Hyperbaric oxygen treatment in acute experimental allergic encephalomyelitis. Contribution of magnetic resonance imaging study.

Magnetic resonance imaging (MRI) has been performed to determine the efficacy of hyperbaric oxygen treatment (HBO) on experimental allergic encephalomyelitis (EAE) in Lewis rats. The animals were exposed for 2 x 3 h in a 24-h period at 2 ATA pure O2. Three HBO treatment protocols were used: a 10-day preventive treatment (beginning on the 1st day postimmunization), a 3-day preventive treatment (beginning on the 1st day postimmunization), and a 10-day symptomatic treatment (beginning on the 11th day postimmunization). Based on clinical and MRI observations, this study demonstrates: (i) that HBO treatment does not reduce the blood-brain barrier (BBB) disturbance and cerebral edema in EAE, (ii) that in an opposite way, it provokes reversible BBB breakdown, and (iii) that preventive HBO treatments results in modification of the course of EAE, possibly by immunosuppression effect during the initial sensitization step.