The n e w e ng l a n d j o u r na l of m e dic i n e

clinical practice

Concussion
Allan H. Ropper, M.D., and Kenneth C. Gorson, M.D.

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 fore-
head. 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 abnor-
malities 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 ex-
pected course, and how should her case be managed?

The Cl inic a l Probl e m

From the Department of Neurology, Car- “Concussion” refers to an immediate and transient loss of consciousness accompa-
itas St. Elizabeth’s Medical Center, and nied by a brief period of amnesia after a blow to the head. This event is so common,
Tufts University School of Medicine,
­Boston. Address reprint requests to Dr. affecting about 128 people per 100,000 population in the United States yearly,1 that
Ropper at the Department of Neurology, almost all physicians are called on at some time to provide care at the scene or to
Caritas St. Elizabeth’s Medical Center, treat the sequelae of concussion. The clinical status of the momentary sensation of
736 Cambridge St., Boston, MA 02135.
being “starstruck,” or dazed, after head injury without a brief period of loss of con-
N Engl J Med 2007;356:166-72. sciousness is uncertain, but it is generally considered the mildest form of concus-
Copyright © 2007 Massachusetts Medical Society. sion.2 Young children have the highest rates of concussion. Sports and bicycle acci-
dents 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 con-
cussion and the postconcussion syndrome. The extent of concussive amnesia rough-
ly 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 in-
formation, such as one’s name and birth date; this type of memory loss is a symp-
tom 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.

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 clinical pr actice

The brief loss of consciousness that character-

izes concussion appears to be the result of rota- Ang
ular
tional forces exerted at the junction of the upper d ece
ler
midbrain and thalamus that cause transient dis- ati
on
Fixed
ruption of the functioning of the reticular neurons object
that maintain alertness (Fig. 1). Other mecha-
nisms, such as seizure or abrupt elevation of in-
tracranial pressure, have been suggested but with
limited supporting evidence. The cause of the ac-
companying amnesia, however, is not known. Rotational force
centered on
midbrain and thalamus
S t r ategie s a nd E v idence

Evaluation of the Patient with Concussion

Those attending to the patient at the scene of the
injury should keep the airway clear and be atten-
tive 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 Midbrain
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 im-
pact 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 neurosur-
gery.8 Cranial computed tomography (CT) without Figure 1. Mechanism of Concussion.
contrast enhancement is adequate to detect im- Biomechanical investigations dating back to the beginning of the 20th cen-
portant intracranial bleeding; magnetic resonance tury suggest that concussion results from a rotational motion of the cerebral
imaging is not necessary for this purpose. hemispheres in the anterior–posterior plane, around the fulcrum of the fixed-
Neurologic signs such as hemiparesis or poor in-place upper brain stem. If the neck is restrained, concussion is difficult
to produce. Concussions as portrayed in movies and cartoons, in which the
arousal certainly necessitate CT, but predicting
back of the head is struck withCOLOR
a bluntFIGURE
object and no motion is transferred
which person is likely to have abnormalities on to the brain, are implausible. The modern view is that there is disruption of
imaging, and at the same time avoiding unnec- the electrophysiological
Draft: and
04 subcellular activities
Date: of the neurons of the retic-
11/22/06
essary scans, has proved difficult. Evidence that ular activating system that are situated in the midbrain and diencephalic re-
Author: rotational
gion, where the maximal Ropperforces are exerted. Alternative mecha-
the injury was minor, including a normal neuro-
nisms for concussive loss of consciousness, such as self-limited cortical
logic examination, does not ensure the absence of Figure #: 01
seizures or a sudden increase in intracranial pressure, have also been pro-
an intracranial lesion. For example, 209 of 1538 posed, but with limited
DE: supporting evidence.
patients with normal neurologic examinations in
one series were found to have abnormalities on Artist: SBL
CT, with 58 requiring neurosurgery.9 On the basis ing. Certain fractures, such as those that are de-
of such findings, some groups have advocated pressed or involve the base of the skull, have some
scanning all patients with concussion, an approach predictive value, as discussed below.11,12
that would lead to a predominance of negative To refine the criteria for CT scanning, several
scans that did not need to be obtained. In the clinical decision rules have been developed. Two
past, the presence of a skull fracture was consid- of these rules — the New Orleans Criteria13 and
ered a marker of intracranial injury,10 but it has the Canadian CT Head Rule14 — have been vali-
since been recognized that a simple fracture actu- dated prospectively. Each contains seven criteria,
ally dissipates much of the energy of an impact although the only ones they have in common are
and is not a strong indicator of intracranial bleed- older age and vomiting (albeit defined slightly

