Sunday, March 14, 2010
3/14/2010
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
3/11/2010
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.
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
3/10/2010
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.
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
3/9/2010
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.
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
3/8/2010
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. http://www.braingate2.org/aboutUs.asp 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.
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. http://www.braingate2.org/aboutUs.asp 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
3/5/2010
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.
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
3/2/2010
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.
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.
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