I. Introduction
Up to 80% of amputees experience phantom limb pain (PLP). Main factors leading to amputation are vascular diseases, trauma, and cancer. Evidence has been presented in the literature supporting both peripheral and central mechanisms responsible for generating PLP, however further investigations are required. Neuroplastic changes affect the sensory neural tracts and their central projections following amputation [1]-[5]. In the absence of the sensory input, maladaptive cortical plasticity may occur, possibly leading to PLP. Consequently, providing an artificially generated sensory input may reverse this cortical reorganization possibly leading to alleviation of PLP [6]-[7]. Amputated peripheral nerves may grow to the surface of the stump forming referred sensation areas (RSAs). As such, stimulation of RSAs may provide direct access to the sensory neural pathways that innervated the limb prior to amputation. Stimulation of RSAs may induce sensations in the phantom limb that may be regarded as artificially induced sensory input. The quality and quantity of such sensory input artificially induced by various types of stimuli may vary considerably when compared to that of the lost limb. Various techniques for stimulus delivering on RSAs may improve the quality and quantity of the induced sensory input. As such, modulation of the stimulus and contextual correlation with other sensory modalities may improve transmission, perception, and integration of the artificially generated sensory input providing a higher impact on cortical reorganization and eventually a more efficient form of therapy for PLP. We designed a long-term study over six months aiming to provide music modulated electrical stimulation of RSAs in upper and lower limb amputees. We report in this paper the analysis of RSAs mapped using mechanical stimuli (vibration and light pressure) and test of surface electrical stimulation of the stump in the case of a bilateral upper limb amputee.