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 The n e w e ng l a n d j o u r na l of m e dic i n e

differently) (Table 1). In two large prospective one of the original studies14 and from both vali-
studies of minor head injury,15,16 the presence of dation studies, the applicability of the rules to this
any of the clinical features in these rules identi- age group is uncertain.
fied essentially all patients requiring immediate It is important to appreciate that no clinically
neurosurgical intervention. In one of these stud- based rule for obtaining a CT scan is likely to be
ies,15 the Canadian rule had slightly lower sensi- universally accurate. In using these rules, the
tivity than the New Orleans rule for any “im- physician should consider the level of acceptable
portant” injury. However, both rules had low risk for overlooking any intracranial lesion as op-
specificity, although it was slightly higher for the posed to missing lesions that require monitoring
Canadian rule, whose use was thus projected to or immediate neurosurgical intervention. With
result in modest but greater reductions in CT these limitations in mind, for patients who are
than use of the New Orleans rule (Table 1). Since 16 to 65 years old and have no postconcussive
patients 15 years and younger were excluded from symptoms except mild headache, no external
signs of injury or basilar skull fracture, and a
Table 1. The New Orleans and Canadian Clinical Decision Rules for CT normal neurologic examination, the frequency of
after Concussion.* intracranial clots that require neurosurgery is so
low (<1%) that it is reasonable to forgo CT scan-
New Orleans Criteria† — Glasgow Coma Scale score of 15
ning. Imaging is routinely recommended for chil-
Headache
Vomiting
dren younger than 16 years, for intoxicated pa-
Age >60 yr tients in whom the manifestations of cerebral
Drug or alcohol intoxication injury are easily obscured, for patients who can-
Persistent anterograde amnesia (deficits in short-term memory) not be dependably observed after discharge, and
Evidence of traumatic soft-tissue or bone injury above clavicles for patients who take anticoagulants or have
Seizure
other bleeding tendencies.
Canadian CT Head Rule‡ — Glasgow Coma Scale score of 13–15
for patients 16 years and older
High risk of neurosurgical intervention
Observation after Concussion
Glasgow Coma Scale score <15 within 2 hr after injury The duration and setting of monitoring depend
Suspected open or depressed skull fracture in part on the periods of unconsciousness and
Any sign of basal skull fracture§ amnesia and the presence or absence of systemic
Two or more episodes of vomiting
injuries. Patients with a normal neurologic exami-
Age >65 yr
nation are generally observed for approximately
Moderate risk of brain injury detected by CT
Retrograde amnesia for ≥30 min 2 hours and safely discharged to the care of a
Dangerous mechanism¶ responsible person.16-18 It is helpful to provide
a written instruction sheet with a list of symptoms
* The presence of at least one criterion from the New Orleans Criteria or the that should prompt a return to the hospital, such
Canadian CT Head Rule is considered an indication for a cranial CT scan.
A score on the Glasgow Coma Scale of 15 signifies a fully alert and oriented as increasing headache, repeated vomiting, weak-
patient, spontaneously conversing and following commands. In the context ness, clumsiness, drowsiness, or fluid from the
of concussion, a score of 13 or 14 denotes disorientation or less than full nose or ear that might represent a leak of cerebro-
alertness. The Canadian CT Head Rule is adapted from Stiell et al.14 with the
permission of the publisher. spinal fluid. Headache and irritability are com-
† The sensitivity and specificity of the New Orleans Criteria are 99% and 5%, re- mon for a day or more after concussion, particu-
spectively, for detecting any ­lesion or clinically important CT abnormality; the larly in children, and sometimes do not appear for
sensitivity and specificity for detecting lesions requiring neurosurgery are
100% and 5%, respectively. Clinically important lesions not requiring imme­ several hours.19 Whether it is necessary to awaken
diate surgery include contusions; subarachnoid blood; small subdural, paren- a patient at night to confirm that he or she can
chymal, and intraventricular hematomas; and certain skull fractures. Data are be aroused has not been established; if this is a
from Haydel et al.,13 Stiell et al.,14 and Smits et al.15
‡ The sensitivity and specificity of the Canadian CT Head Rule criteria for detect- concern, hospitalization is more reasonable. It is
ing clinically important CT lesions are 87% and 39%, respectively; the sensitivity generally recommended that patients not resume
and specificity for detecting lesions requiring neurosurgery are 100% and 38%, normal activity until they are free of headache
respectively. Adapted from Stiell et al.,14 Smits et al.,15 and Stiell et al.16
§ Signs of basal skull fracture include hemotympanum, raccoon eyes, otorrhea and dizziness, but there are no data to indicate
or rhinorrhea, and Battle’s sign (mastoid ecchymosis). that an earlier return may be harmful.
¶ A “dangerous mechanism” refers to a motor vehicle that strikes a pedestrian, New drowsiness, hemiplegia, or aphasia after
ejection from a motor vehicle, or a fall from an elevation of 3 ft (about 1 m)
or more or five or more stairs. concussion is cause for concern about the possi-
bility of a delayed subdural or epidural hematoma

