title: Functional Characterization of At-Level Hypersensitivity in Patients With Spinal Cord Injury.
abstract: At-level and above-level hypersensitivity was assessed in patients with chronic complete thoracic spinal cord injury (SCI). Patients were classified using somatosensory mapping (brush, cold, pinprick) and assigned into 2 groups (ie, patients with at-level hypersensitivity [SCIHs, n = 8] and without at-level hypersensitivity [SCINHs, n = 7]). Gender and age-matched healthy subjects served as controls. Quantitative sensory testing (QST), electrically- and histamine-induced pain and itch, laser Doppler imaging, and laser-evoked potentials (LEP) were recorded at-level and above-level in SCI-patients. Six of 8 SCIHs, but 0 of 7 SCINHs patients suffered from neuropathic below-level pain. Clinical sensory mapping revealed spreading of hypersensitivity to more cranial areas (above-level) in 3 SCIHs. Cold pain threshold measures confirmed clinical hypersensitivity at-level in SCIHs. At-level and above-level hypersensitivity to electrical stimulation did not differ significantly between SCIHs and SCINHs. Mechanical allodynia, cold, and pin-prick hypersensitivity did not relate to impaired sensory function (QST), axon reflex flare, or LEPs. Clinically assessed at-level hypersensitivity was linked to below-level neuropathic pain, suggesting neuronal hyperexcitability contributes to the development of neuropathic pain. However, electrically evoked pain was not significantly different between SCI patients. Thus, SCI-induced enhanced excitability of nociceptive processing does not necessarily lead to neuropathic pain. QST and LEP revealed no crucial role of deafferentation for hypersensitivity development after SCI.
  
  
  
  At-level hypersensitivity after complete thoracic SCI is associated with neuropathic below-level pain if evoked by clinical sensory stimuli. QST, LEP, and electrically-induced axon reflex flare sizes did not indicate somatosensory deafferentation in SCIHs.
authors: Swiss Paraplegic Centre, Centre for Pain Medicine, Nottwil, Switzerland.
authors: Carola
authors: C
authors: Vogel
authors: Department of Anesthesiology, Heidelberg University, Mannheim, Germany. Electronic address: Roman.Rukwied@medma.uni-heidelberg.de.
authors: Roman
authors: R
authors: Rukwied
authors: Swiss Paraplegic Centre, Centre for Pain Medicine, Nottwil, Switzerland.
authors: Lenka
authors: L
authors: Stockinger
authors: Department of Anesthesiology, Heidelberg University, Mannheim, Germany.
authors: Marcus
authors: M
authors: Schley
authors: Department of Anesthesiology, Heidelberg University, Mannheim, Germany.
authors: Martin
authors: M
authors: Schmelz
authors: Swiss Paraplegic Centre, Centre for Pain Medicine, Nottwil, Switzerland.
authors: Wolfgang
authors: W
authors: Schleinzer
authors: Department of Anesthesiology and Intensive Care, Kantonsspital Lucerne, Lucerne, Switzerland.
authors: Christoph
authors: C
authors: Konrad
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006632:Histamine / Q000494:pharmacology; D017442:Histamine Agonists / Q000494:pharmacology; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D019964:Mood Disorders / Q000209:etiology; D009431:Neural Conduction / Q000502:physiology; D009460:Neurologic Examination; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000150:complications*; D013997:Time Factors; D004561:Transcutaneous Electric Nerve Stimulation; D055815:Young Adult
chemical_list: D017442:Histamine Agonists; D006632:Histamine
keywords: Neuropathic pain; at-level hypersensitivity; axon reflex flare; laser-evoked potentials; quantitative sensory testing; sensory mapping