Right-to-Left Shunt in Divers with Neurological Decompression Sickness: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of this study was to assess the association between the presence of a right-to-left shunt (RLS) and neurological decompression sickness (NDCS) and asymptomatic brain lesions among otherwise healthy divers.

BACKGROUND

Next to drowning, NDCS is the most severe phenotype of diving-related disease and may cause permanent damage to the brain and spinal cord. Several observational reports have described the presence of an RLS as a significant risk factor for neurological complications in divers, ranging from asymptomatic brain lesions to NDCS.

METHODS

We systematically reviewed the MEDLINE, Embase, and CENTRAL databases from inception until November 2021. A random-effects model was used to compute odds ratios.

RESULTS

Nine observational studies consisting of 1830 divers (neurological DCS: 954; healthy divers: 876) were included. RLS was significantly more prevalent in divers with NDCS compared to those without (62.6% vs. 27.3%; odds ratio (OR): 3.83; 95% CI: 2.79-5.27). Regarding RLS size, high-grade RLS was more prevalent in the NDCS group than the no NDCS group (57.8% versus 18.4%; OR: 4.98; 95% CI: 2.86-8.67). Further subgroup analysis revealed a stronger association with the inner ear (OR: 12.13; 95% CI: 8.10-18.17) compared to cerebral (OR: 4.96; 95% CI: 2.43-10.12) and spinal cord (OR: 2.47; 95% CI: 2.74-7.42) DCS. RLS was more prevalent in divers with asymptomatic ischemic brain lesions than those without any lesions (46.0% vs. 38.0%); however, this was not statistically significant (OR: 1.53; 95% CI: 0.80-2.91).

CONCLUSIONS

RLS, particularly high-grade RLS, is associated with greater risk of NDCS. No statistically significant association between RLS and asymptomatic brain lesions was found.

C-reactive protein levels are associated with cerebral small vessel-related lesions

OBJECTIVE

Inflammation has received increasing attention as a cause of stroke. Although several lines of evidence suggest that inflammatory processes have a role in arteriosclerotic vascular events, their involvement remains to be determined. The purpose of this study was to examine the associations between serum high-sensitive C-reactive protein (hs-CRP) levels and cerebral small vessel (CSV)-related lesions as a manifestation of arteriosclerosis.

MATERIALS AND METHODS

Neurologically normal subjects without any history of neurologic or psychiatric diseases were enrolled (n = 519). All the participants underwent magnetic resonance imaging (MRI), and their CSV-related lesions (i.e., lacunar infarcts, cerebral microbleeds, deep white matter hyperintensity, and periventricular hyperintensity) were evaluated. The serum levels of hs-CRP were evaluated as common inflammatory markers.

RESULTS

Subjects with higher C-reactive protein (CRP) levels had more lacunar infarcts (P = 0.02). After adjusting for the traditional cardiovascular risk factors, higher hs-CRP levels were still associated with the presence of lacunar infarcts [odds ratio for the highest vs the lowest tertile of hs-CRP, 3.57 (95% confidence interval: 1.30-9.80)]. These associations did not change when the logarithmically transformed values for hs-CRP were included. Furthermore, subjects with higher CRP levels had more cerebral microbleeds (P = 0.03), more severe deep white matter hyperintensity (P = 0.04), and periventricular hyperintensity (P = 0.04); however, these associations were not observed after adjusting for the cardiovascular risk factors.

CONCLUSIONS

Higher levels of hs-CRP were associated with lacunar infarcts. Thus, inflammatory processes may be involved in the pathogenesis of small-vessel disease.