Phantom limb pain in the human brain: Unraveling neural circuitries of phantom limb sensations using positron emission tomography

Abstract

Pain and other phantom limb (PL) sensations have been proposed to be generated in the brain and to be reflected in activation of specific neural circuits. To test this hypothesis, hypnosis was used as a cognitive tool to alternate between the sensation of PL movement and pain in 8 amputees. Brain activity was measured using positron emission tomography. PL movement and pain were represented by a propagation of neuronal activity within the corresponding sensorimotor and pain-processing networks. The sensation of movement was significantly (corrected for multiple comparisons) related to activity in the supplementary motor area and the primary sensorimotor cortex. The sensation of a painful PL posture activated the same brain areas but was weaker and less extended in the supplementary motor area. In contrast to the sensation of movement, pain was significantly related to activity in the thalamus, anterior cingulate, and lateral prefrontal cortex. Subjectively rated PL pain sensation correlated positively to activations in the anterior and posterior cingulate. These findings provide evidence that PL sensations are produced by the same central nervous processes that underlie the experience of the body when it is intact and that the corporeal awareness of PL pain is encoded in a thalamocortical network.

Cerebral Hemodynamic Responses Induced by Specific Acupuncture Sensations During Needling at Trigger Points: A Near-Infrared Spectroscopic Study

“…(2) SMA activity correlated with the intensity of pain (Coghill et al 1999) or an unpleasant sensation (Drzezga et al 2001), (3) SMA activity increased in patients experiencing phantom pain (Dettmers et al 2001;Willoch et al 2000) or allodynia (Peyron et al 2004), and (4) the SMA receives information from the anterior cingulate gyrus, which is involved in the emotional evaluation of pain Van-Hoesen 1992, 1993;Wang et al 2001). Furthermore, de-qi sensation was temporally correlated with the Oxy-Hb concentrations in the SMA.…”

Cortical reorganisation and chronic pain: implications for rehabilitation

“…Recent imaging studies (e.g. 35) have also shown that not only the primary and secondary somatosensory cortex and the posterior parietal cortex are involved in the processing of phantom phenomena but also regions such as the insula and the anterior cingulate. Similar alterations in the cortical processing of sensory information have recently also been reported in patients with complex regional pain syndromes (36).…”

Metal bar prevents phantom limb motion: Case study of an amputation patient who showed a profound change in the awareness of his phantom limb

“…It is now well recognized that amputation results in reorganization of the sensorimotor cortex: with the area previously innervated by the amputated limb now occupied by the adjacent region (Flor et al, 1998;Ramachandran, RogersRamachandran, & Stewart, 1992). Researchers believe that this reorganization may partly explain phantom limb sensation and pain (Flor et al, 1995;Willoch et al, 2000).…”