Mislocalization of tactile stimulation in patients with complex regional pain syndrome

Abstract

Complex-Regional-Pain-Syndromes (CRPS) are characterized by sensory,motor and autonomic dysfunctions. Patterns of sensory symptoms suggest changes within the central nervous system (CNS). Recently, we could show substantial reorganization of somatotopic maps within the central nervous system of patients with CRPS using functional imaging techniques (Maihofner et al. Neurology, 2003). These changes were predicted by CRPS pain and mechanical hyperalgesia. In the present study we looked for potential psychophysical correlates of cortical reorganization in CRPS. Sequential pneumatic non-noxious tactile stimulation was performed at digits 1 and 5 in 24 patients with CRPS of the upper extremities. Both the unaffected and affected side were examined. Patients were interviewed for tactile induced sensations. The occurrence of mislocalizations was correlated with a detailed psychophysical examination in which sensory, motor and autonomic symptoms were assessed. Eight patients (30 %) reported tactile mislocalizations, which were felt in the affected hand. In four cases the referred sensations spread into other nerve territories (ulnar/median nerve). Presence of mechanical hyperalgesia significantly predicted the occurrence of mislocalizations. In contrast, in a healthy control group, no mislocalizations were found. Thus, our results further support the concept of pain-induced reorganization in the somatosensory system of CRPS patients.

Central mechanisms of experimental and chronic neuropathic pain: Findings from functional imaging studies

“…In addition to facilitated neurogenic inflammation and pathological sympatho-afferent coupling, there is accumulating evidence that central nervous system changes may be involved in the pathogenesis of CRPS [79]. Regarding the somatosensory system, there is evidence for a substantial reorganization of the somatotopic map within the primary somatosensory cortex of CRPS patients [79][80][81][82][83][84]. Using functional imaging techniques, a significant shrinkage of the cortical hand representation contralateral to the CRPS affected painful arm was found [79,81,83].…”

“…Cortical reorganization may be able to explain some of the often puzzling clinical signs of CRPS, e.g. the spatial distribution of sensory disturbances in a glove or stocking like distribution, the occurrence of tactile induced referred sensations [82] and hemisensory deficits. Furthermore, there is accumulating evidence that the central motor system shows significant alterations in CRPS.…”

Habenula functional resting-state connectivity in pediatric CRPS

“…Additionally, trophic alterations in skin, hair, nails, and motor function may also occur. Experimental studies have repeatedly documented that patients with CRPS exhibit profound alterations in brain function (Fukumoto et al 1999;Apkarian et al 2001;Maihöfner et al 2004Maihöfner et al , 2005Maihöfner et al , 2006Pleger et al 2006;Lebel et al 2008;Becerra et al 2009;Freund et al 2010), structure (Geha et al 2008;Baliki et al 2011), andchemistry (Fukumoto et al 1999;Grachev et al 2000Grachev et al , 2002Klega et al 2010). Interestingly, there is growing evidence that chronic pain is also characterized by alterations in resting-state functional connectivity (rsFC) as, for example, patients with chronic pain conditions exhibit altered default mode network and attention network rsFC (Baliki et al 2008;Cauda et al 2009bCauda et al , 2010, as well as greater rsFC between pain-related brain regions compared with healthy controls (Cauda et al 2009a).…”

Neuropathic Pain in Ankylosing Spondylitis: A Psychophysics and Brain Imaging Study

“…Most previous studies on other chronic pain conditions have also demonstrated reduced gray matter in regions that are likely involved in pain modulation and limbic function (13)(14)(15)(16)(17)(18)(19). Moreover, imaging studies have linked specific aspects of neuropathic pain, such as allodynia (20), hyperalgesia (21), mislocation (22), and shooting pain (23), with particular brain structures and networks.…”