Brain concussion

Template:DiseaseDisorder infobox Concussion, or mild traumatic brain injury (MTBI), is the most common and least serious type of brain injury. Concussion is a "trauma-induced alteration in mental status that may or may not involve loss of consciousness". A loss of consciousness is infrequent although some definitions require a loss of consciousness. It can be caused by acceleration or deceleration forces, or by a direct blow. Concussion is generally not associated with penetrating injuries, but instead with blunt trauma.

Classification

Grades

American Academy of Neurology clinical practice guidelines grade as follows:

Grade 1:

1. Transient confusion
2. No loss of consciousness
3. Concussion symptoms or mental status abnormalities on examination resolve in less than 15 minutes.

Grade 2:

1. Transient confusion
2. No loss of consciousness
3. Concussion symptoms or mental status abnormalities on examination last more than 15 minutes

Grade 3:

1. Any loss of consciousness, either brief (seconds) or prolonged (minutes).

Symptoms

The frequency of various symptoms has been studied using collegiate football players: the NCAA Concussion Study.

Symptoms of concussion in the NCAA Concussion Study

	Frequency
Headache	85%
Dizziness/balance difficulties	77%
No loss of consciousness nor amnesia	78%
Loss of consciousness	6% (median duration, 30 seconds)
Anterograde amnesia Events after the injury such as exiting the field	19% (median duration, 90 minutes)
Retrograde amnesia Events before the injury such as inability to recall aspects of the play	7% (median duration, 120 minutes)
Delayed onset of symptoms	12% (mean delay; 14+15 minutes)

In a study of concussions in Australian Football League, 44% (102 of 234) were recorded during television broadcast. Among the concussions recorded on television, 25% showed tonic posturing lasting 2 to 30 seconds with "abduction and elevation of semiflexed arms and shoulders in a 'bear-hug' posture" similar to decorticate rigidity while one-quarter of the patients with posturing also had clonic movements usually less than 10 seconds. Seizures may occassionally occur.

Diagnosis

8% of patients have acute intracranial lesions; less than 2% of concussions require neurosurgery.X-ray computed tomography of the head should be considered, especially if the patient fulfills any criteria from the New Orleans Criteria clinical prediction rule for brain injury:

"headache, vomiting, an age over 60 years, drug or alcohol intoxication, deficits in short-term memory, physical evidence of trauma above the clavicles, and seizure"

X-ray of the cervical spine should be considered, especially if the patient fulfills criteria from the Canadian C-Spine Rule clinical prediction rule for neck injury:

• Age 65 years or more
• Paresthesias in extremities
• Dangerous fall ("elevation >=3 ft or 5 stairs; an axial load to the head (e.g., diving); a motor vehicle collision at high speed (>100 km/hr) or with rollover or ejection; a collision involving a motorized recreational vehicle; or a bicycle collision")
• Inability to rotate the neck 45° to the right and left
  • Only test if "simple rear-end motor vehicle collision, sitting position in ED, ambulatory at any time since injury, delayed onset of neck pain, or absence of midline C-spine tenderness"
• Glasgow Coma Scale less than 15 (the Canadian C-Spine Rule was only designed for alert patients)

Pathophysiology

Functional magnetic resonance imaging shows hyperactivity in Brodmann's Area 6 and this is associated with time till recovery.

Prognosis

A cohort study of NCAA football players found that signs and symptoms typically laste 3.5 days and resolvee by one week in 88%. In the same cohort study, slow recovery from concussion is more likely among players with a history of previous concussions and tends to be slower when unconsciousness or amnesia occurred.

Second Impact Syndrome

Second impact syndrome is a controversial syndrome in which case rapid clinical deterioration occurs after a minor injury. If this exists, it is rare.

Cognitive impairment and dementia

Among retired NFL players, "players with three or more reported concussions had a fivefold prevalence of mild cognitive impairment diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion...we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population"

Treatment

Concussion in sports

Various Clinical practice guidelines address management. Additional recommendations have been based on severity of the concussion and prior concussion (see Ropper et al Table 3.

