IF YOU DON'T evaluate neurologic patients on a routine basis, you may not be confident that you know all the ins and outs of this skill. You're not alone: I used to fear these patients too, but I put my mind to learning all I could about neurologic evaluation, and now I love it. When I teach this topic to nurses, I emphasize how all the pieces fall into place once you understand a few basic principles and relationships. I'd like to share what I have learned with you.
Looking at LOC
The neurologic exam starts with the patient's level of consciousness (LOC). It's the earliest and most sensitive indicator that something is changing. Who knows the patient's LOC best? The family. When they tell you that he's different, he's different.
The LOC has two components: arousal (or wakefulness) and awareness. (For more details, see Using the Glasgow Coma Scale.) Controlled by the brainstem, wakefulness is the most fundamental part of LOC. If the patient can open his eyes spontaneously to voice or to pain, the wakefulness center in the brainstem is still functioning.
Awareness, a higher function controlled by the cerebral hemispheres, is the ability to interact with and interpret the environment. You evaluate four components of awareness: orientation, memory, calculation, and fund of knowledge. Let's take a closer look.
* Orientation to person, place, and time. Patients lose their orientation the same way that we do. You know who you are and where you are, but if I asked you the exact date, you may not always know. Similarly, patients lose orientation to time first, then to place, and then to person.
When you're going to evaluate a patient's orientation, get every bit of detail you can. Don't just ask, "What's your name?" Have him tell you his first and last name. Don't just ask, "Where are you?" Find out if he can identify the city, state, and hospital. And when evaluating his sense of time, find out if he can identify the month, day, year, day of the week, recent or upcoming holidays, and so on. When you evaluate him later, the details that start to fall away will be your early clues to deterioration.
* Memory. You can ask the patient all kinds of questions to test his short-term memory. Just don't ask yes-or-no questions; he has a 50/50 chance of getting the answer right, whether or not he has a clue!!
Here's a good technique. You might say, "Mr. Smith, this is a memory quiz. Please remember these three things, and I'll ask you about them later. Apple, orange, dog. Say them back to me: apple, orange, dog." Don't ask obvious things, like January, February, March; those are considered automatic speech and are held in a different part of the brain. After doing the rest of the exam, come back and ask him to tell you the three things.
To test long-term memory, ask the patient things you can check in his chart: "Where were you born? What's your date of birth?" To test judgment, ask questions like, "What would you do if you were in a crowded theater and saw a fire?" To measure the patient's attention span, notice whether you frequently have to ask him if he's paying attention or whether he interacts with you throughout the exam.
* Calculation. To evaluate calculation, many nurses ask patients to subtract by 7 from 100. Although that's the standard, it doesn't make a lot of sense to me because so many people have become dependent on calculators. I use change instead: "If you had $2 and your apple costs $1.25, how many quarters would you get back?"
* Fund of knowledge. Ask the patient to name the president and to tell you what's on the national news these days.
With any change in the patient's LOC, carefully look for hypoxia, hypercarbia, hypotension, hypothermia, drugs, or a postictal state following an unwitnessed or unrecognized seizure as the cause of the change.
Checking motor responses
Following commands is the highest level of motor response. When you ask a patient to follow a command, the normal response is that he follows the command. The problem is that often we don't give him the right command. Suppose, for example, you tell him to squeeze your hand. Infants grasp everything placed in their hands because of a grasp reflex. Adults don't do this because the grasp reflex inhibitor develops, preventing it. However, the grasp reflex inhibitor disappears if the part of the patient's brain that controls the grasp reflex is hypoxic or ischemic. You know this is a reflex, not a response to a command, when you can't get your fingers out of the patient's hand.
So a better test is to ask him to hold up two fingers. No matter how weak he is, you can see those fingers start to move and you know you're getting through to him. If he doesn't hold up two fingers, proceed up the stimulus options all the way to painful stimulus (trapezius squeeze, supraorbital pressure, mandibular pressure, sternal rub, peripheral pain) and try for 30 seconds to get a response. Then when you chart that he doesn't follow commands, you know it's really true.
