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Motor initiation and execution in patients with conversion paralysis
Karin Roelofs1, Gerard P van Galen, Ger P J Keijsers
1Department of Clinical Psychology and Personality, University of Nijmegen, The Netherlands. roelofs@psych.kun.nl
Acta Psychologica
|May 15, 2002
Summary
Patients with conversion paralysis show impaired motor initiation, not motor execution. This suggests a specific deficit in starting movements, particularly those involving explicit spatial and motor planning.
Area of Science:
- Neuroscience
- Psychiatry
- Cognitive Psychology
Background:
- Conversion disorder is a neuropsychiatric condition characterized by motor or sensory deficits.
- Previous hypotheses suggest a dissociation between motor initiation and execution in conversion disorder.
Purpose of the Study:
- To investigate motor initiation and execution in conversion paralysis using speech tasks.
- To test the hypothesis of impaired motor initiation but intact motor execution.
Main Methods:
- Four patients with conversion paralysis performed verbal response reaction time (RT) tasks.
- Tasks included simple choice RT, mental letter rotation, and implicit/explicit mental hand rotation.
- Motor initiation (RT) and motor execution (response duration, RD) were measured.
Main Results:
- Task characteristics significantly affected RT but not RD.
- Factors like instruction type, rotation angle, and affected arm influenced initiation time.
- Response duration remained consistent across conditions.
Conclusions:
- Conversion paralysis is linked to a specific impairment in the explicit initiation of movements.
- Findings support a dissociation between motor initiation and execution in this disorder.
- The deficit appears related to processes with spatial and motor components.