Maladaptive plasticity: imprinting of past experiences onto phantom limb schemata

Phantom limb perception is common following amputation, and is sometimes characterised by pain that resembles the characteristics, intensity or location of past pain. We tested Flor's model that phantom pain results from memory for long-lasting znoxious input.

We report a questionnaire study of 283 amputees, that explored the experience of painful, non-painful and postural somatosensory memories in the phantom. We explore the impact of pre-amputation pain and impairment duration, and complications in the limb (eg, infection, gangrene, surgery, and vascular disease). Differences in mood, coping and adjustment to amputation are also explored in those with somatosensory pain memories.

Our findings support Flor's model, as amputation-related and non-amputation-related pain memories, and non-painful memories comprised pains or sensations that were either enduring/recurring pains or sensations (eg, ingrown toenail, corns, chilblains, arthritis-type pain in winter, night-cramps, or holding a tennis racquet), or resulted from a painful event with a "core-trauma" element (eg, fracture, crushing/penetration injury). Pain memories related to amputation were more common following functional impairment before amputation; infection or surgery prior to amputation; or having diabetic or vascular amputations-which are associated with multiple complications, including neuropathic changes, infection and prior surgery. Furthermore, participants with amputation-related pain memories exhibited higher sensory pain ratings, as well as poorer mood and adjustment to the limitations of amputation.

We propose that somatosensory pain memories likely relate to the generation and maintenance of limb representations upon which intense or emotionally powerful past experiences have been imprinted.