of terminal stance, the subjects shifted their body weight laterally and forward to the opposite leg as it reached initial contact. In this way, the body weight was supposed to quickly transfer to the forward leg, and the posterior limb could initiate swing. During stance, one trainer stabilized the knee to promote extension and the full loading of the limb while the trainer at the pelvis assisted in shifting of the body weight as needed. During leg swing, the trainer achieved toe clearance by increasing knee flexion with an anterior hold of the ankle or dorsum of the foot while being certain to avoid pressure or firm contact with the sole of the foot or the Achilles tendon. Pressure or stimulation of extensor afferents in these areas during swing may provide conflicting sensory information to the cues normally associated with swing and thus cause cessation of forward leg movement and transition to stance. The trainer facilitated knee flexion during swing by providing manual pressure on the medial hamstring tendon. Foot placement on the treadmill was monitored and assisted when necessary. Appropriate simulation of leg movement through the swing and stance phases of gait was one key factor in eliciting stepping on the treadmill. Another factor was providing symmetric interlimb coordination. Particular attention was given by the trainers to achieving simultaneous heel-strike of one limb with lift off of the other limb in order to facilitate swing.

The trainers and the subject monitored the limb and joint kinematics during stepping and attained an optimal stepping pattern by adjusting the treadmill speed, BWS, and level of manual assistance. An optimal stepping pattern was achieved when it was spatially and temporally coordinated and most resembled normal walking. This pattern was then practiced repetitively during step training sessions. The duration of step training sessions was determined by (1) subject fatigue, (2) maintenance of joint kinematics aligned with locomotion, and (3) maintenance of proper weight shift and limb loading patterns across the legs. A full-length mirror was placed in front of the subject for viewing and self-monitoring while training. Step training began by reaching what we considered normal walking speeds (optimized for each subject), and then focused on minimizing the manual assistance, decreasing the BWS, and increasing the duration to three 10-minute sessions. With a normal walking speed as a target,⁴⁸ training speeds were adjusted and selected based on achieving the optimal stepping pattern and often coincided with diminished need for manual assistance.

Training overground walking.

We began locomotor training overground in conjunction with step training on the treadmill when a subject could stand independently while supporting at least 80% of his or her body weight and could independently generate the appropriate stepping kinematics on at least one limb. If a subject could not maintain balance at what we considered normal walking speed, assistance was provided using 1 of 3 different techniques. One approach was to have a trainer stand facing the subject with the subject holding the hands of the trainer. The trainer then walked backward, facilitating a reciprocating arm swing of the subject and offering enough support through the subject's arms to maintain balance but not substantially bear weight with the arms. Another trainer walked behind the subject, assisting with weight shifting and trunk extension at the pelvis, if needed. The second technique used to facilitate arm swing and provide balance was to have 2 trainers hold a pole (approximately 1.2 m × 1.9 cm [4 ft × ¾ in]) on each side of the subject (Fig. 2). The poles were positioned horizontally (parallel to the floor) at the level of the greater trochanter in order for the subject to grip them during ambulation. The trainers then moved the poles forward and back in unison with the stepping of the legs. By having trainers hold the poles, the amount of weight bearing through the arms was minimized. The third approach was to have the subject use assistive devices. The approach used for each subject depended on comfort of the subject, availability of trainers, and locomotor ability of the subject.

Figure 2.

Training for overground walking.

Assistive devices were selected based on principles of locomotor training such as maintaining proper limb and trunk kinematics and minimizing weight bearing by the arms. We found that long trekking poles or walking sticks provided suitable support for balance and appeared to facilitate weight bearing through the legs rather than the arms. We also adjusted the handle height of a rolling walker to achieve a level forearm with 90 degrees of elbow flexion in an effort to minimize upper-extremity weight bearing and forward trunk flexion. However, use of the rolling walker would not allow reciprocal arm swing during training overground and, therefore, was the least desirable approach we used during locomotor training.

To initiate overground walking, subjects stood with their feet in a position simulating a stride, with the majority of their body weight being supported by the limb positioned in terminal stance. They then quickly unloaded this limb and simultaneously loaded the contralateral limb, which initiated the swing phase ipsilaterally. As with step training, if we believed that an individual could not generate the appropriate limb kinematics associated with locomotion overground, manual assistance was provided. For example, a trainer initially assisted a subject in achieving knee flexion and toe clearance during swing by providing manual pressure on the hamstring tendon. As the subject's ability to achieve swing with toe clearance improved, the trainer no longer provided the manual assistance. Subjects were trained 3 to 5 times per week. The frequency of training, total number of sessions, and total time span for training of each subject are detailed in Table 4.

ASIA assessment.

Subject 1, a 20-year-old woman, had a traumatic SCI (T5, 1 year postinjury) and had completed an inpatient rehabilitation program. This subject's injury was classified, prior to training, as ASIA A with a lower-extremity motor score of 0/50. After completion of training, the subject's injury remained classified as ASIA A, and the lower-extremity motor score remained 0/50.

