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A correction has been published: N Engl J Med 2007;356(17):1794.
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This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the authors' clinical recommendations.
A 64-year-old woman slipped on an icy walk, falling forward and striking her forehead. She had a brief convulsion immediately after the fall, was unresponsive for less than 1 minute, and awakened with a severe generalized headache and nausea but no vomiting. In addition to being perplexed about the circumstances of the fall, she could not recall the previous few hours. She was awake and oriented and had no abnormalities on neurologic examination. Tenderness and a scalp contusion were apparent at the site of the impact, and there were abrasions on her right cheek. What is the expected course, and how should her case be managed?
The Clinical Problem
"Concussion" refers to an immediate and transient loss of consciousness accompanied by a brief period of amnesia after a blow to the head. This event is so common, affecting about 128 people per 100,000 population in the United States yearly,1 that almost all physicians are called on at some time to provide care at the scene or to treat the sequelae of concussion. The clinical status of the momentary sensation of being "starstruck," or dazed, after head injury without a brief period of loss of consciousness is uncertain, but it is generally considered the mildest form of concussion.2 Young children have the highest rates of concussion. Sports and bicycle accidents account for the majority of cases among 5- to 14-year-olds, whereas falls and vehicular accidents are the most common causes of concussion in adults.
Considerable confusion persists among physicians and the public regarding concussion and the postconcussion syndrome. The extent of concussive amnesia roughly correlates with the duration of loss of consciousness and the severity of the head injury. There is both anterograde amnesia (the inability to retain new information) and retrograde amnesia, with the latter encompassing the moments before injury or, in rare cases, extending backward for several days or longer.3 In exceptional cases, a very minor blow to the head causes a memory disturbance that lasts for several subsequent hours.4 The period of anterograde memory loss tends to be briefer than the period of retrograde memory loss, and both improve over a period of hours or in less time.5 Concussion does not cause a loss of autobiographical information, such as one's name and birth date; this type of memory loss is a symptom of hysteria or malingering. Patients with concussion-related amnesia do not confabulate, and in many ways the clinical state resembles transient global amnesia.
A single brief convulsion may occur immediately after an otherwise mundane concussion, often leading to the erroneous attribution of the problem to a seizure.6,7 The mechanism is not known, but a brief convulsion neither presages epilepsy nor requires the administration of anticonvulsant medication. Concussion of a more serious grade may be followed by a confusional or delirious state or a period of sleep.
The brief loss of consciousness that characterizes concussion appears to be the result of rotational forces exerted at the junction of the upper midbrain and thalamus that cause transient disruption of the functioning of the reticular neurons that maintain alertness (Figure 1). Other mechanisms, such as seizure or abrupt elevation of intracranial pressure, have been suggested but with limited supporting evidence. The cause of the accompanying amnesia, however, is not known.
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Evaluation of the Patient with Concussion
Those attending to the patient at the scene of the injury should keep the airway clear and be attentive to a possible accompanying neck injury. If the patient has any neck pain, cervical immobilization is required. It is prudent to insist that a patient with concussion be taken to an emergency department for evaluation, although many patients object.
Criteria for Cranial Imaging
The primary concern is that the force of the impact may have caused a subdural, epidural, or parenchymal brain hematoma, although less than 10% of patients have intracranial bleeding after a concussion, and less than 2% require neurosurgery.8 Cranial computed tomography (CT) without contrast enhancement is adequate to detect important intracranial bleeding; magnetic resonance imaging is not necessary for this purpose.
Neurologic signs such as hemiparesis or poor arousal certainly necessitate CT, but predicting which person is likely to have abnormalities on imaging, and at the same time avoiding unnecessary scans, has proved difficult. Evidence that the injury was minor, including a normal neurologic examination, does not ensure the absence of an intracranial lesion. For example, 209 of 1538 patients with normal neurologic examinations in one series were found to have abnormalities on CT, with 58 requiring neurosurgery.9 On the basis of such findings, some groups have advocated scanning all patients with concussion, an approach that would lead to a predominance of negative scans that did not need to be obtained. In the past, the presence of a skull fracture was considered a marker of intracranial injury,10 but it has since been recognized that a simple fracture actually dissipates much of the energy of an impact and is not a strong indicator of intracranial bleeding. Certain fractures, such as those that are depressed or involve the base of the skull, have some predictive value, as discussed below.11,12
To refine the criteria for CT scanning, several clinical decision rules have been developed. Two of these rules — the New Orleans Criteria13 and the Canadian CT Head Rule14 — have been validated prospectively. Each contains seven criteria, although the only ones they have in common are older age and vomiting (albeit defined slightly differently) (Table 1). In two large prospective studies of minor head injury,15,16 the presence of any of the clinical features in these rules identified essentially all patients requiring immediate neurosurgical intervention. In one of these studies,15 the Canadian rule had slightly lower sensitivity than the New Orleans rule for any "important" injury. However, both rules had low specificity, although it was slightly higher for the Canadian rule, whose use was thus projected to result in modest but greater reductions in CT than use of the New Orleans rule (Table 1). Since patients 15 years and younger were excluded from one of the original studies14 and from both validation studies, the applicability of the rules to this age group is uncertain.
