Traumatic Brain Injury
Abstract
Traumatic brain injury (TBI) is a term that encompasses a wide variety of diagnoses, ranging from mild concussions to severe brain injury such as a hematoma or diffuse axonal injury. Severe brain injury can have devastating effects on the patient, and any TBI has the potential to be life-changing, with severe personal, physical, and socioeconomic consequences. The signs and symptoms of traumatic injury may be subtle or immediately recognizable. No matter the presentation, all neuroscience nurses must be familiar with the types of TBI and know the appropriate interventions and treatments.
Keywords: concussion, diffuse axonal injury, epidural hematoma, herniation syndromes, intracerebral hematoma, subdural hematoma
9.1 Traumatic Brain Injury
Injury to the brain from an external force that results in altered brain function has been a major health problem for centuries, indicated by archeological evidence that demonstrates clubbing injuries occurring 1 million years ago. Brain injuries have long been considered fatal. As recently as the 1970s, approximately 90% of patients suffering brain trauma died from their injuries. Today, that rate is less than 20%. Although outcomes are better today, patients with traumatic brian injury (TBI) still face a significant risk of long-term disability or death.
Acute head injury occurs in varying degrees of severity. Severity can range from a relatively simple scalp laceration requiring little or no treatment to a devastating TBI with severe impairment, prolonged hospitalization, and permanent disability or death.
9.1.1 Epidemiology
The U.S. Centers for Disease Control and Prevention (CDC) estimate that each year approximately 275,000 patients with TBI are admitted to hospitals in the United States and 52,000 persons die due to brain injury. In 2017, the CDC reported that approximately 282,000 people were diagnosed with TBI in 2013. Of these, nearly 50,000 died.
Causes of Traumatic Brain Injury
Although there are thousands of possible causes for TBI, the more common ones vary based on sex, age, and locale.
Men are three times more likely than women to sustain a TBI
American Indian/Alaska natives have the highest overall rate of TBI of any racial group; African-Americans have the second-highest rate
The incidence of penetrating injuries such as gunshot wounds is higher in the United States than in any other developed country in the world
Military personnel are more likely to suffer TBI from explosive blasts than regular civilians
Motor vehicle accidents were the leading cause of death in persons 5 to 24 years old
Rates of TBI-related death are highest in the elderly (>75 years), with falls accounting for most deaths
Costs of Traumatic Brain Injury
The actual cost of TBI is incalculable. The direct and indirect costs of treatment and rehabilitation of patients who have sustained TBI in the United States have been estimated at $48.3 billion annually. However, the cost in suffering of patients, their families, and the community is immeasurable (Box 9.1 Risk Factors for TBI).
Box 9.1 Risk Factors for TBI
Age 18 to 25 years or ≥70 years
Male sex (1.5:1)
Use of alcohol or drugs
Active-duty military status
Lack or insufficient use of restraint or safety measures (e.g., helmet or seat belt)
Participation in certain sports (e.g., football)
9.2 Types of Traumatic Brain Injury
Traumatic brain injuries occur as either closed or open injuries. Closed injuries are more common. They frequently are caused by acceleration–deceleration incidents, which cause the brain to strike against one side of the skull, and then rebound to strike the opposite side of the skull. These injuries are also referred to as coup-contrecoup injuries (▶ Fig. 9.1; Video 9.1). Closed head injuries may result in hematomas, contusions, concussions, or diffuse axonal injuries.
Open injuries are those in which the cranial vault is breached, with injury to the brain itself. These injuries are usually seen as skull fractures caused by falls or motor vehicle accidents or as penetrating injuries such as gunshot wounds.
It is common for a patient with TBI to have more than one type of head injury, and often several types, both open and closed (Box 9.2 Mechanisms of TBI).
Box 9.2 Mechanisms of Traumatic Brain Injury
Acceleration–deceleration injuries
Motor vehicle accidents
Shaken baby syndrome
Falls
Direct blow to the head
Falls
Sports injuries
Physical assaults
Debris falling from overhead
Penetrating injuries
Gunshot wounds
Knives/impalement
May be combination of mechanisms.
Fig. 9.1 Coup-contrecoup injury.
9.2.1 Superficial Injuries
Patients with TBI often have superficial injuries to the scalp that also require medical attention. Superficial injuries are not brain injuries; however, they commonly occur in conjunction with TBI (Box 9.3 Clinical Alert: Scalp Lacerations).
