An Update on Concussion

(Editor’s Note:  I’m pleased to share this guest post by one of our first year child psychiatry fellows, Dr. Winston Chung.)

More recently, one of the hot topics in Pediatrics, Neurology, and Psychiatry is the impact of concussion(s) on the developing mind. It came into the public consciousness due to the highly publicized death of beloved NFL football players like Junior Seau, and the tragic accident of 13yo Zackery Lystedt who collapsed after a football game and later required neurosurgery to alleviate the pressure produced by the swelling in his brain.   Increasingly, we’re forced to confront the difficult decision of whether we should allow our kids to play football, hockey, or soccer, and the morality of supporting billion dollar industries that produced a product where men launch themselves at one another destroying their body and mind.

The American Academy of Neurology defines concussion as a biomechanically induced clinical syndrome leading to alteration of brain function, affecting memory, and orientation, and may involve loss of consciousness. Though definitions vary, many clinicians define concussion as a subset of mild Traumatic Brain Injury which is defined as Glasgow Coma Scale score of 13-15, loss of consciousness of less than 30 minutes (if present), and posttraumatic amnesia of 24 hours (if present). There are between 1.5-3.8 million sport-related TBIs in the US each year, the majority of which are mild TBI and concussions. Concussions lead to 100,000 Emergency Room visits each year for school-aged children and represents 9% of all high school sports injuries.

Concussions are produced by acceleration and deceleration forces on the brain, whether linear or rotational. When these forces act on the brain, it stretches and deforms, doing the same to the individual components that make up the brain such as neurons, and blood vessels. The axons that make up the white matter tracts are especially vulnerable to injury given their length. The disruption of the neuronal membranes leads to disruption of neurotransmitters and electrolytes that are neatly sequestered, causing the brain to go into a hypermetabolic state (thus requiring glucose) to return it to its former equilibrium. This leads to a widened gap between the increased energy needs of the neurons and the decreased blood flow to the brain, resulting in an energy crisis.

The result of this disruption are headaches, fatigue, dizziness, slowed mentation, drowsiness, difficulty concentrating, nausea, light sensitivity, noise sensitivity, forgetfulness, blurry vision, sleep disturbance, irritability, depression, vomiting, and tinnitus. Usually the symptoms are self-limiting and they resolve after 7-10 days. However, symptoms in children may resolve more slowly. The mean duration of post-concussion symptoms among patients age 8-23 years who were referred to a concussion clinic was 43+/- 55 days. A minority of the patients reports post-concussion symptoms that persist for months, sometimes years. Repeated head trauma appears to lead to one of two presentations. Mood and behavioral symptoms usually appearing in third decade of life, and cognitive impairment and memory loss developing in fifth decade of life. The majority of subjects who present initially with behavior or mood symptoms progress to have cognitive symptoms before passing away, whereas those who present with cognitive impairment less commonly develop mood symptoms.

One topic that hasn’t been discussed enough in the press is the potential health effects of subconcussive injuries. Subconcussive impact is defined as biomechanically induced injuries to the brain that do not result in clinical symptoms, but may have a cumulative effect leading to chronic traumatic brain injury in some adult patients. Recently, a small study showed white matter microstructure changes in professional soccer players who did not have a history of concussions when compared to age-matched swimmers. And it’s been reported that an offensive lineman in American football can experience over 1,000 subconcussive hits over the level of 10g in the course of a single collegiate season.

(Of note, for further information, please see an excellent presentation on the topic by Dr. Jim Hudziak who discussed concussions at a recent Community Medical School talk at the University of Vermont College of Medicine.  The video will soon be available and can be accessed here.)

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