CMs can help reduce misdiagnosis
CMs can help reduce misdiagnosis
How to differentiate states of consciousness
Recent studies indicate there is a high incidence of diagnostic inaccuracy in patients with disorders of consciousness. A new term, "the minimally conscious state," currently is gaining acceptance and promises to reduce the incidence of misdiagnosis. Understanding the differences between a vegetative state and a minimally conscious state gives payers and providers a valuable basis for evaluating treatment designs.
"The issue of potential misdiagnosis is very controversial," says Joseph T. Giacino, PhD, associate director of neuropsychology for the Center for Head Injuries at the JFK Johnson Rehabilitation Institute Center for Head Injuries in Edison, NJ.
"There are three studies which are widely cited," he explains. "The rate of misdiagnosis reported in those studies ranges from 15% to an alarming 43%. I think the thing to take away from these studies is that there is a degree of misdiagnosis. and it affects the effectiveness of treatment interventions." (See box, p. 57, for studies on states of consciousness.)
Finding consensus
Representatives from the fields of neurology and rehabilitation met last year in Aspen, CO, for the Aspen Neurobehavioral Conference Work- group and developed the "Assessment, Prognosis and Treatment of the Vegetative and Minimally Conscious States: The Aspen Neuro behavioral Conference Consensus Statement," says Giacino, who was a conference participant, adding that the paper recently was prepared for publication.
The consensus statement resolves many of the conflicts that surround the diagnosis of disorders of consciousness in an effort to reduce the high incidence of misdiagnosis in this group of patients, he explains.
The most important thing to emerge from the Aspen meetings, says Giacino, was the introduction and refinement of a new condition known as the minimally conscious state (MCS). "The MCS is a condition of severely altered consciousness characterized by definite, although inconsistent, evidence of conscious behavior," he explains. "The conscious behavior is not present all the time, but when it is, it’s unmistakable. In a vegetative state, there is never evidence of conscious behavior."
Yes, but can you do that again?
There are four specific diagnostic criteria for conscious behavior. The presence of any one of the four is necessary for a diagnosis of MCS, Giacino says:
• Simple command-following. "This must be discernable and reproducible behavior. For example, the patient’s index finger moves a fraction of an inch, when you request the patient to move his hand," he says. "The important issue is that the command following behavior does not occur spontaneously in the patient, but only upon command."
In addition, the criterion is not met if the behavior occurs when a different command is given, he explains. "For example, if you ask a patient to blink his eyes, and he moves his hand, the criterion is not met."
• Any incidence of a yes/no response. "It doesn’t matter if this response is accurate in terms of an appropriate yes’ or no’ response to a particular question," notes Giacino. "What is important in this criteria is that the patient nods or shakes his head reproducibly. This response must also be clearly different from movement attributed to an increase in muscle tone, or even a reflexive muscle activity. If you can dissociate the yes’ and no’ response from any other explanation it would meet the criterion."
• Incidence of intelligible verbalization. "This can be tricky at times," he says. "A patient may make a sound, such as ma,’ and clinicians may wonder whether this was an attempt to say mom’ or just a random sound."
To meet this criterion, the verbalization must include a consonant-vowel-consonant verbalization, he notes. "This means ma’ wouldn’t qualify, but mom’ would qualify," says Giacino, adding the vowel-consonant-vowel verbalization is a distinction used at JFK Johnson and is not necessarily part of the Aspen statement. "The patient must make an intelligible word, but it doesn’t have to be upon request."
• Any incidence of movements or emotional behaviors that occur in response to specific stimulus. "This is the most convoluted, but a very important, criterion," he says. "These are responses to a specific stimulus that occur when the stimulus is present, but which don’t occur in the absence of the stimulus."
He offers case managers six examples to clarify this criterion:
— Emotional responses such as smiling or crying. "We’ve had family members or care providers report that patients in a vegetative state can smile or cry. This alone is not enough to meet the criteria for a diagnosis of MCS. The smiling or crying must occur in response to a specific stimulus, such as the presence of the patient’s family," he explains.
Giacino recalls a patient who appeared to be in a vegetative state two years post-injury. He completed a comprehensive evaluation of the patient at the request of the insurance company and found no evidence of consciousness. As he was preparing to leave, the patient’s wife asked Giacino to watch a video of the patient listening to his wife read a letter from his sister out loud. "As his wife read his sister’s note, the patient began to cry," he says. "I had spent an hour with him and seen no evidence of consciousness, but whenever she read the note from his sister, he cried. When she stopped reading, the crying stopped. If the crying had been random or spontaneous, it wouldn’t have met the criterion."
