Sensory qualities of the phantom hand map in the residual forearm of amputees

Abstract

Objective: Most amputees experience referred sensations, known as a phantom hand map, on the residual forearm, where touch on specific areas is perceived as touch on the amputated hand. The aim of this study was to evaluate the sensory qualities of the phantom hand map. Methods: In 10 traumatic forearm-amputees touch thresholds and discriminative touch of the phantom hand map were assessed and compared with corresponding areas on the contralateral forearm. The study assessed the localization of touch on the phantom hand map, and how distinct and similar to normal touch the referred feeling was. Results: Similar touch thresholds were seen in the phantom hand map and the control site. Tactile discrimination, requiring both detection of stimulus and interpretation, was significantly better in the phantom hand map. Conclusion: This explorative study suggests that the phantom hand map and the superior tactile discrimination seen in the phantom hand map are based on adaptations within the brain. Further studies investigating the neural basis for the phantom hand map are needed.