Serum protein exudation in chronic subdural haematomas: a mechanism for haematoma enlargement?

Abstract

A study was conducted to investigate the role of serum protein exudation in the aetiology of chronic subdural haematoma (SDH). Scintigraphy after intravenous injection of 99mTc-labelled human serum albumin (HSA) was performed in three patients with chronic SDH and a patient with subdural effusion. In another 60 haematomas, the amounts of total protein and albumin as indices of serum exudation were measured, and then compared among low-density, iso-density and high-density haematomas. Accumulation of 99mTc-HSA in the haematoma cavity was seen 6 h after isotope injection and became more evident at 24 h. However, the protein concentrations and albumin ratios in the haematomas exhibited a reciprocal relationship, suggesting that not all the protein in the haematomas was derived from serum exudation. The higher the total protein concentration in the haematoma became, the higher the haematoma density which was observed on CT. The albumin concentration in low-density haematomas was lower than that in iso-density and high-density haematomas, whereas no significant difference was seen between the latter two haematoma types. These results provide morphological evidence for serum protein exudation into the haematoma cavity, and therefore it is possible that serum protein exudation plays a role in the progression of chronic SDH and is related to changes in haematoma density on CT.