Spinal Cord Trauma

Spinal Cord Trauma

The spine is a complex biomechanic and neural structure. The spine provides structural support for the body as the principal compo­nent of the axial skeleton, while protecting the passing spinal cord and nerve roots. Trauma may fracture bones or cause ligamentous disruption. Often bone and ligament damage occur together. Dam­age to these elements reduces the strength of the spine and may cause the spine to be unstable. This compromises both its structural support function and its ability to protect neural elements. Spine trauma may occur with or

without neurologic injury. Neurologic injury from spine trauma is classified as either incomplete. if there is some residual motor or sensory neurologic function below the level of the lesion, or complete, if there is no residual neurologic function below the level of the lesion, as assessed by clinical exam. A patient with complete neurologic dysfunction persisting 24 hours after injury has a very low probability of return of function in the involved area

Neurologic injury from spine trauma may occur immediately or in delayed fashion. Immediate neurologic injury may be due to direct damage to the spinal cord or nerve roots from penetrating injuries, especially from stab wounds or gunshots. Blunt trauma may transfer sufficient force to the spine to cause acute disruption of bone and ligament and lead to subluxation, which is shift of one vertebral element in relation to the adjacent level. Subluxation decreases the size of the spinal canal and neural foramina, and causes compression of the cord or roots. Such neural impingement can also result from propulsion of bone fragments into the canal during fracture. Transection, crush injury, and cord compression impairing perfusion are mechanisms leading to spinal cord injury. Delayed neurologic injury may occur during transportation or examination of a patient who is not properly immobilized.

The Mechanism of Spine Trauma

Trauma causes a wide variety of injury patterns in the spine due to its biomechanic complexity. A mechanistic approach facilitates an understanding of the patterns of injury, as there are only a few types of forces that can be applied to the spine. Although these forces are discussed individually, they often occur in combination. Several of the most common injury patterns are then presented to illustrate the clinical results of these forces and combinations of forces applied at pathologically high levels.

Flexion/Extension. Bending the head and body forward into a fetal position flexes the spine. Flexion loads the spine anteriorly (the vertebral bodies) and distracts the spine posteriorly (the spinous process and interspinous ligaments). High flexion forces occur dur­ing front-end motor vehicle collisions, and backward falls when the head strikes first. Arching the neck and back extends the spine. Ex­tension loads the spine posteriorly and distracts the spine anteriorly. High extension forces occur during rear-end motor vehicle colli­sions (especially if there is no headrest), frontward falls when the head strikes a first, or diving into shallow water.

Compression/Distraction. Force applied along the spinal axis (axial loading) compresses the spine , compression loads the
spine anteriorly and postenorly. High compression forces occur when a falling object strikes the bead or shoulders, or when landing on the feet, buttocks, or head after a fall from height. A pulling force in line with the spinal axis distracts the spine. Distraction unloads the spine anteriorly and posteriorly. Distraction forces occur during a hanging, when the chin or occiput strikes an object first during a fall, or when a passenger submanres under a loose seat belt during a front-end motor vehicle collision.

Rotation. Force applied tangential to the spinal axis rotates the spine. Rotation depends on the range of motion of intervertebral facet joints. High rotational forces occur during off-center impacts to the body or head or during glancing automobile accidents.

Patterns of Injury

Certain patterns of injury resulting from the forces described above or from combinations of those force occur commonly and should be recognized during plain film imaging of the spine. Always completely evaluate the spine. A patient with a spine injury at one level is at significant risk for additional injuries at other levels.

Cervical. The cervical spine is more mobile than the thora­
columbar spine. Stability comes primarily from the multiple ligamentous connections of adjacent vertebral levels. Disruption of the cervical ligaments can lead to instability in the absence of fracture. The mass of the head transmits significant forces to the cervical spine during abrupt acceleration or deceleration, increasing risk for injury.

