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Purpose: The aim of this study was to determine whether the follow-up of pain processing recovery in hyperalgesic Fibromyalgia (FM) could be objectively evaluated with brain perfusion ethyl cysteinate dimer single photon computerized tomography (ECD-SPECT) after administration of ketamine.

Materials and Methods: We enrolled 17 hyperalgesic FM women patients (48.5 +/- 11 years, range 25-63).

After treatment with subcutaneous ketamine [an anesthetic/painkiller], 11 patients were considered as "good responders," with a decrease in pain intensity, evaluated by visual analog scale (VAS), greater than 50%.

On the other hand, six patients were considered as "poor responders."

A voxel-based analysis of regional cerebral blood flow (rCBF) was conducted (p (voxel) < 0.001uc), in the two subgroups of patients, before and after treatment, in comparison to a group of 10 healthy subjects, matched for age and gender.

Results: In comparison to baseline brain SPECT, midbrain rCBF showed a greater increase after ketamine in the responder group than in the nonresponder group (p (cluster) = 0.016c). In agreement with the clinical response, the change in midbrain rCBF after ketamine was highly correlated with the reduction of VAS pain score (r = 0.7182; p = 0.0041).

Conclusion: This prospective study suggests that blockade of facilitatory descending modulation of pain with ketamine can be evaluated in the periaqueductal grey with brain perfusion SPECT.

Source: European Journal of Nuclear Medicine and Molecular Imaging. 2007 Dec;34(12):2115-9. PMID: 18278530, by Guedj E, Cammilleri S, Colavolpe C, de Laforte C, Niboyet J, Mundler O. Service Central de Biophysique et de Medecine Nucleaire, Assistance Publique des Hopitaux de Marseille, Centre Hospitalo-Universitaire de la Timone, Marseille, France. [E-mail: eric.guedj@ap-hm.fr]