Penetrating Bain Injuries

Dr Mukhtar

PG Neurosurgery

HMC, Peshawar

Roadmap

• Ballistics• Pathology• Clinical findings• Management• Complications

Ballistics

• Internal Ballistics• External Ballistics• Terminal Ballistics• Civilian Gunshot Wounds to the Head (GWHs)• Military GWHs• Wounding Energy E = ½ m (Vi2-Vr2)• Projectile Power P = mV3

Ballistics

• Projectile Velocities• Civilian firearms = <700 m/sec• Military & IEDs = >700 m/sec• Improvised Explosive Devices = >700 m/sec

Ballistics

• Kinetics• Gunshot dynamics

1. Juxtamissile pressure waves @1000s atm

2. Longitudinal strong shock waves = immediately post-impact1. @ 80 atm / 10 µsec / 1460 m/sec

3. Ordinary pressure waves @ 20-30 atm 1. creating the temporary cavity

Ballistics

Ballistics

• Cavities1. Temporary cavity with negative pressure

2. Permanent cavity (Projectile track)

Ballistics

Ballistics

• Cased ammunition and complex explosives• Complex ballistics• Combination of;

• Primary blast overpressure• Penetrating brain injury• Closed head injury• Thermal & Ischemic injury

• Fragments tend to be low velocity spall

Pathology

• Penetration of the scalp, skull, dura and parenchyma• Severity of injury is related to penetration of areas of the

brain• Greater damage with projectiles which crosses the

midline• 90% mortality with Civilian GSWH• Pathology of blast induced trauma is complex and

combination of all

Clinical findings

• Demographics• 87% males, most in third & fourth decades of life• Most (90%) are homicides• 1-3% suicidal• 5-8% accidental

Clinical findings

• Level of consciousness• Determined by brainstem, tegmentum, RAS

involvement• In civilian PBIs unconsciousness is the rule• In military casualties and in complex explosions

consciousness level varies• Time since PBI is major determinant of the final

GCS and post-op outcome

Clinical findings

• Brainstem functions• Pupillary light responses• Corneal & Doll’s eye reflexes• Cold caloric• Cough & Gag reflexes

• Abnormality of any or all of the above functions indicate brain shift/herniation/increased ICP/severity of injury

Clinical findings

• Focal deficit• Dependent on the entry site & target site damage• Cranial nerve damage is the most common• Visual field defects are the second most common• Orbital injuries needs special assessment• Sensorimotor or purely sensory/motor aphasia are

commonly associated with bullet injury than with a fragment penetration.

Clinical findings

• Mild TBI and PTSD• Mild TBI in blast injuries related to

psychobehavioral consequences and PTSD• no clear understanding of the exact pathogenetic

mechanisms• Friedlander waves

Management Plan

• Prehospital resuscitation, intubation if possible• ABC as in ATLS protocols• Pressure hemostasis• Shock correction• Investigate• Operate

Management

• Imaging studies• CT complemented by MDCT is the gold standard

• It delineates the cerebral vascular profile• Air sinuses involvement• Helps in surgical planning• Prognostication• CTA is advised for those at risk of developing

TICAs

Management

• Medical Management:• Acquisition and implementation of various guidelines

for:• Prehospital rescue• Intubation• Oxygenation• Ventilation• Volume resuscitation• Broad spectrum antibiotics• Anticonvulsants

Management

• Surgical Management:• Devitalized, burnt skin edges• Hard to repair scalp defects• Plastic techniques/consultation with a plastic

surgeon• CSF leakage risks• Superficial foreign bodies/bone fragments removal• Hemostasis• Dural assessment• Skin closure with continuous monofilament sutures

Surgical management

• Craniectomies vs Craniotomies:• Previously practiced Craniectomies are abandoned

due to loss of bone, need of cranioplasties and infection at the bone implantation site.

• Craniotomy with bone flap cleansing and replacement is the standard practice

Surgical Management

• Debridement & Dural closure• preserve eloquent cortex (if possible)• Multidisciplinary approach even for debridement

• Get involve Ophthalmologist, ENT, Plastic surgeon & OMFS

• Minimalistic approach only for small fragment or less destructive injury

• No aggressive dissection after scattered fragments

Surgical Management

• Repair of the skull base• Early repair of the skull base in transtemporal or

transfrontal injuries• To alleviate the risk of CSF fistula and traumatic

encephalocele formation• Restoring anatomical continuity

Complications

• Vascular Complications:

1. TICA incidence is 3% - 40%

2. AVFs and dissection are less common

3. Risk of TICA increased if midline is crossed

4. Early diagnosis is essential to prevent subsequent bleed

5. BTF guidelines advises for mandatory angiography (conventional or CTA) in PBIs

6. Orbitofaciocraniocerebral injuries, pterional injuries & those with intracranial hematomas are at high risk for TICA development.

Complications

• Intracranial Infections

1. Missile wounds are contaminated wounds

2. Both gram +ve and gram –ve are implicated

3. Broad spectrum antibiotic cover essential in all PBIs (BTF guidelines)

4. Meticulous debridement is the key to prevention

Complications

• Posttraumatic Epilepsy

1. PBI is one of the major risk factors for posttraumatic epilepsy

2. Incidence higher than in closed head injury

3. Risk factors

4. retained bone fragments were not significant for the development of epilepsy.

Prognosis

• Evacuation within the first hour post-injury• prognosis for civilian GSWHs remains abysmal• 85% dies within first few hours of injury• Effects of PBI on intelligence especially if left hemisphere• Size and location of the missile injury is determinant• left dorsofrontal injuries had the most severely

affected intelligence• LoC in case of mild TBI in explosions is associated with

PTSD

Thanks