Postoperative Brain Abscesses and Infections After Neurosurgery: Clinical Characteristics, Risk Profiles, Microbiological Findings, and Longitudinal DWI and ADC MRI Analysis

Postoperative surgical site infections (brain abscesses and empyemas) are serious complications after neurosurgical procedures and differ from primary abscesses regarding risk factors, pathogen spectrum, and clinical course. What are the clinical characteristics, laboratory and microbiological profiles, and longitudinal DWI/ADC imaging changes of postoperative surgical site infections, and which factors are associated with patient outcome? This retrospective single-center study included patients treated for postoperative surgical site infections between 2014 and 2024. Demographics, surgical methods, comorbidities, neurological scales (GCS, KPS, GOS, mRS), laboratory markers (CRP, leukocytes, IL-6), antibiotic therapy, and microbiology were analyzed. Serial MRI with DWI and ADC quantification was evaluated preoperatively and at three postoperative time points (within 7 days, 4–12 weeks, and last follow-up). 113 patients (55 males, 58 females) had a mean age of 56.8 ± 15.1 years and underwent 361 surgeries (3.2/patient); bone flap removal was necessary in 73.5%. The presence of a diffusion restriction decreased from 60.4% preoperatively to 16.1% at final follow-up, accompanied by a significant postoperative ADC increase. Infections most frequently followed surgery for glioma (37.2%) and meningioma (22.1%). Staphylococci and Gram-negative bacteria predominated; polymicrobial infections were frequent. Mean total antibiotic duration was 48.0 ± 25.9 days (epidural infections) and 44.1 ± 19.3 days (subdural infections). Postoperative surgical site infections exhibit distinct microbiology and risk patterns. Combined surgical revision and targeted prolonged antibiotics are essential. Longitudinal DWI and ADC quantification serve as objective imaging biomarkers for monitoring abscess activity and treatment response. • Postoperative infections show distinct microbiological patterns and risk profiles • Serial MRI demonstrates progressive decline of diffusion restriction after treatment • ADC values show a consistent longitudinal increase across postoperative follow-up • Subdural infections associate with elevated CRP levels and polymicrobial detection • Recurrence dynamics differ significantly between epidural and subdural infections