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Observation after Concussion
The duration and setting of monitoring depend in part on the periods of unconsciousness and amnesia and the presence or absence of systemic injuries. Patients with a normal neurologic examination are generally observed for approximately 2 hours and safely discharged to the care of a responsible person.16,17,18 It is helpful to provide a written instruction sheet with a list of symptoms that should prompt a return to the hospital, such as increasing headache, repeated vomiting, weakness, clumsiness, drowsiness, or fluid from the nose or ear that might represent a leak of cerebrospinal fluid. Headache and irritability are common for a day or more after concussion, particularly in children, and sometimes do not appear for several hours.19 Whether it is necessary to awaken a patient at night to confirm that he or she can be aroused has not been established; if this is a concern, hospitalization is more reasonable. It is generally recommended that patients not resume normal activity until they are free of headache and dizziness, but there are no data to indicate that an earlier return may be harmful.
New drowsiness, hemiplegia, or aphasia after concussion is cause for concern about the possibility of a delayed subdural or epidural hematoma and warrants examination and imaging studies. If these focal signs are not due to intracerebral bleeding, the possibility of a stroke from inevident carotid artery dissection should not be overlooked. When imaging studies of the brain and major cervical and cerebral vessels show no abnormalities, a migrainelike phenomenon is presumed to be responsible for focal neurologic features.20
Certain CT findings influence the duration of observation and the need for hospitalization. Small surface contusions of the brain or limited amounts of subarachnoid hemorrhage occur in approximately 5% of cases. These injuries usually do not give rise to neurologic problems other than headache, but they indicate that the impact was severe and call for more prolonged observation, generally overnight in the hospital. A fracture through the groove of the middle meningeal artery represents a special risk for epidural hematoma. Follow-up imaging is reasonable for all of these intracranial lesions, although its value and optimal timing have not been studied.
Postconcussion Syndrome (Posttraumatic Nervous Instability)
Postconcussion syndrome consists of a constellation of sometimes disabling symptoms, mainly headache, dizziness, and trouble concentrating, in the days and weeks following concussion (Table 2).21,22 The frequency and natural history of the disorder are unclear. In case series, incidences of headache and dizziness have been as high as 90% at 1 month and approximately 25% at 1 year or more, and the incidence of memory difficulty has ranged from 4 to 59% at various times.23 Once established for more than a few weeks, symptoms often persist for months and tend to resist treatment, although they eventually lessen. Unresolved issues of compensation and litigation have been associated with persistent symptoms.24,25 Countries in which litigation after accidents is infrequent have extremely low rates of postconcussive disability,26 and the problem is almost unknown in young children. Nonetheless, difficulty concentrating certainly occurs in the absence of these complicating features and can be demonstrated with neuropsychological tests, in some cases for months after concussion.
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Imbalance and disequilibrium reflect vestibular damage ("vestibular concussion").29 Affected patients have vertigo or experience motion of the environment while walking or driving. The vestibular damage is evident in an abnormal vestibulo-ocular reflex, which is tested by rapidly turning the patient's head several degrees to one side while the patient focuses on a fixed point and observing the patient for a slippage of fixation.
