The subdural evacuation port system: outcomes from a single institution experience and predictors of success.

INTRODUCTION: Numerous surgical options for treatment of chronic subdural hematomas (cSDH) exist. Several reports have examined the Subdural Evacuating Port System (SEPS), a variation of the twist drill craniotomy (TDC) technique. Although high success rates have been reported, a significant portion of patients treated with SEPS fail and require additional procedures. This report examines the largest single institution experience with the SEPS and explores patient and imaging characteristics associated with successful procedures.

METHODS: A retrospective chart review was performed to identify all patients who have undergone SEPS drainage of cSDH. Demographic and radiographic characteristics were evaluated. Demographic data included patient's age, sex, presenting symptoms, pre-procedural GCS score, and use of anticoagulation or antiplatelet agents. The volume of drainage per procedure and radiographic data including laterality, density, and maximal diameter of the collection, presence of septations, midline shift, resolution of the collection 3 weeks post procedure, and measurements to assess atrophy were collected. Total length of stay and time in the intensive care unit was also recorded. Results were classified as a success or failure based on the need for additional procedures including craniotomy or burr hole craniotomy in the operating room. Patients treated with two SEPS procedures during the same hospitalization and no other procedures were included in the success group for statistical analyses.

RESULTS: 171 subdural collections were treated in 159 patients (147 unilateral and 12 bilateral). One hundred thirty three collections (77.8%) were successfully drained. In a comparison of the success and failure groups, there were no statistically significant differences (p<0.05) in the patients' mean age, sex, presenting Glasgow Coma Scale score, coagulation profile, presenting symptoms (except altered mental status and language disturbance), subdural diameter or laterality, midline shift, presence of atrophy, density of most acute portion, or time in hospital. In the success group, there was a shorter mean stay in the intensive care unit (S: 4.1±4.5 days vs F: 5.4±4.6 days; p=0.03) and a larger output drained (S: 131.1±71.2ml vs F: 99.0±84.2ml; p=0.04). Success was less likely with mixed density collections (S: 38.2% vs F: 64.3%; p=0.02) and with collections containing greater than 2 intrahematomal septations (S: 17.1% vs F: 40.7%; p=0.007). In successful cases, mean volumes for collections prior to SEPS, immediately after SEPS, and on delayed scans (≥30 days since SEPS placement) the respective volumes were 83.1±35.1ml, 41.5±23.2ml, and 37.9±26.5ml. Both post-SEPS volumes were less than the pre-SEPS volume (p<0.0001). 76.0% of patients with delayed scans had complete resolution of cSDH or minimal residual cSDH with no local mass effect on the most recent imaging. The mean period of follow-up imaging was 95.6±196.2 days. Only one patient in our series required an emergent craniotomy following immediate complications from SEPS placement.

CONCLUSIONS: The SEPS is an effective, safe, and durable treatment for cSDH. Although we consider the SEPS a first-line treatment for the majority of patients with cSDH, management of cSDH must be tailored to each patient. In mixed density collections with large proportions of acute hemorrhage and in collections with numerous intrahematomal septations, alternative surgical techniques should be considered as first-line therapies.