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 clinical pr actice

and warrants examination and imaging studies. Table 2. International Classification of Diseases, 10th Revision, Criteria
If these focal signs are not due to intracerebral for Postconcussion Syndrome (Code 310-2).
bleeding, the possibility of a stroke from inevident Interval between head trauma with loss of consciousness and development
carotid artery dissection should not be overlooked. of symptoms, ≤4 wk
When imaging studies of the brain and major Symptoms in at least three of the following categories:
cervical and cerebral vessels show no abnormali- Headache, dizziness, fatigue, noise intolerance
ties, a migrainelike phenomenon is presumed to Irritability, depression, anxiety, emotional lability
be responsible for focal neurologic features.20 Subjective concentration, memory, or intellectual difficulties without
neuropsychological evidence of marked impairment
Certain CT findings influence the duration of
Insomnia
observation and the need for hospitalization. Reduced alcohol tolerance
Small surface contusions of the brain or limited Preoccupation with above symptoms and fear of brain damage, with
amounts of subarachnoid hemorrhage occur in hypochondriacal concern and adoption of sick role
approximately 5% of cases. These injuries usually
do not give rise to neurologic problems other
than headache, but they indicate that the impact ry.27,28 Postconcussive symptoms are more com-
was severe and call for more prolonged observa- mon among patients who express a preoccupation
tion, generally overnight in the hospital. A frac- with brain damage or who have a marked inten-
ture through the groove of the middle meningeal sification of symptoms after mental or physical
artery represents a special risk for epidural hema- effort.
toma. Follow-up imaging is reasonable for all of Imbalance and disequilibrium reflect vestibu-
these intracranial lesions, although its value and lar damage (“vestibular concussion”).29 Affected
optimal timing have not been studied. patients have vertigo or experience motion of the
environment while walking or driving. The ves-
Postconcussion Syndrome (Posttraumatic tibular damage is evident in an abnormal vestib-
Nervous Instability) ulo-ocular reflex, which is tested by rapidly turn-
Postconcussion syndrome consists of a constella- ing the patient’s head several degrees to one side
tion of sometimes disabling symptoms, mainly while the patient focuses on a fixed point and ob-
headache, dizziness, and trouble concentrating, serving the patient for a slippage of fixation.
in the days and weeks following concussion (Ta- Data from controlled trials are lacking to guide
ble 2).21,22 The frequency and natural history of treatment of the postconcussion syndrome. How-
the disorder are unclear. In case series, incidences ever, reassurance and education about the effects
of headache and dizziness have been as high as of concussion in an early single encounter have
90% at 1 month and approximately 25% at 1 year been shown to reduce the incidence and duration
or more, and the incidence of memory difficulty of symptoms at 6 months.30 Clinical experience
has ranged from 4 to 59% at various times.23 suggests a benefit from the use of mild analgesics
Once established for more than a few weeks, for headache, avoidance of narcotics, and the use
symptoms often persist for months and tend to of meclizine, promethazine (Phenergan), and ves-
resist treatment, although they eventually lessen. tibular exercises for dizziness, although these
Unresolved issues of compensation and litigation treatments have not been carefully studied in the
have been associated with persistent symptoms.24,25 postconcussion syndrome. Antidepressants are
Countries in which litigation after accidents is in- used in practice for patients with protracted symp-
frequent have extremely low rates of postconcus- toms of worry, sleeplessness, poor concentration,
sive disability,26 and the problem is almost un- and daily headache, but data on the effec­tiveness
known in young children. Nonetheless, difficulty of antidepressants in these cases are also limited;
concentrating certainly occurs in the absence of one small study has failed to demonstrate a ben-
these complicating features and can be demon- efit of antidepressants for headache after head
strated with neuropsychological tests, in some injury.31 In patients with a history of migraine,
cases for months after concussion. concussion may trigger prolonged headaches.
Anxiety and depression are reported by more Clinical experience supports using therapies for
than a third of patients with persistent postcon- spontaneously occurring migraine (triptans, anti-
cussive symptoms, but it has been difficult to convulsants, calcium-channel or beta-adrenergic
establish whether these traits preceded the inju- blockers, or corticosteroids).32

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 The n e w e ng l a n d j o u r na l of m e dic i n e

