46 Mild Head Injury

Judith Marcoux and Abdulrazag Ajlan

Fig. 46.1 (A) Noncontrasted head computed tomography scan showing a left temporal small contre-coup contusion in the brain window and (B) a right mastoid fracture with a small amount of pneumocephalus in the bone window.

Clinical Presentation

A 22-year-old man is involved in a fight and is assaulted on the right side of his head.

On clinical examination in the emergency room (ER), he opens his eyes to voice, but he is somnolent and confused. He obeys commands and has no focal deficit. There is no sign of external trauma

A computed tomography (CT) scan of the head is done and depicted in Fig. 46.1.

Questions

How can you make the diagnosis of a mild traumatic brain injury (TBI)?
What are the indications for a CT scan in a mild TBI?
Which patient with a mild TBI will require hospital admission?
What is the prognosis of a mild TBI?

Answers

How can you make the diagnosis of a mild TBI?

A mild TBI is an acute brain injury resulting from a mechanical energy to the head from external physical forces.

To make the diagnosis of a mild TBI, you need to have at least one of the following:

A documented period of altered mental status (loss of consciousness or confusion)

Duration of the loss of consciousness less than 30 minutes

Duration of the posttraumatic amnesia less than 24 hours

Any other transitory neurologic sign or focal neurologic sign (e.g., seizure)

An intracranial lesion not requiring a neurosurgical intervention (if a neurosurgical intervention is required, the injury will be classified as moderate)

A Glasgow Coma Scale (GCS) score between 13 and 15, 30 minutes or more after the accident (sudden deterioration and signs of herniation will be classified as a moderate or severe TBI)

These findings should not be due to alcohol or drug intoxication, medication, other injuries, their treatment, other problems (e.g., psychological trauma, language barrier…), or a penetrating brain injury (classified as moderate).1

The term “concussion” should no longer be used as its definition was vague and varied considerably in the literature.²
What are the indications for a CT scan in a mild TBI?
- To decide who is going to need a CT scan, you need to know which patient is at risk of developing serious complications. Two phase III studies address this question^3,4 in adults; the following criteria are a combination of the results of these studies:
  - At history:
    - Age 60 years or more
    - Dangerous mechanism of injury (see below)
    - Any vomiting
    - Headache (not specific)
    - Any seizure activity
    - Anterograde amnesia
  - On examination:
    - GCS <15
    - Drug or alcohol intoxication
    - Skull fracture (suspected open or depressed skull fracture or signs of basal skull fracture
    - Evidence of trauma above the clavicles
- If any of these factors is positive, the patient should have a CT scan done.
- A dangerous mechanism of injury is when the velocity or force of impact generated overcomes the human body’s ability to compensate. The following mechanisms carry a high risk for intracranial injury:
  - Pedestrian struck by a motor vehicle
  - Occupant ejected from a motor vehicle
  - Fall from a height of more than 3 feet (1 m) or five stairs
Which patient with a mild TBI will require hospital admission?
- Patients with a mild TBI requiring an admission are those with a GCS <15 or an abnormal CT scan (defined as a significant intracranial lesion).
- Nonsignificant lesions include^4,5
  - An isolated cerebral contusion of ≤5 mm
  - A subarachnoid hemorrhage with thickness ≤1 mm
  - A subdural hematoma with thickness ≤4 mm
  - Isolated pneumocephalus
  - Depressed skull fracture that does not extend to the inner table
What is the prognosis of a mild TBI?
- A person presenting with a GCS score of 15 has a 0.08% risk of requiring a surgical intervention and 1% risk if the GCS is 13 or 14.
  - 0.07% of patients with a mild TBI will develop late posttraumatic epilepsy.³
  - The mortality rate in adults with a mild TBI is 0.01% if the GCS score is 14–15 and 1.1% if the GCS score is 13.
  - An excellent prognosis is reached.
    - In 98% of the patients with a GCS of 15
    - In 95% with a GCS of 14
    - In 76% with a GCS of 13
- In children, the mortality rate is 0% if the GCS was 14 or 15 and 0 to 0.25% if the GCS was 13 with a postadmission deterioration.
  - The overall prognosis in children is excellent in more than 99% of the cases.⁶
  - When post-TBI symptoms are present in children, they are usually transient and are resolved by 2 weeks to 3 months.
  - Few children will have short term or long-term cognitive deficit.
- In adults, most studies show that cognitive deficits will resolve within 3 months. Some individuals, however, will suffer from persistent symptoms.
- The main determinant for acute and late morbidity is the presence of compensation or litigation.7
  - Other possible factors (that are inconsistent between studies) are
    - Female gender
    - Being married
    - Being off work due to the injury
    - Not being at fault for a collision
    - Nausea or memory problems postinjury
    - Other injuries
    - History of preexisting physical limitations
    - Prior neurologic illness or head injury
    - Psychiatric problems
    - Life stressors
    - Being a student
    - Sustaining TBI in a motor vehicle collision
    - Age over 40 years