Lovato, Luis M. MD
Learning Objectives: After participating in this activity, the physician should be better able to:
1. Categorize the pathophysiology and clinical features associated with concussion.
2. Create a treatment plan using the New Orleans Criteria for obtaining head imaging on patients with minor head trauma.
3. Devise a strategy for therapy that stresses the importance of the lucid interval and an observation period after concussion.
Article from the 2010 Reading List
Ropper AH, Gorson KC
N Engl J Med
This article is part of the Clinical Practice series that appears regularly in the New England Journal of Medicine. The authors begin by highlighting how little is actually known about the pathophysiology of concussion. External head trauma is thought to transmit rotational forces to the midbrain causing electrophysiologic disruption of the reticular activating system, which is responsible for arousal. With concussion, functional impairment is transient, and does not result in any known microscopic or macroscopic anatomic changes. When impairment is more than transient or when imaging is positive after head trauma, the term concussion does not apply.
According to the article, confusion and amnesia are common with concussion. Anterograde amnesia (inability to retain new information after the trauma) is usually less extensive than retrograde amnesia (inability to recall events immediately prior to the trauma). The authors offer some clinical advice for differentiating patients with true concussive amnesia from those with secondary gain. Patients with concussive amnesia do not forget long-standing biographical information such as name and birth date, and they do not confabulate.
The article cites the widely known New Orleans Criteria as one clinical decision rule by which to base imaging decisions after head trauma. (N Engl J Med 2000;343:100.) According to this rule, patients with mild head trauma, loss of consciousness, a normal neurologic exam, and a normal Glasgow Coma Scale (GCS=15) do not require imaging if all of the following criteria are absent: headache, vomiting, age over 60, intoxication, persistent anterograde amnesia, evidence of traumatic soft-tissue or bone injury above the clavicles, and seizure. According to the rule, the presence of just one factor necessitates imaging.
After a concussion, these authors recommend an observation period of at least two hours to monitor for any signs of deterioration and then to discharge with clear return precautions to the care of a responsible person. The authors also mention two other important clinical pearls. First, delayed onset symptoms such as headache, vomiting, lethargy, or even hard neurologic signs in a patient who initially looked well (the lucid interval) should raise concern for an epidural or subdural bleed. Secondly, patients with hard neurological findings after a negative head CT should prompt the clinician to consider ischemic stroke from a carotid artery injury.
A good portion of the article discusses the controversial post-concussion syndrome (PCS), a constellation of symptoms that occurs after a concussion, and can include persistent headache, dizziness, blurry vision, and a variety of other emotional and cognitive symptoms, sometimes for months after a concussion.
Finally, the article ends with a discussion of sports-related concussion, and mentions the conflicting evidence regarding long-term effects (if any) of repeated concussion in athletes that participate in team contact sports. The authors also present the Guidelines for the Management of Sport-Related Concussion from the American Academy of Neurology (AAN). These guidelines offer a strategy based on consensus opinion to guide the team physician managing head trauma from the sidelines, including recommendations on when an athlete can safely return to the playing field. (Neurology 1997;48:581.)
Comment: Trying to resolve competing academy and expert definitions of the term “concussion” can lead to more headache and confusion than the condition itself. Lack of consensus mostly stems from whether loss of consciousness is a defining point. This article opens with its own definition of concussion: “An immediate and transient loss of consciousness (LOC) accompanied by a brief period of amnesia after a blow to the head.” The article also prominently cites, however, guidelines published by the AAN regarding sports-related concussion, which base their grading system primarily on the length of transient confusion, reserving LOC only for the most severe concussion (Grade III). (Neurology 1997;48: 581.) At least one author advocates abandoning the imprecise term concussion altogether, but stops short of offering a satisfactory replacement. (Eur Neurol 2008;59[3-4]:113.) For now, I am comfortable settling on an abridged version of the AAN's definition of concussion: trauma-induced altered mental status with or without loss of consciousness.
Practically, as an emergency physician, what's more important than the definition of concussion is whether I need to obtain imaging. To CT or not to CT: That is the question. The goal of a clinical decision rule here would be to establish an evidence-based best practice to help the physician catch all important intracranial abnormalities while simultaneously limiting unnecessary imaging (and radiation). Most decision instruments in medicine, however, are imperfect, and care must be taken to ensure they are used only to supplement decision-making not replace medical judgment.