Jefferson Fracture. Jefferson's fracture is a bursting fracture

of the ring of C1 (the atlas) due to compression forces. There are usually two or more fractures through the ring of C1. The open­ mouth odontoid view may show lateral dislocation of the lateral masses of C1. The rule of Spence states that 7 mm or greater com­bined dislocation indicates disruption of the transverse ligament. The transverse ligament stabilizes C1 with respect to C2. Jefferson fractures dislocated less than 7 mm are usually treated with a rigid collar, while those dislocated 7 mm or greater are usually treated with a halo vest. Surgical intervention is not indicated.

Odontoid Fractures. The odontoid process. or dens. is the large
ellipse of bone arising anteriorly from C2 (the axis) and project­ ing up through the ring of C1 (the atlas). Several strong ligaments connect the odontoid to C1 and to the base of the skull. Odontoid fractures usually result from flexion forces. Odontoid fractures are classified as type I, I1, or111. A type I fracture involves the tip only

A type2 fracture passes through the base of the odontoid process. A type 3 fracture passes through the body of C2. Types I and 2 are considered unstable and should be externally immobilized by a halo vest or fused surgically. Surgery is often undertaken for widely displaced fractures (poor chance of fusing) and for those that fail ex­ternal immobilization. Type 3 fractures usually fuse with external immobilization only.

Hangman's Fracture. Traditionally considered a hyperextension/distraction injury from placement of the noose under the angle of the jaw. hangman's fractures may also occur with hyperexten­sion/compression, as with diving accidents, or hyperflexion. it is def­ inition is bilateral C2 pars Interarticularis fracture. The pars interar­ticularis is the bone between superior and infenor facet joints. The bony connection between Cl and C3 is lost. Hangman's fractures heal well with external immobilizauon Surgery is indicated If there is spinal cord compression or after failure of external immobiliza­tion

Jumptd Facets-Hyperflexion Injury. The facet joints of the cervical spine slope forward, and the facet from the level above can slide up and forward over the facet from the level below if the joint capsule is torn. Hyperflexion/rotation can cause a unilateral jumped facet. whereas straight hyperflexion leads to bilateral jumped facets. Patients with a unilateral injury are usually neurologically intact, while those with bilateral injury usually have spinal cord damage. The anteroposterior diameter of the spinal canal decreases more with bilateral injury, leading to spinal cord compression.

Thoracolumbar. The thoracic spine is significantly stabi­lized by the rib cage. The lumbar spine bas comparatively very large vertebrae. Thus the thoracolumbar spine has a higher thresh­ old for injury than the cervical spine. The three-column model is useful for categorizing thoracolumbar injuries. The anterior longitu­dinal ligament and the anterior half of the vertebral body constitute the anterior column. The posterior half of the vertebral body and the posterior longitudinal ligament constitute the middle column. The pedicles, facet joints, laminae, spinous processes, and inter­ spinous ligaments constitute the posterior column.

Compression Fracture. This is a compression flexion injury

causing failure of the anterior column only. it is stable and not as­sociated with neurologic deficit. although the patient may still have significant pain.

Burst Fracture. This is a pure axial compression injury causing failure of the anterior and middle columns. It is unstable. and perhaps half of patients have neurologic deficit due to compression of the cord or cauda equina from bone fragments retropulsed into the spinal canal.

Chance Fracture. This is a flexion-distraction injury causing

failure of the middle and posterior columns. It is typically unstable and is often associated with neurologic deficit.

Fracture-Dislocation. This is failure of the anterior, middle

and posterior columns caused by flexion/distraction, shear, or com­pression forces. Neurologic deficit can result from retropulsion of middle column bone fragments into the spinal canal or from sub­luxation causing decreased canal diameter 

Initial Assessment and Management

The possibility of a spine injury must be considered in all trauma patients. A patient with no symptoms referable to neurologic injury. a normal neurologic exam. no neck or back pain. and a known mechanism of injury unlikely to cause spine injury is at minimal risk for significant injury to the spine. Victims of moderate or severe trauma. especially those with Injuries to other organ systems. usually fail to meet these criteria or cannot be assessed adequately. The latter is often due to impaired sensorium or significant pain. Because of the potentially catastrophic consequences of missing occult spine instability in a neurologically intact patient. a high level of clinical suspicion should govern patient care until completion of clinical and radiographic evaluation.

