title: Different underlying pain mechanisms despite identical pain characteristics: a case report of a patient with spinal cord injury.
abstract: Pain following spinal cord injury has been classified as nociceptive (musculoskeletal, visceral) or neuropathic (above, at, below level). There is no clear relation between the etiology and reported symptoms. Thus, due to different underlying mechanisms, the treatment is often ineffective. We report on a patient with spinal cord injury with neurological level of injury at T8 suffering from bilateral burning and prickling pain in the T9-11 dermatomes bilaterally (at-level pain), as well as diffusely in both legs from below the torso (below-level pain), accompanied by musculoskeletal low back pain. Bilateral comparison of quantitative sensory testing (QST) and skin biopsy revealed completely different findings in the dermatome T9 despite identical at-level pain characteristics. On the right side, QST revealed a normal sensory profile; the intraepidermal nerve fiber density (IENFD) was reduced, but not as severe as the contralateral side. On the left side there was a severe sensory loss with a stronger reduction of the IENDF, similar to the areas below the neurological level. These findings were significantly related to the treatment results. Pregabalin induced unilateral pain relief only in the area with remaining sensory function, whereas the left-sided at-level pain was unchanged. Thus, 2 different underlying mechanisms leading to bilaterally neuropathic pain with identical symptoms and with different treatment success were demonstrated in a single patient. The at-level pain in areas with remaining sensory function despite IENFD reduction could be relieved by pregabalin. Thus, in an individual case, QST may be helpful to better understand pain-generating mechanisms and to initiate successful treatment.
authors.affiliation: Department of Pain Management, Ruhr-University Bochum, BG Universitätsklinikum Bergmannsheil GmbH, Germany Department of Radiology, Ruhr-University Bochum, BG Universitätsklinikum Bergmannsheil GmbH, Germany Department of Neurotraumatology and Spinal Cord Injuries, Ruhr-University Bochum, BG Universitätsklinikum Bergmannsheil GmbH, Germany Department of Neurology, University of Kiel, Kiel, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Westermann
authors.forename: Elena K
authors.initials: EK
authors.lastname: Krumova
authors.forename: Werner
authors.initials: W
authors.lastname: Pennekamp
authors.forename: Christoph
authors.initials: C
authors.lastname: Horch
authors.forename: Ralf
authors.initials: R
authors.lastname: Baron
authors.forename: Christoph
authors.initials: C
authors.lastname: Maier
mesh_terms: D006801:Humans; D008297:Male; D008875:Middle Aged; D009420:Nervous System / Q000503:physiopathology*; D009437:Neuralgia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold; D012677:Sensation / Q000502:physiology; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*