Objective: To report an unusual disorder of body schema and its neurologic and neuropsychological correlates.
Design and methods: We describe a patient with a reduplicative phantom illusion of her lower limbs. Motor and sensory functions, as well as mental representation of body and space, were studied during the reduplication experience until its resolution.
Setting: Clinical neurology department in a primary care hospital.
Patient: A 64-year-old, left-handed woman who experienced the uncontrollable and distressing feeling of having 4 legs, without delusional belief, after surgical removal of a right-predominant parasagittal parietal meningioma. This phenomenon spontaneously resolved after 2 weeks.
Intervention: None.
Main outcome measures: Clinical neurologic examinations and standardized neuropsychological tests, with emphasis on tests assessing orientation to body parts, right-left discrimination, and mental orientation in space.
Results: The patient had severe weakness and proprioceptive sensory loss in both lower limbs. She had no disturbances of body schema knowledge but a striking impairment in tasks requiring mental orientation in space, particularly for right-left laterality discrimination. Resolution of the reduplication experience correlated with improvement in the affected spatial abilities, while motor, sensory, and other cognitive functioning did not significantly change.
Conclusion: This patient's reduplicative phantom illusion might be related to the combination of the severe somatosensory loss with an underlying impaired mental representation of relative positions in space.