Elsevier

The Lancet

Volume 354, Issue 9188, 23 October 1999, Pages 1464-1466
The Lancet

Hypothesis
Cortical origin of pathological pain

https://doi.org/10.1016/S0140-6736(99)05003-5Get rights and content

Summary

Pain without accompanying tissue pathology poses a classic puzzle, presented in extreme form by phantom pain in a non-existent amputated limb. A clue to the origin of such pain is given by the recent discovery of a region of cortex active in response to incongruence between motor intention, awareness of movement, and visual feedback. Phantom-limb sensation, and repetitive strain injuries or focal hand dystonias in writers, musicians, or keyboard operators, are accompanied by plastic changes in sensorimotor cortex and by pathological pain. Disorganised or inappropriate cortical representation of proprioception may falsely signal incongruence between motor intention and movement, which results in pathological pain in the same way that incongruence between vestibular and visual sensation results in motion sickness.

Section snippets

Hypothesis

How might this centre be involved in pathological pain? Let us assume that the unilateral right cortical centre monitoring incongruence of sensation (CIS), proposed by Ramachandran from his experiments on patients with left neglect,20 is the one shown in the functional imaging studies. The CIS is strongly influenced by unilateral vestibular stimulation,20, 21 and if vestibular and proprioceptive sensation of balance and body displacement are incongruent with vision, we feel nausea. In an

Testing the hypothesis

Evidence to support the hypothesis includes preliminary reports that watching a virtual image of a phantom limb move in synchrony with motor commands may relieve phantom-limb pain,8 and that exercises to restore normal sensory cortical maps may relieve RSI16 or focal hand dystonia in musicians.17 Extending the design of these exercises to emphasise visual monitoring of movements should increase their effectiveness.

Pharmacological agents that act centrally to relieve motion sickness, for example

Therapy

How may these observations be useful in the design of therapy? Relief of early symptoms might be achieved with centrally acting pharmacological agents that give prophylaxis for motion sickness. Restoring a normal sensory cortical map by daily exercises, in which individual fingers are vibrated or asynchronously moved through wide excursions under close visual monitoring, might reverse the symptoms of RSI, and so might learning to read braille.22 Typists susceptible to RSI might be advised to

References (24)

  • NN Byl et al.

    The neural consequences of repetition: clinical implications of a learning hypothesis

    J Hand Ther

    (1997)
  • VS Ramachandran

    Anosognosia in parietal lobe syndrome

    Conscious Cogn

    (1995)
  • E Bisiach et al.

    Remission of somatoparaphrenic delusion through vestibular stimulation

    Neuropsychologia

    (1991)
  • GR Fink et al.

    The neural consequences of conflict between intention and the senses

    Brain

    (1999)
  • VS Ramachandran et al.

    The perception of phantom limbs: the DO Hebb lecture

    Brain

    (1998)
  • D Borsook et al.

    Acute plasticity in the human somatosensory cortex following amputation

    Neuroreport

    (1998)
  • S Knecht et al.

    Plasticity of plasticity? Changes in the pattern of perceptual correlates of reorganization after amputation

    Brain

    (1998)
  • TT Yang et al.

    Noninvasive detection of cerebral plasticity in adult human somatosensory cortex

    Neuroreport

    (1994)
  • H Flor et al.

    Cortical reorganization and phantom phenomena in congenital and traumatic upper-extremity amputees

    Exp Brain Res

    (1998)
  • MA Goodale

    Vision for perception and vision for action in the primate brain

    Novartis Found Symp

    (1998)
  • VS Ramachandran et al.

    Synaesthesia in phantom limbs induced with mirrors

    Proc R Soc Lond B Biol Sci

    (1996)
  • JH Kaas et al.

    Multiple representations of the body within the primary somatosensory cortex of primates

    Science

    (1979)
  • Cited by (0)

    View full text