Traumatic subdural effusion evolves into chronic subdural hematoma: two stages of the same inflammatory reaction?

Traumatic subdural effusion (TSE) is one of the main associated complications of brain trauma. About half of the asymptomatic TSEs ultimately evolve into chronic subdural hematomas (CSDHs), most of which will be inevitably treated by surgical evacuation. With the emergence of subdural hydroma (SDH), rupture of bridge-veins, bleeding of the hydroma wall, hyperfunction of fibrinolysis and increasing protein content in the hydroma are some of the traditionally cited explanations of the pathogenesis of TSE evolving into CSHD. Despite intensive research and subsequent advances in surgical techniques of CSDH, a single treatment with measurable clinical impact on the evolution interruption has yet to be investigated. Compared with peripheral venous blood, inflammatory cytokines were elevated in TSE and CSDH demonstrated by a number of investigators. Neoformation of capillaries, vascular hyper-permeability, serum protein exudation and other characteristics of aseptic inflammatory reaction were observed. Meanwhile, steroid was applied to treat CSDH in several groups, which was generally used as an effective anti-inflammatory agent. Based on systemic thinking, we hypothesize that TSE and CSDH are different stages, with different appearances, of the same inflammatory reaction. The evolution from TSE into CSDH and propagation of CSDH seem to be the results of local aseptic inflammation. Our hypothesis holds potential as a target for therapeutic intervention.