Brain trauma and rehabilitation

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Brad Voytek
Friday, January 21, 2011; 12:00 PM

Bradley Voytek, Ph. D., a neuroscientist at the University of California at Berkeley, will answer your questions about how the brain recovers after an injury, such as in the case of Rep. Gabrielle Giffords.

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Brad Voytek: Hello everyone, thanks for joining us here. Just so everyone is aware, I want to say right up front that I'm not a medical doctor, nor do I know any specific details about Rep. Giffords' condition.That said, I hope I can answer all of your questions within the next hour or so.

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speech: When will we know if she will be able to talk? If she can speak, how long until she reaches her full potential? In other words, will her speaking never get better after several weeks/months/years?

Brad Voytek: There's no way to really be certain. There is a lot of variability between subjects in terms of their recovery. As Dr. Brown said in his article, Rep. Giffords youth and intelligence will work in her favor, though.Recovery from brain damage is a long process that will require a lot of work and rehabilitation. That said, if recovery does happen, speech generally improves over time, albeit sometimes very slowly.

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Compensations in the brain: Someone mentioned that other parts of the brain can compensate for a damaged part, as in the case of Giffords. Is that right? And is the area where she was injured the speech center, and is there a compensatory avenue to restore speech if this is so?

Brad Voytek: So my research suggests that recovery of "higher" cognitive functions, such as working memory, is supported by intact brain regions. I wrote a "lay" post about my research here:http://blog.ketyov.com/2010/11/voytek-neuron-paper-dynamic.htmlNow, other researchers, including Dr. Corbetta, who is interviewed in the Washington Post article, has specifically studied how the brain supports language recovery. There is an excellent research paper by Blasi and colleagues published in 2002 in Neuron called, "Word retrieval learning modulates right frontal cortex in patients with left frontal damage" that shows that, in patients with damage to the language regions of the brain (usually on the left side), those who recovered showed activity in the intact parts of the right side of the brain that seem to now be supporting language.

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Washington, D.C.: Doesn't it ironically help the congresswoman that the bullet entered and exited her brain, as opposed to it staying in her skull and having to have it removed?

Brad Voytek: From what I understand about gunshot wounds and brain injury, you are correct.A low caliber bullet (such as a 22) may not have enough power to after breaking through the skull to then break back out of the skull. This means that, after entering the brain, the bullet would hit the inside of the skull and bounce off, thus damaging even more brain tissue. In essence, the bullet can ricochet inside the skull a few times.A larger caliber bullet would generally have enough power to enter and exit the skull, causing less damage then a bullet that ricochets around inside.

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Brain injury and stroke: My mother suffered a severe stroke 25 years ago and lost some speech and all ride side capabilities. With rehab she could walk and be independent. She is now 85 and is losing more speech and mobility. She has not had another stroke but cannot walk or talk well. Do retrained parts of the brain get "tired"? Thank you

Brad Voytek: Well, during normal, healthy aging, we begin to lose cognitive functioning anyway. It's great that your mother was able to regain functioning after stroke! However, as she got older, she was probably experiencing normal cognitive degeneration associated with aging. This is likely why your mother started to lose some of her regained speech and mobility.

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How does the brain heal?: Hi, could you start us off with an overview of how healing in the brain differs from healing in other parts of the body such as a cut to the skin or a broken bone?Can the brain ever fully reconstruct itself to the state it was in prior to such a traumatic injury?

Brad Voytek: This is a very complex question, and I'll try and answer as honestly as possible given our current scientific and medical understanding as I see it.First of all, the degree to which the brain can recovery from damage from stroke, traumatic brain injury, and so on is very unclear. If I was forced to guess, a "full" recovery after massive brain damage is probably not likely, though the tools we have to assess that are not available.What does it mean to "fully" recover? Of course anyone who suffers from brain damage will be changed, regardless.That said, there are a lot of researchers out there trying their best to speed the recovery process. Only within the last few years have we seen a strong increase in neuroscience-based treatments. There are a number of researchers and research institutes that are trying to use the tools of modern neuroscience to help guide treatments.For recovery of paralysis and hemiplegia, for example, in people who have lost function of an arm due to brain damage, there is constraint induced movement therapy that tries to force patients to use their damaged arm in order to retrain their intact, undamaged brain.In the cognitive domain, there are groups such as Michael Merzenich's Brain Plasticity Institute, who are working on ways of using brain training to help recovery.

