Monday, March 29, 2010


The causes of strokes can be broken down into three main categories: 1) hemorrhage, 2) embolic, 3) thrombotic. Intracerebral hemorrhage occurs when a blood vessel breaks, releasing blood directly into the brain tissue. This can happen from a weakness in the vessel wall, when the blood pressure is too high, or when a person’s blood is not able to clot, for example, when they are placed on “blood thinners.” The resulting blood clot forms a mass and can squeeze surrounding brain, rapidly leading to death or severe brain damage. Often, by the time the patient reaches medical care, it is too late to reverse the damage and many neurosurgeons believe surgery is not worthwhile.

Embolic strokes occur when a blood clot or piece of cholesterol plaque breaks off a heart valve or inside of a blood vessel and flows upstream to becomes lodged in a smaller vessel. This prevents blood from nourishing to the tissue supplied by the vessel. The size of the stroke depends upon where along the vessel it is blocked. Disease that damages the heart valves or the lining of the heart chambers are common causes for emboli.

Thrombotic strokes occur commonly in the carotid and vertebral arteries that supply the brain. Vessel disease, like arteriolosclerosis can narrow the inside of the vessel, slowing blood like a kink in a hose and eventually resulting in a clot that stops flow entirely. There is a narrow window of time that, if this the cause of the stroke is diagnosed and the proper facilities are available, drugs called “clot busters” may help dissolve the blockage and restore flow.

More hospitals are establishing stroke teams, a group of specialized doctors and nurses who can provide the expertise to diagnose and treat stroke as rapidly as possible.

Saturday, March 27, 2010


In my last blog I mentioned preprogrammed motor activity, so I thought this might be a good time to expand on that concept. There is a vast literature on motor control – the physiology of how we execute movements - and the brain pathways involved in even simple tasks are complex.

Think back to when you learned how to ride a bike. Initially there were several things you needed to learn; how to balance, how to peddle, how to turn, how to stop, and how to shift gears. To help balance, you may initially have used trainer wheels. But as you progressed, the trainer wheels came off and you became more confident. Part of this learning process was that repetitive movements like peddling were becoming programmed into your nervous system so that you didn’t have to think about them and you could focus on more important tasks, such as where to turn.

Another example is shooting baskets. The first time you threw a basketball at a hoop you probably didn’t come close to hitting it, much less sinking the shot. The weight of the ball was new and you had no concept of the forces needed to send it in the right trajectory. As you practiced, your nervous system learned to make numerous calculations extremely rapidly and your accuracy improved. Some of these calculations went from the conscious to the unconscious level. In addition your nervous system transitioned from linear processing to parallel processing. In parallel processing a process is broken down into several component tasks which are solved simultaneously and then made whole again.

Friday, March 26, 2010


A comment to the 3/22/ post asked. “… An "expert" said that when you are driving and receiving information through the phone, your brain goes into something he called sensory overload. Your peripheral vision is severely reduced and you basically are looking straight ahead. I can understand this when actually holding a cell phone to your ear. They did not make a distinction between hands free devices and holding a phone however. So my question is this.....would it be different if you were hands free and talking on the phone or would you still be overloaded. And if this is the case, how does this relate to talking to a passenger? Is that the same dynamic or different? Explain sensory overload.”

Sensory overload is a condition where the senses are strained and to the point it becomes difficult to focus on the task at hand. We commonly experience this situation if, say, we’re talking on the phone and our spouse asks us a question. It’s impossible to carry on the phone conversation and answer, so we pause the conversation long enough to take care of our spouse. Okay, you say, but that’s not the same as driving and talking. Well, yes it is. Can you type a letter while carrying on a conversation? No you can’t. And it doesn’t make any difference if you’re holding the phone or not – concentrating on the conversation at hand detracts from paying attention to driving.

The deceiving thing about driving is that much of the brain’s motor activity is automatic in that the visual information coming into our brain elicits a preprogrammed response, like turning through a curve in the road. This lulls us into believing we can do other things while driving. (I’ve seen drivers putting on makeup while driving 60 mph on the freeway). But the truth is the brain really can only really concentrate on one task at a time. The more you try to multitask, the poorer your performance in any of the tasks.

Driving requires constant vigilance. The more that vigilance that is distracted, the longer the reaction time to an unplanned event and the less we are aware of what’s going on around us. This holds true regardless of whether the conversation is on the phone or with the passenger next to us.

