Recognizing uncommon presentations of psychogenic (functional) movement disorders

Area of Science:

• Neurology
• Movement Disorders
• Psychosomatic Medicine

Background:

• Psychogenic or functional movement disorders (PMDs) present diagnostic challenges.
• Key diagnostic clues include sudden onset, incongruous symptoms, distractibility, and lack of response to medication.
• Common PMDs include tremor, dystonia, and myoclonus.

Purpose of the Study:

• To review the frequency, clinical features, and diagnostic tools for uncommon psychogenic movement disorders.
• To discuss presentations such as psychogenic parkinsonism, tics, chorea, and facial/palatal/ocular movements.
• To explore PMDs in extreme age groups and in the context of mass psychogenic illness.

Main Methods:

• Review of literature on frequency and distinct clinical features of uncommon PMDs.
• Analysis of functional imaging and neurophysiological tests for diagnosis.
• Discussion of specific presentations and contexts of PMDs.

Main Results:

• Psychogenic parkinsonism (PP) affects <10% of PMD patients; differentiated by lack of amplitude decrement and cogwheel rigidity.
• Psychogenic tics occur in ~5% of PMD patients; lack of transient suppressibility is key.
• Specific movements like convergence ocular spasm show high specificity for psychogenic origin.

Conclusions:

• Clinical features and ancillary studies are crucial for diagnosing uncommon psychogenic movement disorders.
• Understanding these features aids in differentiating PMDs from organic conditions.
• Diagnosis is improved by considering specific movement types and patient demographics.