CME

Concussion: Evaluation and management

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Release date: August 1, 2017
Expiration date: July 31, 2018
Estimated time of completion: 1 hour

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ABSTRACT

Concussion is a common problem often managed by nonneurologists. It is often accompanied by headaches, dizziness, sleep disturbance, psychiatric symptoms, and cognitive issues. Here, we outline how to evaluate and manage concussion, including treatment of the most common symptoms.

KEY POINTS

  • Concussion results from a traumatic acceleration of the brain that leads to a metabolic mismatch, with an increased demand for adenosine triphosphate but decreased blood flow to the brain. This “energy crisis” results in variable signs and symptoms, most commonly headache, dizziness, sleep disturbance, cognitive problems, and emotional difficulties.
  • Initial therapy involves several days of cognitive and physical rest, followed by a gradual return to physical and cognitive activities.
  • There is no direct treatment for the physiology of concussion, but early treatment of symptoms and education about recovery and accommodations aids functional recovery.

 

References

Concussion, also known as mild traumatic brain injury, affects more than 600 adults per 100,000 each year and is commonly treated by nonneurologists.1 Public attention to concussion has been increasing, particularly to concussion sustained during sports. Coincident with this increased attention, the diagnosis of concussion continues to increase in the outpatient setting. Thus, a review of the topic is timely.

ACCELERATION OF THE BRAIN DUE TO TRAUMA

The definition of concussion has changed considerably over the years. It is currently defined as a pathophysiologic process that results from an acceleration or deceleration of the brain induced by trauma.2 It is largely a temporary, functional problem, as opposed to a gross structural injury.2–5

The acceleration of the brain that results in a concussion is usually initiated by a direct blow to the head, although direct impact is not required.6 As the brain rotates, different areas accelerate at different rates, resulting in a shear strain imparted to the parenchyma.

This shear strain causes deformation of axonal membranes and opening of membrane-associated sodium-potassium channels. This in turn leads to release of excitatory neurotransmitters, ultimately culminating in a wave of neuronal depolarization and a spreading depression-like phenomenon that may mediate the loss of consciousness, posttraumatic amnesia, confusion, and many of the other immediate signs and symptoms associated with concussion.

The sudden metabolic demand created by the massive excitatory phenomena triggers an increased utilization of glucose to restore cellular homeostasis. At the same time, cerebral blood flow decreases after concussion, which, in the setting of increased glucose demand, leads to an “energy crisis”: an increased need for adenosine triphosphate with a concomitant decreased delivery of glucose.7 This mismatch between energy demand and supply is thought to underlie the most common signs and symptoms of concussion.

ASSESSMENT

History

The history of present illness is essential to a diagnosis of concussion. In the classic scenario, an otherwise asymptomatic person sustains some trauma to the head that is followed immediately by the signs and symptoms of concussion.

The most obvious sign of a concussion is loss of consciousness or a period of confusion with subsequent amnesia (also known as posttraumatic amnesia). However, a variety of symptoms may occur, such as headache, drowsiness, poor balance, and slowed verbal output (Table 1).

Many of these signs and symptoms are nonspecific and may occur without concussion or other trauma.8,9 Thus, the diagnosis of concussion cannot be made on the basis of symptoms alone, but only in the overall context of history, physical examination, and, at times, additional clinical assessments.

The symptoms of concussion should gradually improve. While they may be exacerbated by certain activities or stimuli, the overall trend should be one of symptom improvement. If symptoms are worsening over time, alternative explanations for the patient’s symptoms should be considered.

Physical examination

A thorough neurologic examination should be conducted in all patients with suspected concussion and include the following.

A mental status examination should include assessment of attention, memory, and recall. Orientation is normal except in the most acute examinations.

Cranial nerve examination must include careful assessment of eye-movement control, including smooth pursuit and saccades. However, even in patients with prominent subjective dizziness, considerable experience may be needed to actually demonstrate abnormalities.

Balance testing. Balance demands careful assessment and, especially for young athletes, this testing should be more difficult than the tandem gait and eyes-closed, feet-together tests.

Standard strength, sensory, reflex, and coordination testing is usually normal.

Any focal neurologic findings should prompt consideration of other causes or of a more serious injury and should lead to further evaluation, including brain imaging.

Diagnostic tests

Current clinical brain imaging cannot diagnose a concussion. The purpose of neuroimaging is to assess for other etiologies or injuries, such as hemorrhage or contusion, that may cause similar symptoms but require different management.

Several guidelines are available to assess the need for imaging in the setting of recent trauma, of which 2 are typically used10–12:

The Canadian CT Head Rule10 states that computed tomography (CT) is indicated in any of the following situations:

  • The patient fails to reach a Glasgow Coma Scale score of 15—on a scale of 3 (worst) to 15 (best)—within 2 hours
  • There is a suspected open skull fracture
  • There is any sign of basal skull fracture
  • The patient has 2 or more episodes of vomiting
  • The patient is 65 or older
  • The patient has retrograde amnesia (ie, cannot remember events that occurred before the injury) for 30 minutes or more
  • The mechanism of injury was dangerous (eg, a pedestrian was struck by a motor vehicle, or the patient fell from > 3 feet or > 5 stairs).

The New Orleans Criteria11 state that a patient warrants CT of the head if any of the following is present:

  • Severe headache
  • Vomiting
  • Age over 60
  • Drug or alcohol intoxication
  • Deficit in short-term memory
  • Physical evidence of trauma above the clavicles
  • Seizure.

Caveats: these imaging guidelines apply to adults; those for pediatric patients differ.12 Also, because they were designed for use in an emergency department, their utility in clinical practice outside the emergency department is unclear.

Electroencephalography is not necessary in the evaluation of concussion unless a seizure disorder is believed to be the cause of the injury.

Concussion in athletes

Athletes who participate in contact and collision sports are at higher risk of concussion than the nonathletic population. Therefore, specific assessments of symptoms, balance, oculomotor function, cognitive function, and reaction time have been developed for athletes.

Ideally, these measures are taken at preseason baseline, so that they are available for comparison with postinjury assessments after a known or suspected concussion. These assessments can be used to help make the diagnosis of concussion in cases that are unclear and to help monitor recovery. Objective measures of injury are especially useful for athletes who may be reluctant to report symptoms in order to return to play.

Like most medical tests, these assessments need to be properly interpreted in the overall context of the medical history and physical examination by those who know how to administer them. It is important to remember that the natural history of concussion recovery differs between sport-related concussion and concussion that occurs outside of sports.8

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