Mild Traumatic Brain Injury
Cheryl A. Glass and Kimberly D. Waltrip
Definition
Head injury is defined as any external structural damage (i.e., a blow, a jolt, a bump) or functional impairment of cranial content, including the scalp, skull, meninges, blood vessels, or brain. Any of the following may occur immediately after the initial injury: loss of consciousness or decreased awareness, memory loss specific to events immediately pre- or postinjury, altered mental status, and neuro deficits involving motor strength, balance, vision, sensation, and speech. Mild traumatic brain injury (mTBI) results in a disruption of brain function (altered mental status) indicating severity of the initial injury. mTBI-related deficits are often mild in nature without overt symptoms. Radiographic testing is negative for anatomic abnormality (e.g., cerebral edema, hemorrhage). Concussion is a commonly used term to describe mTBI, where a loss of consciousness may have occurred; confusion is also associated. Ninety percent of patients with concussive injuries do not experience decreased LOC. Serious complications of mTBI include asymptomatic extradural hematomas, fatal thrombosis of the basilar artery, and hemorrhage from existing conditions such as fibrous dysplasia or essential thrombocytopenia.
The American Academy of Neurology offers the following guidelines for grading the severity of concussions:
A.Grade 1: Transient confusion; no loss of consciousness; resolution of mental-status abnormalities in less than 15 minutes.
B.Grade 2: Transient confusion; no loss of consciousness; concussion symptoms or mental-status abnormalities with amnesia for longer than 15 minutes.
C.Grade 3: Loss of consciousness (IIIa, unresponsive period lasts seconds; IIIb, unresponsive period lasts minutes).
The Glasgow Coma Scale (GCS) can also be used to grade the severity of concussions. A GCS score of 13 to 15 that is measured approximately 30 minutes after the injury would be classified as a mild traumatic brain injury. The GCS can be found at www.mdcalc.com/glasgow-coma-scale-score-gcs.
Incidence
A.The full incidence unknown, many individuals with mTBI do not seek medical attention, affecting the actual number of reported cases.
B.Traumatic brain injury (TBI) is a major cause of death and disability in the United States. TBIs contribute to about 30% of all injury deaths.
C.Elderly patients (>65 years) represent 10% of patients with an mTBI; however, this population represents approximately 50% of TBI-related deaths.
Predisposing Factors
A.Motor vehicle accidents (MVAs).
B.Assaults.
C.Sports- and recreation-related trauma.
D.Male gender.
E.Ages of increased incidence:
1.0 to 4 years.
2.15 to 19 years.
3.65 years and older.
F.Military occupation (i.e., exposure to blasts).
G.Falls.
Pathogenesis
A.Head-injured patients can potentially sustain two different types of injuries: primary (impact) injury and secondary injury:
1.A primary injury is a direct result from the injury and occurs at the time of initial insult. This type of injury is purely mechanical and may be focal (contusion or laceration, bone fragmentation), or diffuse, as in concussion or diffuse axonal injury (DAI). These injuries do not require surgical intervention.
2.Secondary injury is caused by a flow-metabolism mismatch. It is a complication of primary brain damage. This includes ischemic and hypoxic damage, cerebral edema, intracranial hemorrhage (ICH), and the impact of prolonged increased intracranial pressure (ICP), hydrocephalus, and infection. Secondary injury has delayed onset, occurring in a matter of seconds, minutes, hours, or days.
Common Complaints
A.Headaches that are often constant, generalized, or frontal and may last days or weeks are the most common posttraumatic symptom. Headaches usually occur within the first 14 days of the mTBI.
B.Brief amnestic epoch surrounding impact.
C.Faintness.
D.Nausea/vomiting.
E.Changes in vision, often slight blurring.
F.Drowsiness.
G.Loss of consciousness.
H.Confusion.
Other Signs and Symptoms
Other presenting symptoms and complaints are identified in four categories: physical, emotional, cognitive, and sleepcycle disturbances:
A.Physical:
1.Reported or observed injury to the head.
2.Dizziness.
3.Fatigue.
4.Decrease/change in balance.
5.Photophobia.
6.Sensitivity to noise.
7.Numbness/tingling.
8.Seizures, delayed onset status postinjury.
B.Emotional:
1.Irritability.
2.Nervousness.
3.Depression.
C.Cognitive:
1.Difficulty concentrating.
2.Memory impairment:
a.Short-term memory loss.
b.Repetition.
3.Confusion.
4.Slow responses/difficulty processing.
5.Changes in reaction time.
6.Changes in speech.
7.Disorientation.
8.Fatigue.
9.Altered taste and smell.
D.Sleep-cycle disturbance:
1.Feeling drowsy.
2.Difficulty falling asleep.
3.Sleeping more or less than usual.
Subjective Data
A.Obtain a description of injury from the patient or witness of the traumatic event, if possible. Identify the cause of the head injury, how it occurred (direct or indirect injury), and what type of force was exerted.
