Clinical diagnosis of psychogenic disorders of nervous system functions

Psychogenic impairments of neurological functions are by no means rare. It may mimic almost all variants of neurological disturbances of motor, sensor y or coordinatory functions. The most common presentation is impaired gait, paresis, seizures or sensory deficits. Tremor, dystonia and other basal ga nglia symptoms are less common. The diagnosis is based first of all, on gen eral features like fluctuation, intermittent remission, inconsistent presen tation of symptoms, change or decrease of (non-organic) neurological sympto ms if the attention of the patient is distracted or if it flags; or, rarely , remission during psychotherapy and, secondly, the absence of features cha racterising the respective organic disorder imitated by the psychogenic. Fo r individual psychogenic disorders specific clinical tests are of high diag nostic significance like the co-activation sign of psychogenic tremor. Labo ratory tests are only helpful by excluding organic conditions. The pattern of the underlying psychopathological abnormalities is not uniform. The diag nosis has to be based on proper neurological criteria, rather than on a dem onstration of psychiatric abnormality.