The aim of the study is to evaluate the effect of hyperbaric oxygen therapy (HBOT) on patients suffering from chronic pain syndrome (Fibromyalgia).

The study is a prospective, randomized, cross-over trial. Patients will be randomized into two groups (test and control) to receive the HBOT at the beginning of the trial or 2 months afterwards. The control group will receive its treatment after the elapsed two months.

This study will be a prospective, randomized cross over study. After signing a written informed consent, all patients will be invited to a 2 hour examination, including pain sensitivity examination and a series of questionnaires. In addition, prior to the beginning of the treatment all patients will have chest X-ray, neurological examination, cognitive evaluation and brain metabolism evaluation (SPECT scan). A similar evaluation will be done after the 8 weeks, test versus control time period, and another evaluation will be held after 16 weeks. The HBOT procedure will be performed in the hyperbaric chamber at Assaf Harofeh Medical Center, Israel.

The following HBOT protocol will be applied for the treated group: 8-week, 5 times a week administration of 100% O2 for 90 minutes at a pressure of 2 ATA. After 8 weeks the control group, that did not received HBOT, will receive the same HBOT protocols.

At baseline, after 2 months and after 4 months all patients will undergo complete neurologic and pain evaluation and brain SPECT scan (total of 3 evaluation and scan per patient).

Inclusion Criteria:

• fibromyalgia diagnosed by physical examination of pain sensitivity, by Dolorimeter and finger pressure.

Exclusion Criteria:

• any past hyperbaric oxygen therapy
• chest x-ray pathology which does not allow the income into the hyperbaric chamber.
• middle ear problems.
• patients, who cannot "pump", equals middle ear pressure, effectively.
• patients who suffer from claustrophobia.
• inability or Refusing to sign the Informed Consent Form