A reappraisal of the mechanisms of action of ketamine to treat complex regional pain syndrome in the light of cortical excitability changes.

Objective: To evaluate the changes in glutamate/GABA balance of intracortical excitability produced by ketamine, delivered at subanaesthetic dose to treat patients with complex regional pain syndrome (CRPS).

Methods: In 19 patients with CRPS, we assessed the effect of a 5-day ketamine protocol on various clinical aspects, including pain and depression, and on cortical excitability parameters provided by transcranial magnetic stimulation testing.

Results: The rest motor threshold (RMT) and the amplitude of the motor evoked potentials at 120% of RMT were not modified after ketamine therapy.

Three-phase Bone Scintigraphy Can Predict the Analgesic Efficacy of Ketamine Therapy in CRPS.

Objectives: The efficacy of ketamine in relieving complex regional pain syndrome (CRPS) lacks predictive factors. The value of three-phase bone scintigraphy (TPBS) was assessed for this purpose.

Materials And Methods: TPBS was performed in 105 patients with unilateral, focal CRPS of type 1 before 5 days of ketamine infusions.