Incidence, demographic and clinical characteristics of 107 cases (79% female, mean age 39 years) with functional weakness of <2 years duration compared to 46 controls with neurological weakness (83% female, median age 39 years, duration 11 months) were studied at the University of Edinburgh, UK. The incidence was estimated at 3.9/100,000/year for patients over age 16 years. Socioeconomic status was similar in the two groups. Cases with functional weakness had more physical disability, especially pain, than controls. They had a higher frequency of psychiatric disorders (major depression, anxiety disorder, panic disorder, and somatization disorder). They were less likely to agree that stress was a possible cause of symptoms, and twice as likely as controls to report that they were not working because of their symptoms. Hemiparesis was the most common presentation of functional weakness, in 63% cases; monoparesis occurred in 16%. There was no preponderance of left-sided symptoms. Positive physical signs included La belle indifference (3%), collapsing weakness (70%), Hoover' sign (56%), midline split (19%), decreased vibration (39%), and decreased temperature sensation (24%). 
COMMENT. Alternative terms for functional weakness include conversion disorder or dissociative motor disorder, psychogenic or non-organic paralysis. The term functional weakness was used to describe the specific symptom and to avoid terms suggestive of etiology. Patients were all adults, and the incidence among children is higher, especially in primary care and orthopedics. Children attending a psychiatric clinic with conversion disorder may have dissociative disorders, emotional and sexual abuse, physical neglect, and other psychiatric comorbidities . In 52 children admitted to a pediatric teaching hospital with conversion disorder over a 10-year period, the disorder was rare below 8 years of age and girls outnumbered boys three to one. Gait disturbance was the main complaint in 36 children. Pain was present in 40 (77%) children, a frequency similar to the above study in adults. At discharge, 32 (62%) were completely recovered or had appreciably improved. A core group was difficult to diagnose and showed little response to treatment .