Upon completion of this chapter, the learner should be able to:
Summarize the anatomy and physiology of typical causes of complete paralysis.
List and describe the related pathologies that often accompany complete paralysis.
Describe compensatory movement strategies and therapeutic techniques used with individuals with complete paralysis.
Describe typical interventions used with individuals with complete paralysis and apply them to a case.
Summarize special considerations for interventions used with individuals with complete paralysis.
This chapter focuses on interventions that address complete paralysis of a specific muscle, muscle group, or body region. This condition is most commonly the result of damage to the corticospinal system, the portion of the nervous system carrying voluntary motor commands from the motor cortex to the neurons innervating the skeletal muscles of the limbs and trunk. In this chapter, complete paralysis refers to a total and permanent loss of voluntary motor function in at least one region of the body. This loss most frequently results from interruption of motor commands to the extremities and trunk, as occurs globally with a complete spinal cord injury (SCI) or, in some cases, in more specific regions after an incomplete SCI. Complete paralysis of an individual muscle or small groups of muscles can also result from a nerve root or peripheral nerve injury, depending on the severity of injury.
Damage to the corticospinal system can be attributed to many pathologies, including trauma, infection, compression, and ischemia. The most common example, as illustrated throughout this chapter, is damage to the corticospinal system from an SCI. An SCI can occur in a variety of traumatic and nontraumatic ways. Common traumatic causes are motor vehicle crashes, falls, violence, and sports accidents (National Spinal Cord Injury Statistical Center [NSCISC], 2017). Common nontraumatic causes include spinal stenosis and neoplasm (McKinley, 1999b, NSCISC 2016).
In a normally functioning nervous system, motor control is achieved with a complex interplay between central and peripheral structures. In the corticospinal system, motor commands travel in tracts descending from the cerebral cortex through the midbrain, pons, medulla, and spinal cord to synapse in the cord directly on both alpha motor neurons and interneurons (Fix, 2005). The interneurons in turn synapse with alpha motor neurons at the same level of the cord, at nearby levels, and at distant levels (Haines, 2007; Lundy-Ekman, 2007). The axons of the alpha motor neurons exit the spinal cord and travel peripherally through the spinal nerves, often through plexuses, then through named peripheral nerves to the skeletal muscles (Crossman, 2000). Each alpha motor neuron innervates a number of fibers, called a motor unit, within a single muscle (Kiernan, 2005). Alpha motor neurons are the “final common pathway” for motor behavior; all voluntary and involuntary motor commands to skeletal muscles travel through these neurons (Kandel, 2000).