The trauma patient should be kept on a hard flat board with straps and pads used for Immobilization. A hard cervical collar is kept in place. These steps minimize forces transferred through the spine, and therefore decrease the chance of causing dislocation, subluxation, or neural compression during transport to the trauma bay. The patient is then moved from the board to a Hatstretcher. The primary survey and resuscitation are completed
Physical exam and initial x-rays follow, For the exam, approach the patient as described in the section on . Evaluating for spine or spinal cord mjury is easier and more informative

patients. If the patient is awake, ask if he or she recalls details of the nature of the trauma, and if there was loss of consciousness, numb­ness, or inability to move any or all limbs. Assess motor function by response to commands or pain, as appropriate. Assess pin prick, light touch., and joint position if possible. Determining the anatom­ically lowest level of intact sensation can pinpoint the level of the lesion along the spine. Test sensation in an ascending fashion, as the patient will be better able to note when he or she first feels the stimulus, rather than when he or she can no longer feel it. Docu­ment muscle stretch reflexes. lower sacral reflexes (i.e  anal wink

American Spinal Injury Association CIassification. The American Spinal Injury Association (ASIA) provides a method of classifying patients with spine injuries. The classification in­ dicates completeness and level of the injury and the associated
deficit.  should be avail­able in the trauma bay and completed for any spine injury patient. The association also has worked to develop recommendations and guidelines to standardize the care of SCI patients in an effort to improve the quality of care

Neurologic Syndromes

Penetrating, compressive. or ischemic cord injury) can lead to several characteristic presentations based on the anatomy of injury The neurologic deficits may be deduced from the anatomy of the long sensory and motor tracts and understanding of their decussa­tions . Four patterns are discussed. First, injury to the entire cord at a given level results in anatomic or functional cord transection with total loss of motor and sensory function below the level of the lesion. The typical mechanism is severe traumatic ver­tebral subluxation reducing spinal canal diameter and crushing the cord. Second, injury to half the cord at a given level results in Brown­ Sequard syndrome. with loss of motor control and proprioception ipsilaterally. and loss of nociception and thermoception contralater­ally. The typical mechanism is a Slab or gunshot wound. Third, in­jury to the interior of the cord results in central cord syndrome, with upper extremity worse than lower extremity weakness  and varying degrees of numbness. The typical mechanism is transient compres­sion of the cervical cord by the ligamentum flavum buckling in posteriorly during traumatic neck hyperextension. This syndrome occurs in patients With preexisting cervical stenosis. Fourth, injury to the ventral half of the cord results in anterior cord syndrome, with paralysis and loss of nociception and thermoception bilaterally. The typical mechanism is acute disc herniation or ischemia from anterior spinal artery occlusion

Studies and invsitagation 

Anteroposterior (AP) and lateral plain films provide a rapid sur­vey of the bony spine. Plain film' detect fractures and dislocations well. Adequate visualizauon of the lower cervical and upper thoracic spine is often impossible because of the
plain film imaging of the cervical spine includes an open-mouth odontoid view to assess the odontoid and the lateral masses of Cl Fine-slice cr scan with sagittal and coronal reconstructions provides good detail of bone anatomy, and is good for characterizing fractures seen on plain films, as well as visualizing C7- Tl when not well seen on plain films. MRI provides the best soft tissue imaging. Canal compromise from subluxation, acute disc herniations. or lig­amentous disruption is clearly seen. MRI also may detect damage to the spinal cord itself. including contusions or areas of ischemia.