Thursday, March 25, 2010


Having just mentioned the Blood Brain Barrier, it’s a good time to discuss Multiple Sclerosis. MS is an autoimmune disease. Auto immune diseases are strange in that the same immune system that guards our body against infections for some reason turns against certain our own body and attacks them in the same manner.
When this occurs in the brain to cause MS, lymph cells attack the blood brain barrier to break it down, allowing other immune system components into the brain where they attack the myelin, the insulation on neurons. When this happens, the myelin becomes damaged to the point the nerves no longer can transmit information. The name multiple sclerosis refers to the multiple scars (known as plaques) that form as a result of the immune attack. Although myelin also coats peripheral nerves, they are seldom involved in the disease.

Neuroscientists know a great deal about MS, but they do not know what causes or triggers this autoimmunity. Some believe it results from a prior infection as if an immune response against the infection gets confused and attacks the BBB and myelin instead. Genetics does not play a strong role in this disease. The frustrating aspect about this disease is it is intermittent, meaning a person may have one or two attacks and no others. Another person may have attacks one after another in a very progressive course. Once the diagnosis is made, there is no way to predict what will happen. The good news is that there are at least five-modifying treatments that are approved for treatment and have various degrees of efficacy.

Tuesday, March 23, 2010


Because I’ve blogged about drugs lately, it’s a good time to mention the Blood Brain Barrier. If we swallow a pill, it is digested and enters the blood stream. The drug passes from our blood into all tissues, but not necessarily into the brain. This is because of a special barrier, the Blood Brain Barrier, which is fairly selective about what can and cannot reach brain tissue. The barrier is actually made up of tightly packed brain connective tissue called astrocytes that surround the blood vessels.

The good news is that the BBB acts very effectively to protect the brain from common bacterial infections. The bad news is that when brain infections do occur, the BBB may block drugs meant to fight the infecting agent. In addition, this barrier makes it more difficult to deliver wanted drugs to specific brain regions. This is especially problematic when treating brain tumors with chemotherapy. There are various chemical ways of temporarily opening the BBB to enhance drug delivery. Also, since the brain actively takes up glucose and other molecules, some drugs have been attached to these molecules to enhance their delivery. Finally, small tubes can be placed into tumor beds and attached to reservoirs that have been implanted just under the scalp so that drugs can be injected directly into the desired location.

It is hoped that nanotechnology will also provide innovative methods for delivering drugs to the targeted areas.

Monday, March 22, 2010


Got a great question after my 3/21 post, check it out. She asks, “… how do you see this technological age affecting young people? Are we creating a generation of people that have a difficult time doing one thing at a time? Can the brain really multitask all that well?”

First, let’s define what I’m talking about. To me an example of multitasking is a student in class who is Tweeting, text messaging, and trying to listen at the same time. The effects of this type of multitasking are not good. Some of the negative effects are: 1) it’s promoting an excessive need to “stay connected” at the expense of other activities, 2) reliance on electronic communication at the expense of direct interaction can result in the poor development of social skills and increased isolation. 3) It can also result in poor development of executive functioning characterized by an inability to focus on any task. More simply put, regardless of what a multitasker might think, it results in a person who is less competent, less efficient, and socially less skilled. So yes, this kind of multitasking can definitely cause cognitive problems.

Sunday, March 21, 2010


Recently, I’ve seen a lot of television ads for Aricept, so I thought the Alzheimer’s drugs would be a good topic to write about. Neurons communicate with one another by sending impulses across synapses and the synapses do this with chemicals (that are called neurotransmitters). There are a variety of neurotransmitters in different regions of the brain, one of them being acetylcholine, which is used the hippocampus (a region important in memory storage and retrieval).

Acetylcholine is destroyed by the enzyme cholinesterase. Aricept works by blocking the action of cholinesterase (thus is called a cholinesterase inhibitor). In doing so, it raises brain levels of acetylcholine. The idea is that increasing brain levels of this crucial neurotransmitter will benefit memory and behavior. But because the underlying cause for the loss of neurons continues, the effect of a drug like Aricept only postpones the worsening by about 6 to 12 months. These drugs do not reverse the eventual course of the disease.

Other anti-alzheimer drugs are Exelon and Razadyne. Because of varying side effects and possible interactions with other medications, doctors may try different cholinesterase inhibitors until the most effective one is found for the individual. Namenda regulates glutamate, another neurotransmitter which plays a key role in processing information.

When you take a pill it is adsorbed from your gut and then goes everywhere in the body rather than exclusively to the target, like the brain. Acetylcholine is necessary not only for some brain regions, but also in various nerves that control the heart, gut, bladder, and a variety of other function. This is why the undesirable side-effects of anticholinesterase inhibitors are so wide spread.

