CTE: what we don’t know

Sunday, May 24, 2015

There is danger in learning medicine by assertions published by the press, and there is risk in relying upon isolated extracted quotes that may or may not reflect an expert’s view. It is especially difficult when the science behind a theory is very new. Changes in medical knowledge happen slowly and early adopters of new theories are often proven wrong…or are driven to develop compelling research that makes a difference in how medical care is provided.

All this to talk about chronic traumatic encephalopathy (CTE) and the criticism of Gary Bettman, NHL commissioner, when he was suggested in a press conference, that the correlation between heed trauma and CTE has yet to be proven.

From a medical science standpoint, there is no evidence yet that one (concussion) necessarily leads to the other (CTE),” said Bettman to reporters on hand. “I know there are a lot of theories, but if you ask people who study it, they tell you there is no statistical correlation that can definitively make that conclusion.

Mr. Bettman was taken to task by researchers, broadcasters and others who want to be able to explain the consequences of repetitive head injuries, and how to prevent concussions in sports, the military and other workplaces, from causing significant brain deterioration, and loss of mental function and early death.

Chris Nowinski, the executive director and co-founder of the Sports Legacy Institute an also works with the Boston University CTE Center, was quoted by Josh Cooper of Yahoo Sports:

We have plenty of medical and scientific evidence that brain trauma leads to CTE. In fact the experts from the Department of Defense and the National Institute of Health are both on record saying they personally believe that CTE is caused by brain trauma.

Ray Slover of the Chicago Tribune wrote the following:

Gary Bettman might have been speaking as a lawyer as well as head of the National Hockey League this week when he said there was no established link between concussions and chronic traumatic encephalopathy.

He also might have been the NHL equivalent of an ostrich sticking his head in the sand or a climate-change denier. Bettman’s stand certainly seems to fly in the face of medical evidence.

Keith Olbermann named Mr. Bettman the worst person in the sports world on his May 22, 2015 television program.

For all this rhetoric, perhaps it’s important to take a step back and try to acknowledge that we know only what we know. Perhaps we should turn to the experts for their understanding of CTE and its causes. This is a relatively new disease entity, so new in fact, that there was not a standardize set of criteria to make the diagnosis. In February 2015, a consensus conference was held by the National Institutes of Health. The diagnosis can only be made at autopsy, when abnormal tau proteins are found irregularly scattered within the depths of brain tissue and cells. The abnormal protein “pathology has only been found in individuals exposed to brain trauma, typically multiple episodes.  How common this pathology occurs at autopsy and the nature and degree of trauma necessary to cause this neurodegeneration remain to be determined.”

The “to be determined” is a big step for science when it comes to cause and effect. In the presentation of the group’s consensus, Dr. Ann McKee, of the CTE Center, wrote the following bullet points:

“Relationship between concussion, subconcussion and CTE is unclear”

  • Concussion, subconcussion and post-concussion syndrome: most likely reversible states of neuronal and axonal derangement
  • CTE- a latent, progressive neurodegenerative disease.
  • Repetitive injury superimposed on unresolved injury may initiate a series of metabolic and cytoskeletal disturbances that trigger a pathological cascade leading to CTE in susceptible individuals
  • The number of concussions does not correlate with CTE or predict CTE
  • However, the severity of CTE is significantly associated with length of exposure in American football, and it is likely that this is a result of the cumulative effects of subconcussive injury

There is still much work to be done to build on the initial finding of the CTE group. Many more brains need to be analyzed, since a sampling bias needs to be removed from the research. The brain banks that accept tissue donated from athletes and their families who suspect that a major neurologic problem exists. This may skew what might be happening in the general population. Many people have minor head injuries and perhaps the Tau deposition is more commonly spread throughout the population than presently known. The special pathology tests are note routinely done on every autopsy, but the deposits of tau protein in CTE differs than the same protein distribution in Alzheimer’s Disease. Volunteers from the general public are being recruited to keep diaries of their lives and donate their brains science. This will not be a short term project.

