Head injuries occur in 110 to 400 out of every 100,000 adults each year, but are much more common in children—around 692 per 100,000 children younger than 15. Mild traumatic brain injury (TBI) occurs in 75% to 85% of these cases. While serious emotional, cognitive, and behavioral changes are known sequelae of severe TBI, it appears at least in some cases, mild TBI has more significant and longer term effects than previously believed.

Severe TBI
Severe TBI is generally defined as brain injury resulting in loss of consciousness (LOC) for greater than six hours and a Glascow Coma Scale (GCS) score of three to eight. Documented behavioral effects of severe TBI include more disruptive behavior in general, new onset conduct disorder in particular (Gerring JP et al, Brain Inj 2009;23(12):944–955), and increases in aggressive behavior Cole WR et al, Brain Inj 2008;22(12):932–939).

Cognitive effects have been noted for all core academic skills, leading to a reported 79% of kids with severe TBI having failed grades or received special education services within two years post-injury (Ewing-Cobbs L et al, J Clin Exp Neuropsychol 1998;20(6):769–781). Emergence of new onset ADHD (so-called secondary ADHD or SADHD) is a documented phenomenon (Max JE et al, J Am Acad Child Adolesc Psychiatry 2005;44(10):1041–1049), and reports of increases in depressive and anxiety disorders have also been made.

Mild TBI
Definitions of mild TBI vary, but perhaps the simplest is brain injury resulting in any LOC less than 30 minutes, or amnesia, confusion, or disorientation, and a GCS score greater than 12. It is essentially synonymous with the colloquial term “concussion.”

The outcome of mild TBI is far more controversial. Post-concussive syndrome (PCS) is a term frequently used to refer to a constellation of symptoms noted after mild TBI, including complaints of headache, dizziness, fatigue, depressed or anxious mood, sleep disturbance, light sensitivity, forgetfulness, irritability, emotional instability, and concentration difficulties. (It is called post-concussional disorder in DSM-IV.)

Estimates of PCS are 6% to 35% in mild TBI in children. Symptoms of PCS appear to resolve in large part for most patients within the first few months post-injury, but there is evidence for persistent PCS and other behavior problems in a minority of children with mild TBI (Taylor HG et al, Neuropsychol 2010;24(2):148–159). For example, one study found a significant increased risk for psychiatric illness in children with no prior history of psychiatric illness in the three years after mild TBI, especially hyperactivity in the first year after mild TBI (Massagli TL et al, Arch Phys Med Rehab 2004;85(9):1428–1434).

Controversy surrounds the diagnosis of post-concussive syndrome. There is a question as to whether the symptoms experienced can truly be attributed to brain injury per se. Studies have shown increased rates of pre-trauma behavior problems (eg, ADHD), and that some symptoms (eg, SADHD, behavioral problems) have occurred at similar rates following orthopedic non-brain injury and following mild TBI.

Therefore the question is whether behavior problems attributed to mild TBI are cause or effect, and if the answer is effect, effect of what? Are children with behavior problems more likely to be injured in general? Or does the experience of being injured, and not the organ system injured, cause the symptoms described as post-concussive syndrome?

One study attempted to answer these questions by looking at 186 children ages eight to 15 with mild TBI and a comparison group of 99 kids with uncomplicated orthopedic injuries. Patients and their parents were asked to rate their symptoms within three weeks after injury and at one, three, and 12 months post-injury. The mild TBI group had higher ratings of symptoms consistent with post-concussive syndrome both at baseline and at follow-up than the orthopedic injury group. Notably, parent ratings of cognitive symptoms did not peak until three months after a brain injury. More severe ratings were associated with motor vehicle related trauma, loss of consciousness, neuroimaging abnormalities and hospitalization (Taylor op.cit). The study, however, did not discuss in detail what symptoms were most commonly reported or elevated, so it’s difficult to draw more specific conclusions.

Clinically, however, it is clear that many clinicians and families report worsening behavior, concentration, and impulse control in the months after even mild head injury. It is important to our patients and their families to hear that these symptoms are probably related to the injury, and more importantly, will likely improve over time. In my experience, symptoms improve greatly over the first few weeks, then often resolve over the next six months.

For those who don’t improve, careful psychiatric treatment, both psychosocial and possibly psychopharmacological may be warranted. Medications to treat symptoms of inattention and impulsivity (eg, stimulants) or aggression and irritability (eg, valproic acid) are anecdotally helpful. At the moment, there are no clear clinical guidelines as to how to treat these children, beyond the basics of all good psychiatric care—thoughtful individualized assessment, monitoring, and symptom management. It is also very important to minimize the chance of recurrent TBI, as this may lead to even more severe consequences (Byard RW and Vink R, Forensic Sci Med Pathol 2009;5(1):36–38).