Saturday, March 20, 2010


Yesterday I saw an ad on TV for a device that claims to exercise and strengthen one’s brain. Use it or lose it, the pitch man said. This tweaked my interest, so I Googled brain training and was amazed at the number of products and on-line programs available. I found some of the advertising claims to be ridiculous in over stating what the device could do.

Numerous studies have shown that with age comes a decline of mental capabilities characterized by slowed thinking, a reduced ability to learn (“You can’t teach an old dog new tricks.”), and impaired memory. The cause of this decline can be attributed to various factors, some inherited, some inflicted on us - vascular changes, stress, and a decrease in the number of nerve cells – and some life style choices like alcohol consumption. The question is, can we do things to slow or even reverse these changes?

You bet there are. A body of research shows a relationship between staying physically fit and mentally fit – in other words, keeping physically active pays benefits in preserving mental function. In addition, several studies confirm that mental stimulation slows this natural decline. So doing things like reading or playing Spider solitaire on your computer help, but sitting in a recliner watching old movies probably doesn’t.

The “brain training” products I checked out require concentration and attention, both of which are important for sustaining short term memory. So in this regard, most of these devices do force the participant to mentally work and this type of mental “exercise” is good for preserving function. The problem, of course, is that just like physical exercise, many of us lack the discipline to expend the effort in a daily routine.

Thursday, March 18, 2010


Well, I survived my hospitalization and am now home. Notice I didn’t say I survived surgery. The surgery was the easy part. Being in the hospital was difficult. Mostly because it was an exercise in sleep deprivation. Not surprisingly, I didn’t sleep much the night before surgery. And although I was under general anesthesia during the procedure, that really doesn’t count as sleep.

Around 6 pm the day of surgery the fun started. An elderly woman (an assumption made by the sound of her voice) in the room across the hall started yelling. “Help.” When someone from the nursing team investigated she’d ask from something trivial, like coffee. This continued all evening until about 2 am. Even after closing my door, and eventually the nurses closed her door, I could hear her calling.

Clearly, she was “sundowning.”

Sundowning symptoms typically occurs in late afternoon, evening, and night and hence the name. It is a symptom of certain forms of dementia such as Alzheimer's disease (It occurs in about 45% of Alzheimer's patients. A sundowner may exhibit mood swings, become abnormally demanding, suspicious, upset, or disoriented, and see or hear things that aren’t there. The cause of sundowning is unknown, but may be related to disturbed circadian rhythm (the roughly 24-hour cycle our bodies and mind go through). Contributing factors may include medications that can cause agitation or confusion, and sleep disorders.

Because sundowning can be due to loss of brain cells, it’s not easily treated. Especially in the case of my neighbor across the hall. But a few things that may help are: 1) plan for activities and exposure to light during the day to encourage nighttime sleepiness. 2) Limit caffeine and sugar to morning hours. 3) Serve dinner early and offer a light snack before bedtime. 4) Keep a night light on to reduce agitation that occurs when surroundings are dark or unfamiliar. In a strange or unfamiliar setting such as a hospital, bring familiar items such as photographs or a radio from home.

Sunday, March 14, 2010


Tomorrow morning at O Dark Hundred, I will be admitted to hospital for surgery. Talk about role reversal - the doctor becomes patient. Doctors, by the way, usually make lousy patients. But I’ll try to break that mold and follow orders. Because several cognitive effects of general anesthesia linger in the brain for days (even if after the patient “recovers”) I’ll not be “right” mentally. I’ll be lethargic, take naps, and will not be able to concentrate as well as I normally would. Meaning, the last thing I should attempt is to write a blog segment. So expect a week to pass before you see another post.

Thursday, March 11, 2010


We all know from first hand experience what pain is. Although noxious, pain is beneficial because it warns of impending tissue damage. Even single cell organisms without nerves sense and try to avoid damage (called negative chemotaxis). There are two pathways in the spinal cord that carry pain messages to the brain – one is fast conducting, the other is slow conducting. This is why if you touch a hot frying pan you first feel a stab of pain, followed by a much different pain (which, for a split second, you realize will happen). Although we think of pain as a sensation associated with touch, it occurs when other sensory systems are threatened too. We squint in discomfort when strong light hits our retina or we plug our ears at loud sounds.

Most pain resolves as soon as the offending stimulus is removed. However, chronic pain may produce nervous system changes that become permanent, leaving behind lingering discomfort. In other words, making pain for pain’s sake.