A great doctor or scientist knows what they know and what they don’t. It is hard to pursue the mysteries of the human body. Mr. Bettman reminded us that while we think we might know some answers, there are significant gaps in our understanding of the brain. Head trauma may cause CTE but we don’t know how many are needed, how severe or how often they might occur and what victims are more susceptible to the disease. We do not know how to make the diagnosis when people are alive, nor how to treat them to prevent the development of CTE. And we don;’t know how to treat CTE should the symptoms be recognized. The bottom line is that we don’t know very much.





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diagnostic errors

Monday, May 18, 2015

It’s the spectacular play that makes the highlight package on Sportscenter. Fans can be amazed at the amazing catch or incredible shot. But at the end of the day, it’s mistakes that lose games and cost championships. Sometimes, it’s the referee or umpire who misses a call and is blamed for adversity. The solution often offered is technology with instant replay, slow motion and multiple camera angles to oversee what had been judged in the blink of an eye. Victors are those who avoid the most mistakes and take advantage of the errors of their opponents.

It is not widely publicized, but mistakes happen in medicine and at an alarming rate. There is a presumption, by patient and family, that technology decreases the risk of errors and makes for better care. That line of thinking opens a Pandora’s box of wrong. Some doctors feel obligated to order tests to confirm their clinical suspicions. Some suffer from a lack of confidence to stand by their bedside decisions. Others believe that ordering a test will decrease their perceived risk of being sued, the concept of “covering their butt”. And sometimes, tests are ordered because families want the reassurance of technology, since blood tests and x-rays can be tangible proof that all is well…except those tests are only as good as their interpretation, done by a radiologist or pathologist who is an anonymous, faceless provider. All the doctor or patient sees are the results on a computer screen. After all, if it’s in the computer, it must be true.

But mistakes happen and at a relatively high rate. X-ray results aren’t always perfect and different radiologists can interpret the same picture in different ways. When reviewing a radiologist’s reports, the error rate can range between 3 and 3.5%. More complicated studies like CT, MRI and ultrasound can have error rates as high as 7%. Interestingly, if one asks more than one radiologist to read a film, the resulting discrepancy rate can run higher than 30%, meaning they don’t agree with each other a third of the time. But that does not necessarily lead to patient harm, because any test result needs to be interpreted in the context of the bedside assessment of the patient.

The key begins with ordering the test in the first place. There needs to be an expectation that the extra information will be a decision maker for the doctor when it comes to diagnosis and treatment. There needs to be a plan of action for each positive or negative result. Blood tests can be very reassuring when they are normal, except when there are false positives and false negatives. The doctor needs to understand the limitations of each blood test and not be falsely reassured when a test comes back normal, only because it was drawn too early in the disease process…or too late. Imagine taking a pregnancy test immediately after intercourse, knowing that it is too early to turn positive, and yet relying on that result for the next none months.

No matter how much or how little technology is used, getting the right diagnosis is tough. Studies from Johns Hopkins estimate 80,000-180,000 patients in the US are harmed each year because of diagnostic errors. Most happen in the doctor’s office as opposed to the hospital and most are due to a missed diagnosis, rather than a delayed or wrong one. Which brings the discussion back to using technology as a crutch instead of a tool.

Diagnosis is based on history. The patient will tell the doctor what’s wrong if the doctor has time to listen, ask the right questions and interpret the answers. Patients and families are often frustrated when the same questions are repeatedly asked by the person who escorts them to the exam room, the nurse who takes their vital signs and the doctor who seems to be in too much of a hurry to really listen. Each listener can interpret an answer in a different way, and nuance can be helpful in pointing the doctor in the right direction to make a diagnosis. Physical exam is helpful but the guiding light tends to be the history, the old fashioned sitting down and talking to the patient. Diagnosis may be self evident but most often it takes time.

Errors will happen in sports and in the doctor’s office. Minimizing the number of errors should increase the chances of winning; the stakes are just a little higher for the patient. There is an art to diagnosis and technology offers few short cuts. For those who prefer computer algorithms in making a diagnosis, try asking a computer to assess the wife’s face that frowns when her husband minimizes a complaint with that recognition leading to a new line of questioning and perhaps the right answer. Nobody said anything about talking needing words.

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