Concussion during Athletics Recommendations are generally conservative, re-

Athletes who have had a concussion have a slight- flecting concern about an increased risk of a sec-
ly higher incidence of subsequent concussions ond concussion.
during the same playing season.33 Extensive test-
ing of several hundred amateur and professional A r e a s of Uncer ta in t y
athletes after a single concussion has demonstrat­
ed a return to baseline cognitive and motor per- The cerebral lesions associated with severe trau-
formance within several weeks.34,35 Several stud- matic brain injury certainly cause cognitive and
ies of collegiate rugby and soccer players have personality changes, but the effects of concussion
shown decreased scores on selected neuropsycho- are less clear.43 A recent concern has been the pos-
logical tests in proportion to the number of self- sibility of persistent cognitive decline as a result
reported head injuries,36 but other studies, includ- of single or repeated concussions, even from non-
ing a recent one of Australian football players,37 concussive “heading” of the ball in soccer, termed
indicate no such association. The occurrence of “microtrauma” or “subconcussive” injury. The mag­
cognitive decline after repeated concussion has nitude of the risk of microtrauma, in particular, if
been more clearly demonstrated in boxers who it exists, has been difficult to ascertain because few
have sustained multiple knockouts. There has also studies include measures of performance before
been concern that a second impact within a short the injury and control groups have been of uncer-
period could lead to catastrophic neurologic dam- tain comparability. Better-designed studies have
age. This largely unfounded concern is based on not demonstrated a loss of intellectual function.
rare and mostly disputed cases in which a second The appropriate duration of abstinence from sports
mild head injury in children caused massive ce- after concussion has not been determined. In ad-
rebral edema.38,39 dition, the causes and optimal management of
There are scant data to guide decisions about postconcussive symptoms remain unclear.
the timing of a return to sports after concus-
sion.40‑42 Evaluation at the sidelines generally in- Guidel ine s
cludes tests of mental function and coordination
and provocation of symptoms such as headache, The American Academy of Neurology,44 the Cana-
dizziness, or unsteadiness with exertion (Table 3). dian Academy of Sport Medicine,45 and several

Table 3. Guidelines for the Management of Sport-Related Concussion.*

Symptoms First Concussion Second Concussion

Grade 1: no loss of con­ Remove from play Allow return to play after 1 wk
sciousness, transient Examine at 5-min intervals if there are no symptoms
­confusion, resolution May return to play if symptoms dis­appear and results at rest or with exertion
of symptoms and mental of mental-function examination return to normal
abnormalities in <15 min† within 15 min
Grade 2: as above, but with Remove from play and disallow play for rest of day Allow return to play after 2-wk
mental symptoms for Examine for signs of intracranial lesion at sidelines and period of no symptoms at
>15 min obtain further examination by a trained person on rest or with exertion
same day Remove from play for season
Allow return to play after 1 wk if neurologic examination if imaging shows abnor-
is normal mality
Grade 3: any loss Perform thorough neurologic examination in hospital Withhold from play until
of consciousness and obtain imaging studies when indicated symptoms have been ab-
Assess neurologic status daily until postconcussive sent for at least 1 mo
symptoms resolve or stabilize
Remove from play for 1 wk if loss of consciousness lasts
seconds; for 2 wk if it lasts minutes; must be asymp-
tomatic at rest and with exertion to return to play

* These guidelines reflect consensus opinion, are not evidence-based, and are under revision. Adapted from the American
Academy of Neurology guidelines.44
† Testing includes orientation, repetition of digit strings, recall of word list at 0 and 5 minutes, recall of recent game events,
recall of current events, pupillary symmetry, finger-to-nose and tandem-gait tests, Romberg’s test, and provocative test-
ing for symptoms with a 4-yd (3.5-m) sprint, five push-ups, five sit-ups, and five knee bends.

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 clinical pr actice

international symposiums41 have developed rec- should be reviewed with the patient, including the
ommendations for the evaluation and management possibility that headache, dizziness, and mild dif-
of concussion in athletes. These guidelines reflect ficulty concentrating may persist for days or weeks.
expert opinion in the absence of data, and there A temporary leave from work or change to less tax-
is no consensus on which set of guidelines or ing assignments may be appropriate, and if there
grading system is most appropriate. The recom- is litigation, its prompt resolution should be en-
mendations of the American Academy of Neurol- couraged. In the absence of controlled trials to
ogy (Table 3) are under revision but do provide guide postconcussion management, it is reason-
one approach to making sideline decisions. able to treat persistent headaches and dizziness
with medications and nonpharmacologic strategies
Sum m a r y a nd R ec om mendat ions commonly used for these symptoms. If impaired
concentration persists for several weeks, neuropsy-
The patient in the vignette had a concussion com- chological test­ing should be considered to docu-
plicated by an impact-related seizure but had a ment and monitor the deficit.
normal neurologic examination. Because she was No potential conflict of interest relevant to this article was re-
over the age of 60 and had facial and scalp bruises, ported.
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 nor- A video showing
mal examination and scan, she could be safely dis- the head move-
charged to the care of a trusted person who was ment causing
given written instructions to check on the patient concussion is
available with the
several times over the next 24 hours and to return full text of this
if drowsiness, vomiting, confusion, weakness, or article at www.
increased headache occurs. There is no indication nejm.org.
for an anticonvulsant, but non-narcotic analgesics
may be given. The common sequelae of concussion

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