American Academy of Neurology

Clinical practice guidelines from the American Academy of Neurology although not revised since 1997, provide current advice on managing concussion in sports:

Grade 1:

1. "Remove from contest"
2. "Examine immediately and at 5 minute intervals for the development of mental status abnormalities or post-concussive symptoms at rest and with exertion."
3. "May return to contest if mental status abnormalities or post-concussive symptoms clear within 15 minutes.
4. "A second Grade 1 concussion in the same contest eliminates the player from competition that day, with the player returning only if asymptomatic for one week at rest and with exercise."

Grade 2:

1. "Remove from contest and disallow return that day."
2. "Examine on-site frequently for signs of evolving intracranial pathology."
3. "A trained person should reexamine the athlete the following day."
4. "A physician should perform a neurologic examination to clear the athlete for return to play after 1 full asymptomatic week at rest and with exertion."
5. CT or MRI scanning is recommended in all instances where headache or other associated symptoms worsen or persist longer than one week."
6. Following a second Grade 2 concussion, return to play should be deferred until the athlete has had at least two weeks symptom-free at rest and with exertion."
7. Terminating the season for that player is mandated by any abnormality on CT or MRI scan consistent with brain swelling, contusion, or other intracranial pathology."

Grade 3:

1. "Transport the athlete from the field to the nearest emergency department by ambulance if still unconscious or if worrisome signs are detected (with cervical spine immobilization, if indicated)."
2. "A thorough neurologic evaluation should be performed emergently, including appropriate neuroimaging procedures when indicated."
3. "Hospital admission is indicated if any signs of pathology are detected, or if the mental status of the athlete remains abnormal."
4. "If findings are normal at the time of the initial medical evaluation, the athlete may be sent home. Explicit written instructions will help the family or responsible party observe the athlete over a period of time."
5. "Neurologic status should be assessed daily thereafter until all symptoms have stabilized or resolved."
6. "Prolonged unconsciousness, persistent mental status alterations, worsening postconcussion symptoms, or abnormalities on neurologic examination require urgent neurosurgical evaluation or transfer to a trauma center."
7. "After a brief (seconds) Grade 3 concussion, the athlete should be withheld from play until asymptomatic for 1 week at rest and with exertion."
8. "After a prolonged (minutes) Grade 3 concussion, the athlete should be withheld from play for 2 weeks at rest and with exertion."
9. "Following a second Grade 3 concussion, the athlete should be withheld from play for a minimum of 1 asymptomatic month. The evaluating physician may elect to extend that period beyond 1 month, depending on clinical evaluation and other circumstances."
10. "CT or MRI scanning is recommended for athletes whose headache or other associated symptoms worsen or persist longer than 1 week."
11. "Any abnormality on CT or MRI consistent with brain swelling, contusion, or other intracranial pathology should result in termination of the season for that athlete and return to play in the future should be seriously discouraged in discussions with the athlete."

2nd International Conference on Concussion in Sport

The 2nd International Conference on Concussion in Sport recommends:

For the acute injury:

1. The player should not be allowed to return to play in the current game or practice.
2. The player should not be left alone, and regular monitoring for deterioration is essential over the initial few hours after injury.
3. The player should be medically evaluated after the injury.
4. Return to play must follow a medically supervised stepwise process.
5. A player should never return to play while symptomatic.

Return to play protocol:

1. No activity, complete rest. Once asymptomatic, proceed to level 2.
2. Light aerobic exercise such as walking or stationary cycling, no resistance training.
3. Sport specific exercise—for example, skating in hockey, running in soccer; progressive addition of resistance training at steps 3 or 4.
4. Non-contact training drills.
5. Full contact training after medical clearance.
6. Game play.

External links

• Sport Concussion Assessment Tool (SCAT card). Complete version is available at http://bjsm.bmj.com/cgi/content/full/39/4/196/F1.