Civilian gunshot wounds have reached epidemic proportions in the United States.

Every year, approximately 100,000 Americans are victims of gun violence, a rate far greater than any other industrialized nation. Gunshot wounds to the spine (GSWS) now represent the second most common cause of spinal cord injury (SCI) in most metropolitan areas. Of the 11,000 new cases of spinal cord injury that occur each year, approximately 1,200 (11%) are due to GSWS. This dramatic rise in GSWS in urban areas can be attributed primarily to gang- and drug-related violence.

Gunshot wounds to the thoracic region are the most common, followed by the thoracolumbar and cervical regions. Of these gunshot wounds, the majority do not cause spinal cord injury; however, spinal cord injuries that do result are more likely to cause complete sensorimotor paralysis compared to blunt spinal trauma.

The treatment of patients with spinal cord injuries from gunshot wounds represents a significant medical and economic challenge. Compared to nonviolent injuries, spinal cord injuries from gunshot wounds are more likely to be complete injuries, the victims are younger, and they are less likely to be employed or have health insurance to help cover the estimated $1.5 to $4.5 million in lifetime medical expenses.

The amount of tissue damage caused by a GSW is proportional to the amount of energy transferred from the bullet on impact. The amount of bullet energy transferred to impacted tissues increases exponentially with the velocity at which the projectile is travelling. Understanding the injury patterns caused by weapons with different muzzle velocities are important for treating patients who have suffered gunshot wounds. Most civilian firearms, typically pistols and handguns, have muzzle velocities of less than 350 m/s (2,000 ft/s) and are considered “low energy.” Military assault rifles and hunting rifles have muzzle velocities greater than 600 m/s and are considered “high energy.” Shotguns are low-velocity, high-energy firearms due to the combined mass of the pellets. The closer the range of a gunshot, the less energy will be lost during transit; thus, more energy will be transferred to the victim in close-range shootings. With higher-energy GSWs, there tends to be a larger radius of injury, leading to more devitalized tissue around the bullet tract.

In addition to velocity, the wounding potential of a bullet depends on its composition, design, and size. Bullets may be jacketed with a thin layer of copper, brass, or nickel. Fully jacketed bullets exhibit little deformation with firing and are designed for accuracy to hit long-range targets. Bullet fragmentation occurs on impact with hollow-point, nonjacketed, or partially jacketed bullets resulting in multiple fragment trajectories which exponentially extends the circumference of tissue damage. Additionally, the jacketing metal may result in delayed local and systemic toxicities.

Spinal cord injury from GSWS may be due to direct injury (transection/laceration/contusion), indirect injury from a concussive/blast effect, and/or vascular injury resulting in spinal cord ischemia. Additionally, secondary hematoma formation and mass effect from bullet or bone fragments can lead to ongoing spinal cord compression and secondary injury. Gunshot injuries that occur in the civilian population are typically from low-velocity handguns; however, with increasing frequency, urban centers are identifying and treating more high-velocity injuries from military-grade assault weapons. The pattern of the SCI differs based on the velocity of the projectile. High-velocity bullets may produce SCI by a concussive effect of the bullet passing in close proximity but not through the spinal canal. These types of injuries carry a slightly better prognosis than SCI from low-velocity
civilian weapons where neurologic injury is more commonly due to direct trauma to the cord. This phenomenon may explain the large percentage of civilian gunshot wounds that present with complete cord injuries.

The initial treatment of GSW victims prioritizes the maintenance of airway, breathing, and circulation, above all else. The airway should be evaluated and secured and hemodynamic stability assessed. The incidence of associated visceral injuries may be as high as 25%. Early identification of these injuries including pneumothorax, airway, or vascular injury is critical as their treatment takes priority over any associated spinal column or spinal cord injury. Initial management of a patient with a GSWS may be complicated by hypotension due to acute blood loss or neurogenic shock from loss of sympathetic vasomotor tone, or both. In the acute setting, differentiating between neurogenic and hypovolemic shock may be difficult. The initial management involves volume resuscitation and vasopressors for persistent hypotension. In neurogenic shock, use of dopamine or phenylephrine are useful in restoring peripheral vascular tone and are the vasopressors of choice. In addition, the volume resuscitation with neurogenic shock is typically 1.5 to 2 L followed by use of vasopressors whereas hypovolemic shock from blood loss may require intravenous fluids in the 5 to 10 L range.

Once the patient is stable from a hemodynamic and cardiopulmonary standpoint, the focus is turned to the spinal injury and identification of other associated wounds. A complete history and physical should be completed. Tetanus prophylaxis is routinely administered in all GSW patients as soon as possible. Information about the circumstances surrounding the injury, including the type of weapon involved and the distance at which the victim was shot, should be documented when it is available. In an awake, cooperative patient, a complete neurologic examination is performed and documented using the American Spinal Injury Association (ASIA) scale. Comatose or sedated patients can be evaluated by their response to painful stimuli in the upper and lower extremities. Deep tendon reflexes are usually absent below the level of injury in patients with complete neurologic deficit due to spinal shock. Particular attention should be given to the presence of the rectal sphincter tone and the bulbocavernosus reflex which will determine whether the patient has a complete versus an incomplete injury.

In addition to a complete neurologic assessment, a thorough evaluation of nonneurologic injuries should be completed with the assistance of a trauma surgeon. The entry and exit wounds should be identified and inspected for foreign material or cerebrospinal fluid. Depending on the site of the entry and exit wounds, the bullet trajectory can be inferred and appropriate diagnostic tests pursued. Treatment of nonneurologic injuries is of primary importance and explorations of the neck, chest or abdomen take precedence over management of spinal injuries.

The initial radiologic evaluation typically consists of plain radiographs, anteroposterior (AP), and lateral, of the involved areas. Standard radiographic views of the involved spinal region should always be obtained even in
the absence of neurologic deficits. In patients with injury patterns concerning for spinal instability, passive flexion/extension radiographs may be used to evaluate for segmental instability in an awake, cooperative patient without a neurologic deficit. Klein et al. retrospectively analyzed 244 patients with substantial spinal injuries secondary to GSWs and found that 13% presented with no neurologic symptoms. They concluded that complete radiographic spine evaluation was mandatory after a GSW to the face, neck, or trunk, even without neurologic deficit.

The widespread availability of CT scanners in most medical centers has made this modality the radiologic examination of choice for GSWs to the spine. Thin-slice CT images allow for evaluation of the extent of injury and for accurate localization of fracture or bullet fragments. Compressive lesions can be identified along with bone/bullet fragments compressing the neural elements. Coronal and sagittal reconstruction enable further evaluation of the integrity of the three spinal columns and are also useful in identification of intercannalicular bullet or bone fragments within the spinal canal. CT myelography may be used to assess or confirm neural compression and may aid in the identification of a cerebrospinal fluid (CSF) fistula. CT angiography has become an important diagnostic tool in the identification of associated vascular injuries or visceral wounds and has become the standard of care in the evaluation of gunshot wounds in most trauma centers.