Penetrating and Blunt Trauma to the Neck

Handgun Wounds

Civilian handgun injuries traditionally result from projectiles with low muzzle velocity (90 m/s). An impact velocity of 50 m/s penetrates skin, and an impact velocity of 65 m/s will fracture bone. These slow-velocity projectiles have been known to push aside vital structures such as arteries. Penetrating wounds caused by small-caliber handguns have a less damaging effect than other projectiles of higher velocity.

Guns are classified by projectile type, speed, and caliber (diameter of muzzle bore). Bullets that travel faster than 610 m/s are considered high-velocity projectiles. Handguns or pistols (.22 caliber to .45 caliber) have muzzle velocities that range from 210 to 600 m/s. Caliber is a term interchangeable with the designation of the cartridge (i.e., .22-caliber pistol). Handguns can develop up to 1000 foot pounds of energy. A .44-caliber magnum, which has a large powder charge, can create even more hypervelocity; thus injury from this gun can cause tissue destruction comparable with that caused by a rifle bullet, a larger projectile.

The yaw of the bullet describes the deflection of the projectile around the axis of travel. If the yaw is minimal (i.e., the projectile tumbles only slightly) and the bullet enters perpendicular to the body surface, the bullet will pass through the tissues with little energy transmitted. A tumbling bullet causes injury in a wider path. The projectile can follow tissue planes and may not injure vital structures. A bullet also can deflect from bones of the mandible or cervical spine. Unfortunately, civilian gunshot wounds increasingly involve heavier projectiles with higher velocity handguns. In all cases, a full inspection of the entire naked body and palpation of the head are necessary to reveal all entrance and exit wounds. This information may be useful in predicting damage.

Low-velocity bullets are usually lead shielded and often leave a radiographic track. A diagnosis based on physical signs of injury, after full and careful organ system evaluation, is often sufficient for these injuries if all presentations are normal. Radiographic confirmation or surgical exploration should follow any uncertainty or deterioration of physical signs.

Rifle Wounds

Most military rifles have a jacket of strong metal, usually copper, that surrounds a lead projectile. This permits smoother and longer flight because of less drag and less aerodynamic compression. Similarly, because of the lack of deformation, these military bullets create a clean hole with a through-and-through wound without a lead track to follow. The M16 military rifle has a bullet that is designed to tumble, and, therefore, it causes more tissue injury. It is against the terms of the Hague Convention of 1908 for military projectiles to include expanding bullets such as hollow point, soft nose, or dumdum bullets. These soft-tip bullets expand on contact and cause greater soft tissue injury. They create a large wound cavity, may not cause an exit wound, and may fragment, and partial projectiles can cause injury far from the primary direct path. Hunting rifles use these expanding bullets; therefore the civilian wounds caused by these projectiles can be more devastating than a comparable wound inflicted by a military weapon.

Most military rifles have a muzzle velocity of 760 m/s. High-velocity missiles (>610 m/s) not only tear tissue but also transmit energy to surrounding tissue. A cavity of up to 30 times the size of the missile may be created and may pulsate over 5 to 10 m/s, with several waves of contraction and expansion of the tissue ( Fig. 120.1 ). This may explain the finding of a punctured viscus without direct penetration and should alert the surgeon to examine the trachea and esophagus, even when a bullet wound is 2 inches away ( Fig. 120.2 ).

High-energy missiles are not easily deflected and cause significant destruction along their path as the energy is absorbed by the surrounding tissue. Deer rifles fire a projectile designed to mushroom on impact, which causes a large amount of tissue destruction within a small area.

The mortality from all high-velocity rifle injuries inflicted directly on the neck is significant. These patients usually do not survive and are not available for study. In view of the expected severity of injury, all known victims of high-velocity rifle injuries who survive upon reaching the hospital merit strong consideration for surgical exploration. For stable patients, angiograms should be considered before surgery. In helping to determine whether mandatory surgical exploration or further preoperative diagnostic tests are needed, knowledge of the size and velocity of the intruding missile is helpful.

