An Expert Witness on Concussions Explains Concussions in Plain Terms

By Vernon B. Williams, MD

There has been a dramatic increase in published information regarding concussion in the last several years. But availability of more information has not necessarily resulted in effective knowledge transfer. E.O. Wilson once wrote, “We are drowning in information, while starving for wisdom. The world henceforth will be run by synthesizers, people able to put together the right information at the right time, think critically about it, and make important choices wisely.”  This sentiment can be appropriately applied to the current state of affairs regarding concussion. Some of the most frequently asked questions about concussion (whether talking to physicians, athletes and their family members, or other stakeholders) remain very basic:

  • “Exactly what is a concussion?”
  • “What happens to the brain during a concussion?”
  • “How long will it take to recover?”

Most people (even many physicians) thought until recently that a concussion is when you get knocked out. Massive education efforts have attempted to provide explanations definitions that correct that misinformation. Still, most of the information used to frame concussion and to educate others is either super technical or oversimplified. The scientific and medical education efforts (typically presented at medical conferences or in scientific journals) have been geared to improving fund of knowledge related to epidemiology, pathophysiology, anatomic assessments, and essentials of medical management. The public education efforts (typically presented in the lay press, and public service announcements) are usually meant to provide very basic warnings about the dangers of repeated concussions and returning to play too soon. In my experience as a Sports Neurologist evaluating and treating concussion at every level of competition (including youth/club leagues, high school and collegiate athletes as well as professionals) both kinds of efforts would benefit from further explanation of very basic concussion issues. I find it very useful to “translate” information we as concussion experts understand, into a form of communication that all stakeholders (athletes, parents, and even non-concussion expert physicians) can use to understand the injury and make better decisions through improved insight.

What is a sports concussion?

  • Medical Explanation: Concussion is a complex pathophysiologic process affecting the brain, induced by traumatic biomechanical forces. It is most commonly characterized by the rapid onset of a constellation of symptoms or cognitive impairment that is self-limited and resolves spontaneously.
  • Translation: A concussion is a brain injury. Period. It does not require loss of consciousness. Any impact or force to the head or body that results in a change in how the brain works counts as a concussion. Symptoms typically come on quickly. But in some cases the symptoms develop and evolve over minutes to hours. They can involve headaches, dizziness, imbalance, visual disturbance, confusion, memory loss or a number of other symptoms. Fortunately, for the overwhelming majority of people, the symptoms normally improve on their own.

What happens to the brain? Can you see a concussion on imaging tests? How long does a concussion last?

  • Medical Explanation: Concussions are felt to represent acute metabolic and physiologic changes in the brain that are not visible on traditional imaging studies. Using advanced imaging techniques there may be diffuse axonal damage from stretch injury visible as ultra-structural damage (Diffusion Tensor Imaging) or metabolic abnormalities noted (fMRI, MRS). The metabolic changes may last for days to weeks, despite resolution of clinical symptoms.
  • Translation: You can’t see a concussion on x-ray, CAT scan, or most MRI’s. But the lack of abnormality on those tests does not mean the brain hasn’t been injured. The injury occurs on a cellular level. When special methods are used, there is evidence of change in how the brain is working that last for days to weeks (evidence of persistent brain dysfunction) even when the injured athlete feels that they are back to 100% and the physical examination is normal. Newer tests even show abnormalities in the brain in individuals who have been exposed to repeated impacts without clinically diagnosed concussion.

What actually causes the headaches, confusion, imbalance, and other symptoms? Why can’t I just return to play when I feel better?

  • Medical Explanation: The metabolic mismatch related to alterations in blood flow and glucose metabolism may be the cause of post-concussion cognitive, affective, and physical signs and symptoms. Evidence indicates the highest risk for recurrent concussion is during the immediate several days after a concussion occurs. In addition, the duration of time needed for recovery from a second concussion is much longer, and symptoms are often far more severe. A complete and detailed assessment should be performed on concussed athletes with documentation of resolution of symptoms, normal examination, and return to baseline on any pre-concussion testing prior to return to play.
  • Translation: After concussion, there is an increased need for fuel/energy so that the brain can heal and normalize intracellular and extracellular concentrations of key elements like potassium, calcium and magnesium. But there is a global decrease in blood flow (meaning there is also a decrease in fuel available to correct the abnormalities.) This has been called a “metabolic mismatch”. It is felt that as long as this is the case, the athlete will likely have symptoms and be unable to perform at their best. In fact, attempts to return to play during this time of recovery will likely result in increased symptoms, prolong the duration of symptoms, and may increase the risk of another concussion or other musculoskeletal injury. Rarely, a severe and catastrophic complication called second impact syndrome may result from a second concussion that occurs prior to complete resolution of a previous concussion. For these reasons, it is critical to protect athletes by restricting return to play until all available signs indicate the brain is sufficiently healed and recovered.

Why do concussion symptoms vary from person to person in terms of how long they last? What is chronic post-concussion syndrome and how should it be handled?

Medical Explanation: Factors known to affect concussion symptom duration include age, sex, medical history, concussion history, presenting symptoms, and probably genetic predisposition. Concussed athletes with prolonged symptoms may require more specialized medical evaluation and management techniques as cervicogenic headache, vestibular dysfunction, and/or oculomotor dysfunction may contribute to chronicity and dysfunction. The development of pathologic compensatory mechanism may significantly delay or prevent symptom resolution and contribute to further affective symptoms as well as negatively influence performance.

Translation: Each concussion is unique. Individual people will vary in terms of how quickly they improve. A specific individual will often have differences in how quickly they improve after one concussion compared to another. Concussion recovery tends to take longer in adolescents and children than in adults. Those with history of previous concussion, learning disabilities and/or migraine often take longer than those without those histories. If post-concussion dizziness and imbalance are present, it may take longer to recover. Females tend to take longer to recover than males. The take-home message is that of unique and individual concussions in unique and individual people.

In some cases, concussion symptoms will fail to improve on their own. This may indicate that an injury to the neck and spine, or problems of the visual and balance systems need more specific treatment (because they haven’t healed on their own). Failure to recognize these kinds of issues can result in long-standing problems with physical performance and can contribute to depression and anxiety (further worsening an athlete’s overall condition.) Early recognition and institution of appropriate treatment is a critical aspect of concussion management.

About the Author: Vernon B. Williams, MD is a Sports Neurologist and Pain Medicine Physician. He is the Founding Director, Center for Sports Neurology at the Kerlan-Jobe Orthopedic Clinic in Los Angeles, California, the Director of Pain Medicine at the Kerlan-Jobe Orthopedic Clinic, the Founding Director of the Sports Neurology Fellowship at the Kerlan-Jobe Center for Sports Neurology and the Chief Medical Officer of the Sports Concussion Institute. Dr. Williams serves as consultant to the Los Angeles Lakers, Los Angeles Dodgers, Los Angeles Kings, Los Angeles Sparks, Anaheim Ducks, Loyola University, Fullerton College, and numerous high schools. He completed his Pain Medicine Fellowship at Johns Hopkins. He is a frequent speaker on sports neurology, concussion, and pain. Dr. Williams is an experienced expert witness and independent medical examiner.