— Vocalizations or gestures. "These must be a direct response to a particular stimulus not demonstrated in the absence of the stimulus. For example, you go to the patient’s bedside, wave, and say, Hello.’ Whenever you do this, the patient’s wrist flexes in a wave-like gesture. The patient appears to wave, and this gesture never occurs under any other circumstances."
— Ability to follow and reach for an object. "An example of this is presenting an object and moving it from the patient’s visual field to the left or to the right. As you move the object, the patient reaches to the correct side relative to the object. If you can demonstrate that the patient is reaching in the direction of the object and that this occurs with regularity, it is a good example of this criterion."
— Attempts to touch or hold an object. "To meet this criterion, the patient also must demonstrate some ability to discriminate what the object is," notes Giacino. "For example, if you hand the patient a coffee cup, the patient opens his fingers to reach around the cup. If you hand someone a pencil, the grasp necessary to hold it is different from the grasp necessary to hold a cup. There must be some differentiated finger or hand movement that demonstrates the patient is aware what type of object this is."
A vegetative patient cannot hold an object, he adds. "Stimulation of the palm may cause a release of the grasp reflex. However, a patient in a vegetative state can’t make the adjustment needed to differentiate objects. This is why it is important to use different types of objects to test for this criterion."
Giacino recalls one patient who appeared to be in a vegetative state. "He was not following commands, but I took an object and stroked the side of his index finger with it. He lifted his hand up, felt where the object was, and grabbed it. A patient in a vegetative state will never do this."
— Visual tracking or pursuit eye movements. To meet this criterion, the patient must fix on an object in the environment with his eyes and sustain fixation on the object as it moves around in the environment, he says. "The question here is how long must the patient fixate on the object to constitute tracking. This issue is not addressed clearly in the Aspen statement. However, I think that other statements have required sustained fixation of a minimum of two seconds or 20-degree movement."
At JFK Johnson, clinicians require patients to sustain eye fixation through a 45-degree arc from midline in any direction, Giacino adds. "This is a very important criterion because it is often the first indicator that a patient is emerging from a vegetative to a MCS. We use a mirror, because the patient’s own face is such a powerful stimulus. We move the mirror slowly 45 degrees in all directions. When a patient is capable of following this, you will not miss the response. It is just too clear."
— Avoidance of barriers. "This criterion often sounds strange, but there is a reason it is included," he says. He cites an example of a woman who never demonstrated any kind of function. She never spoke or gave any clear indication of conscious behavior. Yet when placed in a wheelchair, the patient could move around the hallway avoiding all obstacles.
"She continued to show no other signs of consciousness," he says. "I followed her for nine months post-injury. At that point, she was walking. She walked aimlessly. She never hit anything. She walked around the perimeter of a pool table. But, it was all aimless. What do you call this?"
The patient came very close to a vegetative state. "I think this patient captures the diagnosis of MCS. She was in this state due to a metabolic coma. I think it’s likely that [the coma destroyed] her cortex, her seat of higher reasoning, but [she] was left with her lower structures, like basic sensory reactions and basic motor functions," Giacino says.
Accurate diagnosis = accurate prognosis
MCS is a newly defined condition, so data are scarce. JFK Johnson has published a study that compared 12-month outcomes for patients in a vegetative state to MCS patients. "When these patients came in one month post-injury, there was little discernible difference between the two groups," he notes.
However, when a functional disability rating scale was used to reevaluate the patients at three, six, and 12 months post-injury, clinicians found significant differences between vegetative and MCS patients in terms of recovery.
"We then made one other distinction," Giacino says. "We further defined the groups in terms of those whose consciousness disorder was caused by trauma and those whose consciousness disorder was not caused by trauma. We found the most striking improvement occurred in MCS patients whose condition was caused by trauma. The study must be reproduced but it gives us the ability to begin to say there is a clear separation in outcomes between vegetative and MCS patients."
In addition, he says, the rate of recovery is helpful in predicting outcomes. "How fast a person is changing is a powerful predictor of their final outcome, regardless of how poorly they were functioning when admitted to rehab." To determine recovery rate, subtract the patient’s week-one functional disability rating score from the patient’s week-four score to get a "change" score, he says. "A 1991 study found that patients with a change score of six or more points in the first month had significantly better outcomes than patients with lower change scores. It didn’t matter whether the patient’s functional disability rating scores were high or low, as long as the change score was high."
Case managers who insist that rehabilitation teams use new, more accurate diagnostic criteria for disorders of consciousness will make better decisions about treatment interventions and help reduce the incidence of misdiagnosis, Giacino says.
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