**2.5. Complications**

Complications can be related to the spine injury itself or to the surrounding organs.

Spine-associated complications are continuous CSF leak; infection (less than 1% will develop chronic abscess and osteomyelitis) and rarely meningitis; chronic epidural granulation (sometimes will present as progressive myelopathy); and there are reports of arachnoiditis and syringomyelia. Retained foreign body reaction may present as late-onset myelopathy due to foreign body migration. Metal particles such as copper or silver may cause a marked inflammatory reaction, while nickel and lead particles can be a source of an intermediate reaction. Oxidation of metallic fragments and rust deposit were also described [28].

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 diaphragm were rarely described.

In both civilian and military injuries of the vast majority, more than 80% of affected victims are men, with the highest incidence at their third decade [42–46]. The most common involved level is the thoracic spine (approximately 50%), and the least is the lumbar spine [3, 37, 47–49]. The incidence of thoracic spine injuries tends to reduce in more developed armies with better

The term "ballistics" refers to the scientific analysis of projectile motion and is divided to

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

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

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

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].

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

. Thus, a

Penetrating Spinal Cord Injury

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

mass and velocity both comprise the well-known formula of kinetic energy = 1/2 mv<sup>2</sup>

• Internal ballistics refers to the projectile's behavior within the barrel of the firearm.

• External ballistics deals with the projectile's path and motion while in the air. • Terminal ballistics describes what happens upon the impact with the target.

personal protective equipment [50].

and treatment strategy [53, 54].

*3.2.1. Internal ballistics*

*3.2.2. External ballistics*

body and the extent of tissue damage.

**3.2. Ballistics**

three main stages:
