Sensorimotor returning in complex regional pain syndrome parallels pain reduction

Burkhard Pleger, Martin Tegenthoff, Patrick Ragert, Ann-Freya Förster, Hubert R. Dinse, Peter Schwenkreis, Volkmar Nicolas, Christoph Maier
2005 Annals of Neurology  
Patients with complex regional pain syndrome (CRPS) and intractable pain showed a shrinkage of cortical maps on primary (SI) and secondary somatosensory cortex (SII) contralateral to the affected limb. This was paralleled by an impairment of the two-point discrimination thresholds. Behavioral treatment over 1 to 6 months consisting of graded sensorimotor retuning led to a persistent decrease in pain intensity, which was accompanied by a restoration of the impaired tactile discrimination and
more » ... ining of cortical map size in contralateral SI and SII. This suggests that the reversal of tactile impairment and cortical reorganization in CRPS is associated with a decrease in pain. Ann Neurol 2005;57:425-429 Complex regional pain syndrome (CRPS) is a serious complication that occurs with (type II) or without (type I) apparent peripheral nerve lesion after an often disproportionate trauma of a limb. 1,2 Several theories proposed the existence of pathophysiological mechanisms of central origin. 3-8 Recent findings provide evidence for a shrinkage of cortical maps on primary somatosensory cortex (SI) contralateral to the CRPS affected limb. 3,6,7 The degree of reduction thereby appeared to be linked to pain intensity. 6, 7 In this study, we sought to determine whether behavioral treatment implicating the reinforcement of sensory feedback mechanisms may alter cortical reorganization and also pain perception. In six patients with intractable pain due to CRPS type I of one upper limb, drug therapy was accompanied by a pain adapted sensorimotor training program consisting of graded desensitization protocols and motor tasks in ascending difficulty. To assess possible alterations of cortical maps in SI and SII (primary and secondary somatosensory cortex) (Table 1) , patients were subjected to functional magnetic resonance imaging (fMRI) during electrical stimulation of the index finger (IF) before and after therapy. We combined each fMRI session with measurements of the two-point discrimination thresholds on the tip of the IF to assess therapy-induced changes in tactile perception. Patients and Methods Informed consent was obtained from all patients, and the study was approved by the local ethics committee. All patients first underwent electroneurographic and clinical neurological examination to exclude a peripheral nerve injury (CRPS type II) as another possible origin of cortical reorganization. 9 Patients with cutaneous damage and edema of the CRPS affected IF were excluded to avoid erroneous highstimulation intensities during fMRI because of peripheral disturbances. Only patients in whom signs of CRPS affected the whole hand including all digits were recruited. In all patients, we found an increased bone metabolism of the affected hand as shown by three-phase scintigraphy. 10
doi:10.1002/ana.20394 pmid:15732114 fatcat:bvqcvs6as5eerh7pk6wq4krcyy