Diagnosis and Treatment of Functional (Psychogenic) Parkinsonism
Functional (psychogenic) parkinsonism (FP) is recognized by the mandatory combination of marked slowness without progressive decrement on repetitive manual tasks and variable resistance against passive movements in the absence of cogwheel rigidity. Other functional phenotypes, such as functional tremor and functional gait impairment, may coexist. Although neither necessary nor sufficient for the diagnosis of FP, supportive historical clues include the sudden onset of symptoms and absent or nonphysiologic response to levodopa. In selected cases where examination features remain insufficient to render a clinically definite FP diagnosis, normal dopaminergic transporter imaging (DAT scan) confirms “laboratory supported” FP. The management of FP begins with diagnostic debriefing, as the full acceptance of the diagnosis is critical in ensuring patient involvement in individualized psychoeducation, psychotherapy, and physical and occupational therapy.