51 Gunshot Wound to the Head

Remi Nader

Fig. 51.1 Computed tomography scan of the head. Scout images (A) anteroposterior and (B) lateral as well as pertinent axial images (C) and (D) are shown. The bullet entry site appears to be just under the left mastoid process and the bullet fragments appear to have traveled through the mastoid air cells and are lodged up into the left parietal lobe.

Fig. 51.2 Computed tomography scan of the head show ing pertinent (A,B) axial and (C,D) coronal reconstructed images. See text for further details.

Clinical Presentation

A 25-year-old man presents to the emergency room after sustaining a self-inflicted gunshot wound to the head ~1 hour ago. A low-caliber handgun was used.

The patient is intubated on arrival. He is awake and agitated.

On examination: the pupils are both 3 mm and reactive and he is moving all four extremities purposefully, localizing with both arms.

No other pertinent findings were noted on history or examination.

An initial computed tomography (CT) scan is obtained (Fig. 51.1).

Questions

Describe the findings on the CT scan.

What is your initial management?

Once the patient is stabilized, you elect to place a ventriculostomy. Initial intracranial pressure (ICP) is ~25 cm H₂O. What are the measures for treating ICP?

Despite appropriate medical management, he continues to deteriorate. His ICP continues to increase up to 50 cm H₂O and he develops a left dilated pupil ~4 hours after admission. An urgent CT is obtained and shown in Fig. 51.2.
Describe the CT scan findings.
What is your management at this time?
What are the indications to operate on gunshot wounds to the head?
What are the contraindications for surgery?

You decide to resect the hematoma and dÿbride the bullet path. Postoperatively, the patient does well for 24 hours, while under sedation and mannitol with head of bed elevated and PCO₂ of 30. His ICP starts increasing from 20 to ~35 cm H₂O. His pupils are still equal and reactive. You cannot obtain further neurologic assessment due to the sedation. Another CT scan done postoperatively is shown in Fig. 51.3.
How would you manage the ICP problem now? What are your options?
What is the expected prognosis?

Fig. 51.3 Computed tomography scan of the head showing pertinent (A–C) axial and (D) coronal reconstructed images. The hematoma has been evacuated. There is significant diff use brain edema, sulcal eff acement, tight basal cisterns, and small ventricles. These findings may be suggestive of increased intracranial pressure.

Answers

Describe the findings on the CT scan.

Scout images show bullet fragments extending from below the left mastoid through the skull at the level of the mastoid air cells and a larger bullet fragment lodged in the left parietal lobe.
Axial images show tight but open quadrigeminal cisterns.
Rostral cuts show small (1.5 cm in diameter) intracerebral hematoma in the left parietal lobe.
Some diffuse subarachnoid hemorrhage is seen.
No significant midline shift

What is your initial management?

ABCs of trauma: Insure that the airway is secured, the patient is ventilated, and the blood pressure and pulse are adequate. Resuscitate if needed. Start intravenous (i.v.) line and fluids; place a Foley catheter.

Admit to intensive care unit (ICU).

Administer tetanus toxoid.

Start antiepileptics: load with phenytoin loading dose (1 gram over 1 hour) and give phenytoin 100 mg every 8 hours.

Provide broad-spectrum antibiotic coverage with both gram-negative and gram-positive coverage (such as nafcillin and ceftriaxone).

Administer H₂ agonists for ulcer prophylaxis.

Check laboratory studies: complete blood count, electrolytes, coagulation profile (prothrombin time [PT], partial thromboplastin time [PTT]), type and screen, and toxicology screen

Consider urgent ventriculostomy placement.1

The patient at this time does not appear to need evacuation of the hematoma or bullet fragments as there is no mass effect on the brain. However, he is likely to develop significant swelling and increased ICP in the next 24 hours and will need ICP lowering treatment.²
Once the patient is stabilized, you elect to place a ventriculostomy. Initial ICP is ~25 cm H₂O. What are the measures for treating ICP?
- A detailed description of the management of ICP is outlined in Case 50, Intracranial Pressure Management. Here follows a summary of the pertinent points:
  - Elevate the head of the bed by 30 degrees.
  - Make sure there are no constrictions to the patient’s jugular venous outflow (collars, etc.).
  - Avoid hypotension, hypertension, or hypoxia.
  - Hyperventilation to a PCO₂ of 30 to 35 mm Hg may be used as a short-term measure to treat surges in the ICP.³
  - Mannitol 0.5 to 1 g per kg i.v. infusion – this may be repeated every 4 hours, but one needs to ensure that the serum osmolality is kept lower than 320.⁴
  - Sedation with morphine and midazolam drips or alternatively with a fentanyl drip⁵
  - Pharmacological paralysis (e.g., with vecuronium)
- If the ICP is not controlled after the above measures, serious consideration should be given to repeating the imaging studies and considering surgical evacuation of space-occupying lesions or third tier measures²
Describe the CT scan findings.
- Expansion of the hematoma to a size of ~3.5 cm in diameter
- Midline shift is now present (of at least 1 cm)
What is your management at this time?
- The patient needs urgent surgical evacuation of the hematoma and decompression.
- Options include:
  - Craniotomy and resection of hematoma ± debridement of the bullet tract
  - Decompressive craniectomy ± hematoma evacuation
What are the indications to operate on gunshot wounds to the head?
- Patients with favorable neurologic exam or Glasgow Coma Score (GCS), i.e., patients with none of the contraindications described in the following questions.
- Debridement of devitalized tissue or bone fragments
- Evacuations of a hematoma
- Separation of intracranial component from air sinuses²
What are the contraindications for surgery?
- Bullet traveling across the midline or the geographic center of the brain
- Bullet traveling across ventricles⁶
- Bullets traveling across more than one contiguous lobe of the brain^2,7
How would you manage the ICP problem now? What are your options?
- At this time, it becomes necessary to employ second tier measures, as explained in Question 3.
- Also consider the following surgical options:
  - Removing the bone flap by performing a craniectomy
  - Further debridement of devitalized brain in the area around the tract of the bullet
What is the expected prognosis?
- In this case, if the patient gets through the first 72 hours with ICP better controlled, he has a chance of surviving.
- However, he will most likely be severely disabled as the injury did involve eloquent areas of the dominant hemisphere.
- Overall, he has a poor prognosis with survival around 30%.^8,9