What is Post-Concussion Syndrome?

I recently talked with journalist Nathaniel Parish Flannery who writes about cycling. He was writing an article about pro cyclist Ian Boswell. Boswell had a crash in 2019 that resulted in long-term concussion symptoms. Flannery found our conversation and my book, Shaken Brain, very helpful, and he tells Boswell’s story in a Forbes article. I’m pleased that journalists like Flannery are sharing accurate and accessible information about concussions through the stories of real people who experience the consequences.

As an introduction to the topic, here’s some background:

Post-Concussion Syndrome and ICD-10

Post-concussion syndrome (PCS) consists of symptoms that may persist for weeks, months, or years after a concussion. Symptoms may be related to cognitive, behavioral, emotional, or physical health. In the 1990s, in the organization’s International Classification of Diseases (ICD), the World Health Organization (WHO), defined PCS as the presence of three or more of the following eight symptoms following a concussion: 

• headache
• dizziness  
• fatigue
• irritability  
• insomnia  
• concentration  
• memory difficulty  
• intolerance of stress, emotion, or alcohol 

Two things distinguish post-concussion syndrome from a concussion (also referred to as a mild brain injury).

One is the time frame. The initial symptoms caused by a concussion typically appear soon after the trauma and resolve within about two to four weeks. PCS symptoms persist after the acute period and they may continue for months or even years.

The other difference is the intensity and progression of symptoms. While symptoms from the initial injury can get better over time, some PCS may instead worsen over time, especially without treatment.

The medical literature can be confusing. Some writers define PCS as symptoms continuing after one week, one month, or three months. Persistent PCS is generally defined as symptoms lasting more than either three or six months. For people with these symptoms, the time frames are less important than the fact that they are suffering and need expert care and treatment.

Post-Concussion Syndrome Recovery

Sports guidelines have stated in the past that most athletes recover from a concussion in seven to ten days.  That statistic is based on an estimate from out-of-date studies. More recent studies of larger groups of more diverse patient populations show a less promising prognosis. 

For example, a United States multicenter study found that 82% of subjects had at least one PCS symptom at six months and 12 months. Population studies from other countries also suggest that concussion carries a significant risk of developing chronic symptoms. One Canadian study documented that, on average, subjects had eight PCS symptoms that lasted seven months, and only 27% fully recovered. Two-thirds of patients who recovered did so in the first year, and no patients who had symptoms at three years recovered.  A group of New Zealand researchers found that nearly half of subjects had four or more post-concussion symptoms at one year after the injury. Being female or from a non-white ethnic group, having had another brain injury or another co-morbidity, alcohol use, was associated with a poorer outcome. The levels of anxiety, depression, and reduced quality of life were comparable to the general population.

None of these population studies addresses the question of treatment. Clinicians know that proper diagnosis and treatment for symptoms can improve outcomes after concussion and PCS.

Risk Factors for PCS

There are some risk factors for the development of PCS. History of one of these disorders have been associated with increased risk of PCS and also need to be evaluated and treated:

• Migraines or other headaches
• Mental health disorders
• Learning disabilities or dyslexia
• Attention-deficit/hyperactivity disorder
• Sleep disorders

Two PCS Stories

Pro Cyclist Ian Boswell

Pro cyclist Ian Boswell’s story is consistent with a diagnosis of post-concussion syndrome. He reports continuing symptoms like difficulty thinking and focusing, even though he has improved over time. 

Dr. Seth Fischer, a medical student

Seth Fischer, a medical student and concussion survivor who was the subject of two interviews I conducted a year apart, described firsthand how PCS affected his life. His symptoms – headaches, body aches, dizziness, blurred vision, and sensitivity to light, movement, and sound – lasted off and on for more than a year after the bike accident on the University of California Davis campus. Seth described how the chronic pain and depression he experienced fed into one another, making both worse. It was a tough time in his life, but he is in his residency now, training to become an anesthesiologist.

Seth’s and Ian’s stories are just two of many. For people with PCS, life can be an ongoing battle of chronic pain and other symptoms that are hard to treat, and every aspect of life can be affected.

Why Post-Concussion Syndrome Is Controversial

PCS is a controversial topic in medicine. While the data show that many people experience symptoms long after a concussion, PCS may vary significantly from patient to patient, which is not typical of a “syndrome.” Watch my video interviews with Seth Fischer and with three physiatrists (physical medicine and rehabilitation physicians) who talk about the range of treatments for post-concussion symptoms. 

Treatment is not addressed in the recovery studies I mentioned earlier in this blog. Many people with concussion do not get comprehensive evaluation and treatment which, of course, can change outcomes.