Definitive Management

Spinal-Dose Steroids. The National Acute Spinal Cord In­jury Study (NASCIS)  provide the basis for the common practice of administering high-dose steroids to patients
with acute spinal cord injury. A 30-mglkg IV bolus of methylpred­nisolone is given over 15 minutes, followed by a 5.4-mglkg per hour infusion begun 45 minutes later. The infusion is continued for 23 hours if the bolus is given within 3 hours of injury, or for 47 hours if the bolus is given within 8 hours of injury. The papers in­dicate greater motor and sensory recovery at 6 weeks, 6 months. and 1 year after acute spinal cord injury in patients who received metbylprednisolone. However. the NASClS trial data have been extensively criticized, as many argue that the selection criteria and study design were flawed, making the results ambiguous Patients
who receive such a large corticosteroid dose have increased rates of medical and lCU complications. such as pneumonias, which have a deleterious affect on outcome. A clear consensus on the use of spinal-dose steroids does not exist,  A decision to use or not use spinal-dose steroids may be dictated by local or regional practice patterns, especially given the legal liability issues surround­ing spinal cord injury. Patients with gunshot injuries or nerve root (cauda equina) injury. as well as those on chronic steroid therapy, who are pregnant, or who are less than 14 years old were ex­cluded from the NASClS studies. and should not receive spinal-dose steroids.

Orthotic Devices. Rigid external orthotic devices can stabi­lize the spine by decreasing range of motion and minimizing stress transmitted through the spine. Commonly used rigid cervical ­ orthotics include Philadelphia and Miami-J collars. Cervical collars are inadequate for Cl, C2, or cervicothoracic instability. Cervicotho­racic orthoses (CTOs) brace the upper thorax and the neck, improv­ing stabilization over the cervicothoracic region. Minerva braces improve high cervical stabilization by bracing from the upper tho­rax to the chin and occiput. Halo-vest assemblies provide the most external cervical stabilization. Four pins driven into the skull lock the halo ring in position .Four posts arising from a tight-fitting rigid plastic vest immobilize the halo ring. Lumbar stabilization may be provided by thoracolumbosacral orthoses (TLSOs). A variety of companies manufacture lines of spinal orthotics. A physician familiar with the technique should fit a halo-vest, Assistance from atrained orthotics technician improves fitting and adjustment of the other devices.

Surgery. Neurosurgical intervention has two goals. First is the decompression of the spinal cord or nerve roots in patients with incomplete neurologic deficits. These patients should be decom­ pressed expeditiously. especially if there is evidence of neurologic deterioration over time. Second is the stabilization of injuries judged too unstable to heal with external orthotics only. Spine trauma patients with complete neurologic deficit. without any signs of re­covery. or those without any neurologic deficits who have bony or ligamentous injury requiring open fixation. may be medically sta­bilized before undergoing surgery. Surgical stabilization may be indicated for some injuries that would eventually heal with conser­vative treatment, Surgical stabilization can allow early mobilization. aggressive nursing care. and physical therapy. Solid surgical stabi­lization may also allow a patient to be managed with a rigid cervical
collar who would otherwise require halo-vest immobilization

Continued Care

Regional spinal cord injury centers with nurses. respiratory ther­apists. pulmonologists. pbysical therapists. physiatrists, and neu­rosurgeons specifically trained in caring for these patients may improve outcomes. Frequently encountered ICU issues include hy­potension and aspiration pneumonia. Chronically. prevention and treatment of deep venous thrombosis.autonomic hyperreflexia, and decubitus ulcer formation are important. Patients with high cervical cord injuries (C4 or above) will often be terminally ventilator de­pendent. Many patients with cervical or high thoracic cord injuries require prolonged ventilatory support until the chest wall becomes stiff enough to provide resistance for diaphragmatic breathing. Pa­tients should be transferred to spinal cord injury rehabilitation cen­ters after stabilization of medical and surgical issues.


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