Data from controlled trials are lacking to guide treatment of the postconcussion syndrome. However, reassurance and education about the effects of concussion in an early single encounter have been shown to reduce the incidence and duration of symptoms at 6 months.30 Clinical experience suggests a benefit from the use of mild analgesics for headache, avoidance of narcotics, and the use of meclizine, promethazine (Phenergan), and vestibular exercises for dizziness, although these treatments have not been carefully studied in the postconcussion syndrome. Antidepressants are used in practice for patients with protracted symptoms of worry, sleeplessness, poor concentration, and daily headache, but data on the effectiveness of antidepressants in these cases are also limited; one small study has failed to demonstrate a benefit of antidepressants for headache after head injury.31 In patients with a history of migraine, concussion may trigger prolonged headaches. Clinical experience supports using therapies for spontaneously occurring migraine (triptans, anticonvulsants, calcium-channel or beta-adrenergic blockers, or corticosteroids).32
Concussion during Athletics
Athletes who have had a concussion have a slightly higher incidence of subsequent concussions during the same playing season.33 Extensive testing of several hundred amateur and professional athletes after a single concussion has demonstrated a return to baseline cognitive and motor performance within several weeks.34,35 Several studies of collegiate rugby and soccer players have shown decreased scores on selected neuropsychological tests in proportion to the number of self-reported head injuries,36 but other studies, including a recent one of Australian football players,37 indicate no such association. The occurrence of cognitive decline after repeated concussion has been more clearly demonstrated in boxers who have sustained multiple knockouts. There has also been concern that a second impact within a short period could lead to catastrophic neurologic damage. This largely unfounded concern is based on rare and mostly disputed cases in which a second mild head injury in children caused massive cerebral edema.38,39
There are scant data to guide decisions about the timing of a return to sports after concussion.40,41,42 Evaluation at the sidelines generally includes tests of mental function and coordination and provocation of symptoms such as headache, dizziness, or unsteadiness with exertion (Table 3). Recommendations are generally conservative, reflecting concern about an increased risk of a second concussion.
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The cerebral lesions associated with severe traumatic brain injury certainly cause cognitive and personality changes, but the effects of concussion are less clear.43 A recent concern has been the possibility of persistent cognitive decline as a result of single or repeated concussions, even from nonconcussive "heading" of the ball in soccer, termed "microtrauma" or "subconcussive" injury. The magnitude of the risk of microtrauma, in particular, if it exists, has been difficult to ascertain because few studies include measures of performance before the injury and control groups have been of uncertain comparability. Better-designed studies have not demonstrated a loss of intellectual function. The appropriate duration of abstinence from sports after concussion has not been determined. In addition, the causes and optimal management of postconcussive symptoms remain unclear.
Guidelines
The American Academy of Neurology,44 the Canadian Academy of Sport Medicine,45 and several international symposiums41 have developed recommendations for the evaluation and management of concussion in athletes. These guidelines reflect expert opinion in the absence of data, and there is no consensus on which set of guidelines or grading system is most appropriate. The recommendations of the American Academy of Neurology (Table 3) are under revision but do provide one approach to making sideline decisions.
Summary and Recommendations
The patient in the vignette had a concussion complicated by an impact-related seizure but had a normal neurologic examination. Because she was over the age of 60 and had facial and scalp bruises, as well as prolonged retrograde amnesia, it would be prudent to obtain a cranial CT scan, according the New Orleans and Canadian rules. With a normal examination and scan, she could be safely discharged to the care of a trusted person who was given written instructions to check on the patient several times over the next 24 hours and to return if drowsiness, vomiting, confusion, weakness, or increased headache occurs. There is no indication for an anticonvulsant, but non-narcotic analgesics may be given. The common sequelae of concussion should be reviewed with the patient, including the possibility that headache, dizziness, and mild difficulty concentrating may persist for days or weeks. A temporary leave from work or change to less taxing assignments may be appropriate, and if there is litigation, its prompt resolution should be encouraged. In the absence of controlled trials to guide postconcussion management, it is reasonable to treat persistent headaches and dizziness with medications and nonpharmacologic strategies commonly used for these symptoms. If impaired concentration persists for several weeks, neuropsychological testing should be considered to document and monitor the deficit.
No potential conflict of interest relevant to this article was reported.
Source Information
From the Department of Neurology, Caritas St. Elizabeth's Medical Center, and Tufts University School of Medicine, Boston.
Address reprint requests to Dr. Ropper at the Department of Neurology, Caritas St. Elizabeth's Medical Center, 736 Cambridge St., Boston, MA 02135.
References
iene D, Schrader H, Nestvold K, et al. A controlled historical cohort study on the post-concussion syndrome. Eur J Neurol 2002;9:581-587. [CrossRef][Web of Science][Medline]
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Related Letters:
Concussion
Cantu R. C., Herring S. A., Putukian M., the American College of Sports Medicine , Stricker P. R., Moriarity J., O'Connor F. G., McCambridge T. M., Small E., Bernhardt D. T., Kaji A. H., Gillespie I. A., Ropper A. H., Gorson K. C.
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N Engl J Med 2007;
356:1787-1789, Apr 26, 2007.
Correspondence
This article has been cited by other articles:
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