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Rehabilition Centers: It's been noted that TIRR Memorial Hermann has an outstanding reputation for rehabilitation of brain trauma injuries. Could you name other institutions that are also highly regarded in this particular field?

Brad Voytek: The Rehabilitation Institute of Chicago has an excellent reputation for helping patients with stroke, brain injury, etc.Personally, as I mentioned in another response, I am partial to the groups that are trying to fold in a neuroscientific understanding as a way of maximizing recovery.There are a few main approaches: rehabilitation, repair, and technological. For rehabilitation, the goal is to retrain people after injury. For repair, you have researchers trying to do things like stem-cell therapy (which is still in the very early research stages) to try and repair the damage done. For the technological, you have researchers trying to use technology to assist patients with brain damage. This would be for something like using a brain-computer interface (also in the research stage) to help patients with movement impairments, for example.There are many universities and research centers working on some, or all, of these approaches.

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brain anoxia: What are the neurological recovery prospects for patients with a period of brain anoxia? (My interest in this question is personal, as I had approximately 2 minutes of cardiac arrest prior to AED revival.) Any info you could provide regarding the likely damage to the brain during an anoxic period would also be appreciated. Thanks.

Brad Voytek: I'm sorry to hear about your experience, but I'm glad you're here to talk about it!I'm sorry to say, but I don't know much about anoxia or hypoxia. However, just so others are clear, this question refers to the loss of oxygen to the brain. So anoxia means "without oxygen" and hypoxia means "little oxygen".There are certain brain regions that appear especially susceptible to hypoxia, such as the hippocampus. The hippocampus is important for forming new memories (among other things!), but it is unclear to what extent or how brain cells (neurons) in the hippocampus recover. There's an excellent researcher and colleague of mine at the NIH that studies just that, however: Dr. Jason Snyder studies neurogenesis in the hippocampus and how that relates to memory.

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RECOVERY: How much time can we expect the recovery of brain functions to stop after a stroke/brain injury? That means, how long the recovery phase will be? One or two years?

Brad Voytek: Again, this is unclear.However, there's an excellent recovery research, Paul Bach-y-Rita, who suggests that recovery may be a long, slow, but continually ongoing process, with recovery continuing even 20 years after injury.Some very preliminary analyses based on some of my research suggests that there is a relationship between time-since-stroke and degree of recovery such that patients who are even 10 years post-stroke damage show the most recovery. These are unpublished findings and not peer-reviewed, but the effect seemed pretty clear.

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Personality: Where in the brain does the "personality" dwell? How does the personality change as a result of a severe brain injury?

Brad Voytek: There is no one "personality" region in the brain. The brain is a very complex system that is highly interconnected!While modern neuroimaging techniques such as functional MRI can tell us a lot about how different parts of the brain are associated with certain behaviors, one of the only tools we have in modern neuroscience for studying the localization of functions in the brain in a causal way is by working with patients who have very specific types of brain damage.Simply, if I put you in an fMRI scanner and have you move your right arm, your left motor cortex will be "active". However, the only way to show that your left motor cortex is required to make the movement is to see if you can no longer move if that brain region is damaged.There's a very famous patient in neuroscience history, Phineas Gage, who had an unfortunate accident that damaged his frontal cortex, right about his eyes. He survived, but his personality had changed quite a bit. He went from a normal family man to an aggressive, chaotic man after the damage. This led researchers to suspect that the frontal cortex plays an important role in emotional regulation, which is linked to personality. Antonio and Hanna Damasio have done some very interesting work in this field.

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Brad Voytek: There are so many great questions here! I'm sorry if I'm not getting to all of them. I'll try and answer as many as I can.

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TBI vs Gunshot wound: Can you differentiate the difference between Traumatic Brain Injury (I'm in the health care field), where the brain is often rattled and shaken, vs. a penetrating wound?