Damage to joints (for example, in the low back) can set up inflammation, which, in turn, causes pain, resulting in a regenerative vicious cycle. Inflammation is a complex chemical and cellular response of the body. Drugs like aspirin, naproxsen (Aleve), ibuprofen (known as non-steroidal anti-inflammatory (NSAID) drugs) decrease pain by partially blocking the chemical reactions that promote inflammation. It is a common misnomer to refer to NSAIDs as “pain medication.” They’re not. Any relief of pain they provide is secondary to reducing inflammation.

True pain medications such as narcotics (e.g., morphine, codeine) do not block pain sensors or the nerves. Rather, they blunt the brain’s awareness of pain and thereby make it more tolerable. They also cause a feeling of well-being that reduces suffering. Pain and suffering are not the same. Suffering is an emotional reaction to pain.

Wednesday, March 10, 2010


A reader emailed, asking me to comment on how technology has changed neurosurgery. The glib answer is, “Tremendously.” When I started training we had limited ways of imaging the brain and diagnosed tumors by seeing normal structures distorted by mass. Development of the CT scan allowed us, for the first time, to see changes in the brain substance well before any distortion to surrounding structures developed. Not only has CT scanning improved over the years but MRI provides additional ways to see changes in brain down to the level of the insulation coating nerve cells.

High speed, high capacity chips now provide enough computing power to give surgeons 3-dimentional real-time visualization of tumors and blood vessel abnormalities during surgery, a process called Image-Guided Surgery. Immediately prior to surgery, the patient is taken to an MRI scanner and images made of their brain. These are sent via fiber optic cables to a computer in the operating room. The patient is put to sleep and their head locked into a fixed position on the operating table. Using a special pointer that is sensed by the computer, boney landmarks on the patient’s head (bridge of the nose, the outer corners of the eyes, etc.) are touched while the cross hairs on the computer are moved to exactly the corresponding spot on the MRI image and locked into place on the computer. By correlating 7 reliable skull landmarks in this way the computer can now reinterpret the MRI into a 3 dimensional view from the surgeon’s perspective. In other words, as the surgeon moves the probe over the patient’s head he can see its relative location on the MRI image. This is extremely valuable for planning the shortest, safest approach to a deep tumor as well as providing important feedback during the actual tumor removal.

Before image guided surgery, surgeons had to plan an approach to a tumor by estimating 3 dimensional space from 2 dimensional images, such as X-Rays. The accuracy of doing this was sometimes less than perfect. Now, with the help of image guided surgery, smaller openings can be more accurately placed with the surgeon knowing exactly where the tumor is in relation to the special probe. Although the technology was originally developed for treatment of brain tumors it’s commonly used for to surgery of the sinuses, where it helps avoid damage to brain and nervous system.

Image guided systems are extremely expensive and require trained personnel to operate them so not all hospitals have them. The Medtronic Stealth Station is the most widely used navigation system on the market, and utilizes both electromagnetic and optical tracking technology.

Tuesday, March 9, 2010


Check out Corinthians Countree’s commented on my 3/8/2010 blog. She wrote: A locked-in person is moving a cursor to punch a keyboard; a monkey is feeding itself with a robot arm like it is its own. Both the researchers and the public are using terminology analogous with telepathy. Telepathy or telekinesis? Do we have a thinking problem?

I’d love for Corinthians to elaborate on her question. To me telepathy means the direct communication of thoughts and feelings between people's minds, without the need to use speech, writing, or any other normal signals. Telekinesis is the power to move something by thinking about it without the application of physical force.

Monday, March 8, 2010


Artificial Intelligence is the intelligence of machines and the branch of computer science that aims to create it. In my book Dead Head a human brain was able to produce speech by use of a brain/computer interface – a device for translating thoughts into mechanical actions. One reviewer considered this to be “science fiction.” Well it isn’t.

For years neuroscientists have struggled on decoding brain electrical activity recorded from the scalp down to individual neurons. They’ve made progress, too. One multidisciplinary research team from a consortium of universities has developed a brain/computer interface they call Braingate. This device is a small grid of needle-like electrodes that penetrate the brain surface (the pia) to record from multiple neurons simultaneously. Implanting this device requires surgery to open the scalp, skull and Dura. The cable from the electrode grid is then tunneled to a separate area where it can be connected to a computer. The electrodes are implanted into the brain region that controls movement of the opposite hand of subjects who have lost the ability to use their arms from a variety of neurological diseases such as stroke, muscular dystrophy, or Lou Gehrig’s disease. After the wound heals the electrodes are sampled to determine which ones are recording and which are not.

