LAUSR

Chronic subdural haematoma (CSDH) is a common neurosurgical pathology, yet conflicting opinions exist concerning the pathophysiological processes involved. Many consider CSDH a product of an aged acute subdural haematoma (ASDH) secondary to trauma. However, serial imaging has demonstrated CSDH formation in patients without any initial ASDH. To understand the relevance of acute haemorrhage in a cohort of CSDH patients, transformation from an ASDH were categorised as CSDH-acute transformed (CSDH-AT) and those without any acute haemorrhage at the outset as CSDH-de-Novo (CSDH-DN). A cohort of 41 eligible CSDH patients were included, with baseline imaging following trauma (or spontaneous ASDH) available for assessment of acute haemorrhage. Volumetric analysis of all subdural collections and measurements of baseline atrophy were performed. In 37% of cases there was an ASDH present on baseline imaging (CSDH-AT), whereas 63% had no acute haemorrhage at baseline (CSDH-DN). The CSDH-ATs developed more rapidly (mean 16 days from baseline to diagnosis) and were smaller in volume than the CSDH-DNs, which developed at a mean delay of 57 days. In 54% of the CSDH-DNs a subdural hygroma was present on baseline imaging, and there was a wide range of baseline cerebral atrophy. This study provides radiological evidence for two distinct pathways in the formation of CSDH, with CSDH-DN occurring more commonly and often involving subdural hygroma. Further work is needed to understand whether the pathological origin has implications for patient outcome.