(A Learning Manual for LU IV Students)
Adrian B. Catbagan, M.D.
Department of Orthopedics
College of Medicine
University of the Philippines – Manila
Background
Injuries to the spinal column and spinal cord is one of the most devastating injuries that can happen to an individual. It commonly affects young persons in the most productive age group, those 15-45 years old. It is a significant cause of long-term disability along with the enormous cost of medical care of patients with spinal injuries. It is thus important to recognize and treat these injuries appropriately to minimize disabilities and optimize the functional recovery of these patients.
Review of Anatomy
The spinal column is divided into 5 regions namely the cervical, thoracic, lumbar, sacral and coccygeal segments. The cervical and thoracolumbar regions are the most susceptible to injuries; the cervical region because it is the most mobile segment and the thoracolumbar region because it is a zone of transition between the rigid thoracic spine and the mobile lumbar spine.
The length of the spinal cord is not equal to length of the bony spinal column due to growth differential from birth to adulthood. As such, the spinal cord ends at L1-L2 in the adult and the cauda equina occupies the rest of the spinal canal from L2 to the sacrum. This has implications on the type of neural injuries sustained at each level and the prognosis for neural recovery.
Spinal Injuries
Unlike fractures of extremities, neurologic involvement is the rule rather than the exception. They are often due to vehicular accidents, falls, slips, diving, or penetrating injuries. Because certain neural elements do not regenerate, neurologic recovery is limited or not possible in some instances.
Patient Evaluation
In evaluating patients with a suspected spinal injury, it is important for focus on the associated injuries that are immediately life-threatening. Ensure that the airway is patent, breathing is not impaired and circulation is adequate (ABCs). Treat ABC’s as if no spinal injury was present. Look for concomitant head, thoracic, abdominal or extremity injuries that would require immediate attention.
Having stabilized the patient medically, and having ruled out serious injuries to the other organ systems, the spine needs to be immobilized properly prior to transport. Inadequate immobilization and faulty transport is a common cause of worsening of the initial spinal injury. A makeshift collar or a rigid board can be utilized if a cervical collar or a spine board is not readily available. If the neck or back is in an awkward position, an attempt to straighten it is not recommended.
An abbreviated history taking and rapid physical examination is necessary at the accident site or on initial evaluation at the emergency room. Things to ask and look for are: mechanism of injury, inability to move the limbs, loss of sensation, and associated head injury.
Mechanisms of Injury
The mechanism of injury refers to the manner by which the injury was sustained. There are 3 basic mechanisms, namely flexion, hyperextension and axial loading. A flexion type of injury is incurred when the head or trunk is rapidly bent forwards as in a head-on collision. A vertebral body compression fracture is often produced or in worse cases, a forward displacement of the vertebral body ensues as the anterior force propagates forwards.
A hyperextension injury, on the other hand, is the opposite of a flexion mechanism. The head is thrown backwards and the neck gets hyperextended as in a rear-end collision. It is often referred to as a “whiplash” injury. The posterior structures, like the spinous processes or laminae get fractured or in worse cases, the vertebral body gets displaced posteriorly.
An axial loading injury is sustained when the force is transmitted along the long axis of the spine, as in a diving accident or when a heavy weight falls on the head. Minor injuries result in uncomplicated burst fractures but in more serious injuries, the fracture fragments can get displaced posteriorly into the spinal canal and cause cord compression.
Physical Examination
Once the patient has been medically stabilized and the spine has been immobilized, a thorough physical and neurologic examination is mandatory. Check the dermatomes, test the motor strength and autonomics to determine the spinal level of the injury. It is also important to determine whether the patient is still in spinal shock and whether the neurologic injury is complete on incomplete, for purposes of treatment and prognostication.
Radiologic Assessment
X-rays and other imaging studies to be requested depends on the neurologic level of the injury. For suspected cervical fractures, AP, lateral and open-mouth views should be performed. For thoracic, lumbar and sacral fractures, AP and lateral views would be sufficient.
The CT scan can show fractures missed by x-rays and will also provide a better definition of the fracture with sagittal, coronal and 3-D reconstructed images. If details on the nature and extent of spinal cord injury needs to be visualized, an MRI would be the best imaging modality.
Treatment Principles
Management of spinal injuries include spinal realignment, spinal stabilization and neurologic decompression. The aim is to restore neurologic function and structural integrity of the spine.
Spinal realignment may be achieved by traction or surgery, in case traction is unsuccessful. Stabilization can be obtained by the use of external devices such as a brace or a halo vest or with surgery by inserting metal implants like screws and plates. Decompression can be attained by surgically removing bony or disc material impinging on the spinal cord. One or more of these procedures may be necessary to achieve the goal of restoring neurologic function, spinal alignment, and spinal stability.
Neural Recovery
Recovery of neurologic function is dependent on two factors: reversal or arrest of the secondary injury mechanisms and removal of the mechanical compression on the cord. The secondary injury is pathophysiologic in nature and includes cord ischemia, edema, cellular membrane destabilization, lipid peroxidation, etc. This can be remedied with administration of high-dose steroids, though this remains controversial, and other pharmacologic agents which are still in the experimental stage.
The primary tissue damage is caused by mechanical compression by displaced bone or disc material and needs to be removed by surgical methods. In some instances, the mechanical compression can be relieved non-surgically by realigning the spinal column through traction thereby restoring normal canal diameters.