Temporary phantom limbs evoked by vestibular caloric stimulation in amputees

Objective: Relationships between the vestibular system and the body schema have been suggested but never demonstrated in amputees. We studied the effe cts of vestibular stimulation oil body representation in amputees focusing on the phantom limb phenomenon. Method: Prospective study in 31 amputated s ubjects of one or several limbs before the age of 16 years. The amputees un derwent a caloric vestibular stimulation test, ipsilateral (n = 31) and con tralateral (n = 8) to the side of amputation. Amputees were asked to report their perceptions spontaneously and to answer open questions. Four types o f perceptions were analyzed: normal phantom, deformed phantom, painful phan tom, and no phantom, before, during, and after the vestibular stimulation t est. Data were compared between the two groups for pre- and post-test perce ptions (chi (2) test). Results: Vestibular caloric stimulation provoked tem porary perception of I normal phantom limb in 16 of 17 amputees who previou sly did not experience phantoms. For 12 of 12 amputees who currently experi enced deformed or painful phantom limbs, caloric stimulation led to tempora ry replacement of the abnormal phantom with a non-painful normal phantom. C onclusions: The phenomena observed: 1) throw light on assumed mechanisms co ntrolling construction of static and dynamic engrams used to produce the bo dy schema 2) complete the neuromatrix theory proposed to explain the phanto m limb phenomenon; and 3) suggest that the vestibular system triggers the p rocedure of reconstruction of the global body schema.