FINISH-trial is a prospective, randomized, controlled, parallel group non-inferiority trial comparing single burr-hole evacuation of chronic subdural hematoma (CSDH) with intraoperative irrigation (IR) and evacuation of CSDH without irrigation (N-IR).

FINISH-trial is a prospective, randomized, controlled, parallel group non-inferiority trial comparing single burr-hole evacuation of chronic subdural hematoma (CSDH) with intraoperative irrigation (IR) and evacuation of CSDH without irrigation (N-IR). In both groups, a passive subdural drain is used for 48 hours as a standard of treatment. The study will be conducted in all five neurosurgical departments in Finland. To determine whether operation without irrigation results in non-inferior outcome to operation with irrigation, we will randomize 426 patients into two groups and follow them up for 6 months using recurrence rates as the primary outcome. Secondary outcomes in our study include mortality, neurological outcome and complications.

Inclusion Criteria:

• Patients with a symptomatic unilateral or bilateral CSDH requiring burr-hole evacuation

  o Predominantly hypodense or isodense on imaging (CT/MRI).

• Clinical symptoms correlating with the CSDH

• Patients with bilaterally operated CSDHs will be treated with the same protocol on both sides and analyzed as a single study participant

Exclusion Criteria:

• CSDH requiring surgical treatment other that burr-hole evacuation (e.g. craniotomy)
• CSDH in a patient who has a cerebrospinal fluid shunt
• Patients who have undergone any intracranial surgery before
• Comatose patients (GCS 8 or lower) with absent motor responses to painful stimuli; decerebrate or decorticate posturing
• Patient's postoperative cooperation is suspected to be insufficient for drain usage, i.e. disoriented or semiconscious patient
• Patient has a hematogenic malignancy that has obtained active treatment within the previous five years
• Patient has a central nervous system tumor or malignancy
• Patient has acute infection with fever and requires antibiotic treatment at the moment
• Patient has a high risk of life-threatening thrombosis (e.g. recent coronary stent, recent pulmonary embolism, low cardiac valve replacement) and discontinuation of antithrombotic medication is not recommended

Individual participant data (IPD) is available upon request when General Data Protection Regulation (GDPR) and guiding legislation regulations are fulfilled.

Study protocol and Statistical Analysis Plan (SAP) will be published after the study has started. Other document will be available as study proceeds and after study is completed.

Data access request will be reviewed by FINISH-trial steering group. Requestors will be required to sign a Data Access Agreement.

Due to the nature of the treatment, it is not possible to blind the surgeon and OR staff from the treatment allocation. Measures to minimize bias include:

• The patient will not be informed of treatment allocation
• Treatment allocation will not be documented in medical records i.e. all the personnel participating in patient care after operation will be blinded to allocation
• The study group members collecting postoperative data and performing the statistical analyses will be blinded to treatment arm until the analyses are finished.