Pediatric Spinal Cord and Spinal Column Trauma
Author: Doug Brockmeyer, MD
Injuries to the pediatric spinal column and spinal cord have received increasing attention over the last two decades. Much has been learned in that period of time, but our knowledge about the fundamental differences between pediatric and adult spinal column and spinal cord injuries remains incomplete. Nevertheless, this brief primer will attempt to outline some of the important principles concerning pediatric spinal column and spinal cord injury, as well as describe different types of treatment and rehabilitation. As part of this discussion, measures which can be taken to prevent pediatric spinal column and spinal cord injury will also be discussed.
Although less frequently encountered than spinal trauma in other age groups, pediatric spinal injuries are not rare. The overall incidence of pediatric spine trauma within the overall population of spinal injuries varies between 1% and 11%, depending on the study examined. This variability presumably is dependent upon the volume of spinal trauma at a given medical center and different referral patterns between trauma systems. A reasonable estimate at most major pediatric trauma centers is that 5% of spinal column and spinal cord injuries will occur in the age group between 0 and 16 years of age.
Males more frequently sustained spinal column and spinal cord injuries than females. This fact, however, is influenced by an increased likelihood of vertebral column injury in the "more active" adolescent males in the 10 to 16 year old age group. Some studies have reported a higher incidence of spinal cord and spinal column injuries in females in the 0 to 5 year old age group.
All of these figures, however, must be looked at with some skepticism. Differences between referral patterns, injury grading and treatment and outcome measures between physicians all mask the true incidence and severity of pediatric spinal cord and spinal column injury. The lack of a standardized nationwide database for these injuries has hampered our understanding of this disease process. Until strict guidelines and a national database are established, a complete understanding of injury patterns and injury types will be impossible.
Anatomy and Biomechanical Considerations
There are significant anatomical and biomechanical differences between the pediatric spine and its adult counterpart. Many of the anatomical differences explain the different injury patterns seen in various age groups. The infant spine, defined as that between 0 and 2 years of age, has tremendous mobility and elasticity due to underdevelopment of the neck muscles, incompletely calcified, wedge-shaped vertebrae, and shallow, horizontally oriented spine (facet) joints. In addition to these features, the relatively large size of the head with respect to the torso in young patients, increases the likelihood of cervical spine injuries, especially between the skull and first cervical vertebrae.
The anatomical differences described develop a more mature configuration over time. Between the ages of 2 and 10, tremendous changes occur in the spinal column. Muscles and ligaments strengthen, bones grow and reach a mature shape and size, and areas of cartilage and soft bone are replaced with normal calcified bone. In addition, the body habitus changes so that the head is smaller in proportion to the torso. These changes shift the focus of injury from the upper cervical spine (skull-C1-C2) to the lower cervical spine (C5-C6). It appears that the age related maturation that occurs in the upper pediatric cervical spine is usually completed by approximately age 10 and the maturation of the lower cervical spine occurs by approximately age 14.
The elasticity of the pediatric spinal column probably allows some protection against spinal cord trauma that might cause fracture in older patients. This mobility and elasticity in the infant spine explains the relatively low incidence of spinal column injuries and the proportionately high incidence of spinal cord injuries without radiographic abnormalities (discussed later). In essence, the young spine will stretch, but not break, but this places the spinal cord at increased risk for stretching and disruptive injuries.
Mechanisms of Injury
Numerous mechanisms responsible for the patterns of pediatric spinal cord and spinal column injury have been described. Flexion, extension, rotation, axial (top), loading and distraction (pulling) have all been implicated. Lack of blood flow to the spinal cord either by compression or disruption has also been documented. Compression of the spinal cord from blood clots, fractured bones, bending or buckling of ligaments, and angulation of the spinal column have all been described. It is also possible that underlying diseases that the patient is either born with or develops may also contribute to the risk of spinal cord injury. These problems include, but are not limited to, os odontoideum, Down's syndrome, Chiari malformations, congenital bone abnormalities, rheumatoid arthritis, ankylosing spondylitis, and other underlying infections or tumors may all play a part in the predisposition to spinal column or spinal cord injury.
The actual type of injury responsible for the mechanism varies according to the age of the patient. The youngest age group patients (0 to 10 years) have a high incidence of falls and pedestrian/automobile accidents, while their older counterparts have a higher incidence of motor vehicle accidents, motorcycle accidents and sports related injuries. Obviously, these observations are overgeneralized, but the different reasons responsible for pediatric spinal cord and spinal column injuries according to age do hold true in large studies.
Prevention of Pediatric Spinal Cord and Spinal Column Injury
Needless to say, once a spinal cord or spinal column injury occurs in a child, preventive measures are a moot point. The affected parents are then left wondering what preventive measures could have been taken in order to avoid the injury. Fortunately, there are several organizations, both at local and national levels, that are directed toward the prevention of spinal cord and spinal column injuries in the pediatric age group. One example of such an organization is ThinkFirst for Kids, a non-profit organization organized by national neurosurgical organizations. This and other programs offer school-based instruction on preventative behaviors that ultimately lead to the decreased risk of head and spinal cord injuries. The key feature of these programs is reaching children when they are in grade school and delivering the message while they are still developing their behavior patterns. Research suggests that these behavior patterns are maintained through the adolescent years when the children are at greatest risk. Only through comprehensive and systematic prevention programs will the incidence of tragic spinal cord injuries decrease. The medical community extends its wholehearted support to these programs and the work behind these significant and sometimes tragic injuries.