After reading this chapter, the reader will be able to:
Describe what is meant by the term locomotor central pattern generator
Describe how a therapist might make optimal use of sensory information for promoting locomotor function
Discuss placement of stimulating electrodes for use in eliciting a flexion withdrawal response
List the advantages and disadvantages of each of the three forms of assisted stepping
Describe currently available neuroprosthetic systems for assisted stepping
Describe the mechanism by which epidural stimulation is thought to promote improved locomotor function
The inability to walk is among the most apparent deficits that face an individual after spinal cord injury (SCI). For this reason, it is not surprising that "Will I be able to walk again?" is one of the first questions that an individual asks the physical therapist. Since the 1980s, developments in our understanding of the neural control of locomotion have brought renewed interest to the area of locomotor training after SCI. These developments represent an exciting new focus, as these are among the first rehabilitation techniques to grow out of work that began in the basic science laboratories. This work provides a physiological basis for training to restore and enhance walking recovery after SCI using the intrinsic mechanisms of the central nervous system (CNS), and it has challenged our assumptions concerning the potential for recovery. This focus is in contrast to conventional gait training, which is both currently and historically based on compensation for deficits of paralysis, weakness, balance, and coordination. Braces, assistive devices, and instruction in new strategies (e.g., loading upper extremities for weight bearing, knee extension via a brace) make up traditional rehabilitation practice to compensate for irremediable deficits and achieve bipedal mobility.1 Severity and level of injury, the degree of voluntary motor control (e.g., manual muscle test scores), and sensory preservation are used to predict ambulatory potential.2,3,4,5,6 Impairment-targeted training for strength and endurance in voluntarily activated muscles and requisite joint range of motion are also emphasized.1,7
Walking consists of three essential elements: (1) reciprocal stepping, (2) maintaining equilibrium during propulsion, and (3) adapting to the individual's own behavioral goals and environmental terrain and obstacles.8,9 In this chapter, we will review the key basic science research that has contributed to our understanding of the control of locomotion. The application of this information to humans with SCI, recommendations related to optimizing training, and advantages and disadvantages of the various techniques for restoration of locomotor function will be discussed. Training to restore locomotor function using a body weight support (BWS) system and a treadmill, spinal cord stimulation, and locomotor prostheses will also be discussed. Furthermore, a model for the control of walking will be introduced to frame current developments and serve as a guide for assessing future strategies.
Spinal Cord Contributions to Control of Locomotor ...