Penetrating Cranial Injury

Penetrating cranial injury occurs when a foreign object breaches the skull and dura and enters the intracranial compartment.

Examples include:

• Gunshot wounds
• Fragment injuries
• Knives
• Nails
• Industrial objects
• Bone fragments driven intracranially by high energy trauma

Penetrating injury differs from blunt TBI because it combines:

• Direct tissue laceration
• Vascular injury
• Contamination
• Foreign material
• CSF fistula
• Seizure risk
• Delayed traumatic aneurysm risk

The neurological injury depends strongly on trajectory.

Transventricular, bihemispheric, brainstem and major vascular trajectories generally carry a poorer prognosis.

Assess standard trauma priorities first.

Do not remove an object protruding from the skull in the emergency department.

The object may be tamponading:

• Major artery
• Venous sinus
• Brain wound

Removal must occur under controlled operative conditions with vascular planning.

Document:

• GCS
• Pupils
• Focal deficit
• Entry and exit wounds
• CSF leak
• Active haemorrhage
• Seizure

Noncontrast CT head: first line.

Identify:

• Trajectory
• Haemorrhage
• Bone fragments
• Foreign material
• Ventricular injury
• Mass effect
• Pneumocephalus

CT angiography is important when the trajectory approaches:

• Circle of Willis
• Major intracranial arteries
• Dural venous sinuses
• Skull base vessels

Penetrating injury can produce delayed:

• Pseudoaneurysm
• Arteriovenous fistula
• Arterial dissection

Repeat vascular imaging may be required when initial imaging is negative but the trajectory remains high risk.

Resuscitation

Manage similarly to severe TBI with strict avoidance of:

• Hypoxaemia
• Hypotension
• Hyperthermia
• Severe hypo or hypercapnia

Reverse anticoagulation.

Treat intracranial hypertension.

Surgical objectives

Operate for:

• Significant intracranial mass lesion
• Active surgically accessible bleeding
• Grossly contaminated wound requiring debridement
• Depressed bone causing compression
• Persistent CSF leak
• Accessible foreign body producing mass effect or infection risk
• Dural defect requiring closure
• Vascular lesion requiring treatment

Debridement should be conservative rather than radical.

Remove:

• Necrotic tissue immediately accessible through the wound
• Contaminated bone
• Foreign material that is readily accessible and clinically important

Do not pursue deeply embedded small metallic or bone fragments through normal brain simply to achieve radiographic cleanliness.

The current penetrating TBI framework emphasises preservation of viable brain and treatment of mass effect, vascular injury, contamination and CSF leakage rather than aggressive tract excision.

Protruding object

Leave the object in place until:

• Trajectory has been imaged
• Neurosurgery is prepared
• Vascular control is available
• Operating theatre is ready

Extract under direct surgical control.

Dura

Perform watertight dural closure where feasible to reduce:

• CSF fistula
• Meningitis
• Brain herniation through the wound

Use pericranial or fascial graft when primary closure is impossible.

Antibiotics

Broad prophylactic antibiotics are appropriate for penetrating brain injury, especially when there is contamination, sinus violation or retained organic debris.

A practical severe contaminated injury regimen is:

Ceftriaxone 2 g IV every 12 hours

plus

Metronidazole 500 mg IV every 8 hours

for approximately 3 to 5 days, with modification according to contamination, cultures and local penetrating trauma protocol.

Add anti staphylococcal or resistant Gram positive coverage when the wound environment or healthcare exposure warrants it.

Seizure prophylaxis

Give early antiseizure prophylaxis for 7 days.

A practical regimen is:

Levetiracetam 1 to 1.5 g IV loading dose

then:

500 to 1000 mg every 12 hours

or phenytoin based prophylaxis.

Late epilepsy is common, but prophylactic medication beyond 7 days has not been shown to prevent late post traumatic epilepsy.

Prognosis

Do not base withdrawal decisions on one variable alone.

Assessment should consider:

• GCS after resuscitation
• Pupillary response
• Trajectory
• Brainstem involvement
• Bihemispheric injury
• Vascular injury
• Systemic injuries
• CT evidence of preserved potentially functional brain