Comparison of Ketamine and Esketamine in Patients Suffering From Fibromyalgia Syndrome.

Comparison of Ketamine and Esketamine in Ambulatory Patients Treated for Fibromyalgia Syndrome in Pain Clinic. A Single-center, Prospective, Randomized, Double-blind, Crossover Study.

Ketamine and Esketamine intravenous perfusions can modulate chronic pain. The purpose of this study is to determine if Ketamine or Esketamine are favorable for outpatients suffering from fibromyalgia.

Ketamine and Esketamine intravenous perfusions in Pain Clinic can modulate chronic pain and are therefore part of the therapeutic arsenal of the Anesthesiologist in pain management. Patients with fibromyalgia syndrome have elevated levels of glutamate in the brain. This is demonstrated by functional brain imaging techniques. Elevation of glutamate is demonstrated in the posterior insular cortex, positively correlating with lower pain thresholds which is a hallmark of fibromyalgia syndrome. Ketamine has (e.a.) an inhibitory role of the N-methyl-D-aspartate (NMDA) receptor: it is a non-competitive antagonist of the NMDA receptor. In this context, Esketamine is available recently. This is the levorotatory form of Ketamine.

The main objective of this study is to measure if there is a difference between Ketamine and Esketamine on patients with fibromyalgia syndrome via the fibromyalgia impact questionnaire (FIQ) and measurement of side effects after intravenous perfusion. The fibromyalgia impact questionnaire is a global assessment of symptoms: pain, function, fatigue, stiffness, discomfort when walking up stairs, difficulties at work, anxiety, depression, days not worked and days of good quality in the past week.

Inclusion Criteria:

• Male and female
• Between 18 and 75 years old
• Reads and writes French
• Diagnosis of fibromyalgia syndrome according to Widespread Pain Index (WPI) and Symptom Severity Scale (SSS) score ≥ 13/31
• Both molecules (Ketamine and Esketamine) were administered at least once during an analgesic infusion session in Pain Clinic
• Patient with regular medical follow-up by a pain specialist at least 3 times a year

Exclusion Criteria:

• Allergy or intolerance to Ketamine or Esketamine
• Current infection, fever
• Pregnant or breastfeeding woman
• Serious cardiovascular disorders and severe hypertension
• Increased pressure of cerebrospinal fluid and severe intracranial disease
• Acute intermittent porphyria
• Untreated epilepsy
• Untreated glaucoma
• Difficult or impossible intravenous access
• Chronic Liver Disease Child-Pugh C