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Last updated May 26, 1999
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Divison of Neurology
~ the brain and nerves ~
Please read the Sentinel and Medical Disclaimers.
A brief neurologic
exam
Measuring brain activity,
neurotransmitters
Brain activity during coma
Speed of improvement
after waking up from a coma
Amnesia
Zoning - a form of
petit mal seizures?
Brain damage from lack of oxygen
Brief neurological exam (modified according to patient's condition and ability)
General appearance: what does the patient look and act like in general? Awake? Asleep? Tired? Pleasant? Angry? confused? Well-dressed? Disheveled? Can they talk normally? Happy/sad? Are they in pain? Do they know where they are, what day it is, who they are, why they're in the hospital, and what's wrong with them? It is important to note all these things.
Cranial nerves: there are 12 cranial nerves and they are tested by doing the following things: ask patient to follow a moving object (usually the doctor's finger or pen) with their eyes, check pupillary response (look for constriction) with a flashlight, test vision with an eye chart, test facial sensation by asking patient if a light touch on their face feels normal and the same on both sides, test facial muscles by asking patient to wrinkle forehead, shut eyes very tightly, and show teeth/smile. test hearing by using tuning forks (Weber and Rinne tests, won't go into details), test strength of sternocleidomastoid and trapezius muscles by asking patient to move their chin (turn their head) against doctor's hand, and shrug shoulders. Ask patient to open mouth and say "ahh" to look for movement of palate and uvula, ask patient to stick tongue out (should stick straight out, not to the side). If patient is not conscious, corneal reflex (touch piece of cotton to patient's eye and watch for a blink) and gag reflex (stick something down their throat and watch for gag response) should be done.
Motor: Strength of each major muscle group in the arms and legs (basically each joint) should be tested against examiner's strength. For example, patient would flex biceps (arms) and try to hold them there while examiner tries to straighten the arms. Same goes for the legs. Graded on a 5 point scale -- 5/5 is normal. Right and left sides should be compared.
Sensory: Sensation to light touch, pinprick (pain), and vibration should be tested in arms, legs, and torso. Light touch is tested with a cotton swab, pinprick with a safety pin, and vibration with a tuning fork. Have patient close their eyes and ask, "tell me when you feel something -- does it feel normal?" Right and left sides should be compared.
Cerebellar: patient asked to tap index finger and thumb together as fast as possible (tests fine movement). Patient asked to touch his nose with his finger, then touch the examiner's finger. Repeat over and over with the examiner moving his finger to different spots and see if patient can touch it normally. Also heel-to-shin test involves asking patient to touch one knee with the heel of their opposite foot and drag the foot down the front of their leg. Should be a smooth movement.
Reflexes: biceps, triceps, brachioradialis in the upper extremities, and patellar (knee) and ankle jerks in the legs. Babinski reflex is usually checked by scraping the bottom of the patient's foot with a sharp object and watching for the big toe to go up or down (normal is down).
Parietal lobe function: Ask them to close their eyes, then put a common object in one of their hands (like a pen or a paperclip or a coin). They should be able to tell by feeling what the object is -- if it's a coin, they should be able to tell you if it's a dime or a quarter or a nickel. There are a bunch of other tests you can use for this one.
Gait: patient should be asked to walk, first normally, then with one foot directly in front of the other (heel to toe, called a "tandem walk"), then on tip toes and then on heels. Lastly, the Romberg test involves having the patient stand with both feet together, stretch their arms out in front of them with palms up, and close their eyes. The examiner watches to see if the patient can maintain his balance for at least a minute.
Mental status and cognition: ask patient where they are (name of hospital), what day/date/month/year/season it is, who they are (name), why are they in the hospital. Ask about mood (happy/sad/angry/whatever). Tell patient three objects and ask them to remember them (you will ask them for the objects in 5 minutes or so. I use "ball", "dog", and "honesty" but you can pick anything.) Tell them a proverb and ask them what it means (what does "a stitch in time saves nine mean"?) Ask them to name common objects (like a watch or a pen). Ask them what is the same about two objects (such as an apple and an orange, or a car and a train, etc.). Ask them to write a sentence. Ask them to copy a figure or shape. Ask them to do a 3 step command: take this piece of paper in your right hand, fold it in half, and put it on the table. Ask them to spell the word "WORLD", then ask them to spell it backwards (tests concentration). Ask them to repeat "no if's, and's or but's." Ask them common knowledge stuff, like "who is the president?" Don't forget to ask them at the end for the three objects you told them at the beginning. This whole test is graded out of 30 points. A score of 28 or more is normal.
That's it. There are other tests that you do or change if the person isn't able to follow commands or is physically unable to do these tests -- for example, if they're unconscious.
