I am just full of information today. An orthopedic surgeon asked me regarding HBO and implanted neurostimulators and thanks to Google search I found the answer in seconds.
FROM THE MEDTRONIC MANUAL (pg13): Patients should not dive below 10 meters (33 feet) of water or enter hyperbaric chambers above 2.0 atmospheres absolute (ATA). Pressures below 10 meters (33 feet) of water (or above 2.0 ATA) could damage the neurostimulation system. Before diving or using a hyperbaric chamber, patients should discuss the effects of high pressure with their physician.