WHAT IS BALLISTICS ?
B ) BRIEFLY DESCRIBE THE CURRENT MANAGEMENT OF BALLISTIC INJURY OF SPINE ?
A 5 DEFINITION
1 A The word ballistics comes from the Greek βάλλειν ballein, meaning “to throw”.
1 B Ballistics is the science of mechanics that deals with the launching, flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like
2 the science or art of designing and accelerating projectiles so as to achieve a desired performance.
3 A ballistics body is a body with momentum which is free to move, subject to forces, such as the pressure of gases in a gun or a propulsive nozzle, by rifling in a barrel, by gravity, or by air drag.
4 A ballistic missile is a missile only guided during the relatively brief initial powered phase of flight, whose trajectory is subsequently governed by the laws of classical mechanics, in contrast (for example) to a cruise missile which is aerodynamically guided in powered flight.
MECHANISM OF INJURY
1 There are many different types of bullets but the most common type is composed of a lead core with some type of casing.
2 On striking, the projectile element may travel at speeds of up to 1,500 metres/second, dependent on the ammunition and type of gun.
3 The most important factors in causing significant injury or death are their placement and projectile path.
4 The head and torso are the most vulnerable areas, with incapacitation due to CNS disruption or massive organ destruction and haemorrhage.
5 The extent of tissue and organ trauma will depend on terminal ballistics, which are influenced by the type of bullet, its velocity and mass as well as the physical characteristics of the penetrated tissue.
6 Injury is inflicted in a number of ways -
1 Firstly, the projectile crushes structures along its track, similar to other forms of penetrating injury.
A ) Temporary cavitation causes shearing and compression, sometimes tearing structures (as with solid abdominal viscera) or stretching inelastic tissue (the brain is particularly susceptible), analogous to blunt trauma.
B ) As tissues recoil and hot gases dissipate, soft tissue collapses inwards with the permanent cavity being the resultant defect.
C ) Bullets which display greater yaw will be associated with increased temporary cavitation.
2 Secondly, kinetic energy transfer occurs during retardation of the bullet and this may cause damage outside the tract.
3 Factors influencing the efficiency of kinetic energy transfer include -
A - Projectile’s deformation and fragmentation.
B - Entrance profile and path travelled through the body.
C - Biological characteristics of the transit tissues.
7 Projectiles tend to be classified as low-velocity (<300 hm/second) or high-velocity (>300 hm/second).
A ) Those with higher velocity may be expected, on this basis, to dissipate more energy into surrounding tissue as they slow and cause more tissue damage but this is only a very approximate guide.
B ) This ‘kinetic energy dump’ theory is controversial, since high-velocity injuries are frequently less extensive than would be predicted and fragmentation appears to be the most effective mechanism for wounding rather than yawing or other mechanisms for slowing high-velocity rounds quickly.
8 Secondary contamination.
9 There are, therefore, three mechanisms of tissue damage -
A ) the direct impact of the bullet, the pressure of shock waves
B ) and the temporary cavitation.
C ) GSW in the spine can occur even without direct trauma or violation of the spinal canal.
EPIDEMIOLOGY
1 penetrating injuries to the spine has increased lately and they cause 13–17% of all spine injuries.
2 The incidence of spinal cord lesions caused by gunshots varies considerably, depending on the country, ranging from 13 to 44%.
3 In some series, GSWs are the most common cause of spinal cord lesions, followed by traffic accidents; however, in others the order is the reverse
4 Assaults and arguments represent the main motivation for gunshots among civilians, whereas accidental causes are rare.
5 These victims are usually young people under the age of 30 years, male and of low socioeconomic status, and many suffer from neurological deficits because of the spinal cord lesion
6 Most patients with GSW in the spine have complete spinal cord injury.
7 Some studies show that the location of the lesion determines the deficit, so that cervical lesions lead to complete neurological deficits in ~70% of the cases whereas lesions of the cauda equina and at the lumbosacral level are incomplete in 70% of cases.
8 The main prognostic factor considered for recovery is the initial neurological status—that is, patients with incomplete deficit have superior functional prognoses compared with those initially evaluated as presenting complete deficits.
9 The functional recovery in patients with neurological deficits resulting from GSW is usually worse than that of traffic accident victims or those with stab wounds.
10 The period of follow-up to consider the functional status as definitive is a matter of controversy in the literature, varying from 2 weeks to 6 months.
11 Mortality in patients suffering from GSW increases with the severity of neurological deficit
CLASSIFICATION
A ) The spinal injuries caused by GSW may be classified as -
type I: transfixing (when small fragments are found inside the canal)
type II: intracanal (when the whole projectile is inside the canal)
type III: intervertebral lesions (when the bullet is inside the intervertebral disc space
Type III injuries are subdivided into -
(A) spinal lesion not associated with perforation of abdominal viscera
(B) injury with perforation of abdominal organs.
B ) In most cases of GSW, the injury is transfixing, and only little fragments (altogether <50% of the projectile) remain in the spinal canal.
C ) In the second place come cases in which the projectile is lodged inside the canal comprising 20.4% of cases.
CURRENT MANAGEMENT
1 All patients with non-trivial gunshot injuries need -
A ) Cross-matching of six units of blood.
B ) At least one and, preferably, two large-bore IV cannulae: required for vigorous fluid replacement.
C ) However, avoid hypertension which may exacerbate blood loss - aim for a systolic BP of 100-110 mm Hg.
D ) Investigation: X-ray (AP and lateral) one body region above and one below any wound, as well as the one directly involved, to search for further embedded shot/bullets.
E ) Monitoring: vital signs, blood gases, CXR, ECG monitoring.
F ) High-dependency or intensive care.
EVALUATION
1 The evaluation of a patient with a GSW should first follow the techniques of basic life support known as ‘ABCDE’ (airway, breathing, circulation, disability and exposure).
