By: Nicholas Parekh
Flip through cable channels on a Sunday afternoon, and you are bound to see an NFL game airing. Physicality is inherent to the sport; part of the fun of watching the sport is seeing superhuman athletes run, tackle, and make plays. However, no one can deny that the game poses a serious risk to the athletes. Every sack, tackle, and hit has the potential to cause a concussion – a form of mild traumatic brain injury – even if there is no direct helmet-to-helmet contact.
In recent years, concussions that occur in football, other sports such as rugby, soccer, and boxing, and during military service have been associated with chronic traumatic encephalopathy (CTE), a neurodegenerative disease that results in essentially premature dementia. Concussions can also result in other neurological conditions such as epilepsy by damaging brain cells and changing brain neurochemistry. Studies suggest that concussions may double the risk of epilepsy for the average person and increase the risk of developing it by sixfold in people with a family history of the disorder. This is concerning given the high incidence of concussions, especially among youth athletes. According to the University of Pittsburgh Medical Center (UPMC), about 1.7 to 3 million concussions occur each year with about half of them going undiagnosed and untreated. Two out of every ten high school athletes who play contact sports will experience a concussion during the school year.
First, we must examine correlation studies since experimental studies in this area do not exist (researchers will not intentionally concuss human participants). One study followed a cohort of 330 people who had a concussion and found no increase in the risk of developing epilepsy after following up with them 7.6 years later on average. In this study, they strictly studied the impact of concussions as opposed to moderate or severe traumatic brain injury (TBI). They also excluded concussive convulsions, which are seizures that occur immediately after a mild TBI but are not the same as posttraumatic epilepsy which develops long after the initial injury (months to years). Concussive convulsions are quite rare, only coinciding with one out of every seventy concussions, and they are not associated with the development of posttraumatic epilepsy. A CDC-funded population study found that individuals hospitalized for TBIs were 30 to 90 times more likely to develop posttraumatic epilepsy, and the risk increased with the severity of the TBI. It is important to note that patients hospitalized for TBIs likely have more severe cases (classified as moderate to severe) as opposed to mild concussions. In the state where the study was conducted (South Carolina), over 87.5% of patients who presented to the emergency department with a mild TBI were discharged on the same day and not admitted to the hospital. The study found that the greatest risk factor for the development of posttraumatic epilepsy was the occurrence of posttraumatic seizures, which are seizures that occur while the patient is hospitalized and being treated for the TBI. The researchers also found that TBI patients diagnosed with depression were twice as likely as those without the mood disorder to develop posttraumatic epilepsy. Together, these studies suggest that a few concussions will probably not significantly increase an individual’s risk of developing epilepsy but severe TBIs probably do (another study found that over 50% of people who experienced a severe TBI went on to develop posttraumatic epilepsy).
Posttraumatic epilepsy is not well understood but is hypothesized to arise from excessive inflammation and neuronal death triggered by the initial injury. In the beginning, inflammation and immune cell activation are useful in limiting the extent of brain damage, but these processes are thought to stay “on” and result in neurodegeneration and improper rewiring of the brain which can lead to epilepsy. Due to the lack of understanding of TBI-induced epileptogenesis, there are not many treatments for it besides using anti-epileptic drugs (AEDs) to reduce seizure frequency and intensity. Surgery is difficult due to the generalized brain damage and scar tissue formation resulting from TBI. Future research will likely focus on reducing neuroinflammation while allowing the brain to properly heal to prevent epilepsy.
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