Introduction to Gait Rehabilitation in Spinal Cord Injury

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Original Editor - Ewa Jaraczewska based on the course by Maha Tayseer Mohammad

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Introduction

The walking recovery for patients with spinal cord injury is a target of various rehabilitative approaches. Understanding prognostic factors influencing recovery is necessary when choosing the most appropriate therapeutic intervention.This article discusses two approaches in gait rehabilitation and factors that help to predict ambulation recovery for patients with a spinal cord injury.

Plasticity-Based Approach

The plasticity-based approach in gait rehabilitation in spinal cord injury (SCI) arises from activity-dependent neural adaptation and training research. The afferent input influences the activity-dependent plasticity of the spinal cord, which affects the neurobiological control of walking. The examples can be found in the studies by Sherrington, Grillner and Rossignol who looked at the input of hip position and the effect of load on retraining walking after SCI. As the result of these studies, the rehabilitation strategies to regain the ability to ambulate by the patient with a spinal cord injury focused on hip extension, load and other sensory elements to facilitate walking.

In a plasticity-based approach, a specific task, like locomotion, undergoes intensive practice in a specific training environment while an appropriate sensory input is provided. The training environment may include a treadmill with body-weight support (BWS), a lokomat, or an Exoskeleton. The sensory input can be offered in a form of limb loading and unloading, trunk posture, hip extension, or limb kinematics.

Example: Locomotor training using a Lokomat.

• The goal is to generate stepping in response to specific afferent input associated with the task of walking
• The general guidelines focus on maximising loading of the lower limbs through body-weight support systems or overground walking with assistive devices

Compensatory-Based Approach

Compensation is "a rehabilitation strategy for non-remediable deficits of strength (force-generating capacity), voluntary motor control, sensation, and balance."It is based on the principles that patients use their remaining abilities (compensate) to complete the task, or the task or environment is modified to achieve the established goal.

In compensatory-based approach a task of walking is accomplished with the use of orthosis and assistive devices, and the outcome depends on the degree of motor and sensory loss.

Definitions of Walking Recovery in Spinal Cord Injury

General Definitions

Functional ambulation is “the ability to walk, with or without the aid of appropriate assistive devices (such as prostheses, orthoses, canes or walkers), safely and sufficiently to carry out mobility-related activities of daily living.”

Ambulatory capacity is "the highest level of walking function achieved within a standardised environment." Community ambulation is defined as “independent mobility outside the home, which includes the ability to confidently negotiate uneven terrain, private venues, shopping centres, and other public venues.”

Eight dimensions of community ambulation include the following:

• Ability to manage distances
  • Walk distance from 16 to 677m, depending on the community destination.
• Temporal characteristics
  • Gait velocity, cadence, step length, and step time.
• Speed
  • Crosswalk speed requirements range from .44 to 1.32m/s, vary by country and increase with increasing population size.
• Ambient conditions
  • Lighting, air temperature, weather condition
• Terrain
  • Temporal spatial characteristics of ambulatory participants with SCI are dramatically affected by the surfaces they walk on.
  • Average stride length, cadence, and walking speed of a patient with SCI are decreased while walking on artificial grass, soft, and pebble surfaces compared to a hard surface.
• Physical load
  • Poor roads condition, side-walks with cracks, pot-holes
• Attentional demands
  • Gait alteration in response to obstacles within the path of travel
• Postural transitions
  • Ability to maintain dynamic balance
• Density
  • The number of people and objects in the immediate surroundings

Definitions of Ambulation in Spinal Cord Injury Research

There is no consistent definition of walking recovery after spinal cord injury. The following definitions are used in the publications that discuss predictors for functional outcome of walking:

• Walking recovery is defined as "regained ability to walk independently in the community, with or without the use of devices and braces."
• Functional ambulation is defined as:
  • "The capacity to walk reasonable distances both in and out of home unassisted by another person."
  • "Independent mobility outside the home to access goods and services in the community.”

Four categories of functional ambulation in spinal cord injury and gait speed requirements:

1. Requires supervision to walk indoors and is wheelchair-dependent outdoors: a minimal speed requirement of 0.09 ± 0.01 m/s.
2. Can walk indoors but is wheelchair-dependent outdoors: a minimal speed requirement of 0.15 ± 0.08 m/s.
3. Requires a walking aid outdoors (“assisted walker”): a minimal speed requirement of 0.44 ± 0.14 m/s.
4. Walks without aid: a minimal speed requirement of 0.70 ± 0.13 m/s.

• Outdoor walking is defined "as the self-reported ability to walk more than 100 m outside using one cane, leg orthosis only, or no assistive devices."
  • The ability to manage curbs is considered a critical task for independent community ambulation

Predictors for Functional Outcome of Walking

Motor and Sensory Loss

• Moon et al. have found that hip flexors strength followed by knee extensors are the most important contributors to regain an independent walking in patients with incomplete SCI.
• A clinical prediction rule for ambulation outcomes after traumatic spinal cord injury includes motor scores of the quadriceps femoris (L3), gastrocsoleus (S1) muscles, and light touch sensation of dermatomes L3 and S1.
• The score greater than 33 for the motor scores of the quadriceps (L3), big toe extensors (L5), and the light touch sensory score (S1) indicate the likehood of the patient to regain outdoor walking ability one year after spinal cord injury.
• According to Cathomen and colleagues The motor score of the myotomes L2 and L3 allow us to differentiate between walkers and non-walkers. The motor score of myotomes L4-S1 are considered prognostic factors for indoor versus outdoor walkers (with and without aids).

Severity of the Lesion

The first examination of the patient with the SCI is performed using The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). It allows us to determine the neurological level of injury and the severity of the lesion. The ASIA Impairment Scale (AIS) A through D defines the complete and incomplete lesions.

Patients with the following levels of injury may or may not recover their walking ability:

• AIS A:
  • Achieving functional walking is very limited.
  • 14% of patients who converted to incomplete injury recovered some walking function.
  • Patients with spinal cord injury at the thoracic or lumbar levels (T12-L3) who regain some walking abilities will need the support of braces and devices to walk.
  • Gait is characterised by slow average velocities and great energy expenditure, which may not be functional for the patient.

• AIS B:
  • About 33% of patients will recover the ability to ambulate.
  • Pinprick preservation is a positive factor in walking recovery as compared with a light touch only (less extensive damage to the spinothalamic tracts and posterior column)

• AIS C:
  • About 75% of patient have a positive prognosis for walking recovery.
  • It affects patients converted to AIS D and patients with AIS C who achieve some walking function
  • Walking recovery affects mostly patients with low thoracic or lumbar lesions
  • Patients will be able to ambulate with braces and devices
  • Age is a strong prognostic factor. 80-90% of patients younger than 50 can walk functionally

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