B.Confirm the patient’s level of consciousness (LOC) at the time of injury and after injury. Inquire about amnesia (retrograde and anterograde), which might predict increased severity of the injury. Ask about the occurrence, whether it was observed by others, and duration.
C.Review initial and current symptoms (see Common Complaints
and Other Signs and Symptoms
). Include description, location, severity, and onset of symptoms. It is important to note what has happened since the actual injury. It is not uncommon for patients to report symptoms that reemerge or worsen with exertion.
D.Obtain the patient’s medical history, especially of previous head injuries. Learning disabilities (e.g., attention deficit hyperactivity disorder [ADHD]), developmental disorders, depression, anxiety, sleep disorders, and mood disorders should also be noted because these can affect recovery.
E.Review current medications. Evaluate any recent change in the dosage and polypharmacy issues (number of prescriptions [>4 medications]). Certain medications like warfarin (Coumadin) can be a predisposing factor that can lead to complications.
F.Document any drug and alcohol history.
G.Ask significant others if they have noticed any additional signs or symptoms, behavioral changes, or evidence of seizure activity.
Physical Examination
A.Check pulse, respirations, and blood pressure (BP).
B.Inspect:
1.Observe overall appearance. Note level of awareness.
2.Inspect the skin and head for obvious injury. Periorbital ecchymosis (raccoon’s eyes
), postauricular/mastoid ecchymosis (Battle’s sign), or evidence of a cerebrospinal (CSF) leak (otorrhea, rhinorrhea) suggests a basilar skull fracture.
3.Examine the eyes for the presence of papilledema (indicates increased ICP), proptosis, and periorbital edema.
4.Examine the ears (hemotympanum or possible laceration to the external canal), nose, and throat.
5.Examine for facial fractures.
6.Examine for any trauma (e.g., malalignment, abnormal curvature) to the cervical spine.
C.Auscultate:
1.Auscultate over the globes of the eyes if warranted (bruit may indicate traumatic carotid-cavernous fistula).
2.Auscultate carotid arteries bilaterally if warranted (bruit may indicate carotid dissection).
3.Auscultate the heart and lungs if cardiovascular etiology is suspected.
4.Auscultate the abdomen, if other injuries have occurred from incidental injury such as a contact sport or motor vehicle accident (MVA).
D.Palpate:
1.Palpate for instability of the facial bones, including the zygomatic arch: Can have a palpable step-off with orbital rim fractures.
2.If appropriate, palpate the abdomen and the entire posterior spine to rule out any other incidental injury.
E.Neurologic examination:
1.Assess mental status and memory. Determine whether the patient is awake, alert, cooperative, and oriented (to person, place, time, and situation). Temporary impairment of memory is one of the most common deficits after a head injury.
2.Assess cranial nerve (CN) function:
a.Olfactory (CN I).
b.Ophthalmoscopic/visual exam (CN II).
c.Pupillary response (CN III).
d.EOM (CNs III, IV, VI).
e.Facial sensation and muscles of mastication (CN V).
f.Facial expression and taste (CN VII).
3.Perform a motor examination on all four extremities.
4.Perform a sensory exam on all four extremities.
Diagnostic Tests
A.A plain film of the skull is usually not obtained for a minor traumatic injury. If the patient has suspected skull fracture or clinical indications for imaging, a CT scan is preferred. This type of imaging will usually reveal any linear or basilar skull fractures.
B.CT scan is indicated for patients with the following:
1.Decreasing consciousness during or after the injury.
2.Focal neurologic deficits.
3.Potential, penetrating, or depressed skull fractures.
4.Increasing or persistent severe headache with nausea or vomiting.
5.Seizures postinjury.
6.Alcohol or substance intoxication.
7.Amnesia status postinjury.
8.Unreliable or questionable accuracy regarding the history of the injury.
C.Consider anteroposterior (AP) and lateral spine films for suspected soft tissue injury or vertebral fracture, especially if the patient has experienced an amnestic episode or cannot recall the accident.
D.Drug screen.
E.Blood alcohol level.
Differential Diagnoses
A.Concussion (mTBI).
B.Contusion.
C.ICH.
D.Shearing injury.
E.Skull fracture.
F.Subarachnoid hemorrhage (SAH), traumatic.
G.Subdural hematoma (SDH).
H.Epidural hematoma (EDH).
I.Vascular occlusion or dissection.
Plan
A.General interventions:
1.Admit to the hospital for decreased LOC, seizure activity, focal deficits, penetrating or depressed skull fracture, vomiting, serious facial injuries, and positive head CT findings.
2.Hospitalization may be required if the patient has an injured middle meningeal artery or if venous sinus or fractures posteriorly in the skull are suspected. Posterior fossa hematomas may present suddenly (will see a wide pulse pressure).
3.Consider possible secondary injuries including cerebral edema, cerebral infarction, cerebral hemorrhage, hydrocephalus, and infection.
4.The patient should not be impaired from alcohol or other drugs when leaving the clinic, which can impact and potentially mask neurologic function or emerging deficits.
5.Hospital admission should be considered for patients without home observation/supervision.