Measuring activity in the brain; neurotransmitters
Neurotransmitters are molecules which act as chemical "signals" or messengers by traveling from one cell to another, especially between neurons in the brain but they act all over the body. Certain neurotransmitters may activate a neuron or shut it down, thus forming the basis of how the brain works. Hundreds of neurotransmitters have been identified, but there are surely many more in the body that haven't been discovered yet -- thousands, maybe millions. The most famous ones are acetylcholine, dopamine, serotonin, norepinephrine, GABA, and glutamate because scientists think these have profound effects on the way the brain works and thus on behavior. For example, it is thought that an excess of dopamine may contribute to schizophrenia; too little serotonin and norepinephrine may cause depression; too little acetylcholine may cause Alzheimers' Disease, etc.
Measuring neurotransmitters:
You can use blood tests. You could detect and directly measure the amount of certain neurotransmitters in the blood, but this is difficult because neurotransmitters are usually broken down (metabolized) immediately by enzymes to inactivate them so they don't keep stimulating a cell like a broken record. So scientists measure levels of neurotransmitter breakdown products floating around in the blood as an indirect measure of how much of a certain neurotransmitter is being used by the body. For example, dopamine's major breakdown products are DOPAC and HVA (abbreviations of long icky chemical names). By measuring the amount of DOPAC and HVA in the blood, you can get an idea of how much dopamine a person is producing/using.
Machine that can measure what part of the brain is working when people do certain things:
Radiologists invented a neat machine called a PET scanner (Positron Emission Tomography). It's really expensive to use (much more than an MRI) so it's mostly used in research. A PET scanner detects metabolic activity in the brain by measuring the levels of positrons (miniscule nuclear particles) coming off the brain. You can inject a person with radioactively labeled glucose which the brain uses as fuel, then have them perform a certain activity (whatever you want -- thinking, putting a puzzle together, whatever) while they're inside a PET scanner (it looks sorta like an MRI machine, if you've ever seen one -- kinda like a big donut that you slide the person inside of). Watch the computer screen that the PET scanner is hooked up to, and the part of the brain required to perform the activity "lights up" on the screen as bright red or yellow. Just another way of learning how the brain works and which parts are needed to do what.
From what I understand, most people don't remember anything from the time they were in a coma. I think there are reports of people sometimes remembering bits of things, like hearing voices, but this is definitely the exception rather than the rule and I've never met anyone who said they could remember anything. There is brain activity (otherwise the person would be brain dead, not comatose), but it is pretty slow-wave, minimal amplitude activity on an EEG tracing. A person in a drug-induced coma can be given enough sedatives (Versed or pentobarbital usually used) to basically flat-line their brain activity if necessary (sometimes you do this to people in status epilepticus to make them stop seizing). Drugs used on a comatose patient can muddy the picture. They may get benzodiazepines like Versed for sedation, which have the side effect of amnesia.
You can monitor the brain's electrical activity with an EEG (electroencephalogram). This doesn't give you specific information about whether they're going to remember, though. The person's level of consciousness can also be assessed with a standard neurological exam which tests the person's response to pain and verbal stimulation. You give comatose people a score using the "Glasgow Coma Scale". The person gets points for how well they respond to stimuli with their eyes (can they spontaneously open their eyes, etc.), their voice (do they respond verbally to commands or just groan or say nothing at all, etc.), and their body movements (will they follow commands or just reflexively withdraw in response to pain, etc.). The lowest score for each category is a "1", so a dead person would get a GCS of 3 (if a person is truly comatose but still alive, they could also have a GCS of 3).
Speed of improvement after waking up from a coma
I think it's safe to say that it really does depend on the individual case, particularly why the person was in a coma in the first place. For comas induced by certain drug overdoses (such as heroin and other opiates) and also those due to hypoglycemia (low blood sugar), the proper antidote (naloxone for heroin and glucose solution for hypoglycemia) will result in an almost instantaneous reversal of the coma and the person becoming quite "coherent" in a few minutes. Of course with opiate overdose you have all the symptoms of opiate withdrawal as well (runny nose and watery eyes, flu-like symptoms, etc.).
If a person has been in a coma for a long time, such as something involving injury to the brain, or if they've been sedated heavily with pain medicine or anesthetic, emergence from a coma will often be much more gradual -- hours or even a day or so. In the case of anesthesia/pain medicine, they'll come out when the drug is excreted/metabolized from their body. It is common for a person to be quite disoriented upon emergence from a coma, as they usually wake up in a different place than they last remember being.
specifically, short-term memory loss
This condition is officially called "Amnestic Disorder" or "Amnestic Syndrome" or "Total Anterograde Amnesia". It is caused by damage to an area in the brain called the hippocampus, which is thought to be the place where short-term memories are converted to long-term memories for storage in the cortex (gray matter) of the brain. When this conversion center is damaged, a person is unable to store memories long-term. "Anterograde" means that you can't make new memories of everything forward from the point of the accident/trauma. This contrasts with "retrograde" amnesia in which you can't remember things in the past (like a person who suddenly can't remember who they are or where they came from), but you can still new memories of what happens from the present on.