But suppose that while you're charting this, the patient pulls out his I.V. device or extubates himself. This is a perfectly normal motor response-not as high level as following commands, but it's purposeful movement, or localizing. Something bothered him and he can locate it and attempt to remove it.
Withdrawing is the third highest level of motor function, after following commands and purposeful movement. If you're inflicting peripheral pain on a patient and he pulls his hand away, you don't know if that's a reflex or purposeful movement. Keep the painful stimulus on his hand and don't let go, even when he pulls away. If he continues to pull away after that initial movement, he's withdrawing.
Posturing is an abnormal motor function that indicates major trouble (see Abnormal posture response to stimuli). The two types are flexion (formerly decorticate) posturing and extension (formerly decerebrate) posturing. In both postures, the legs are rigidly extended. Flexion posturing is the less severe of the two. If you restore adequate oxygenation and adequate perfusion (in other words, increase the patient's blood pressure), the posturing often can be eliminated. Most patients who posture despite good blood pressure and oxygenation have a high potential to remain in a persistent vegetative state.
You can perform the following tests if your patient is able to follow commands.
* Assess your patient's strength. Test only normal motor responses and record the answer as a fraction. The denominator is always 5, and the numerator is the patient's score. For example, if you ask the patient to lift his arm and nothing happens even when you inflict pain, his score would be 0/5. But the next week, you see or feel a flicker in his biceps muscle when you do this test, so his score becomes 1/5.
If his arm or wrist moves across the bed (joint movement), you'd give him a 2/5. If he can lift it off the bed but drops it as soon as you touch it, that's a 3/5; he can overcome gravity, but he has no strength. To get a 4/5, he has to resist you a little bit, but you win. To get a 5/5, he lifts that arm and you arm wrestle and he wins or it's a draw.
What about the legs? One test is enough to give you a baseline assessment. You can ask the patient to pretend he's pushing on a car accelerator pedal as hard as he can. Or ask him to pull his toes up toward his nose and hold that position without flexing his knees or lifting his feet. You'll be able to see when the toes start to fall a little bit. You could also ask him to raise or lower each leg against your resistance.
* Next, check for drift, an indicator of motor weakness. Depending on his condition, the patient can be lying down, sitting, or standing. Tell him to hold his arms out straight, parallel to the floor, with his palms up, as if he's holding a pizza. Then tell him to close his eyes.
The normal response is to hold that pizza steady. If he's a little weak, the weaker hand will shake a little bit. As he gets weaker, his hand will start to turn palm down (or pronate), and if he has a lot of weakness, his arm will drift downward (pronator drift). Contact the neurologist or neurosurgeon immediately if a patient develops a new drift.
* Finally, check his coordination. To test rapid alternating movement, ask the patient to touch his fingers, one at a time, to his thumb as fast as he can, on both hands. If he misses the thumb, or one hand is much slower than the other, he has a lack of coordination with rapid alternating movement.
Next, ask him to place his finger on his nose. If his finger lands on his forehead, cheek, or someplace else, he doesn't have good coordination. If his finger lands a little bit to the side of his nose, you can double-check coordination by asking him to touch your finger while you keep moving it. This is harder to do than it sounds; he has to concentrate. Don't expect a perfectly smooth response.
To test leg coordination, ask him to pretend to press the accelerator with both feet simultaneously. Then have him lift his feet up off the bed and continue to press against the imaginary gas pedal. Try it. You think your feet would be perfectly straight and coordinated, but they veer a little bit, don't they? That's normal. But if one foot is moving rapidly and the other is moving slowly, you'd document a lack of coordination for the patient's lower extremities on that side.