The scalp consists of five layers that cover the skull (▶ Fig. 9.2)
The subgaleal space is a common space for blood to collect, forming a “goose egg.”
The scalp is extremely vascular, making exsanguination (i.e., extensive blood loss) possible
Treatment of scalp lacerations depends on the extent of injury
Scalp lacerations may indicate the presence of a skull fracture beneath the scalp
Box 9.3 Clinical Alert: Scalp Lacerations
The presence of a scalp laceration may indicate the following:
Extensive blood loss, possibly exsanguination
Presence of a skull fracture under the laceration
Potential for infection
Fig. 9.2 Layers of the scalp.
9.2.2 Skull Fractures
The skull is the bony structure housing the brain.
Composed of frontal, temporal, parietal, and occipital bones
Includes multiple facial bones
The floor of the skull is called the skull base and is rough and uneven
Asymmetrical
Variable thickness
Types of Skull Fractures
Fractures of the skull are categorized by type of break:
Linear
Comminuted
Basal
Depressed
Linear Skull Fracture
Simple break with no bone displacement (▶ Fig. 9.3)
Most common in a low-velocity-impact accident
Fig. 9.3 Linear skull fracture.
Comminuted Skull Fracture
Fragmented interruption of the skull (▶ Fig. 9.4)
Caused by multiple linear fractures.
Fig. 9.4 CT scan using bone window of a comminuted skull fracture (arrows).
Basal Skull Fracture
Linear fracture of the skull base (▶ Fig. 9.5)
When fractured, the rough skull base may tear the dura, resulting in a cerebrospinal fluid (CSF) leak (Box 9.4 Causes and Signs of Cerebrospinal Fluid Leaks)
Watch for characteristic signs of basal skull fracture; see also Chapter 2: Assessment
Battle’s sign (ecchymosis over mastoid bone)
Raccoon eyes (periorbital ecchymosis)
Box 9.4 Causes and Signs of Cerebrospinal Fluid Leaks
CSF leaks may occur because of the following causes:
Certain surgical approaches (e.g., retrosigmoid, transsphenoidal), see also Chapter 15: Neurosurgical Interventions
Basal skull fractures
Signs of CSF leaks
Rhinorrhea
Clear liquid dripping from the nose
Awareness of fluid dripping down back of the throat
Metallic taste in the back of the throat
Otorrhea
Clear liquid discharge from ear
Halo sign
Stain on bed linens or clothes from the wound, nose, or ears
Usually clear with yellow ring (halo)
Reservoir sign
Dripping of fluid from the nose upon leaning forward
Fig. 9.5 CT scan using bone window of a patient with extensive basal skull fractures (arrows).
Depressed Skull Fracture
Displacement of comminuted fracture (▶ Fig. 9.6)
Usually seen in conjunction with other injuries, such as contusions or lacerations
Degree of neurologic impairment depends on the location and severity of the injury to the brain
Fig. 9.6 Depressed skull fracture.
Clinical Manifestations of Skull Fractures
Skull fractures alone do not cause neurologic symptoms.
Often occur in conjunction with other types of brain injuries
Hematomas
Contusions
Penetrating wounds (e.g., gunshot wounds; ▶ Fig. 9.7)
Clinical manifestations are related to TBI associated with the skull fracture.
Fig. 9.7 Gunshot wound.
9.2.3 Hematomas
A hematoma is a localized collection of blood that is often clotted. Intracranial hematomas are defined by their location (▶ Fig. 9.8 and ▶ Table 9.1):
Epidural
Subdural
Intraparenchymal
Fig. 9.8 Locations of hematomas.
Type of hematoma | Onset of symptoms | Appearance on CT |
EDH | Immediate, with initial loss of consciousness, followed by lucid interval, then neurologic decline | Hyperdense, elliptical |
IPH | Immediate | Hyperdense, frequently in frontal or temporal lobes |
Acute SDH | Within 48 h after injury | Hyperdense |
Subacute SDH | 48 h to 3 wk after injury | Isodense |
Chronic SDH | 3 wk to several months after injury | Hypodense |
Abbreviations: CT, computed tomography; EDH, epidural hematoma; IPH, intraparenchymal hemorrhage; SDH, subdural hematoma. | ||
Epidural Hematoma
Bleeding into the space between the skull and the dura (▶ Fig. 9.9)
Usually caused by laceration of an artery or vein
About 85% of epidural hematomas (EDHs) are caused by arterial bleeding.
Fig. 9.9 Epidural hematoma.
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