Role of angiogenic growth factors and inflammatory cytokine on recurrence of chronic subdural hematoma

Abstract

Background Chronic subdural hematoma, a benign illness with established surgical treatment, occasionally presents as an annoying recurrence. In this paper, we assess the role of local inflammation and angiogenesis on the recurrence of CSH by measuring relevant biochemical factors from surgical specimens. Methods During a 2-year period, a prospective comparative study was conducted on 66 consecutive patients with CSH who underwent the same one burr-hole drainage procedure. In the initial operation, the subdural fluid and outer membrane were collected and stored. In the subdural fluid, concentrations of VEGF, bFGF, and IL-6 were measured by the ELISA technique. And semiquantitative analyses were performed with the outer membrane, which was stained by an immunohistochemical method. All data were compared between patients with and without recurrence. Results The mean concentrations of IL-6, VEGF, and bFGF in subdural fluid in 52 nonrecurrent patients were 1980.2 ± 229.1, 8262.1 ± 971.9, and 8.6 ± 1.4 pg/mL, whereas those in 14 recurrent patients were 2411.3 ± 446.7, 8646.0 ± 793.3, and 9.8 ± 2.6 pg/mL, respectively. Concentration of IL-6 was significantly higher in recurrent patients than in nonrecurrent patients, but no significant differences were found in VEGF and bFGF concentrations. Immunohistochemical staining of the outer membrane showed significantly stronger staining of the VEGF and bFGF in recurrent patients than in those without recurrence, but not of the IL-6. Conclusions When patients with CSH exhibit higher concentrations of IL-6 in the subdural fluid, or enhanced expression of VEGF and bFGF in the outer membrane at the initial operation, recurrence is more likely to occur and a precautious follow-up evaluation is mandated. With regard to the recurrence, local inflammation seems to be responsible for continuous bleeding by capillary exudation in the earlier phase, whereas angiogenesis appears to render maturation of the outer membrane by sprouting vascular networks in the later phase.