Chapter 28: Rehabilitation Medicine

INTRODUCTION

Rehabilitation medicine is the multispecialty discipline involved in diagnosis and therapy of individuals with congenital and acquired disabilities. The goals of rehabilitation medicine are to maximize functional capabilities and improve quality of life. Disabilities are described using the World Health Organization’s International Classification of Function, Health, and Disability. Three aspects are evaluated in every patient: (1) the impact of the disability on body structure and function, (2) the impact of the disability on activity and participation in society, and (3) the environmental factors with an impact on the individual’s function. These three areas are the common framework for discussion of a disabling condition and its therapy.

PEDIATRIC BRAIN INJURY

Various estimates indicate that there are up to 500,000 pediatric traumatic brain injuries in the United States every year, resulting in 37,000–50,000 hospitalizations. Mortality rates vary significantly by region (relative risk 1.19–4.2 nationally), but, overall, pediatric brain injuries result in 2000–3000 deaths annually. The cost of these injuries is significant, particularly when also considering that survivors of pediatric brain injury may have long-term deficits with lifetime needs.

Pathogenesis

Brain injury is classically divided into two categories based on the timing of the pathologic findings: primary and secondary injury.

Primary injury occurs at the time of trauma, causing focal and diffuse mechanical damage to both the neurons and glia as well as the vasculature and is typically irreversible. Focal damage includes skull fracture, parenchymal bruising or contusion, extraparenchymal or intraparenchymal hemorrhage, blood clots, tearing of blood vessels, or penetrating injury. Diffuse damage includes diffuse axonal injury and edema. Consequences of primary injury, either focal or diffuse, include cellular disruption with release of excitatory amino acids, opiate peptides, and inflammatory cytokines.

Secondary injury is the loss of cellular function accompanying primary injury that results in loss of cerebrovascular regulation, altered cellular homeostasis, or cell death and functional dysregulation. Mitochondrial dysfunction due to dysregulation of Ca++ and other cations and anions leads to depletion of ATP to drive homeostatic cellular pumps. This leads to oxidation of cellular DNA, protein and lipids causing among other things cell death. These multiple mechanisms can also lead to increased extracellular glutamate resulting in excess depolarization further stressing compromised cells. A primary injury can initiate the processes of secondary programmed cell death (apoptosis), which further exacerbates the primary injury. Secondary injury may develop hours or days after the initial insult. It appears to be precipitated by elevated intracranial pressure, cerebral edema, and release of neurochemical mediators. Current treatment paradigms are focused on treating and preventing secondary injury.

Clinical Findings

Classification & Assessment of Injury Severity