Approach to traumatic brain injury: Clinical sciences

Traumatic brain injury, or TBI for short, is caused by a penetrating or blunt force to the head resulting in temporary or permanent impairment of brain function. Common mechanisms of injury include direct head trauma from falls or being struck by an object, acceleration-deceleration or whiplash from motor vehicle crashes, or foreign body penetration like gunshot wounds.

The degree of injury ranges from mild to severe as classified by the Glasgow coma scale, or GCS. This scale measures eye-opening, verbal, and motor responses to stimuli on a scale from 3 to 15, with 3 representing a comatose state, and 15 being normal. Traditionally, a GCS score of 13 to 15 represents mild TBI, 9 to 12 indicates moderate injury, and a score of 8 or below is considered to be severe.

Your first step in evaluating a patient presenting with TBI is to perform the primary survey by assessing their ABCDE. First, secure the Airway and consider endotracheal intubation or a surgical airway if the patient cannot protect or maintain their own airway. Be sure to immobilize the cervical spine and maintain immobilization during endotracheal intubation until cervical spine fracture has been ruled out. Next, ensure adequate Breathing or ventilation. Then, assess Circulation and obtain 2 large bore IVs or IO access while continuously monitoring vitals. Next, assess the patient’s Disability and neurologic status by calculating their GCS and assessing pupillary reflex. Keep in mind that the patient’s GCS can change rapidly. Also, remember that a GCS of 8 means intubate if you haven’t already! Finally, Expose the patient and remove all clothing to assess for any other associated injuries, and then cover the patient with warm blankets to prevent hypothermia.

Once these important steps are done, you can move on to a secondary survey, which includes history and physical exam.

Here are some important clinical pearls! First, if the patient is not lucid, family members, bystanders, or EMTs who brought them into the hospital might be able to give you important elements of history such as the mechanism of injury and when they lost consciousness. Next, as part of your physical exam, perform a full neurologic examination. Finally, as you are doing your exam, keep in mind that even a mild head trauma can rapidly progress, so it’s important to be on your toes.

Alright, let’s start with penetrating TBI. History might reveal a gunshot or foreign body, like shrapnel, penetrating trauma with loss of consciousness, amnesia, post-traumatic seizures, headaches, nausea, or vomiting.

Upon examination, you’ll find an open wound with an exposed skull or brain matter. Neurologic exam shows altered mental status with GCS below 15 and dilated, unequal, non-responsive, or slowly reactive pupils with papilledema on ophthalmoscope. You might also see focal neurologic deficits like sensory or motor deficits. Finally, if the patient is hypertensive, it could be from the Cushing reflex in response to high intracranial pressure.

So, consider a penetrating TBI and order a non-contrast CT of the head. Although imaging is not always needed, a CT can help you identify the foreign object and determine the extent of the injury including associated skull fractures, hematoma or intracranial bleeding, parenchymal edema, or even herniation. With these findings, the diagnosis is penetrating TBI.

Let’s move on to diffuse axonal injury. Patients typically present with blunt head trauma or acceleration-deceleration injury. Additionally, history reveals a post-traumatic loss of consciousness, confusion, dizziness, seizures, headaches, nausea, and vomiting.

Examination might show signs of dysautonomia, such as diaphoresis, vasoplegia, hyperthermia, abnormal muscle tone, posturing, and labile vital signs. Often, brainstem reflexes are intact but patients are in a comatose or vegetative state, so GCS is 3. These findings indicate severe diffuse parenchymal injury.

Next, get a CT or MRI of the brain. Imaging showing multiple, small, hyperdense, or attenuating punctate lesions along the gray-white matter junction, subcortical or deep white matter, corpus callosum, or brainstem confirms your diagnosis of diffuse axonal injury. This condition is associated with poor prognosis.

Moving on, let’s talk about intracranial hemorrhage, which can vary in severity from incidental and nonconsequential, to severe and imminently life-threatening. There are four main types: epidural, subdural, subarachnoid, and intraparenchymal bleeds.

Epidural hematoma occurs with blunt trauma to the temporal bone, leading to fractures. Because the middle meningeal artery is close to the temporal bone, sharp bone fragments or blunt trauma itself can injure it and cause bleeding into the epidural space. It is more common in patients who are younger than 50 because, in older individuals, dura is firmly attached to the skull. Typically, patients present with initial loss of consciousness, then a lucid period, after which their mental status deteriorates. As the hematoma becomes larger, it presses on the oculomotor nerve, leading to ipsilateral pupil dilation on physical exam.

With these findings, suspect epidural hematoma and order a CT of the head. CT will show a biconvex hyperdense area between the brain and the skull. Since dura is attached to the cranial sutures, epidural hematoma does not cross suture lines. So, if you see this, diagnose epidural hematoma.