Step training on a treadmill.

Subject 1 received 85 step training sessions on the treadmill. Prior to training, she was unable to stand or step independently on the treadmill. After step training, she consistently stepped with BWST (10% BWS) requiring only manual assistance for accurate foot placement. When what we believed were the optimal conditions were attained for limb loading, treadmill speed, and kinematics, the subject could produce 3 to 10 consecutive steps without manual assistance on at least one leg. After step training, she was also able to bear 90% of her body weight without manual assistance for 1 minute in an upright, stationary position with the harness and elastic straps to assist with stability.

Training for overground walking.

Subject 1 did not receive training for overground walking.

Functional assessment of locomotor disability.

Subject 1's pretraining scores were 6 (modified independence) for the FIM locomotion subscale walk/wheelchair item, with the wheelchair being the sole means of mobility, and 1 (total assistance) for the FIM locomotion subscale stairs item. After training, the FIM scores did not change.

ASIA assessment.

Subject 2, a 20-year-old man, had a traumatic SCI (T5, 1 month postinjury) and was receiving conventional inpatient rehabilitation therapy in addition to locomotor training. His injury was classified prior to training as ASIA C with a lower-extremity motor score of 2/50. After completing training, the subject's ASIA impairment classification progressed to D, and his lower-extremity motor score had improved to 38/50.

Step training on the treadmill.

Subject 2 received 64 step training sessions with BWST. During initial training, he required manual assistance to complete the lower-limb swing and maintain knee extension. After 3 weeks of training, he could step independently with the left leg and required minimal manual assistance to complete the right leg swing. This stepping pattern was accomplished on the treadmill at a time when the subject had little or no voluntary control of his lower extremities. On completion of the 64 step training sessions, the subject required no BWS and was able to step independently on the treadmill.

Training for overground walking.

Subject 2 received 44 sessions of training for overground walking. He initially used a rolling walker and required manual assistance to complete swing of the right leg. After 4 sessions, he stepped with the rolling walker without assistance. As his stepping with BWST improved, he also increased both speed and duration of overground walking. After 14 sessions of training for overground walking and 34 sessions of step training on a treadmill, he began overground walking with a cane. After completing locomotor training, he progressed to independent ambulation using a single-point cane.

Functional assessment of locomotor disability.

Subject 2's pretraining FIM locomotion subscale walk/wheelchair score was 6 (modified independence) and his locomotion subscale stairs score was 1 (total assistance), with the wheelchair being his sole means of mobility. At the completion of training, his FIM locomotion subscale walk/wheelchair score remained 6 (modified independence), but his mode of locomotion changed from the wheelchair to walking full-time with a cane. Following training, his FIM locomotion subscale stairs score improved to 6 (modified independence), as he could climb stairs independently using a cane.

Functional assessment of walking speed and distance covered.

As subject 2 was nonambulatory prior to training, walking performance overground was not assessed. After training, his overground, self-selected walking speed using a cane was 0.53 m/s and his fast speed was 0.75 m/s. After training, he walked 67 m in 2 minutes.

ASIA assessment.

Subject 3, a 43-year-old man, had a traumatic SCI (C6, 8 months postinjury) and had completed an inpatient rehabilitation program. Prior to training, his injury was classified as ASIA D with a lower-extremity motor score of 32/50. Following completion of training, his ASIA impairment classification remained D, although his lower-extremity motor score increased to 34/50, with 2 muscles upgraded from a score of 1 (palpable or visible contraction) to 2 (active movement, full range of motion with gravity eliminated).

Step training on the treadmill.

Subject 3 received 27 step training sessions. During early training, manual assistance at the pelvis and legs was provided to attain an upright trunk and facilitate lower-limb kinematics. Additionally, arm swing was assisted using the horizontal poles. After locomotor training, the subject progressed to requiring only intermittent assistance for upright posture, knee flexion, and toe clearance. He was then able independently to coordinate arm swing with the lower limbs. He progressed from requiring 45% BWS during his initial training to requiring 20% BWS at the completion of his sessions.

Training for overground walking.

Subject 3 received 15 sessions of training for overground walking in conjunction with step training on the treadmill. Prior to training, he walked using a rolling walker. During training for overground walking, horizontal poles were used to facilitate reciprocal arm swing. Initiating walking from a stride position, maintaining an upright posture, and walking speed were emphasized. The subject's primary residual deficit during overground locomotion was limited toe clearance, bilaterally. After completing the combined step training and overground walking sessions, he walked full-time using forearm crutches.

Functional assessment of locomotor disability.

