title: Analgesic effects of ketamine ointment in patients with complex regional pain syndrome type 1.
abstract: OBJECTIVE
  Ketamine hydrochloride (KET), an agent used for general anesthesia, has local anesthetic effects and N-methyl-D-aspartate (NMDA) receptor antagonist action. Because recent studies emphasized the role of peripherally distributed NMDA receptors in processing the nociceptive information, we investigated whether peripheral application of the ointment containing KET is able to attenuate the symptoms of local neuropathic pain.
  
  
  METHODS
  We applied ointment containing KET (0.25%-1.5%) to the affected area on limbs in 5 patients with complex regional pain syndrome type I (CRPS I) and in 2 patients with type II (CRPS II). One to 2 weeks later, we observed improvement of the report of pain intensity, measured by the visual analog scale, in 4 patients with acute early dystrophic stage of CRPS I. Swelling of the affected limbs subsided as well. No apparent changes were noticed in 1 patient with chronic atrophic stage of CRPS I and in both patients with CRPS II.
  
  
  CONCLUSIONS
  Topical application of KET appears to be beneficial for the patients with acute early dystrophic stage of CRPS I because of either its local anesthetic effect or NMDA receptor antagonist action. Patients with chronic atrophic stage of CRPS I and CRPS II patients do not appear to respond to this treatment.
authors.affiliation: Departments of Orthopedic Surgery, Kochi Medical School, Nankoku, Kochi, Japan. ushidat-koc@umin.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ushida
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Tani
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kanbara
authors.forename: Vadim S
authors.initials: VS
authors.lastname: Zinchuk
authors.forename: Motohiro
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamamoto
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000778:Anesthetics, Dissociative / Q000008:administration & dosage / Q000627:therapeutic use*; D001284:Atrophy; D004487:Edema / Q000188:drug therapy; D006230:Hand Injuries / Q000150:complications / Q000188:drug therapy; D006801:Humans; D006930:Hyperalgesia / Q000188:drug therapy; D007649:Ketamine / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009824:Ointments; D010147:Pain Measurement / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects; D012019:Reflex Sympathetic Dystrophy / Q000188:drug therapy* / Q000473:pathology; D014911:Whiplash Injuries / Q000150:complications / Q000188:drug therapy
chemical_list: D000778:Anesthetics, Dissociative; D009824:Ointments; D007649:Ketamine