Post-Concussion Syndrome: When Symptoms Persist

In most cases, symptoms of concussion clear within a week to ten days.  But, for reasons that are still unknown,¹ 5-10 percent of those who experience a concussion have symptoms that persist (beyond one month under one classification², beyond 3 months in another³), at which point they are typically diagnosed as having post-concussion syndrome (PCS).

Whether PCS is experienced following a concussion seems to be dependent on a combination of factors, including premorbid vulnerabilty (eg. pre-existing medical conditions), postinjury psychological adjustment, and post-injury changes in brain function.  PCS can result in signficant physical, emotional, and cognitive stress.  In addition, in children and young adults, months of PCS can adversely affect one's developmental trajectory by keeping students out of class and straining personal relationships. 

Children more susceptible to PCS

While children report a PCS that is similar to adults and may suffer from the same behavioral, emotional and somatic difficulties following mTBI such as concussion, youth are more susceptible to PCS.⁴  Because the developing brain is more plastic than the mature brain, younger age at the time of mTBI was originally thought to have a beneficial effect on recovery and expected outcome, allowing a younger athlete to better compensate and recover after brain injury. Current literature, however, indicates that the developing brain may actually be more susceptible and vulnerable to diffuse brain injury, which leads to more pronounced and prolonged cognitive deficits and hyperactivity. The most methodologically sound studies have found that children report worse cognitive symptoms more than a year after concussions than adults.⁵

These deficits affect the child's school work and ability to function at home.

• Children aged 6 to 12 years with mTBI have impaired executive functioning and attention 1 year after injury compared with noninjured controls;
• TBI experienced in middle childhood and later appears to be less detrimental than injuries sustained earlier;
• An mTBI may also cause linquistic changes that adversely affect Verbal IQ and expressive language.
• In cases where symptoms persist, PCS may adversely affect a child's conduct and personality, and can lead to extended school absence and limitations on athletic play.
• Children with higher cognitive ability have better outcomes following head injury, because they may be able to recruit alternative and additional brain resources to compensate for tissue damage.
• A concussion may alter a child's long-term developmental trajectory years after the symptoms of PCS subside (although most studies of PCS typically only follow children for up to a year after injury, potentially before the full effects of the injury have manifested themselves). Although these findings may in part be due to undiagnosed mood or conduct disorders in children, which resulted in an original injury.   The long-term effects on cognitive processing, mood, and behavior suggest the need for continued monitoring and intervention in children, even years after initial concussion.  

Characteristics of postconcussion syndrome according to the International Classification of Diseases, 10th Revision (ICD-10)2

History of head trauma with loss of consciousness precedes symptom onset by a maximum of 4 weeks Three or more symptom categories: Headache, dizziness, malaise, fatigue, noise intolerance Irritability, depression, anxiety, emotional lability Subjective concentration, memory, or intellectual difficulties without neuropsychological evidence of marked impairment Insomnia Reduced alcohol intolerance Preoccupation with above symptoms and fear of brain damage with hypochondriacal concern and adoption of sick role

 

Characteristics of postconcussion syndrome according to the American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 4th edition. Washington, DC. American Psychiatric Association; 1994 (DSM-IV-R)3

A history of head trauma that has caused significant cerebral concussion (eg, with a loss of consciousness, posttraumatic amnesia, or seizures) Neuropsychological evidence of difficulty in attention or memory Three or more symptoms that last at least 3 months and have an onset shortly after head trauma or represent substantial worsening of previous symptoms: Fatigue Disordered sleep Headache Dizziness Irritability or agression with little or no provocation Anxiety, depression, or affect lability Changes in personality Apathy or lack of spontaneity The symptoms result in significant impairment in daily functioning that reflects a decline from previous level.

 

 

1. 1. Barlow K, et. al. Epidemiology of Postconcussion Syndrome in Pediatric Mild Traumatic Brain Injury.  Pediatrics 2010;126(2):e374-381. 

2  World Health Organization. The ICD-10 classification of mental and behavioural disorders: diagnostic criteria for research. Geneva (Switzerland): World Health Organization;1993.

3.  APA. Diagnostic and statistical manual of mental disorders. 4th edition. Washington, DC: APA; 1994.

4.  Field M, Collins MW, Lovell MR, Maroon J. Does age play a role in recovery from sports related concussion? A comparison of high school and collegiate athletes.  J Pediatr. 2003;414:546-553.

5.  Daneshvar D, Riley D, Nowinski C, McKee A, Stern R, Cantu R.  Long-Term Consequences: Effects on Normal Development Profile After Concussion. Phys Med Rehabil Clin N Am 22 (2011) 683-700.

Substantially revised February16, 2012