Concussion of the brain

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**Concussion of the brain**
*Classifications and external resources*
ICD-10	S06.0
ICD-9	850

Concussion, or mild traumatic brain injury (MTBI), is the most common and least serious type of traumatic brain injury. A milder type of diffuse axonal injury, concussion involves a transient loss of mental function. It can be caused by acceleration or deceleration forces, or by a direct blow. Concussion is generally not associated with penetrating injuries.

1 Pathophysiology
2 Symptoms
3 Grades
4 Lasting effects
5 Second Impact Syndrome
6 External links
7 See also
8 References

[edit] Pathophysiology

The brain floats within the skull surrounded by cerebrospinal fluid (CSF), one of the functions of which is to protect the brain from normal light "trauma", e.g., being jostled in the skull by walking, jumping, etc., as well as mild head impacts. More severe impacts or the forces associated with rapid acceleration/deceleration may not be absorbed by this cushion.

Concussion is considered a type of diffuse, as opposed to focal, brain injury, meaning that the dysfunction occurs over a more widespread area of the brain.

Excitatory neurotransmitters are released as the result of the traumatic injury and cause the brain to enter a state of hypermetabolism which can last for 7 to 10 days.<ref name="orlando">Orlando Regional Healthcare, Education and Development (2004). Overview of Adult Traumatic Brain Injuries. Retrieved on 2006-10-20.</ref> During this time, the brain needs extra nutrients and is especially sensitive to inadequate blood flow.

Areas of the brain whose function is commonly disturbed in concussion include the reticular formation or the deep structures of the brain, the brainstem or cortices.<ref name="dawodu">Dawodu S (July 15, 2005). Traumatic Brain Injury: Definition, Epidemiology, Pathophysiology. eMedicine.com. Retrieved on 2006-10-20.</ref> Damage to cranial nerves and other white matter tracts may be temporary or permanent.<ref name="baiusa">Brain Injury Association of America. Types of Brain Injury. Retrieved on 2006-10-20.</ref> Other theories hold that concussion is a diffuse injury affecting all parts of the brain, caused by physical trauma that alters neuronal metabolism and excitability through molecular commotion. Having a concussion does not mean that the patient does not have another brain injury as well; in fact, more serious brain trauma is almost always accompanied by concussion.

[edit] Symptoms

Symptoms of concussion can include a period of unconsciousness for less than 30 minutes,<ref>Smith D and Greenwald B (December 19, 2003). Management and Staging of Traumatic Brain Injury. eMedicine.com. Retrieved on 2006-10-20.</ref> vomiting, confusion, and visual disturbances. Amnesia, the hallmark sign of concussion, can be retrograde amnesia (loss of memories that were formed before the injury) or anterograde amnesia (loss of memories formed post-injury).<ref name="orlando"/> Patients with concussion may act confused, for example repeating the same sentences or forgetting where they are. Patients with concussion may have focal neurological deficits, signs that a specific part of the brain is not working correctly.<ref name=" ">Boon R and de Montfor GJ (2002). Brain Injury. Learning Discoveries Psychological Services. Retrieved on 2006-10-20.</ref>

Since concussions do not include damage to the brain's structure, the condition of patients with uncomplicated concussions always either improves or stays the same. Thus, a deteriorating level of consciousness means that the patient has another problem such as a worse type of head injury. Similarly, persistent vomiting, worsening headache, ringing in the ears (tinnitus), drowsiness, unequal pupil size, and increasing disorientation are all indicative of a rise in intracranial pressure (ICP).<ref name="bernhardt">Bernhardt D (July 5, 2006). Concussion. eMedicine.com. Retrieved on 2006-10-20.</ref>

[edit] Grades

Concussion is classified into five grades

The mildest, grade I, involves only confusion.<ref name="shepherd">Shepherd S (August 20, 2004). Head Trauma. eMedicine.com. Retrieved on 2006-10-20.</ref>
Grade II involves anterograde amnesia that lasts less than five minutes as well as confusion.
Grade III involves the symptoms above, as well as retrograde amnesia and unconsciousness for less than five minutes.<ref name="shepherd"/>
Grade IV involves all of the above symptoms, as well as unconsciousness that lasts between 5 and 10 minutes.<ref name="shepherd"/>
Grade V is the same as grade IV, with unconsciousness lasting longer than ten minutes.

