Nervous System Considerations in Diving

How Your Diving Fitness Can Be Affected By Your Central Nervous System Health

By Dr. Hugh Greer, DAN Southwest Regional Coordinator

Some of the most difficult questions DAN medics field every day are questions pertaining to the diseases and illnesses of the central nervous system and their relationships to scuba diving. Central nervous system (CNS) is defined here as the brain and spinal cord and the body functions they control.

What makes these questions so problematic? One reason is because the answers are so varied. First, many of the diseases and illnesses that affect the central nervous system produce symptoms that are the same as, and can be mistaken for, neurological decompression illness. Since DAN began collecting data on recreational divers, we have found that the central nervous system is affected in about 70 to 80 percent of all types and severities of decompression illness.

This has two important consequences:
1) the diver may have his DCI undertreated because he will ignore symptoms of DCI; or
2) the diver may have his DCI overtreated, as it is often difficult to know which symptoms are new when a physician with whom he is unfamiliar is treating him. We don't know if individuals with chronic or long-term central nervous system problems are more susceptible to decompression illness. It does raise a concern that if DCI occurs, will the pre-existing illness be made worse by any additional injury?

Finally, we do not have a storehouse of data on the effects of scuba diving (or more specifically, the effects of high partial pressures of nitrogen) on the illnesses and diseases mentioned in this section. It would be unethical to perform experimental dives on individuals for the purposes of determining the risk of permanent or disabling injury for any given neurological disease.

In this section, Dr. Hugh Greer, a practicing diving medicine neurologist discusses certain conditions affecting the central nervous systems and their implications for diving.

(Joel Dovenbarger, BSN, Vice President, DAN Medical Services)

Nervous System From the MediClip Color Anatomy Collection,
1996, Williams & Wilkins, a Waverley Company