Houben’s diagnosis came after a near-fatal car crash in 1983. According to a report in The Guardian, his mother never wavered in her belief that her son was conscious, and repeatedly brought him to the United States for tests, but to no avail. Twenty-three years after Houben’s accident, a PET scan performed by Dr. Steven Laureys, a leading neurologist and researcher at Belgium’s Coma Science Group, indicated that Houben’s metabolic brain function was nearly normal. With evidence that Houben could be conscious, measures were devised to help him to communicate, including a simple yes/no switch that he could manipulate with his foot.
Now, using a touchscreen computer with help from a therapist, Houben is reportedly writing a book about his experiences. He describes his decades of powerlessness and frustration as he was able to hear others talking about him but was unable to communicate. “I screamed, but there was nothing to hear,” he writes.
(In the days since Houben’s story gained worldwide attention, there has been controversy over the use of “facilitated communication.” In a video of Houben, he is seen assisted in typing by a therapist, raising suspicions, for some, that his words are not his own. I won’t weigh in on the controversy over facilitated communication, as others have done so quite well. There is little reason to doubt that Houben is conscious, and that he remains severely disabled, and whether or not facilitated communication is credible, the critical issue his case illustrates is the problem of misdiagnosis in disorders of consciousness.)
Diagnosing disorders of consciousness is notoriously difficult. A paper published in BMC Neurology earlier this year found that the rate of misdiagnosis is higher than 40 percent. “Despite the importance of diagnostic accuracy, the rate of misdiagnosis has not substantially changed in the past 15 years,” the study noted. One of the paper’s authors was Laureys, the doctor who is credited with unshackling the mind of Rom Houben.
Houben’s case is extreme. Houben reportedly has a form of locked-in syndrome, a very rare condition that causes near total paralysis, but leaves a person fully conscious and aware. Locked-in syndrome can be difficult to distinguish from disorders of consciousness (which include vegetative states and minimally conscious states) because people with the syndrome are unresponsive.
The most frequent category of misdiagnosis involves patients who are in a minimally conscious state, but are diagnosed as vegetative. Vegetative patients are unconscious; they experience sleep/wake cycles but show no behavioral evidence of self or environmental awareness. Minimally conscious patients exhibit signs of awareness, may make purposeful movements, and may have limited and inconsistent abilities to communicate. In practice, the differences between the two states can be subtle and hard to detect, even for experienced and skilled clinicians.
The diagnostic gold standard for disorders of consciousness is a bedside behavioral assessment, but accurate diagnosis can be confounded by numerous factors, including locked-in syndrome, paralysis, aphasia, cortical deafness and blindness, the use of sedatives, tracheotomy, and the limited attentional capacities of patients. Moreover, because some patients progress from a vegetative state to a minimally conscious state, repeated diagnostic assessment is necessary to detect subtle signs of recovery.
The misdiagnosis of disorders of consciousness is a grave and pressing problem for neuroscience, with significant consequences.
- Prognosis differs depending on the diagnosis. Minimally conscious patients have a much better prognosis, and a greater likelihood of recovery, than do permanently vegetative patients.
- Minimally conscious and locked-in patients require different care than do vegetative patients. For example, pain management may be needed by minimally conscious or locked-in persons who, unlike vegetative patients, can experience pain and discomfort. Patients who are misdiagnosed as vegetative may also miss opportunities for rehabilitation on the mistaken assumption that they will not benefit from them. Although many patients with disorders of consciousness remain profoundly disabled, therapeutic interventions to facilitate communication or provide neurological and physical rehabilitation may promote functional recovery for patients like Houben, and the minimally conscious.
- The high rate of misdiagnosis leads to confusion, uncertainty, and lack of confidence for the families and caregivers of patients with disorders of consciousness. Reducing the rate of misdiagnosis could not only increase trust and confidence, but also identify those patients with some hope for recovery and those with virtually none. Such knowledge would help relatives and other surrogates make informed decisions, consistent with the patients’ values and interests.
- U.S. law allows surrogates to make decisions regarding the withdrawal of life support for incompetent patients. Locked-in patients ought to be considered legally competent in the sense that they are conscious and have decisional capacity, but because they are physically incapacitated, they require considerable assistance before they can communicate. Some minimally conscious patients might be capable of expressing preferences as well, although they can communicate only inconsistently, with simple yes/no responses, and it remains uncertain how reliably, and to what extent they are capable of understanding or making decisions. Better diagnostic accuracy is needed for legal distinctions and assessments of competence to be applied with confidence, and to help surrogates to make informed end-of-life decisions with more certainty and clarity.
- Patients who are misdiagnosed as vegetative can become effectively invisible if the behavior of families, clinicians, and caregivers is influenced by the belief that the patient is unconscious. It is not hard to imagine the horror and despair that Houben must have experienced, listening to bedside conversations about his condition, and to hear himself spoken of as if he were not there.
- There is ongoing and promising research on potential treatments for patients with disorders of consciousness, including drug therapies and neurostimulation. Much more research is needed to assess the effectiveness and benefits of these therapies. Accurate diagnosis is important both to identify appropriate research subjects, and to further understanding of the salient neurological features that influence patient outcomes. Thus, better diagnosis is critical to the development of effective treatments for disorders of consciousness.
Is there hope of improving diagnosis? There have been encouraging discoveries in recent years, with functional neuroimaging tests, such as fMRI and the PET scan utilized in Houben’s case, electrophysiological measures, and better behavioral tests specific to disorders of consciousness. These developments show promise as tools for uncovering awareness that was previously undetectable. At the same time, these advances are revealing more about the brains of patients with disorders of consciousness, demonstrating, for example, that there are significant and observable functional differences between the brains of minimally conscious and vegetative individuals. This additional knowledge is inching neuroscience closer to the elusive goal of discovering the neural correlates of consciousness, while also pointing the way to possible treatments and rehabilitative strategies.
At present the use of neuroimaging is not definitive for diagnosis; bedside behavioral diagnosis remains key. It is imperative and urgent that research toward more accurate diagnosis remain a priority, both to release patients like Rom Houben from their diagnostic prisons and to prevent others from suffering the same fate.
L. Syd M. Johnson, PhD, is a research fellow at Novel Tech Ethics, Dalhousie University.