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.

Exploration of small fibers for testing diabetic neuropathies.

Introduction: Electrophysiological exploration of neuropathies is a standard method of investigating the dysfunction of myelinated larger fibers (Aalpha, Abeta). However, this method cannot test dysfunctions in other fibers. To evaluate the smaller (Adelta) and unmyelinated fiber (C-fibers) lesions a quantitative method has been perfected: the study of the sensory thresholds (quantitative sensory testing: QST).