Shotgun Wounds

The severity of shotgun wounds is largely dependent on the distance between the weapon and the victim, the type of weapon used, and the size of the projectile (shot). Pellets have a tendency to scatter as they travel, based on the distance to impact, and the interior muzzle diameter (choke) of the shotgun. At close range, the entire charge can act as a single missile with a KE similar to that of a high-velocity bullet. At further distances, birdshot pellets scatter and act as multiple individual missiles. With larger pellets such as buckshot, significant injuries can occur from individual pellets up to 150 yards away with a standard length barrel. A sawed-off shotgun leads to early spraying of the shot. Shotguns are low-velocity weapons (muzzle velocity of 300 m/s).

Birdshot pellets have a diameter less than or equal to 3.5 mm (0.13 inch) and are categorized as No. 4 shot or smaller. Buckshot pellets have a diameter greater than 3.5 mm and have a greater range, and they can cause significant injury up to 150 m. This is in contrast to birdshot, which has a 12-m maximum range of serious injury ( Tables 120.1 and 120.2 ). Each pellet injury from a buckshot blast is similar to a bullet injury from a handgun. Buckshot wounds are usually more serious than handgun bullet wounds because of the number of missiles involved.

TABLE 120.1

Shotgun Shells

From Ordog GJ: Missile wound of the neck. In Ordog GJ, editor: Management of gunshot wounds , New York, 1988, Elsevier.

Shot Size	Diameter (Inches)	Max. Range (Yards)	Weight (Ounces)
12-Gauge round ball	0.645	1420	0.75
16-Gauge round ball	0.610	1340	1.0
10-Gauge round ball	0.545	1200	1.25
410-Gauge round ball	0.38	850	—
000 Buckshot	0.36	—	6
00 Buckshot	0.34	748	8
0 Buckshot	0.32	704	9
1 Buckshot	0.30	660	11
2 Buckshot	0.27	—	15
3 Buckshot	0.25	—	19
4 Buckshot	0.24	—	21
#1 Shot	0.16	352	73
#2 Shot	0.15	330	90
#3 Shot	0.14	308	109
#4 Shot	0.13	286	135
#5 Shot	0.12	264	170
#6 Shot	0.11	242	225
# Shot	0.095	209	350
#8 Shot	0.09	198	410
#9 Shot	0.08	176	585
#12 Shot	0.05	110	2385.00

The gauge of the gun determines how much shot can be included in a single shell. The actual shot varies from 00 buckshot, which is used for deer hunting and has 8.5 pellets/oz with a larger tissue impact, up to 12 buckshot, which has 2400 pellets/oz and little destructive ability and is used for target shooting. An 8 buckshot with 400 pellets/oz is used for shooting small game, such as rabbits and birds.

At close range, shotgun injuries cause as much damage as rifle injuries because of the massive blast effect to the tissues. When the distance between the shooter and the target is more than 6 m, the details of gauge, shot, powder load, and the choke of the gun become more important. Wadding from the shotgun blast also should be searched for and should be removed from the wound to prevent infection. Radiography is useful for revealing pellets in unexpected locations such as the intracranial, intrathoracic, or intraorbital cavities. Magnetic resonance imaging may be even more valuable than computed tomography (CT) for the stable patient because metal scatter artifact does not occur.

Knife and Bite Injuries

Knife, icepick, cut glass, or razor blade injuries usually proceed along more predictable pathways. However, what appears to be a single-entry wound may be from multiple stab wounds. The history of the attack may be of some help to the physician in determining whether the blow was overhand or underhand, whether both the attacker and the victim were standing, and other similar details. Compared with gunshot wounds to the neck, cervical stab wounds have a higher incidence of subclavian vessel laceration, because stabbings to the neck often occur in a downward direction with the knife slipping over the clavicle and into the subclavian vessels. In gunshot wounds, the direction of the projectile is more perpendicular to the neck; thus the clavicle can protect the subclavian vessels. In regard to spinal injuries, neck stab wounds have a lower incidence than cervical bullet wounds. In regard to stab injuries, stable patients may still need to undergo radiologic studies to detect occult injuries that could show up later as a false aneurysm or an arteriovenous fistula.

In regard to penetrating neck injuries from animal attacks, the treatment options and timing vary depending on the nature of the defect, the animal species, and the experience of the surgeon. In many cases, early surgical reconstruction is performed after irrigation, antisepsis, and debridement. Concurrent rabies and tetanus prophylaxis and antibiotics are included in the treatment plan. Rabies symptoms can be determined by quarantine of the animal with surveillance.