LAUSR

In 2006, I published an article titled, “Psychogenic movement disorders: a crisis for neurology.” I had an epiphany a few years before when I realized that 30% of the patients that I was seeing in my referral movement disorder clinic had a psychogenic disorder. I looked around for information and found very little. I wrote, “The nature of the crisis is that there are many patients, we don’t understand the pathophysiology, we often don’t know how to make the diagnosis, we don’t know how to treat the patients, the patients don’t want to hear that they have a psychiatric disorder and they go from doctor to doctor, psychiatrists don’t seem interested anyway, and the prognosis is terrible.” It was not that this was a new epidemic; functional disorders have been recognized for at least 2500 years. Hippocrates wrote about hysteria. Briquet, Charcot, Janet, and Freud made the subject popular in the 19th century, but then at least through the latter part of the 20th century, the disorder seems to have gone underground. The topic disappeared from textbooks, and neither neurologists or psychiatrists were trained in this area. Neurologists generally sent the patients away without any plan. A psychiatrist about that time told me that conversion disorders were a disorder of the 19th century and that there were no such patients any more. I decided that I should work on this topic, and, fortunately, others also became interested about this same time. The last decade has seen remarkable progress. I will consider the crises in the order I had listed them in the 2006 article. The pathophysiology of functional movement disorders has been largely dominated by Freudian concepts of conversion and, to a lesser extent, Janet’s concept of dissociation. Moreover, in clinicians’ thinking, patients with functional disorders were also mixed up with those with factitious disorder or malingering. So often, although primary and secondary gains might be recognized, neurologists would just tell the patients that nothing was wrong and that they should just get themselves better by trying harder to do so. The first step in improving understanding of pathophysiology was to clearly separate conversion and factitious/malingering, an involuntary disorder and the voluntary look-alikes, respectively. This was aided by an improved classification of psychiatric disorders in the Diagnostic and Statistical Manual (DSM) 5. A second step was the pathophysiological investigation of these patients with neuroimaging and clinical neurophysiology. Such studies show abnormalities of brain function and, more recently, even subtle abnormalities of brain structure. Patients with functional paralysis do not activate the primary motor cortex when attempting to move, but instead activate other areas such as limbic areas or frontal areas. The primary motor cortex is actually inhibited, as can be demonstrated by transcranial magnetic stimulation and functional MRI (fMRI). These findings suggest “top-down” interference with the initiation of motor control signals. Another element of disordered topdown control is likely to be abnormal attention to the body part with the involuntary movement. This is apparent clinically, and physiological evidence for this comes from abnormal modulation of beta desynchronization in a choice reaction time task. Patients with functional myoclonus show a Bereitschaftspotential (BP) prior to their involuntary jerks. The BP was originally described to precede voluntary movement and largely comes from activation of the premotor cortex and supplementary motor area. This shows that functional myoclonus uses the same final mechanism as voluntary movement. Moreover, stimulus-sensitive functional myoclonus behaves like voluntary reaction time movements. Functional tremor behaves in all ways like voluntary rhythmic movements. Indeed, if a patient is asked to make a voluntary rhythmic movement of another body part, the involuntary tremor entrains to the voluntary movement. Hence, *Correspondence to: Mark Hallett, MD, DrMed (hon), Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 7D37, 10 Center Drive, Bethesda, MD 20892-1428; E-mail: [email protected]