The hippocampus is located in the temporal lobe of the brain, so the damage would be localized to that area if the person had no other problems. The two cases I know of were 1) the result of brain surgery for epilepsy where they purposesly took out the temporal lobes of the brain to stop the seizures and 2) a stroke.
Anyway, in amnestic disorder, the person's intellectual abilities and ability to learn new skills (as opposed to new facts) are not affected. In fact, the person in the brain surgery case actually had a slightly higher I.Q. afterwards! These patients can remember new facts as long as the information stays in their short term memory. For example, if a person walks into the room of the patient, the patient can learn the person's name and things about them without trouble. But as soon as the newly introduced person leaves the room and the patient thinks about something else or is distracted, they've lost the information in their short-term memory. If that same person comes into the room again, the patient would not remember or recognize them.
Probably the most famous case of amnestic syndrome is the case of "H.M." which is told in the psychiatry textbook by Kaplan and Saddock (Comprehensive Textbook of Psychiatry, 5th ed, p. 629). H.M. is the person who had brain surgery for epilepsy. In addition to anterograde amnesia (inability to learn new facts), he also had severe retrograde amnesia for events that occured during the year or two before surgery. Recall for events from early life and up to the 2 years before surgery were as good as that of normal people.
H.M. was also able to learn new skills (such as copying geometric figures reversed in a mirror), but he was unable to recall ever learning the task in the first place and couldn't recognize any of the people who had taught him how to do it.
Zoning - a form of petit mal seizures?
Petit mal seizures (a.k.a. "absence seizures") are brief lapses of consciousness, speech, or motor activity. Usually an observer will describe the person as having "staring spells" where the person doesn't respond to anything (calling their name, shaking them, etc.). The seizures last 5 to 20 seconds and usually start up when the child is 5 or 6 years of age. This is one kind of epilepsy that happens almost totallly in children and they often "grow out of" it because I didn't find anywhere that said it was common in adults. Anyway, after the staring spell, the person "snaps out of it" immediately and doesn't recall that anything weird happened. Sometimes the person will do something called "automatisms" or repetitive movements during the seizure, such as eye blinking or lip smacking (is Jim's jaw-clenching? <g>). Sometimes hyperventilating will bring on a seizure. An EEG will show a characteristic pattern during a seizure, and a neurological exam would not show anything abnormal between seizures.
Jim's zone-outs could theoretically and plausibly be misdiagnosed as petit mal seizures by a neurologist, especially if they witnessed one and didn't know about the whole senses thing. He certainly looks like he could be having a petit mal seizure when he zones out. Things that wouldn't go along with a diagnosis of petit mal seizures would be that Jim is an adult, not a child, so he's the wrong age. I guess it's possible that he'd always had the problem and never grew out of it. Also, I think he realizes what's happening when he zones, though he doesn't seem able to bring himself out of it, and he remembers zoning (petit mal seizures give you amnesia for the time of the seizure).
Petit mal seizures are treated with a medication. Two are available: 1) ethosuximide and 2) valproic acid (brand name Depakote). Side effects of ethosuximide include drowsiness, nausea, and rarely problems with blood cells (increased or decreased red/white blood cells). Side effects of valproic acid (which I'm more familiar with -- I think it's more commonly prescribed than ethosuximide) include weight gain, hair loss (Jim doesn't need that, does he?), tremor, and liver problems. Both drugs require measuring of drug levels in order to adjust the dosage to a "therapeutic level," so the patient has to get their blood drawn every few weeks while the dosage is being adjusted, and every few months afterwards. Overdosage is also dangerous. If they start having more seizures, then a drug level is always checked. With valproic acid, liver function tests (another blood test) are done every so often to make sure the liver is not being damaged. One more thing -- a person doesn't have to stay on the medication their whole life. If they don't have any seizures for 2 years, the drug can be discontinued.
Brain damage from lack of oxygen
Permanent brain damage occurs after the brain has no oxygen for 6 to 8 minutes. Specific results from brain damage due to anoxia (lack of oxygen) vary quite a bit. Muscular weakness, memory loss, problems with cognition (thinking), sensory loss, difficulty with vision, speech, etc. -- all could be feasible. Seizures (epilepsy) are also a very common result of brain damage.
You check for brain damage by doing a very good physical exam, paying particular attention to mental status (asking the person who they are, where they are, what day it is, asking them to perform certain commands and repeat certain words or phrases, write something, etc.) and neurological exam -- muscular strength, sensation, vision, coordination, etc. If a person has symptoms of seizures, you can do an EEG (a test where you stick electrodes on the person's head and record the electrical activity generated by the brain). You can also perform imaging of the brain with an MRI scan to look for obvious structural abnormalities.
Dead brain cells do not regenerate. However, the body has an amazing capability to adapt following severe brain injury. For example, people who have head trauma in car accidents, or people who have strokes, often can go through rehabilitation and regain much function that was initially lost. There are many theories on how this exactly happens, but no one knows for sure how it does -- just that the brain has an amazing ability to recover.