Decompression sickness with cerebral ischaemic lesions may occur even in divers who commit no technical errors when diving. This study sought to determine whether an acquired or inborn thrombophilic factor might be involved.

Forty four divers with spinal cord lesions (36 men; 8 women; aged 39.9 + / - 4.7 years) were compared with 44 controls (34 men; 10 women, mean age 38.2 + / - 5.1 years). Coagulation screening included assays for proteins S and C, thrombin III and Factor VIII and assays for circulating antibodies. Factor V Leiden and mutation G20210A in Factor II were looked for. Total plasma homocystine (Hcy), an atheroma associated factor (assayed by FPIA), folate, vitamin B12 (by microbiological assay), the co-factors of B12 metabolism were also measured. Subjects were also genotyped for mutation C677T on the MTHFR gene.

The results were as follows: Coagulation screening – normal protein C and S, no antithrombin III deficit or evidence for the presence of the G20210A mutation; 3 / 44 were heterozygous for Factor V Leiden; 1 / 44 had IgG antiphospholipid antibodies (at a 9 per cent level). These results are not significantly different from those reported in the general population though none of the abnormalities were found in the study controls. 3/44 divers had elevated Factor VIII levels, but repeat assays on Day 2 were much lower. 11/44 divers had a moderate increase in Hcy levels (20 per cent); in 7 divers Hcy levels were > 15 micromol/L and in 4 others > 12 Controls showed increases no higher than 2.3 per cent. 2 / 11 divers had normal vitamins levels and another 11 folate or vitamin B12 deficiency or both; only 2.3 per cent of controls showed a significant vitamin B12 deficit. 7 / 26 (27 per cent) divers were homozygous for the C677T mutation vs 12 per cent of 98 healthy controls.

The paper concludes that a high percentage of patients with unexplained diving accidents had moderately elevated homocystine levels (HHC) and a folate and / or vitamin B12 deficiency that are easy to detect, plus a genetic predisposition to HHC or to coagulation abnormalities. Easy-to-perform homocystine, vitamin B12 and folate assays may prove useful for the primary prevention of diving accidents.

29 references.