**3.2. Ballistics**

Extra-spinal complications are head injuries (5% of patients have low GCS on admission, and, hence, it may mask the diagnosis of SCI), vascular injury (most commonly, the carotid artery, but there are cases of injury to the vertebral artery as well) [29, 30], brachial plexus injury (it may superimpose cord injury), trachea and esophagus injury (the hypotheses is that these patients are too sick to survive), and thoracic organ injuries such as hemothorax, pneumothorax, and hemopneumothorax with a self-resolving emphysema. Less common injuries involve the major vessels, pericardium, and even the heart. Chylothorax and tear of the dia-

Missile-penetrating spinal cord injury (MPSCI) can be a devastating event and may cause severe and long-term morbidity and mortality. As in other SCI, these injuries have a substan-

MPSCI was first described in 1762 by a surgeon named Andre Louis that removed a bullet from the lumbar spine of a patient, who later on regained motion in his lower extremities [9]. Many famous fatalities of MPSCI are known throughout the history. Among them was Lord H. Nelson who was shot by a French sniper in the Trafalgar battle. The injury was to his shoulder, and he was described as experiencing immediate paraplegia. He died shortly after. Other known cases were the American presidents, J.A. Garfield and A. Lincoln. As a general rule, these injuries have a high rate of mortality and hence discouraged any treatment for many centuries [31]. Only at the end of World War II, surgeons started to treat it aggressively. Pool had reported [32] 57% marked neurological improvement with laminectomy compared with only 4.5% spontaneous improvement with previously untreated patients. Later, studies that were published following the Korea and Vietnam wars had shown no benefit of laminectomies in cases of complete and incomplete SCI. They concluded that surgery should be considered only in grossly contaminated wounds and for patients with progressive neurological deterioration [33–35].

MPSCI can be divided by the kind of the penetrating missile, that is to say, bullet vs. shrapnel or any other foreign body that penetrates, by blast, the patient body. Another way to classify these injuries is by the muzzle velocity of the shouting firearm: high versus low. The third option would be to classify them by the amount of penetrating particles—a solitary missile penetration versus multiple, usually combined with a blast injury. Segregation can also be

Military MPSCI epidemiology depends greatly on military conflicts around the world. Like any other military injury inflicted, it is more common in areas of worldwide conflicts and less

Civilian MPSCI are easy to quantify. This is now the third most common cause of spinal injury in civilian population accounting for one-fifth of all spine injuries after MVA and fall from height [36, 37]. They also account for 13–17% of all causes of spinal trauma [10, 38–41].

tial economic and psychosocial burden to patient, their family, and society.

phragm were rarely described.

74 Essentials of Spinal Cord Injury Medicine

**3. Missile-penetrating spinal cord injury**

done for civilian versus military injuries.

**3.1. Epidemiology**

common in peaceful areas.

The term "ballistics" refers to the scientific analysis of projectile motion and is divided to three main stages:


Wound ballistics is considered a subgroup of terminal ballistics and is the main concern of medical personnel [43, 51, 52]. Wound (terminal) ballistics, together with the characteristics of the damaged tissue and its reaction to the penetrating missile, dictate the severity of the injury and treatment strategy [53, 54].

Although surgeons are naturally mostly concerned with the terminal ballistics, understanding of the entire bullet course is crucial, since it has a direct effect on its introduction into the body and the extent of tissue damage.

#### *3.2.1. Internal ballistics*

All bullets are fired through a barrel, which is usually a tube of variable length with internal spiral grooving. The bullet is accelerated down the barrel to reach its final exit velocity due to high pressure expanding gases from the combustion of its propellant [55, 56]. During its path within the barrel, the bullet acquires its spin as it is engaged by the spiral grooves of the barrel. This spin is essential for the appropriate orientation of the bullet during its flight [57].

Bullets are usually classified as "high" or "low" velocity, which corresponds to the type of firearm they were shot from—a rifle or a pistol, respectively [58]. Low velocity usually refers to subsonic speed of about 350 m/s, while high velocity can reach up to 600–900 m/s [57].

