title: Thalamic activity and biochemical changes in individuals with neuropathic pain after spinal cord injury.
abstract: There is increasing evidence relating thalamic changes to the generation and/or maintenance of neuropathic pain. We have recently reported that neuropathic orofacial pain is associated with altered thalamic anatomy, biochemistry, and activity, which may result in disturbed thalamocortical oscillatory circuits. Despite this evidence, it is possible that these thalamic changes are not responsible for the presence of pain per se, but result as a consequence of the injury. To clarify this subject, we compared brain activity and biochemistry in 12 people with below-level neuropathic pain after complete thoracic spinal cord injury with 11 people with similar injuries and no neuropathic pain and 21 age- and gender-matched healthy control subjects. Quantitative arterial spinal labelling was used to measure thalamic activity, and magnetic resonance spectroscopy was used to determine changes in neuronal variability quantifying N-acetylaspartate and alterations in inhibitory function quantifying gamma amino butyric acid. This study revealed that the presence of neuropathic pain is associated with significant changes in thalamic biochemistry and neuronal activity. More specifically, the presence of neuropathic pain after spinal cord injury is associated with significant reductions in thalamic N-acetylaspartate, gamma amino butyric acid content, and blood flow in the region of the thalamic reticular nucleus. Spinal cord injury on its own did not account for these changes. These findings support the hypothesis that neuropathic pain is associated with altered thalamic structure and function, which may disturb central processing and play a key role in the experience of neuropathic pain.
authors: Pain Management Research Institute, Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards, New South Wales, Australia Department of Anatomy and Histology, University of Sydney, Sydney, New South Wales, Australia Neuroscience Research Australia, Randwick, NSW 2031, Australia Sydney Medical School-Northern, University of Sydney, Sydney, New South Wales, Australia Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA F.M. Kirby Research Center for Functional MRI, Baltimore, MD, USA Department of Pain Management, HammondCare, Greenwich Hospital, Greenwich, New South Wales, Australia.
authors: S M
authors: SM
authors: Gustin
authors: P J
authors: PJ
authors: Wrigley
authors: A M
authors: AM
authors: Youssef
authors: L
authors: L
authors: McIndoe
authors: S L
authors: SL
authors: Wilcox
authors: C D
authors: CD
authors: Rae
authors: R A E
authors: RAE
authors: Edden
authors: P J
authors: PJ
authors: Siddall
authors: L A
authors: LA
authors: Henderson
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D010147:Pain Measurement; D013113:Spin Labels; D013119:Spinal Cord Injuries / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D013788:Thalamus / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D013113:Spin Labels; D001224:Aspartic Acid; C000179:N-acetylaspartate
keywords: Gamma amino butyric acid; MRI; Neuropathic pain; Spinal cord injury; Thalamus