The goal of the New Orleans Clinical Decision Rule, for example, was to define clinical parameters that can determine which patients do not require a head CT after minor head trauma. In this study, when all seven criteria were negative (23% of enrolled patients), no patients had a positive CT. (N Engl J Med 2000;343:100.) But should this necessarily imply that if one criterion is positive, then a CT must be performed? Certainly evidence of persistent amnesia after trauma would concern an experienced emergency physician much more than a superficial scratch on the cheek, yet both clinical parameters are weighted equally if the rule is indiscriminately applied.
And what about important clinical factors the rule fails to address? Most seasoned emergency physicians would rightfully choose not to ignore the presence of coagulopathy when deciding to image a head trauma patient, yet coagulopathy is not a New Orleans criterion. Finally, back to the importance of terminology and definitions, comes the most important take-home point. The authors of the New Orleans Criteria defined minor head injury as loss of consciousness and a normal exam. This rule should never be applied to patients who did not lose consciousness, a critical point often missed when the decision-rule calculators come flying out of coat pockets. Indiscriminately applying this rule to every head trauma patient with evidence of trauma above the clavicles would most certainly lead to unnecessary imaging.
Post-concussion syndrome (PCS) and persistent post-concussive syndrome (PPCS) are beasts best left for the primary physician to tame. Very strict criteria are required to diagnose each condition, but unfortunately these criteria vary depending on the source. Interestingly, one meta-analysis of 2353 patients who had suffered closed head injury showed more disability in patients with financial incentives or unresolved litigation despite less apparent injury. (Am J Psychiatry 1996;153: 7.) Long-term prognosis for PCS is generally considered excellent.
The classic teaching of the lucid interval is usually reserved for medical textbooks and bedside rounds, but this phenomenon was mentioned prominently in the lay press in March 2009 after the Tony-winning actress Natasha Richardson tragically succumbed to the complications of an epidural bleed following a ski accident in Quebec. Reportedly, the first emergency response team was turned away when the actress refused medical attention, but her condition deteriorated over the next several hours. (New York Times, March 20, 2009; http://bit.ly/NYTrichardson.) Taking the lucid interval into consideration, the authors’ recommendation to observe a patient after concussion for a minimum of two hours seems prudent, especially when a decision to forego imaging is made.
Available evidence is conflicting on the long-term effects of repeated concussion on team athletes. Consensus opinion guidelines from the AAN on managing sports-related concussion from the sidelines allow an athlete to return to the contest after the first Grade I concussion (transient confusion < 15 min, no LOC). (Neurology 1997;48:581.) In other sports, however, the toll on the athlete is much more evident. Chronic traumatic encephalopathy describes a large spectrum of permanent functional impairment resulting from repeated head trauma ranging from mild cognitive and movement disorders to frank dementia. (Int J Psychiatry Med 1995;25;249.) The AAN takes a harder stand on sports that include intentional trauma to the brain (e.g., boxing, mixed martial arts, extreme fighting), recommending the implementation of regulations to limit head trauma in these sports and mandatory educational, counseling, and medical services for these athletes. (http://bit.ly/AANconcussion.)
Applying the New Orleans Clinical Decision Rule
After head injury with transient loss of consciousness, a normal neurologic exam, and a normal Glasgow Coma Scale score, a head CT is not required if all of the following conditions are absent.
* Age > 60 yrs.
* Drug or alcohol intoxication
* Persistent anterograde amnesia
* Evidence of trauma above the clavicles
Source: N Engl J Med 2000;343(2):100.
CME Participation Instructions
To earn CME credit, you must read the article in Emergency Medicine News, and complete the evaluation questions and quiz, answering at least 80 percent of the questions correctly. Mail the completed quiz with your check for $12 payable to Lippincott Continuing Medical Education Institute, Inc., Two Commerce Square, 2001 Market St., Third Fl., Philadelphia, PA 19103. Only the first entry will be considered for credit, and must be received by Lippincott Continuing Medical Education Institute by March 31, 2011. Acknowledgment will be sent to you within six to eight weeks of participation.
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Find a FastLink to American Academy of Neurology guidelines for treating athletes with concussion in this month's issue of EMNow on EM-News.com.
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