The impact of 3D volumetrically assessed pre- and postoperative radiographic parameters of chronic subdural hematoma on clinical improvement and recurrence after surgery.

Objective: This study aimed to identify the hematoma volume (HV) and midline shift (MLS) grade that need to be reduced for immediate postoperative improvement in patients with surgically treated chronic subdural hematoma (CSDH). Additionally, the study investigated risk factors for recurrence and explored whether specific anatomical burr hole locations and drain directions can influence these outcomes.

Methods: This retrospective analysis included patients treated for hemispheric CSDH using burr hole trephination and subdural drain placement during a study period over 3 years. Volumetric assessment of HV and subdural air (SA) was performed with 3D reconstruction. Analysis A examined the relationship between postoperative HV and MLS reduction and immediate postoperative improvement of hematoma-associated signs and symptoms. Analysis B involved bivariate and multivariate analyses to identify risk factors for recurrence. Analysis C evaluated whether anatomical burr hole location and drain placement influenced postoperative outcomes. Patients were divided into three groups (group 1, frontal burr hole with parietal drain; group 2, frontal burr hole with frontal/temporal drain; group 3, parietal burr hole with frontal drain).

Results: Analysis A found that patients with immediate postoperative improvement had significantly lower residual HV (38.5% vs 52%, p = 0.02) and MLS (37.3% vs. 60%, p = 0.039). Analysis B identified specific items associated with recurrence, including clopidogrel use (p = 0.029), statin use (p = 0.017), lower preoperative platelet count (p = 0.035), and higher preoperative HV (p < 0.001) and MLS (p = 0.024). Additionally, postoperative SA (p = 0.029) was associated with recurrence. Clopidogrel use and postoperative SA remained significant in multivariate analysis (p = 0.022 and p = 0.009, respectively). Cutoff values for preoperative HV (≥ 122.3 ml) and SA (≥ 6.95 ml) were identified, with high negative predictive values of 96.3% and 90.5%, respectively. Analysis C did not demonstrate any superiority of any of the treatment groups regarding HV and MLS reduction nor recurrence and complications.

Conclusions: Reducing HV and MLS is crucial for immediate symptom relief in CSDH patients. Preoperative use of clopidogrel and postoperative SA are key factors associated with recurrence. The choice of burr hole and drain locations can be individualized.