Sensory changes in the forehead of patients with complex regional pain syndrome

Abstract

The aim of this study was to investigate involvement of central mechanisms in complex regional pain syndrome (CRPS). In particular, we wished to determine whether hyperalgesia extends ipsilaterally from the affected limb to the forehead. The heat-pain threshold, pressure-pain threshold, and ratings of cold and sharpness were investigated on each side of the forehead and in the affected and unaffected limbs of 38 patients with features of CRPS. In addition, touch thresholds were investigated in the limbs. The pressure-pain threshold was lower on the ipsilateral forehead than contralaterally, consistent with the presence of static mechanical hyperalgesia.Although the heat-pain threshold and ratings of sharpness and cold did not differ between the two sides of the forehead in the group as a whole, the sharpness of pinprick sensations in the affected limb was mirrored by similar sensations in the ipsilateral forehead. Conversely, diminished sensitivity to light touch in the affected limb was associated with diminished sensitivity to sharpness, cold and heat-pain in the ipsilateral forehead. These findings suggest that central nociceptive processing is disrupted in CRPS, possibly due to disturbances in the thalamus or higher cortical centres.

Reduction of allodynia in patients with complex regional pain syndrome: A double-blind placebo-controlled trial of topical ketamine

“…In addition, this site was generally more sensitive to warmth than contralaterally. In a previous study of sensory disturbances in CRPS, we detected hyperalgesia to deep pressure on the symptomatic side of the forehead in the majority of patients; in addition, hyperalgesia to punctate stimulation extended ipsilaterally to the forehead in patients with punctate hyperalgesia in the symptomatic limb [21]. For unknown reasons, a greater range of sensory modalities was disrupted on the symptomatic side of the forehead in the present cohort of patients; this might have been a sampling effect or possibly was due to greater precision of measurement as measures were averaged across two sessions in the present study.…”

“…Complex regional pain syndrome (CRPS) can develop after apparently trivial injury and is often associated with widespread sensory disturbances that can spread to other areas of the body [21,64,77]. Unfortunately, the treatment of neuropathic pain states, including CRPS, remains a significant challenge with an unmet need for specific and targeted therapies [19].…”

“…A double-blind placebocontrolled trial was used with simultaneous plasma estimations of ketamine and its principal metabolite. Sensory effects were investigated in the CRPS-affected limb and also in the forehead, to determine if the effects of ketamine were restricted to the site of application or whether topical ketamine also impeded the hemilateral sensory disturbances associated with CRPS [21].…”

Topically applied capsaicin inhibits sensitivity to touch but not to warmth or heat-pain in the region of secondary mechanical hyperalgesia

“…Moreover, in conditions such as complex regional pain syndrome, sensory impairment may extend well outside the region of injury and pain-sometimes in a hemilateral distribution (Thimineur et al 1998;Rommel et al 1999Rommel et al , 2001Drummond and Finch 2006). Similar effects, although on a smaller scale, have been reproduced in human experimental pain models (Apkarian et al 1994;Bolanowski et al 2000;Leffler et al 2000b;Magerl and Treede 2004).…”

Involvement of Opioid Receptors and α2-Adrenoceptors in Inhibitory Pain Modulation Processes: A Double-Blind Placebo-Controlled Crossover Study

“…2,55 It is important to establish whether acute or chronic failure of the lateralised pain modulation processes explored in this study underlies symptoms in unilateral disorders such as migraine 5 or complex regional pain syndrome. 8,23 M A N U S C R I P T M A N U S C R I P T …”