Capsaicin 8% patch treatment for amputation stump and phantom limb pain: a clinical and functional MRI study
Authors Privitera R, Birch R, Sinisi M, Mihaylov IR, Leech R, Anand P
Received 2 May 2017
Accepted for publication 10 June 2017
Published 13 July 2017 Volume 2017:10 Pages 1623—1634
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Minal Joshi
Peer reviewer comments 3
Editor who approved publication: Dr E Alfonso Romero-Sandoval
Rosario Privitera,1 Rolfe Birch,1 Marco Sinisi,2 Iordan R Mihaylov,3 Robert Leech,4 Praveen Anand1
1Peripheral Neuropathy Unit, Centre for Clinical Translation, Hammersmith Hospital, Imperial College London, London, UK; 2Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Stanmore, Middlesex, UK; 3Department of Pain Medicine, Royal National Orthopaedic Hospital NHS Trust, Stanmore, UK; 4Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
Purpose: The aim of this study was to measure the efficacy of a single 60 min application of capsaicin 8% patch in reducing chronic amputation stump and phantom limb pain, associated hypersensitivity with quantitative sensory testing, and changes in brain cortical maps using functional MRI (fMRI) scans.
Methods: A capsaicin 8% patch (Qutenza) treatment study was conducted on 14 patients with single limb amputation, who reported pain intensity on the Numerical Pain Rating Scale ≥4/10 for chronic stump or phantom limb pain. Pain assessments, quantitative sensory testing, and fMRI (for the lip pursing task) were performed at baseline and 4 weeks after application of capsaicin 8% patch to the amputation stump. The shift into the hand representation area of the cerebral cortex with the lip pursing task has been correlated with phantom limb pain intensity in previous studies, and was the fMRI clinical model for cortical plasticity used in this study.
Results: The mean reduction in spontaneous amputation stump pain, phantom limb pain, and evoked stump pain were −1.007 (p=0.028), −1.414 (p=0.018), and −2.029 (p=0.007), respectively. The areas of brush allodynia and pinprick hypersensitivity in the amputation stump showed marked decreases: −165 cm2, −80% (p=0.001) and −132 cm2, −72% (p=0.001), respectively. fMRI analyses provided objective evidence of the restoration of the brain map, that is, reversal of the shift into the hand representation of the cerebral cortex with the lip pursing task (p<0.05).
Conclusion: The results show that capsaicin 8% patch treatment leads to significant reduction in chronic pain and, particularly, in the area of stump hypersensitivity, which may enable patients to wear prostheses, thereby improving mobility and rehabilitation. Phantom limb pain (“central” pain) and associated brain plasticity may be modulated by peripheral inputs, as they can be ameliorated by the peripherally restricted effect of the capsaicin 8% patch.
Keywords: amputation, phantom limb pain, capsaicin, fMRI
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