2.1 General information
The study was approved by the institution’s Joint Research Ethics Committee in November 2021, and the requirement for informed consent was waived. Data from 61 patients with brain abscesses treated at a single hospital from October 2016 to October 2021 were retrospectively analyzed, and the patients were divided into three groups based on the surgical methods used to treat them. Twelve patients who underwent transneuroendoscopic puncture drainage or abscess resection were assigned to a neuroendoscopy group, 20 patients who underwent transcranial puncture and drainage were assigned to a burr-hole drainage group, and 29 patients who underwent traditional craniotomy abscess resection were assigned to a craniotomy group. The mean diameter of all abscesses was 3.11 ± 1.47 cm. The mean Glasgow Coma Scale (GCS) score of all patients on admission was 13.37 ± 1.65. There were 56 cases of single-locular abscess, and 5 cases of multilocular abscess. There were no significant differences in any of the baseline data assessed between the three groups(Table 1).
2.2 Inclusion criteria
Age ≥ 15 years, all brain abscesses in the brain parenchyma confirmed by surgery and pathology, and complete clinical data.
2.3 Exclusion criteria
Age < 15 years, scalp abscess involvement, subdural abscess involvement, epidural abscess involvement, pituitary abscess involvement, and lost to follow-up.
In accordance with guideline recommendations , empirical antimicrobial therapy (vancomycin combined with anti-monas cephalosporins or carbapenems) was initiated after admission, and targeted antibiotics were administered based on the results of pus culture after surgery. The course of treatment was 4–6 weeks, or until computed tomography or magnetic resonance imaging depicted absorption of the lesion .
2.4.1 Neuroendoscopy group
A Karl Storz neuroendoscope was used (hard endoscope, 0°, hard lens length 15 cm, outer diameter 4 mm). The procedures performed included rigid neuroendoscopic abscess drainage under general anesthesia (Figure 1 a–f) and abscess resection (Figure 2 a–d). Neuroendoscopic abscess drainage was performed to introduce the neuroendoscope into the abscess cavity, suck and remove the pus under direct vision, and clean up the foreign body in the abscess cavity and the pus coating on the abscess wall. At the same time the cavity partition was opened and gentamicin in normal saline was used to repeatedly rinse the area until the solution was translucent, and the drainage tube was placed into the lesion cavity (Figure 1 e). Abscess resection was performed to remove the abscess after it was separated along the edema around the abscess wall under neuroendoscopy. In some cases in which the abscess was large, part of the abscess was punctured and aspirated to reduce some of the cerebral pressure prior to removal (Figure 2 b–c).
2.4.2 Burr-hole drainage group
Burr-hole drainage was performed under general anesthesia, and computed tomography or magnetic resonance imaging were used to locate the puncture point and plan the puncture path before the operation. Patients were placed in a supine or lateral recumbent position, and a straight incision approximately 3–5 cm in length was made on the scalp in accordance with the positioning point. The skull was drilled, the dura was opened, and the first puncture was made with a long needle in accordance with the originally set position and direction. Extraction was then performed after entering the abscess cavity, to obtain pus for culturing. The drainage tube was inserted into the abscess cavity via a guide core, the remaining pus was extracted, gentamicin in normal saline was used to rinse the abscess cavity, and lastly the drainage bag was connected and the drainage tube was fixed to suture the wound.
2.4.3 Craniotomy group
Computed tomography or magnetic resonance imaging were performed before surgery. The surgical approach was selected based on the preoperative position, the skin was cut, the bone flap was milled out, the dura mater was cut, then the cortex was cut—avoiding the functional area—and the abscess area was reached. In cases in which the abscess was large, some of the pus was released to avoid it spilling and contaminating the brain tissue. After the pus was completely aspirated, the abscess was carefully peeled off along its outer wall, and the surrounding edema brain tissue was removed under a microscope.
2.5 Surgical timing, postoperative reexamination, and follow-up
In patients with severe illness, rapid progression, and a Glasgow coma scale(GCS) score ≤ 8 the operation was performed within 72 h. Conversely, in patients with stable condition and a GCS score > 8 the operation was postponed to 72 h after onset (mean 4.86 ± 0.87 days). Computed tomography or magnetic resonance imaging were reviewed 24 h, 2 weeks, and 28 days after discharge. Routine outpatient follow-up was performed 28 days after discharge, and non-outpatient follow-up was performed by telephone. Glasgow Outcome Score (GOS) was evaluated based on follow-up.
2.6 Surgical efficacy indicators
The size of the brain abscess cavity before and after the operation was compared using head imaging acquired within 2 weeks after the operation. If the diameter of the abscess cavity was reduced by > 80% and the compression and space-occupying effects of the abscess had resolved, the results were considered significant. If the diameter of the abscess was reduced by > 30% and the intracranial symptoms were controlled to an extent, the operation was considered effective. If the abscess diameter was reduced by < 30% or the abscess was enlarged, and postoperative symptoms were not controlled, the operation was considered ineffective. Significantly effective + effective = total effective. Recurrence of brain abscess refers to the appearance of a new abscess at the same location as the original brain abscess.
2.7 Clinical efficacy indicators
Clinical efficacy indicators included the time to symptom relief, the time until inflammatory indicators returned to normal, days of postoperative hospitalization, total cost of hospitalization, the duration of the operation, and GOS at discharge.
2.8 Postoperative complications and 28-day follow-up indicators
Postoperative intracranial and extracranial complications were assessed, as were 28-day discharge survival rate, abscess recurrence rate, and GOS.
2.9 Statistical analysis
Data were analyzed using SPSS 24.0 software. All quantitative data were normally distributed, and are expressed as mean ± standard deviation. Means of multiple groups were compared via one-way analysis of variance. The least significant difference test was used for pairwise comparisons between multiple groups. All qualitative data conformed to a normal distribution, and are represented as frequencies and percentages. The chi square test or Fisher’s exact probability test were used to compare rates between groups. Partitions derived via the chi square method were used for pairwise comparisons between multiple groups. The Bonferroni method was used for correction. p < 0.05 was considered statistically significant.