EFFECTS OF MEMANTINE ON PAIN IN PATIENTS WITH COMPLEX REGIONAL PAIN SYNDROME--A RETROSPECTIVE STUDY.

INTRODUCTION: Memantine was discovered in 1968 and is used as a treatment for Alzheimer's disease. We evaluated the use of memantine to treat complex regional pain syndrome in this retrospective study.

PATIENTS AND METHODS: 56 patients with CRPS, who were treated with trial of memantine for at least two months with 40mg QHS from 2007 until 2009.

RESULTS: 34 females and 22 male patients. Age-46.0 +/- 9.7 years. Number of years with CRPS-9.24 ± 5.7 years. Mean age-46.0 +/- 9.7 years. Memantine was started at 5 or 10 mg QHS, before being increased by 5 or 10mg every 4-7 days, as tolerated, to a maximumdose of 40 mg - 60 mg, as tolerated. In all, 13 patients showed complete remission from CRPS with VAS 0 and the disappearance of allodynea for at least nine months after the use of memantine. In addition, 18 patients showed partial improvement of VAS and allodynea. Eight patients showed no improvement even after continuous use of memantine at a dose of 40 mg QHS for two months. Seven patients could not take more than 5 mg of memantine per day and had to stop it due to side effects. In terms of subjective improvement in short-term memory, nine patients showed much improvement, 14 patients showed some improvement, three patients showed no changes and one patient did not answer the questionnaire. Regarding subjective feelings of a having better quality of life, 17 patient answered yes, three did not feel any changes, six could not give an answer and two did not fill out the questionnaire.

CONCLUSIONS: Memantine is a promising option for the treatment of CRPS. A randomised controlled study is needed to evaluate its efficacy.