The bullet itself, and most importantly—its mass, also influences wound ballistics, since the mass and velocity both comprise the well-known formula of kinetic energy = 1/2 mv<sup>2</sup> . Thus, a bullet fired from a handgun of 6.35 mm caliber, with a muzzle velocity of about 350 m/s and a mass of about 3.5 g, carries the energy of about 85 J. On the contrary, bullet fired from an assault rifle, such as the 7.62 mm caliber AK-47, with a mass of 8 g and muzzle velocity of about 800 m/sec, may reach the energy of about 2100 J—almost 25 times more than a handgun [59].

#### *3.2.2. External ballistics*

Once leaving the barrel, a bullet is subjected to several forces that might influence its energydelivering capacity. First, it is affected by the escaping gases just as it is exiting the barrel [60] that might destabilize it and thereafter to the drag forces as it traverses the air, which increases with rising velocity [51].

the damage is usually due to the mechanical impact of the bullet. Sometimes, there is not even an exit wound and the bullet stays within the tissue. Alternatively, high-velocity rifles usually have an exit wound, and they leave behind them a distinct tract, usually very damaged and often contaminated because of the "suction" effect of the wound. One might find cloth frag-

Penetrating Spinal Cord Injury

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http://dx.doi.org/10.5772/intechopen.76857

As in any other trauma, MPSCI should be first treated according the ATLS principles [71]. This initial evaluation will reveal concomitant injuries. Rapid evacuation to a hospital is crucial. This is especially true for the military scenario, in which more than one injury is the rule. The Prehospital Trauma Life Support and the Military Trauma Life Support (PHTLS and the MTLS) emphasize the importance of rapid evacuation from the scene of injury. It recommends that only securing airway and breathing together with partial circulatory control (control external bleeding) are done at the scene, and, thus, instead of doing the whole "ABCDE"

After arrival to the hospital, these patients are initially evaluated in the trauma bay by a multidisciplinary team. Following initial resuscitations and stabilization, physical examination is undertaken. The sensitivity and specificity of this were shown to be high, in detecting spinal cord injury (100% and 87%, respectively) [72]. It should be emphasized that civilian and military scenarios are different. In the civilian, most injuries are inflicted by low-velocity weapons with a solitary injury and less comorbidity. The evacuation period is normally short, and most patients arrive conscious to the emergency room. Neurological examination in this setting is more feasible and accurate. The opposite is true for the military scenario where most injuries are of high-velocity nature, and usually there is more than one injury. Usually, since most of casualties have a longer period of evacuation, they are brought to the trauma bay intubated, and thus their neurologic assessment is limited. The clinician should rely mostly on the anamnestic report of the evacuation team that considering the circumstance might not always be accurate. After securing airway, birthing, and circulation, and after an initial neurologic assessment was performed, the patient should be completely exposed to inspect the entire body. Documentation of the entry and exit wounds should be done. It should be kept in mind that in high-velocity weapons, more than one exit wound may be found. In a low-velocity weapon,

Tetanus prophylaxis history should be inquired and treated accordingly. In cases of unknown

Antibiotic treatment is usually given; however, no consensus for the type and duration of treatment exist. Evidence to support different antibiotic treatments in cases of organ perforation such as the larynx/esophagus in cervical injuries compared with abdominal viscera in thoracic injuries is low. There is, however, some evidence to support administration of a wide range of antibiotic treatments as prophylaxis [73]. Interestingly, a Cochrane review

immunization, tetanus immunoglobulin is required in addition to toxoid treatment.

scheme, the team should perform stages A, B, and half C ("scoop and run").

Treatment for associated injuries to other organs should be addressed.

ments in a wound cavity [70].

no exit wound is usually the rule.

**3.3. Initial evaluation and management**

This combination of forces acting on the exiting bullet creates an overturning moment, which causes the bullet to diverge from its original line of trajectory. This divergence is called "yaw," and it is expressed by the angle between the bullet's axis and the velocity vector [36, 61]. Because of the bullet's spin, yawing results in complex spiral revolution of the tip about its center of mass. Eventually, if the distance the bullet travels is long enough, yawing becomes irreversible, and tumbling occurs—meaning the bullet advances base-forward [62, 63].

It is quite clear that as the distance between the firearm and the target is shortened, these are less so-called disturbances to the bullet's path, and hence it can deliver more energy upon the impact. Muzzle velocity decreases significantly after 45 m for most pistol bullets and after 100 m for rifle bullets [64]. Unfortunately, most civilian gunshot wounds (GSW) are inflicted from an average distance of only 10 m [65].