Subject 3's initial FIM locomotion subscale walk/wheelchair score was 6 (modified independence) and his stairs score was 1 (total assistance). Prior to training, this subject used the wheelchair as the most frequent mode of mobility and could not ascend stairs. He was able to walk using a rolling walker, but he was not able to walk using a less restrictive assistive device such as forearm crutches. Following training, his primary means of mobility had improved from a wheelchair to walking with an FIM score of 6 (modified independence). His FIM stairs score improved to 6 (modified independence), as he required a handrail to climb stairs. Subject 3 had also progressed from using a rolling walker to using forearm crutches.

Functional assessment of walking speed and distance covered.

Before training, subject 3 walked overground using a rolling walker at 0.09 m/s (self-selected, comfortable speed) with an asymmetrical stride. He walked at 0.16 m/s with the rolling walker when requested to walk as fast as possible. He also walked 12 m in 2 minutes using the rolling walker. He exhibited forward flexion of the trunk and weight bearing through the upper extremities throughout the gait cycle. He advanced his lower extremities by hip hiking with extended knees and plantar-flexed ankles. Foot contact occurred, with a plantar-flexed ankle resulting in toe-to-heel contact.

After locomotor training, the subject's overground walking speed using a rolling walker increased to 0.33 m/s at a self-selected speed and to 0.50 m/s at a fast walking speed. He was also able to walk with forearm crutches at a self-selected walking speed of 0.20 m/s and a fast walking speed of 0.27 m/s. He walked 68 m in 2 minutes using a rolling walker and 36.6 m in 2 minutes using forearm crutches. He was able to take multiple steps without the use of assistive devices, though very slowly and with balance difficulties.

Functional assessment of balance.

Subject 3 initially had scores of 30/56 on the Berg Balance Test and 28% on the Falls Efficacy Scale. Following training, the Berg Balance Test score improved to 43/56 and the Falls Efficacy Scale score improved to 16%. Initial balance assessments indicated that the subject was at risk for falling⁴³ and had diminished confidence in performing certain everyday tasks without falling.⁴⁴ These improvements after training indicated a decrease in falls risk and a greater confidence in the subject's ability to perform everyday tasks without falling.^43,44

Functional assessment of handicap.

Before training, subject 3's SF-36 physical function score was 10%. After training, this score increased to 20%, indicating that he perceived that his health status after training did not limit his activities as greatly as it did prior to training.⁴⁶ His initial CHART score of 76% improved to 89% after training, also supporting a decrease in the degree of self-rated handicap.⁴⁷ After training, self-ratings also showed a decline in the degree of difficulty for walking, climbing stairs, and getting around in the home. Self-rating scores declined (1) from 10 to 3 for climbing stairs, (2) from 9 to 5 for walking, with clonus being an occasional problem, and (3) from 8 to 4 for getting around in the house and being able to go outside.

ASIA assessment.

Subject 4, a 45-year-old man, had a decompression injury (T9, 3 months postinjury) and had completed inpatient rehabilitation. Prior to training, his injury was classified as ASIA D with a lower-extremity motor score of 46/50. After completing the training, his ASIA classification and lower-extremity motor score remained the same.

Step training on the treadmill.

Subject 4 received 5 step training sessions with supervision, followed by 10 independent step training sessions at a health club. He did not require BWS or manual assistance during training, as he balanced independently, maintained his full body weight load, and achieved appropriate stepping kinematics on the treadmill. Following training, he stepped on the treadmill for 30 minutes at what we considered a normal walking speed of 1.3 m/s and maintained appropriate limb kinematics.

Training for overground walking.

Subject 4 did not receive any training for overground walking.

Functional assessment of locomotor disability.

Prior to training, subject 4 achieved scores of 6 (modified independence) on both the FIM locomotion subscale walk/wheelchair and stair items. He was a full-time ambulator without assistive devices but required more than a reasonable amount of time to walk 45.7 m (150 ft). He required the use of a handrail for safety during stair climbing. After training, his FIM locomotion subscale walk/wheelchair and stair scores improved to 7 (complete independence). He thus walked at what we considered a normal speed and could safely go up and down a flight of stairs without depending on any type of handrail or support.

Functional assessment of walking speed.

Subject 4 initially walked overground at 0.6 m/s (self-selected, comfortable speed) and at 1.2 m/s when requested to walk as quickly as possible. At the fast speed, he exhibited uncoordinated steps, exaggerated limb excursion, scissoring, and difficulty maintaining balance. After training, his overground, self-selected walking speed increased to 1.6 m/s and his fast speed increased to 1.9 m/s. He was then able to walk faster with no change in the coordination of his gait pattern. When he tried to run, his gait pattern deteriorated, demonstrating balance difficulties, step asymmetry, and uncoordinated limbs. At a 1-month follow-up evaluation after completion of training, his overground, self-selected walking speed was 1.2 m/s and his fast walking speed was 1.8 m/s. These speeds were retained at a 4-month follow-up evaluation, with a self-selected walking speed of 1.3 m/s and a fast walking speed of 1.9 m/s.