EXTENSIVE REORGANIZATION OF PRIMARY SOMATOSENSORY CORTEX IN CHRONIC BACK PAIN PATIENTS

The hypothesis of reorganization of the primary somatosensory cortex i n states of chronic pain was assessed in 10 low back pain patients and nine matched healthy controls. Intracutaneous electric stimuli were a pplied to the left back and index finger at a standard, a non-painful and a painful intensity. Magnetic fields were recorded by a 37-channel BTi biomagnetometer from the hemisphere contralateral to the site of stimulation. The power of the early evoked magnetic field (<100 ms) el icited by painful stimulation of the painful back in very chronic pati ents was elevated relative to that elicited by painful back stimulatio n of healthy controls and showed a linear increase with chronicity (r = 0.74). The maximum activity elicited in primary somatosensory cortex was shifted more medially in the very chronic back pain subjects. The se data suggest that chronic pain is accompanied by cortical reorganiz ation and may serve an important function in the persistence of the pa in experience. (C) 1997 Elsevier Science Ireland Ltd.