title: Memantine treatment of complex regional pain syndrome: a preliminary report of six cases.
abstract: OBJECTIVE
  Recent studies have confirmed the contribution of the central nervous system (CNS) to the pathogenesis of Complex Regional Pain Syndrome (CRPS), because animal models of neuropathic pain syndromes demonstrate an overexpression of N-methyl-D-aspartate-receptors in the CNS. The aim of this work was to study the influence of a central acting drug-the N-methyl-D-aspartate receptor antagonist Memantine-in patients with CRPS of one upper extremity. Here we present the results of 6 patients treated with Memantine for 8 weeks.
  
  
  METHODS
  All patients developed CRPS after traumatic injury to one upper extremity. To document changes during the study, levels of pain were measured after clenching the hand using a numeric pain intensity scale ranging from 0 (no pain) to 10 (maximum pain). Motor symptoms were documented for the fingers (fingertips to palm and fingernails to table) and the wrist (flexion/extension). Furthermore, the force was analyzed using a JAMAR-Dynamometer and a Pinchmeter. For assessment of central changes, functional magnetic resonance imaging and magnetoencephalography were used to further document the results of other experiments in 1 patient. Autonomic changes were photographed and pictures were compared before and after treatment with Memantine.
  
  
  RESULTS
  Six months after treatment with Memantine, all patients showed a significant decrease in their levels of pain which coincided with an improvement in motor symptoms and autonomic changes. The functional magnetic resonance imaging and magnetoencephalography results provided evidence of cortical reorganization [changes in somatotopic maps in the primary somatosensory cortex (S1)]. These changes returned to a cortical pattern comparable to the unaffected side after treatment with Memantine.
  
  
  CONCLUSIONS
  Based on these first results, the use of Memantine for treatment of CRPS seems promising and supports the hypothesis of a CNS contribution to the pathogenesis and maintenance of neuropathic pain syndromes.
authors.affiliation: Klinik für Hand, Plastische, Rekonstruktive und Verbrennungschirurgie, BG-Unfallklinik, Eberhard-Karls Universität Tübingen, Germany. nsinis@bgu-tuebingen.de
authors.forename: Nektarios
authors.initials: N
authors.lastname: Sinis
authors.forename: Niels
authors.initials: N
authors.lastname: Birbaumer
authors.forename: Sylvia
authors.initials: S
authors.lastname: Gustin
authors.forename: Anja
authors.initials: A
authors.lastname: Schwarz
authors.forename: Sabine
authors.initials: S
authors.lastname: Bredanger
authors.forename: Stephan Thomas
authors.initials: ST
authors.lastname: Becker
authors.forename: Klaus
authors.initials: K
authors.lastname: Unertl
authors.forename: Hans-Eberhard
authors.initials: HE
authors.lastname: Schaller
authors.forename: Max
authors.initials: M
authors.lastname: Haerle
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D020918:Complex Regional Pain Syndromes / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D018691:Excitatory Amino Acid Antagonists / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008559:Memantine / Q000627:therapeutic use*; D008875:Middle Aged; D009043:Motor Activity / Q000187:drug effects; D010147:Pain Measurement; D013997:Time Factors
chemical_list: D018691:Excitatory Amino Acid Antagonists; D008559:Memantine