Brad Voytek: This bouncing inside the skull causes damage to the regions hitting the skull. There is also a sharp, bony ridge on the front base of the skull. In coup and contrecoup, this acts almost like a saw which tears at bits of the brain resting near it.Furthermore, patients in this case may also experience "sheering". The brain has a very soft consistency, almost like jello. When it experiences a major concussive force, different parts of the brain can move at different rates, which can tear the axons that connect different brain regions. So even if no damage is done to the brain cell bodies, because their connections are damaged, there can still be serious behavioral impairments.Then there is a penetrating TBI, which is something like a gunshot. The effects of these depend on what parts of the brain were damaged. But note that something like a gunshot wound is also associated with a lot of concussive force.

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Imaging: It seems like doctors would need the ability to see how her brain is responding to various treatments. What sorts of imaging techniques would her doctors be using?

Brad Voytek: Ideally, doctors would use all tools available, But this is not often practical nor entirely necessary. What I mean is, while there are a lot of researchers using a variety of brain imaging tools to understand how recovery might work and how we can speed it up, there are very few predictive tools that we have. The reason is that there is so much variability between people, what kind of damage they experienced, and so on.I mentioned earlier that in coup and contrecoup injuries, patients may experience "sheering", whereing the axons that connect brain cells get torn due to concussive forces. There have been very exciting advancements in what is known as "diffusion tensor imaging" (and related techniques) that can look at these white matter tracts and their integrity.While I have high hopes for these tools, they are not yet ready for medicine, sadly.

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Brad Voytek: Thanks everyone for your patience! I'm going to keep going for a bit longer than the alloted hour. I want to answer as many of these questions as I can!

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Handedness: What role (if any) does handedness play in recovery from a traumatic brain injury (TBI)? I survived a TBI that was confined to the left side of my brain; I'm left-handed and have made a full recovery. Perhaps the right side of my brain was better able to compensate for the injury.

Brad Voytek: That's absolutely fascinating! I'm glad you've recovered.I'm honestly not really sure about any research on this... but it's not hard to imagine that because the injury was confined to the "non-dominant" hemisphere of your brain, that the intact "dominant" hemisphere was better able to assume control over some of the functions that were affected from the brain damage.For those who aren't aware, the left hemisphere of the brain controls movements mostly for the right side of the body, and vice versa. Similarly, body sensations from the right side of the body are sent mostly to the left hemisphere of the brain.As a right-handed male, there is about a 99% chance that language will be controlled by the left hemisphere of my brain. This is about 95% for a right-handed female. The numbers are a bit different for left-handers.

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traumatic brain swelling: What exactly causes the brain to catastrophically swell when when traumatized? Is this usually a beneficial response?

Brad Voytek: Well, in trauma, this swelling is caused by what's known as "vasogenic cerebral edema". More simply, this is caused by damage to brian tissues that allows for the accumulation of fluid in the space around brain tissue. This accumulation of fluid causes swelling. In the case of a gunshot wound, this swelling can be expansive.Because the brain exists in an enclosed space (the skull), it doesn't have anywhere to swell to. This causes the brain to swell until it pushes against the inside of the skull, which can damage brain tissues. It also swells down, through the base of the skull where the spinal cord emerges. This puts pressure on the brainstem, damaging it. The brainstem controls important functions vital for life (such as heart rate and respiration), and can quickly lead to coma and death.This is why, in Rep. Giffords' case, the surgeons removed a large piece of her skull.Read this for me details, as I've done research with people who have had this type of surgery:http://blog.ketyov.com/2011/01/gabrielle-giffords-brain-surgery.html

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strokes and gender: How does the damage caused by a bullet such as in the congresswoman's case compare to the damage caused by a stroke? And, is it true that women recover from brain damage better than men do (something I've heard about strokes)? If so, what would explain that?

Brad Voytek: Jun Li and colleagues titled, "Estrogen enhances neurogenesis and behavioral recovery after stroke" which may point to a critical difference.

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Brad Voytek: Sorry to those whose questions I couldn't get to! I've gone 20 minutes longer that I'd intended, and I've got to run.This was great, though.If I didn't get to your question, feel free to get in touch with me later. While I'm not a medical doctor and can't (or won't!) give any medical advice, I'm happy to answer general brain/neuro questions.http://darb.ketyov.com/


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