Emergency Medicine

Identifying and Managing Cerebral Concussion

The authors point out the landmarks and pitfalls of this medically and legally tricky terrain: understanding the pathology of concussion, evaluating the extent of injury, determining when a CT scan is necessary, assessing pediatric head trauma, grading a concussion, and controlling risk factors for second-impact syndrome and post-concussive syndrome.

By Kenny V. Banh, MD, and Michael D. Burg, MD, FACEP

You’re moonlighting as your local high school football team’s doctor when the star quarterback on your team is blindsided by a devastating helmet-on-helmet tackle. He gets up and walks groggily to the sidelines, where he collapses. Rushing to his side to assess him, you are relieved to see him open his eyes and sit up. He is awake and orientated but does not recall the hit. You bench him because he’s complaining of dizziness, but this clears quickly and within five minutes he is throwing a ball on the sidelines. The coach is pressuring you to return his star to the game, but the player’s mother is concerned and asks if someone should call 911.

What should you do now?

HALLMARKS OF CONCUSSION

Mild traumatic brain injury (MTBI), more commonly known as a cerebral concussion, is defined as a traumatically induced alteration in mental status that may or may not involve a loss of consciousness (LOC). Its hallmarks are confusion and amnesia. The cerebral changes in MTBI occur at a microscopic level and are not apparent on routine brain imaging. The evaluation and treatment of the concussed patient is medically and legally challenging due to possible long-term sequelae; also, disagreements exist between medical groups about concussion grading and management and recommendations for return to activity.

Football is the sport most often associated with concussion; the incidence in high school football players is approximately 19%. However, studies have shown nearly the same incidence in other contact sports such as lacrosse, hockey, and soccer.

Our understanding of concussion pathophysiology continues to evolve. Originally, it was posited that traumatic shearing forces from an impact interfered with the brain’s electrical activity. However, animal research seems to show that LOC following head injury results from secondary brain damage. Increased neuronal vulnerability to damage following the initial insult can be explained by ionic fluxes, acute metabolic changes, and cerebral blood flow alterations. More specifically, various studies have found massive increases in extracellular potassium concentrations lasting up to five minutes after head trauma. This transient hyperkalemia produces an inhibitory effect on action potentials that may require several seconds to reach the threshold necessary to induce LOC. This may explain why some concussed patients walk for a while before collapsing, as did the quarterback in our scenario.

EVALUATING THE EXTENT OF INJURY

The first step in evaluating the concussed patient is making sure that a more serious injury has not occurred. The ABCs of airway, breathing, and circulation should be assessed immediately; this is more important than a cognitive evaluation. It should be followed by a quick physical examination to screen for other significant injuries. As a part of the subsequent neurologic examination, the Glasgow Coma Scale (GCS) (see table below) is a useful tool for evaluating the brain-injured patient. The GCS is a reproducible, easily performed test of basic neurologic functioning that can be repeated if the patient’s condition changes.

Any patient with LOC lasting more than five minutes, focal neurologic findings, or evident skull fracture requires immediate transport to a trauma center and computed tomography (CT) imaging of the brain. Maintaining cervical spine immobilization with a hard collar and backboard and attending to other injuries may be necessary during transport. Clinical indications of skull fractures include cerebrospinal fluid in the nares or ear canals, hemotympanum, Battle’s sign (postauricular ecchymosis), or raccoon’s eyes (infraorbital ecchymosis). In addition to a noncontrast CT scan of the head, many patients with these findings will also require advanced therapies and interventions such as pharmacologic paralysis, endotracheal intubation, and hyperventilation that are beyond the scope of this article.

Concussed patients who experience LOC should quickly recover to a GCS of 14 to 15. Once awake (and assuming no other significant injuries exist that preclude movement), patients still at the scene of their injury can be removed for a complete neurologic evaluation. Because amnesia is a hallmark of MTBI, the patient should be asked if he remembers the events immediately preceding the injury. Asking “Do you know where you are?” or “What day is it?” may help determine the patient’s level of alertness and orientation. Higher-level brain function can be ascertained by asking the patient to perform simple arithmetic (“What is two plus two?”). The patient should also be asked about other neurologic complaints such as dizziness, nausea, weakness, and headache. All concussed patients should be rechecked frequently; a worsening neurologic status may signal that a more serious brain injury has occurred.