2 Only after this is completed should the patient be cared for regarding the spinal lesion
3 If possible, useful information should be collected, such as the direction of the shot, type of weapon or bullet, the proximity of the discharging gun and the number of shots.
4 A rigid collar must be placed to protect the cervical spine until radiographs are complete and properly analyzed.
5 However, long and unnecessary immobilization potentially brings a negative prognosis and even mortality
6 The patient should be undressed and moved carefully in search of bullet holes.
7 As already stated, most GSWs are transfixing.
8 The bullet holes must be differentiated as entry (with regular and clean edges) or exit (appearance of small explosion) holes.
9 There should not be a deep digital exploration of holes, especially in the abdominal region.
10 Physical examination of the spine should follow, as in other types of trauma in this region, with palpation of all the spinous processes in search of crepitus, gaps and pain points and with a complete neurological examination.
2 The initial approach of GSW should follow ATLS (advanced trauma life support) principles, addressing injuries with higher mortality risk, upper airway lesions in the face and neck, and injuries of great vessels.
3 Exsanguination followed by hemothorax and pneumothorax is the main cause of death in patients injured by firearms.
4 Lesions of abdominal viscera must be surgically dealt with, including abdominal cavity washing/cleaning and debridement of the wound.
5 Fractures of long bones should be washed, debrided and fixed externally, and spinal injuries should be left for a second surgical procedure.
6 Medication treatment
A ) Tetanus vaccination -
1 The patient’s vaccination status must be checked.
2 If there is any doubt about the last dose of antitetanus vaccine administered, vaccination should be performed while still in the emergency room.
B ) Antibiotics -
1 Antibiotic therapy should be initiated immediately with broad-spectrum antibiotics in all cases for 48–72 h, especially in patients with perforation of the gastrointestinal tract, with high risk for infection (especially when the colon is affected, which presents a greater risk of infection than perforation of the stomach or small intestine).
2 This type of injury is present in 23.7% of GSW of the spine - In these cases, exploratory laparotomy is recommended, with surgical lavage of the abdominal cavity with abundant saline after repair or bypass of the intestine for a loop or Hartman type colostomy.
3 The surgical removal of the bullet and bone debridement in the spine path are not considered necessary or effective in preventing infectious complications, and leaving the bullet lodged in the spine is not a risk factor for infection.
4 The administration of broad-spectrum antibiotics intravenously extended for 7–14 days
5 Spinal injury patients should receive immediate broad-spectrum antibiotic therapy, and all cases are evaluated by the hospital infections committee.
6 Usually, the choice is for teicoplanin, at a dose of 400 mg twice daily, and amikacin, 750 mg in one dose daily for 5 days.
7 In cases with bowel perforation, add metronidazole at a dosage of 500 mg, three times daily, for a period of 5–7 days.
C ) Corticosteroids
1 The use of corticosteroids in high doses in patients with spinal cord injury has been advocated for many years.
2 However, since the implementation of the National Acute Spinal Cord Injury Study II (NASCIS-II) in 1990,
several authors have questioned the use of high-dose methylprednisolone because of the risks of complications and side effects, with little relevant effects on neurological outcomes.
3 Several published studies have found no evidence for the use of high doses of methylprednisolone in patients with spinal cord injury
4 In patients injured by firearms, the NASCIS-II protocol failed too.
5 using doses of 4–6 mg dexamethasone, every 4 h TILL 24 HRS
D ) Surgical treatment
1 treatment of GSW in the spine remains controversial.
2 decompressive laminectomy has been shown as ineffective for neurological recovery and the removal of the bullet may not be capable of reducing infection
3 The main evidence for recovery is in cases of incomplete deficits, especially in the lumbar region (cauda equina) in which the procedure is performed early.
4 The only absolute indication for surgery in spinal GSW is the presence of cutaneous or pleural liquor fistula or the presence of documented progression of the neurological deficit associated with compression of neural elements in imaging examinations.
5 Laminectomy should be considered in patients with partial neurological deficit, especially those with cauda equina, with imaging showing involvement of the spinal canal by bone or metal fragments.
6 The surgery should be performed in the first 24–48 h, provided that the potentially fatal injuries have been treated and the patient is clinically stable.
The indications for surgery should be as follows -
1 Neurological deterioration in a patient with incomplete deficit
2 Presence of externalized liquoric fistula (risk of meningitis)
3 Mechanical instability
4 Installed toxicity
5 Location of the bullet at risk for migration (inside the disk or intracanal)
6 Location of the bullet at risk of toxicity (articular or intracanal)
COMPLICATIONS
A ) 1 Pain is probably the most common complication in the long term and is quite prevalent in cases of involvement of the cauda equina and conus medullaris.
B ) The removal of the bullet is not associated with the resolution of the pain.
C ) This situation is usually managed with administration of drugs, such as tricyclic antidepressants and anticonvulsants such as amitriptyline or gabapentin.
D ) The mechanism of tricyclic antidepressants in ameliorating neuropathic pain is not well understood; they probably reduce the pain by their unique ability to inhibit the presynaptic reuptake of biogenic amines, such as serotonin and noradrenaline.
1 Other mechanisms may involve blockage of ion channel and n-methyl d-aspartate receptors.
E ) Anticonvulsants such as gabapentin and pregabalin have a moderate to large effect on improvement of pain relief, as shown in randomized controlled trials.
1 Their action in neuropathic pain is not clear, either, however; they bind calcium channels and modulate calcium influx as well as influence GABAergic neurotransmission, and block new synapse formation, which may relieve pain
2 In refractory cases, surgical procedures, such as the ablation of the nociceptive root, can be performeD
2 LEAD INTOXICATION
3 MENINGITIS