[Acute decompression illness following hyperbaric exposure: clinical features of central nervous system involvement]

Decompression illness (DCI) is a general term encompassing all pathological changes secondary to reduction of environmental pressure. This condition has two forms: decompression sickness (DCS) and arterial gas embolism (AGE) secondary to pulmonary barotrauma. Moreover, DCS is categorized as minor, such as limb and/or joint pains or skin rash (Type I), and serious, as in cardiopulmonary and/or central nervous system involvements (Type II). Cerebral and spinal injuries have been symptomatically classified into AGE and DCS. Brain scans of patients with AGE or DCS showed multiple cerebral infarctions in the terminal and/or border zones of the cerebral arteries. Brain involvements of patients in both AGE and DCS show no differences in neurological or neuro-radiological findings. From the neurological and radiological standpoint, it is therefore impossible to distinguish these two conditions. Despite established treatments for neurological DCI (both AGE and DCS), it is unclear whether US Navy treatment Table 6 is preferable to standard hyperbaric oxygen therapy such as 2.4 atmospheres pressure for 90 minutes. Japanese laws and regulations have peculiarities that permit air diving to 90 meters depth, but with explicit prohibition of the use of oxygen for decompression, albeit a limited use of mixed gas is permissible. Moreover, currently the health screening for hyperbaric workers does not include detailed examination of the cardiopulmonary or the central nervous system.