Decompression Illness in Repetitive Breath-Hold Diving: Why Ischemic Lesions Involve the Brain?

Area of Science:

• Physiology
• Neurology
• Diving Medicine

Background:

• Breath-hold (BH) diving leads to nitrogen (N2) accumulation, potentially causing decompression illness (DCI).
• Repetitive BH dives with short surface intervals have been linked to venous gas emboli in commercial divers.
• The diving syndrome 'Taravana' in pearl divers likely represents DCI with predominant cerebral involvement.

Purpose of the Study:

• To review clinical manifestations of DCI in repetitive BH divers.
• To explore potential mechanisms of DCI following BH diving based on clinical and neuroimaging data.

Main Methods:

• Review of clinical manifestations and neuroradiological findings in BH divers.
• Analysis of neuroimaging studies showing ischemic lesions in cerebral arteries.
• Discussion of proposed mechanisms for arterial gas embolism in BH divers.

Main Results:

• Neuroradiological studies reveal symptomatic and asymptomatic ischemic lesions in the brain (cortex, basal ganglia, cerebellum) of BH divers.
• Lesions are consistent with cerebral arterial gas embolism, particularly in watershed areas and deep perforating arteries.
• Proposed mechanism involves arterialized venous gas bubbles passing through the lungs, potentially mixed with thrombi, leading to arterial occlusion and N2 expansion.

Conclusions:

• DCI is a significant risk in repetitive BH diving, manifesting primarily as cerebral events.
• Normobaric oxygen therapy may be beneficial as first aid.
• Preventive measures include limiting dive duration and increasing surface intervals to mitigate DCI risk.