Answers to Your Questions About Brain Injury

Scientists and doctors have only just begun to unravel the mysteries of brain injuries. Here, some of the country's leading experts answer your questions about brain trauma.

What is brain damage? Are there different kinds?

There are many different kinds of brain damage. Neurons can be damaged directly and killed. There can be tearing and shearing of the axons, white matter connections between areas, often seen in closed-head injuries. Swelling applies pressure on the brain that can kill neurons. Loss of oxygen kills neurons, and selectively affects different areas first.

- Susan Bookheimer, Brain Mapping and Research Institute, UCLA

Are certain areas of the brain more important than others for survival? Why?

The brain stem controls regulatory functions like breathing, heart rate. These functions are critical for survival. The cortex is less necessary for survival, but is very important for making us the individuals that we are. Thus, it is possible to have an intact brain stem in a living person but very little else if the cortex is not functional.

- Susan Bookheimer, Brain Mapping and Research Institute, UCLA

How durable is the brain? How much trauma can it take?

This depends on a lot of factors. For a first injury in a young person, where there isn't gross damage such as large tissue destruction, removal or brain stem damage, or no loss of oxygen to the brain, there is a remarkable ability to improve.

But many factors can reduce the potential for recovery. Bleeding in the brain stem, large mass effects such as the massive intracranial bleeding of Ariel Sharon, the need for surgery to remove pieces of brain, and most important loss of oxygen due to substantial blood loss, all are bad signs. For someone with a previous head injury, even a small bump can have huge effects, as the brain may have already used up its "reserve."

- Susan Bookheimer, Brain Mapping and Research Institute, UCLA

Humans can tolerate very little acceleration/deceleration injury, because of the large brain size, its softness, and our upright posture. Think of a heavy, soft fruit on a branch that gets a hit. In contrast, think about the woodpecker -- that little guy gets thousands of hits to the head and doesn't miss a beat. Or how about bighorn sheep in the rutting season -- these animals have adapted by developing a complex cranial anatomy to hold the brain in the skull, like a walnut in its shell, so it can't move with even large force impacts.

- Dr. Ross Bullock, director of clinical neurotrauma, Virginia Commonwealth University

How difficult is it to rehabilitate the brain? Meaning can you re-create ability or function that is lost?

Each case is unique. While most mild traumatic brain injury patients fully recover, many suffer persisting cognitive disabilities, such as loss of memory and poor concentration, even with rehabilitation. In general, the more severe the initial injury, the less likely the patient will fully recover with rehabilitation. However, even some severe brain injury patients can ultimately return to normal life after rehabilitation despite extensive damage to the brain.

- Dr. Douglas H. Smith, director, University of Pennsylvania Center for Brain Injury

The brain cannot be "rehabilitated" per se. Over time, areas of the brain that were rendered dysfunctional can improve, and these areas can make up for permanently destroyed areas of the brain. Rehabilitation, in general, improves the overall coordination of brain-body function but permanently injured areas of brain are forever lost. One can re-create functions that are lost by having another noninjured or less-injured area of the brain subserve the area that is permanently injured.

- Dr. W. Welch, chief of neurosurgery, University of Pittsburgh

Do brain cells ever grow back?

Dead brain cells do not "grow back," and there is no consistent evidence that surviving neurons can replicate. There is abundant evidence for "sprouting" in which surviving neurons send out axonal "sprouts" (extensions) into areas of damage to communicate with other neurons that have lost their input.

- Dr. Martin Weiss, chairman, department of neurosurgery, USC

What are the critical things to look for in the days after brain damage? What is the recovery time in terms of stages? How long does it take to know what damage is going to last?

The speed in which the person returns to consciousness and the early rate of recovery will predict the rate of further change, usually. It can take days or even weeks to have a good idea. Serious swelling and intracranial pressure can cause additional damage, as can infections.

- Susan Bookheimer, Brain Mapping and Research Institute, UCLA

It may take weeks or even months to fully ascertain function that is permanently lost because of the potential for overlap of brain function. In general, overlap/improvement can occur for two to three years. Obviously, and again in the most general of terms, the longer it takes to identify meaningful recovery, the worse the prognosis for overall recovery.

- Dr. W. Welch, chief of neurosurgery, University of Pittsburgh

With battlefield damage especially, what do you look for in terms of trauma, shrapnel, special considerations? Why?

Penetrating injury such as shrapnel can complicate traumatic brain injury by causing bleeding inside the skull, creating high pressure that can choke off blood supply. In addition, penetrating injury may damage important regions of the brain that control specific functions. Overall, blast injury also commonly affects the chest, breaking ribs and causing lung tissue damage. This can result in impaired breathing or create air emboli entering the blood, both of which can worsen the extent of a brain injury.

- Dr. Douglas H. Smith, director, University of Pennsylvania Center for Brain Injury

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