Spinal and Neurogenic Shock

Spinal and neurogenic shock  Transient loss of spinal cord function can occur following spinal column injury  Clinicians must assume that hypotension following trauma results from hemorrhage  Neurogenic shock from spinal cord injury may cause hypotension and bradycardia o Use of pressors may be necessary to stabilize blood pressure o Use of atropine or pacing may be necessary to stabilize heart rate

Secondary survey  Carefully inspect the patient's entire body, beginning with the head  Palpate entire spine and paraspinal musculature for areas of tenderness or deformity  A step-off in the spine may indicate vertebral subluxation or fracture  Widening of an interspinous space indicates a tear in the posterior ligament complex and a potentially unstable spinal injury (this finding may be difficult to appreciate)  A focused but systematic neurologic evaluation should be performed in all patients o Assess the presence and symmetry of both voluntary and involuntary movements o Priapism may occur with severe spinal cord injury o An abnormal breathing pattern may indicate a cervical injury (diaphragm innervated by the phrenic nerve) o Attention should be paid to the symmetry of peripheral strength, sensation, reflexes, and proprioception o Any sensory deficits, including the dermatome where they occur, should be noted o Bowel or bladder incontinence is an important finding

Clinical decision rules for obtaining radiographs — Both the NEXUS Low-risk Criteria and the Canadian C-spine rule are well validated and sensitive, and either can be used to determine the need for cervical spine imaging.

NEXUS — The first decision rule to be developed was the NEXUS Low-risk Criteria (NLC), which was prospectively validated in a large, multicenter, observational study. The NLC decision instrument stipulates that radiography is not necessary if patients satisfy ALL five of the following low- risk criteria:  Absence of posterior midline cervical tenderness  Normal level of alertness  No evidence of intoxication  No abnormal neurologic findings  No painful distracting injuries Altered level of consciousness is defined in the NLC as follows:

 Glasgow coma scale score below 15

 Disorientation to person, place, time, or events

 Inability to remember three objects at five minutes

 Delayed or inappropriate response to external stimuli A brief, transient loss of consciousness at the time of a motor vehicle collision does not preclude the application of the NLC, assuming the patient meets all other criteria.

Canadian C-spine rule — Due to the low specificity of NEXUS Low-risk Criteria (12.9 percent), some researchers expressed concern that use of these criteria might increase the use of radiography in some regions of the United State (US) and in the majority of countries outside of the US. These researchers subsequently developed the Canadian C-spine rule (CCR), based upon three clinical questions derived from 25 clinical variables associated with spine injury. The CCR involves the following steps:  Condition One: Perform radiography in patients with any of the following:  Age 65 years or older  Dangerous mechanism of injury: fall from 1 m (3 ft) or five stairs; axial load to the head, such as diving accident; motor vehicle crash at high speed (>100 km/hour [>62 mph]); motorized recreational vehicle accident; ejection from a vehicle; bicycle collision with an immovable object, such as tree or parked car  Paresthesias in the extremities  Condition Two: In patients with none of the high risk characteristics listed in Condition One above, assess for any low-risk factor that allows for safe assessment of neck range of motion. The low-risk factors are as follows:  Simple rear end motor vehicle accident; excludes: pushed into oncoming traffic; hit by bus or large truck; rollover; hit by high speed (>100 km/hour [>62 mph]) vehicle  Sitting position in emergency department  Ambulatory at any time  Delayed onset of neck pain  Absence of midline cervical spine tenderness Patients who do not exhibit any of the low-risk factors listed here are NOT suitable for range of motion testing and must be assessed with radiographs. If a patient does exhibit any of the low-risk factors, perform range of motion testing, as described in Condition Three below.  Condition Three: Test active range of motion. Perform radiography in patients who are not able to rotate their neck actively 45 degrees both left and right. Patients able to rotate their neck, regardless of pain, do not require imaging. In the derivation study, the CCR demonstrated a sensitivity of 100 percent and a specificity of 42.5 percent for identifying clinically important cervical spine injuries

NEXUS versus Canadian C-spine rule — Both the NEXUS Low-risk Criteria and the Canadian C-spine rule are well validated and sensitive, and either can be used to determine the need for cervical spine imaging. Nevertheless, controversy persists about which of the two rules is more specific and more useful.

Plain x-rays versus CT  It is reasonable to use plain radiographs to assess for cervical spinal column injury in patients without a severe mechanism of injury or neurologic abnormalities, in whom adequate x-rays are likely to be obtainable, and in whom CT imaging for other potential injuries is not planned  Routine cervical spine radiographs for trauma must include anterior-posterior (AP), lateral, and odontoid (ie, open- mouth) views at a minimum  Adequate views are essential  Depending upon the patient population, up to 72 percent of plain films may be inadequate to visualize the complete cervical spine, necessitating performance of a CT

 Once a CT is performed, plain radiographs add no further clinically relevant information and should not be obtained

 The C7 vertebra may be obscured in muscular or obese patients, as well as patients with spinal lesions that cause paralysis of the muscles that depress the shoulders o The shoulders can be lowered by pulling the patient's hands toward their feet, using slow steady traction

 A CT scan is obtained if visualization of the cervical spine remains inadequate despite these additional maneuvers and views

Interpretation of plain radiographs  If plain radiographs are used to assess the cervical spine, the clinician must be certain that the views obtained are adequate and systematically examined  On the lateral view, the entire cervical spine, from the base of the occiput to the top of the first thoracic vertebra must be clearly visible  On the odontoid view, the dens and both lateral masses must be clearly visible  Inadequate views are not acceptable  Once adequate views are obtained, examine each for alignment of the vertebrae; appearance, position, and spacing between vertebrae; and appearance of the soft tissues  ABC’s method for interpreting the three major views (lateral, odontoid, and anterior-posterior)