Trial Participants
intracranial arachnoidal cysts
All patients with a cSDH where surgical treatment was indicated were screened for inclusion in the study. Inclusion criteria were (1) cSDH requiring burr hole evacuation and (2) patients older than 18 years. Exclusion criteria were as follows: (1) surgical treatment for cSDH by means other than burr hole evacuation, (2) patients with a cerebrospinal fluid shunt, (3) patients with intracranial arachnoidal cysts, and (4) patients who have undergone intracranial surgery previously. Study participants with bilateral cSDH were treated with the same treatment allocation on both sides and included as a single study participant. Written informed consent was obtained from either participants or in cases where not possible, the documented next of kin. Race and ethnicity information is not routinely recorded in Sweden; thus, it was not collected for this study.