Introduction: Psychogenic disorders, also referred to as somatoform, conversion, somatization, hysteria, and medically unexplained symptoms, are among the most challenging disorders to diagnose and treat. Psychogenic movement disorders are increasingly encountered in specialized clinics, and represent approximately 15% of all patients evaluated in the Baylor College of Medicine Movement Disorders Clinic.
Objective: To characterize psychogenic tremor and provide data on prognosis and long-term outcome in a large group of patients with psychogenic tremor followed in a movement disorders clinic.
Methods: Patients evaluated at the Baylor College of Medicine Movement Disorders Clinic in Houston, Texas, between 1990 and 2003 with the diagnosis of psychogenic movement disorder (PMD), who consented to be interviewed, were administered a structured questionnaire designed to assess current motor and psychological function.
Results: psychogenic tremor is the most common PMD, accounting for 4.1% of all patients evaluated in our clinic. We were able to obtain clinical information on a total of 228 of 517 (44.1%) patients with PMD, followed for a mean of 3.4+/-2.8 years. Among the 127 patients diagnosed with psychogenic tremor, 92 (72.4%) were female, the mean age at initial evaluation was 43.7+/-14.1 years, and the mean duration of symptoms was 4.6+/-7.6 years. The following clinical features were considered to be characteristic of psychogenic tremor: abrupt onset (78.7%), distractibility (72.4%), variable amplitude and frequency (62.2%), intermittent occurrence (35.4%), inconsistent movement (29.9%), and variable direction (17.3%). Assessment of long-term outcome showed that 56.6% of patients reported improvement in their tremor. Factors predictable of a favorable outcome were elimination of stressors and patient's perception of effective treatment by the physician.
Conclusion: This largest longitudinal study of patients with psychogenic tremor provides data on the clinical characteristics and natural history of this most common PMD. The accurate diagnosis of psychogenic tremor is based not only on exclusion of other causes but is also dependent on positive clinical criteria, the presence of which should avoid unnecessary investigation. The prognosis of psychogenic tremor may be improved with appropriate behavioral and pharmacologic management.