WHEN IS BRAIN IMAGING NECESSARY?

Most emergency physicians will not witness the actual event that leads to MTBI but will instead care for conscious patients who have suffered some form of head trauma. Again, the ABCs are the top priority, followed closely by the need to determine if significant brain injury or other major trauma exists. Once a more serious injury is ruled out, the difficult question of “Who needs brain imaging?” arises. A relatively small subset of head trauma patients will have brain lesions requiring inpatient observation or even neurosurgical intervention. Failure to diagnose these injuries may result in devastating consequences. Complicating the evaluation of the MTBI patient is the fact that expert medical organizations do not agree on the criteria for brain imaging in trauma patients.

The CT scan is the diagnostic imaging modality of choice for intracranial traumatic lesions—that is, epidural and subdural hematomas and hemorrhagic contusions. Its use in the evaluation of MTBI patients has increased in recent years, no doubt influenced by medicolegal concerns. Various guidelines exist to aid physicians in determining who needs CT imaging; the 2000 New Orleans Criteria (see box below) are simple, well-validated, and especially easy to use.

These rather conservative New Orleans guidelines may reduce the need for interfacility patient transfers and CT scan use, while still being sensitive enough to detect all clinically significant brain injuries. Lesions found on CT scan following head trauma warrant neurosurgical consultation and evaluation. Patients with normal CT scans whose mental status deteriorates also require neurosurgical and trauma surgery consultations. It is a generally accepted practice to hospitalize any patient with a concussion and perseveration or continued retrograde amnesia.

It is important to note that seizures occur in about 12% of MTBI patients, and while often concerning to observers, they do not signify that a more serious brain injury exists. Seizures may be the result of electrical inhibition from transient extracellular hyperkalemia and are not helpful markers in the evaluation and management of MTBI patients. Nevertheless, seizure is one of the criteria for imaging in the New Orleans guidelines.

PEDIATRIC PATIENTS

While the New Orleans Criteria are helpful with adults and theoretically apply to patients as young as three years of age, they have not been externally validated in patients under 16. Evaluating infants is particularly challenging, not only because of anatomic features of the brain and skull that make them more susceptible to intracranial injury from minor head trauma, but also because they are more difficult to assess neurologically.

The American Academy of Pediatrics has guidelines for the evaluation of minor head trauma in patients over two years of age. These guidelines assume that there is a return to a normal activity level and recommend imaging only if LOC has occurred. Monitoring by a responsible adult must be assured. Children who experience a brief LOC (less than one minute) may either be closely observed or imaged. However, given that studies show the incidence of intracranial injury to be between 2% and 7% in children with LOC, many clinicians recommend imaging all children with LOC of any duration. Observation remains a valid option, especially if imaging services are not readily available, the child looks well, and a significant amount of time has elapsed since the injury.

Choosing the proper method of evaluation is more problematic when LOC has not occurred or when the history is uncertain. Maintaining a high index of suspicion for child abuse is essential. A history that is inconsistent with the physical examination findings, evidence of old injuries, or signs of neglect should prompt a thorough investigation and a call to child protective services.

A consensus panel of pediatricians created guidelines for evaluating minor head trauma in children under two years of age that assign patients to high-, intermediate-, and low-risk groups. High-risk patients are those with depressed mental status, focal neurologic findings, depressed or basilar skull fractures, irritability, or a bulging fontanelle. Most of these findings indicate significant brain trauma and mandate that a CT scan be done. Other infants in the high-risk category include those with a high-impact mechanism of injury (more than a three-foot fall) or with scalp hematomas and those who have fallen onto a hard surface. Cases of unwitnessed trauma or suspected child abuse would also be considered high-risk.

The intermediate-risk group includes children with multiple episodes of vomiting, a history of lethargy or irritability, a skull fracture that is more than 24 hours old, or behavioral changes that have resolved. Children in the intermediate group with only one risk factor may be closely observed for four to six hours, although imaging is also appropriate and widely done.

The low-risk group includes infants with minor mechanisms of injury who are completely asymptomatic two hours after the event. They may be managed with observation by a responsible adult.

While these recommendations are the consensus of an expert panel, they have not been validated by any large well-done study. Many clinicians recommend imaging for any infant with LOC, a prolonged change in behavior following head trauma, or a significant mechanism of injury.

