Four legs. Illusory reduplication of the lower limbs after bilateral parietal lobe damage.

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.