The transfer of the sensation of an amputated limb to another body part is called referred phantom sensation (RPS). A previous report discusses a case of RPS of the fingers on the face that appeared after amputation of the upper limb. The RPS changed shape several months later, and it also exhibited a change in the somatotopy corresponding to the amputated limb and its surrounding area. Here we record and discuss the immediate and temporal changes in the RPS representation in an adult female who had undergone thigh amputation. The RPS examination was conducted once a day at the same time for four consecutive days. Additionally, on Day 4, a second test was performed 5 minutes after the first. The overall tendency was that the sensation of the amputated lower leg occurred mainly on the anterior part of the thigh, and the sensation of the amputated foot and toes occurred mainly on the surface of the amputated thigh. However, recorded body part localization maps of the RPS showed different results at each test. We consider that although there is some degree of coherent localization, the RPS representation may change frequently. We also consider that the somatotopy corresponding to the amputated limb and its surrounding area is not immobile, but constantly changes and fluctuates, for as long as more than four years after amputation.

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We explored the characteristics and changes over time of a supernumerary phantom limb (SPL) in a patient who had suffered an acute stroke. A 41-year-old right-handed Japanese male complained of the sensation of an SPL on his right side after a left putamen hemorrhage, and associated hematoma and edema compression were found in his left thalamus and internal capsule. Computed tomography and magnetic resonance imaging identified the lesion causing the left hemispheric stroke. The patient was treated without surgery. A neurological examination revealed severe hemiplegia and sensory disturbances on the right side of the patient’s body. The SPL sensation had started from his right shoulder on the day of onset and eventually disappeared by 14 days post-onset. The SPL had voluntary movement and changed in shape over time. We consider that maintaining auditory comprehension and the ability to accurately express the symptom led to the discovery of the appearance of an SPL. We hypothesize that the lack of sensory and motor information for limb perception contributes to the appearance of an SPL. Regardless of the damaged hemisphere, we consider that the appearance of an SPL is related to the transection of nerve fibers in the thalamus and motor-related cortex due to hematoma, edema, or compression of the thalamus and internal capsule. In this case, we also consider the loss of neural information necessary to perceive the paralyzed limb as crucial.

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