Memantine Treatment of Complex Regional Pain Syndrome: A Preliminary Report of S

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Clin J Pain. 2007 March/April;23(3):237-243.

Memantine Treatment of Complex Regional Pain Syndrome: A Preliminary

Report of Six Cases.

Sinis N, Birbaumer N, Gustin S, Schwarz A, Bredanger S, Becker ST,

Unertl K, Schaller HE, Haerle M.

*Klinik fur Hand, Plastische, Rekonstruktive und

Verbrennungschirurgie, BG-Unfallklinik daggerInstitut fur

Medizinische Psychologie und Verhaltensneurobiologie section

signKlinik fur Anasthesiologie und Transfusionsmedizin, Abteilung

fur Anasthesiologie und Intensivmedizin, Eberhard-Karls Universitat

Tubingen parallelKlinik fur Mund, Kiefer und Gesichtschirurgie,

Universitatsklinikum Schleswig, Holstein, Campus Kiel double

daggerCenter for Cognitive Neuroscience, University of Trento, Italy.

OBJECTIVES: 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.

DISCUSSION: 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.