The subjects are then shown a computer screen similar to an old game of Pong where the object is to move the cursor into a target. Because the electrodes are within the arm/hand region of cortex, subjects “think” of moving the object with their hands and can learn to manipulate the cursor so with surprising accuracy. As subjects gain efficiency in controlling the cursor, they can spell out commands (for those who have lost their ability to talk) or move robotic devices that can help them accomplish tasks.

The downside of Braingate2 is the requirement of an implanted recording device. To work around this other research has sought to decoding brain activity recorded at a distance from the brain, like the scalp. But with increased recording distance comes weaker signals and interference from other electrical activity (such as muscle and even heart contractions) (see 2/19/2010 blog) including surround brain. As a result, scalp recording are more complex and difficult to control by subjects, so progress is slower than with Braingate.

The good news is that as complicated and cumbersome as these experiments are today, they indicate tremendous strides in technology that may one day help the neurologically damaged patient.

Friday, March 5, 2010


The spine is divided into five regions – cervical, thoracic, lumbar, sacral, and coccyx – and is comprised of bones (vertebra) stacked one on top of the other. From each vertebral body extends additional bones (the pedicles and lamina) that form the cylindrical canal that protects the spinal cord. Between each vertebra is a disc and between each pedicle is a joint. This entire column is held together by ligaments in much the same way as the joints of the finger are constructed. Large bundles of muscle run parallel to the spine.

So what can cause back pain? Well, a lot of things but two very common causes of low back pain are muscle strain and tissue inflammation. Just like arthritis can cause pain in, say, a finger joint, it can cause pain in the back. Because most arthritis is due to inflammation, symptoms often respond to anti-inflammatory medications such as Aleve or ibuprofen. And just like you can strain an ankle, you can injure the ligaments in the back by overexertion. Ankle strains are treated by splinting to reduce motion. When the back is strained, the muscles try to splint it by tightening. But this, in turn, can cause more pain. Unlike the finger or ankle, the back is difficult to splint even with corset-like braces. Once injured, a vicious cycle begins with pain causing spasm causing more pain causing more spasm. When this happens, muscle relaxants can be used for a short period of time. Other physical treatments such as massage and heat can help relieve spasm.

Age also extracts a toll on the back. Just like the joints in our knees can, with age, lose cartilage, so do the (facet) joints in the spine. The water content and elasticity of our discs decreases which results in a loss of space between vertebrae. Because the nerves to our limbs exit the spinal canal on their way to our muscles, any loss of space between the vertebrae runs the risk of pinching these nerves. In some cases the disc may compress a nerve, but instead of producing back pain this usually results in pain that radiates down the leg to the foot.

Diagnosis and treating the myriad causes of back pain can be frustrating for both patient and physician. Although modern imaging techniques, such as CT and MRI, may be excellent for showing us the anatomy of the spine, they often can’t show us the cause of pain. Pain, after all, is a symptom of other problems.

So be kind to your back - lift properly, keep your back muscles strong, and don’t over do manual work.

Tuesday, March 2, 2010


The sides (hemispheres) of the brain are specialized. For most of us (even most left handed people) the left hemisphere is devoted to language related tasks whereas the right deals with special relationships, such as recognizing faces. Loss of language abilities is termed aphasia. The loss of ability to recognize objects is termed agnosia. One of the most common causes of either aphasia or agnosia is stroke.

The hemispheres are divided into four lobes, Frontal, Parietal, Occipital, Temporal, that have different functions. The frontal lobe is devoted to producing movement, the Parietal interprets sensation, the Occipital controls vision, and the Temporal serves hearing. Large strokes that damage the majority of the left hemisphere result in loss of both speech production and recognition and is termed global aphasia. However, strokes involving small branches of the arteries supplying the left hemisphere may cause very specific deficits in language. Primarily frontal lobe damage can result in the inability to speak while still being able to understand spoken and written words. Likewise, selective damage to only the Parietal lobe can affect our ability to monitor what we are saying. This results in a person who can form sounds but cannot monitor the words or content of what they say – so their sentences and words become gibberish or nonsense. This type of aphasia is called Fluent Aphasia.

In very rare instances when the area between the Parietal and Occipital lobes are damaged some very selective neurologic problems arise. For example, being able to speak and understand spoken words but not being able to read written words. Likewise, with involvement of the Temporal-Parietal region some rare forms of aphasia allow the person to read but not understand spoken words.

The above explanations are overly simplified, but give examples how listening to the ability of a patient processes language can help the neurologist understand what parts of the brain are not functioning properly.