High-pressure nervous syndrome

High-pressure nervous syndrome (HPNS) is a neurological and physiological diving disorder that results when a diver descends below about 500 feet (150 m) using a breathing gas containing helium. The effects depend on the rate of descent and the depth.

Symptoms

HPNS can present with a variety of symptoms including tremors, myoclonic jerking, somnolence, EEG changes, visual disturbance, nausea, dizziness, and decreased mental performance. These symptoms may increase in severity with increasing depth.

Causes

The exact cause of HPNS is not fully understood. It is believed to be a response of the central nervous system to the hyperbaric conditions experienced at great depths. The use of breathing gases containing helium, which is often used in deep-sea diving due to its low solubility in tissues, appears to contribute to the development of HPNS.

Prevention and Treatment

Prevention of HPNS primarily involves limiting the rate of descent, particularly below 500 feet, and using a breathing gas mixture that minimizes the amount of helium. Once symptoms have developed, ascent to shallower depths can alleviate them. There is currently no specific treatment for HPNS.

See Also

• Decompression sickness
• Diving disorders
• Hyperbaric medicine

References

High-pressure nervous syndrome Resources
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