Monitoring vital signs
You can evaluate the patient for increased intracranial pressure (ICP) by looking for Cushing's triad, a late sign of increased ICP and an indicator that the brain is about to herniate. The three characteristics of Cushing's triad are:
* a widening pulse pressure resulting from a rising systolic blood pressure with an unchanged diastolic blood pressure
* bradycardia, with a heart rate in the 40s or 50s
* development of abnormal respiration.
What about temperature? Most patients with head injuries are febrile, which is dangerous because fever increases the brain's oxygen demands 6% to 10% for every degree above normal. Fever from infection can be treated with medication, but fever from damage to the hypothalamus won't respond well to antipyretics such as acetaminophen (Tylenol). Use temperature-regulating blankets instead, and wrap the patient's hands and feet to warm peripheral temperature sensors. This decreases shivering and reduces the chance that the hypothalamus will reset the patient's internal thermostat.
Neurologic patients are rarely hypothermic unless they've just come out of the operating room. Hypothermia in a neurologic patient usually means death is imminent.
Guarding against neurologic change
We've been taught to watch the patient's ICP measurement to recognize early signs of brain herniation. But the brain's ability to adjust to changes in volume of brain tissue, cerebrospinal fluid, or blood without sustaining an increase in ICP can throw us off track. As intracranial bleeding progresses, ICP doesn't increase immediately because the body compensates by getting rid of extra water and extra spinal fluid and even by constricting blood vessels in the brain to allow space for an expanding lesion or hemorrhage. By the time ICP rises, the body's compensatory mechanisms have failed, and interventions are less likely to succeed.
If you don't notice the earliest clues, ICP will continue to rise until the brain herniates (see A look at brain herniation). Here's what to watch for:
* Changes in LOC. These are the earliest and most subtle changes. When you evaluate your patient, you'll find it takes more stimulation to get the same results.
* Loss of detail and orientation. He can tell you the year and the month, but not the day. Eventually he can't tell you the month, and lastly, he can't remember the year.
* Forgetfulness. The patient knew why he was here yesterday, but today he can't remember. He asks a lot of repetitive questions.
* Restlessness. This is a major clue; sudden restlessness usually points to a potential respiratory problem. Don't wait for an arterial blood gas analysis. Is he breathing as deeply and as frequently as before? If not, administer supplemental oxygen. If he's still restless, you know you must consider a possible neurologic change.
* Sudden quietness. When a restless patient suddenly becomes quiet, that's a strong danger signal. Has he just exhausted himself, or has he experienced a serious neurologic change? Reevaluate him using maximum stimulation. If he's exhausted, he'll respond and then fall back to sleep. If you get no response, the patient is in real trouble.
* Pupillary changes. The pupils will usually change on the same side as the lesion. The first and most subtle clue to trouble is that the pupil reacts, but sluggishly. By the time the pupil becomes fixed and dilated, the patient's third cranial nerve is affected because part of the temporal lobe is herniating onto the brainstem.
* Motor changes. Motor changes occur on the opposite side of the injury, tumor, or stroke. Resistance to passive movement is your first motor clue. You'll also notice a subtle weakness; the patient's strength score drops, for example, from 5/5 to 4/5. As things get worse, he'll develop that pronator drift, a weakness (paresis), and then paralysis (plegia).
* Vital signs. You won't detect early vital sign clues unless you're working in a monitored unit. Then you might see intermittent bouts of unexplained hypertension: The patient's alarm goes off while he's asleep because his systolic blood pressure is suddenly 180 when it's normally about 150.
To summarize, a patient with impending or actual brain herniation is unarousable despite deep pain and has a unilaterally fixed and dilated pupil, substantial motor weakness (or posturing or no response despite deep pain), and Cushing's triad (widening pulse pressure, bradycardia, and irregular respirations).
Making a difference
Your savvy evaluation can make a real difference to patients in danger of suffering devastating and irreversible brain damage. Once I learned how to spot trouble early enough to make a difference for these patients, I came to love neuro. I hope you will too.
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