CONCUSSION GRADING

The Congress of Neurological Surgeons and the American Academy of Neurology (AAN) have published guidelines on a grading system for concussion, but there is no consensus on the best standard. The table on page 18 (top) outlines the grading systems proposed by these two organizations. Concussion grading depends on whether or not LOC occurred, the length of time it lasted, and the level of neurologic disturbance following the injury.

There are serious concerns regarding when the patient can resume a normal level of activity. The reason is something known as second-impact syndrome (SIS). This entity was first described in 1973 following the deaths of two young athletes with concussions who returned to playing sports while still symptomatic and died after relatively minor second impacts. Twenty-six documented deaths from SIS have occurred since then.

Individuals who suffer a second concussive event while symptomatic from the first may experience malignant cerebral edema resulting in death. Concussion grading, therefore, assumes great significance. According to the AAN guidelines, a grade 1 or mild MTBI (also known as a “ding”) involves no LOC. In such cases, the patient should not resume normal activity for at least 15 minutes and serial examinations should be performed during that time. If the findings are normal, the patient may return to normal activity that day. A grade 2 or moderate concussion patient must refrain from normal activity and must remain asymptomatic for one week before being allowed to return to that level of activity. Grade 3 or severe MTBI patients with a brief LOC are treated as grade 2 patients, but those with a prolonged LOC (more than one minute) should not return to normal activity for two to four weeks (see table below).

These recommendations always assume that the patient is asymptomatic and has returned to baseline cog-nitive capacity. It is important to note that the Congress of Neurological Surgeons management guidelines are similar but slightly more conservative, recommending imaging and possible hospitalization for all patients with grade III concussions.

POST-CONCUSSIVE SYNDROME

Post-concussive syndrome is a well-documented, sometimes debilitating condition seen after MTBI. Symptoms can be divided into three categories: somatic, neuropsychiatric, and cognitive. Somatic symptoms include headache, balance disturbances, dizziness, and nausea. Neuropsychiatric complaints include anxiety, depression, and irritability. Attention or memory impairment and decreased thought-processing ability are common cognitive symptoms.

It is widely recommended that return to activity should occur in a graded fashion to reduce the risk of both SIS and post-concussive syndrome. In the case of our star quarterback, simple gradations such as aerobic workouts, followed by noncontact drills, followed by anaerobic workouts (such as weight lifting), and finally full-contact drills can be used. During this period of time, any recurrence of symptoms demands a reduction in activity level. These basic rules are safe and much easier to remember and utilize than the various neurology and neurosurgical guidelines.

The controversy surrounding the management of first episodes of MTBI is mild compared to the disagreement swirling about recurrent concussions and post-concussive syndrome. The general consensus is that a single MTBI usually results in little or no long-term neuropsychological impairment. However, each progressive concussion sustained will add to a patient’s risk for SIS and post-concussive syndrome. How to safely allow athletes to compete without suffering persistent neurocognitive symptoms (the worst level of which is known as dementia pugilistica or being “punch-drunk”) is still hotly debated. Certainly there is no denying that serial concussions have prematurely terminated the careers of many athletes, such as former San Francisco 49ers quarterback Steve Young and hockey great Pat LaFontaine.

The old rule of “Three strikes and you’re out” is simple enough to remember but inadequate when evaluating patients with concussions and post-concussive symptoms. The AAN recommends upgrading each subsequent concussion by one grade when evaluating patients for return to activity (see table below). While this system is also easy to follow, current practice is to treat each concussion and its sequelae on a case-by-case basis. One concussion with prolonged neurologic symptoms may be enough to stop playing contact sports permanently in the case of one patient, while a series of five “dings” may result in minimal disruption in activity with no long-term morbidity in another. Consider neuropsychological testing and referral to a neurologist for all patients who sustain recurrent concussions or for those with persistent post-concussive symptoms.

To return to our clinical scenario, it is clear that the quarterback should not be allowed to return to the game. He suffered a brief grade 3 concussion. In fact, he should not participate in any contact drills for at least a week. However, despite his short LOC your neurologic assessment precludes the need for hospital evaluation and imaging.

Remembering the basic principles outlined in this article can help team physicians, clinic practitioners, and emergency physicians manage patients who have sustained MTBI.