The American Academy of Neurology (AAN) guidelines make it clear that permanent brain injury can occur with either Grade 2 or Grade 3 concussion. Thus, it is clear that subtle brain injury can have permanent consequences if the acute symptoms of the concussion continue for more than 15 minutes.

Each grade comes with different recommendations for patients who play sports:

In grade I, the patient may return to contact sports in 20 minutes.
A patient with a second time grade 1 concussion may return to play contact sports in 2 weeks after being asymptomatic for a week.
In grade II, the patient may return to contact sports in 1 week.
A second time grade II may return to play contact sports 1 month after being asymptomatic for a week.
In grade III, the patient may return to contact sports in 1 month.
For a patient with a second time grade III concussion, the season is over.

However, if the patient has repeated concussions after contact sports, grade I x 3, grade II x 2, and especially grade III x 2, then it should be recommended that the season is over and a thorough medical evaluation should be considered mandatory.

[edit] Lasting effects

Some concussions can have serious, lasting effects. The symptoms of most concussions are resolved in 48 to 72 hours, but in many patients, problems persist.<ref name="tolias">Tolias C and Sgouros S (February 4, 2005). Initial Evaluation and Management of CNS Injury. eMedicine.com. Retrieved on 2006-10-20.</ref><ref name="shepherd"/> In postconcussive syndrome (PCS), concussion symptoms do not resolve for weeks, months, or even years, and the patient may have headaches, light and sound sensitivity, memory and attention problems, dizziness, difficulty with directed movements, depression, and anxiety. Symptoms usually peak 4 to 6 weeks after the concussion, but may go on longer, some even lasting a year or more.<ref name="shepherd"/> Children commonly experience more severe symptoms of postconcussion syndrome than adults do.<ref name="shepherd"/> Physical therapy plus rest is the best recovery technique, and symptoms usually go away on their own.

Multiple small head injuries that daze the patient can also result in cognitive and physical deficits that occur in what is commonly known as dementia pugilistica, or "punch drunk" syndrome, which is associated with boxers.<ref name="drake">Drake D and Cifu D (August 17, 2006). Repetitive Head Injury Syndrome. eMedicine.com. Retrieved on 2006-10-20.</ref>

[edit] Second Impact Syndrome

If a patient receives a second blow days or weeks after a concussion, before concussion symptoms have gone away, they are at risk of developing Second Impact Syndrome (SIS) or recurrent traumatic brain injury. In this rare condition, the brain swells dangerously after a minor blow. No one is certain of the cause of this often fatal complication, but some think the swelling is due to the brain's arterioles' loss of ability to regulate their diameter, and therefore a loss of control over cerebral blood flow.<ref name="tolias"/>

In this dangerous condition, intracranial pressure rapidly rises, the brain can herniate, and brainstem failure can occur within five minutes.<ref name="drake">Drake D and Cifu D (August 17, 2006). Repetitive Head Injury Syndrome. eMedicine.com. Retrieved on 2006-10-20.</ref> When this condition occurs, surgery does not help and there is little hope for recovery.<ref name="tolias"/> When it is not fatal, the patient can experience persistent muscle spasms and tenseness, emotional instability, hallucinations, and cognitive problems.<ref name="baiusa">Brain Injury Association of America. Types of Brain Injury. Retrieved on 2006-10-20.</ref> The condition is fairly rare, with only 35 recorded cases in a 13 year period from football injuries, not all of which were confirmed to be due to SIS.<ref name="drake"/>

[edit] External links

TBI Resource Guide Information, services and products relating to brain injury, brain injury recovery, and post-acute rehabilitation.
Dr.Diane.com Informative source on concussion and related rehabilitation services.