A Reliable Neurologic Examination

Patients in a prolonged comatose state deserve our care and respect. Out of respect for patients, they should never be used. I hesitated to mention them, but I continue to hear them to my dismay. I suggest using the term prolonged coma instead. Anatomy of the main brain structures responsible for awareness How does coma occur? Electrical circuits are a good metaphor when it comes to explaining coma. We now know that neurons in the brain emit electrical signals downstream, causing neurotransmitters to jump to other neurons and ignite them. So, electrical circuits aren’t too far off as an analogy for explaining coma. Several structures in the brain and brainstem basically switch on the lights in our bodies. Parts of the thalamus can turn off and on. If a switch becomes loose and malfunctions, a person goes in and out of consciousness. There are multiple connections between the switchboard and the surface of the brain, known as the cortex. Thinking is controlled by the cortex, and in humans, this part of the brain is well developed.

Prisoner Of Life

Using electrical circuits as a metaphor, the brainstem is the battery, the thalamus is the switchboard, and the other parts of the brain are represented by a computer and computer monitor. Picture the brain as a malfunctioning system in which the separate components are no longer connected. Trauma from an injury cuts the wires by severing nerve tracts. The same thing can happen if a stroke blocks blood flow to a part of the brain, which then dies. Now let’s expand our electrical circuit analogy to the interior workings of a television or computer monitor to explain conditions of abnormal consciousness. Stupor and a minimally conscious state are similar to a screen going in and out of focus. A vegetative state is snow on the screen, and if signals are reaching the patient’s brain, they’re nothing meaningful. Coma is a blank screen, but the system can reboot. Brain death is a blank screen as well, but the system cannot be rebooted. Many comas result from major physical injury to the brain, often from a traumatic accident. Taking an overdose of prescribed medication, using illicit drugs or having severely abnormal blood values can lead to a coma. In those cases, all the brain’s structures are affected, not just one or two.

The Quiet Voice At The End Of The Day

Think of it as a power loss or sudden power surge. High doses of medication can cause people to be unaware of their surroundings. This is basically the same as what happens when a person receives anesthesia before surgery. In these situations, patients wake up nicely when the medication is discontinued. Sometimes, high doses of medication are given to comatose patients to facilitate placement of a tube for mechanical ventilation. Fortunately, most patients who are comatose for several days eventually awaken. The issue is whether the person will be the same and if not, if the apparent damage is permanent. An even smaller percentage never awaken. There often is a light at the end of the tunnel for many of the patients we see. We look for signs of improvement, such as not just opening their eyes but fixating, tracking and looking around, and occasionally trying to mouth words. This is because comatose patients don’t have normal reflexes. They can’t protect their airways, allowing secretions to pool in the back of their throats.

Have You Heard?

They also don’t breathe sufficiently or deeply enough. Lapsing into a deeper coma relaxes the airway muscles even further, causing collapse and a dangerous lack of oxygen and eventually a buildup of carbon dioxide. This is the most common reason that comatose patients are placed on mechanical ventilators. A comatose patient’s heart rhythm also may change suddenly, and blood pressure may drop if the heart doesn’t pump regularly and forcefully enough. Neurologists and neurointensivists often see patients in a coma from a serious brain injury who are already on some sort of life support, such as a ventilator. Patients experiencing cardiac arrest mostly have a cardiac problem. All of these are essential to ensure a reliable neurologic examination. Examination of an unresponsive patient with a very low blood pressure, low oxygen readings and ongoing bleeding that requires massive blood transfusion yields little useful information. In fact, I’ve seen many patients in this desperate condition who later perk up after their vital signs return to normal values. A systematic evaluation begins with a test for response to a stimulus. Many people interpret a comatose patient’s closed eyes as a lack of response and open eyes, conversely, as an indication that the person can communicate. Even deeply comatose patients may briefly open their eyes spontaneously, but not blink. All patients in a prolonged coma will eventually open their eyes, but it may mean little. On the other hand, alert patients may be unable to open their eyes voluntarily due to swelling or bruising of the eyelids or an inability to perform this purposeful action after a major stroke. Therefore, opening or closing of the eyes by itself isn’t a significant indicator of whether a comatose patient has normal or abnormal consciousness. When I examine a comatose patient, I look specifically for brain abnormalities that can cause coma. As noted earlier, they may be isolated in a single part of the brain or involve multiple areas. Health care providers often use scales to evaluate patients, and the most popular one in neurology is the Glasgow Coma Scale. The scale is fairly simple, provides uniform ratings and is very helpful to health care providers who aren’t neurologists. It’s certainly better than the vague terms mentioned previously. The information that scales provide is nowhere near what can be learned with a complete neurologic examination. An examination is far more complex and cannot be reduced to simple assessments. My neurologic examinations usually begin with a test of how the patient responds to stimuli or a loud voice. Yelling at a patient may cause the eyes to open, and I then ask the person to follow a command.