Patterns of Surgical Conversion in Spinal Epidural Abscess: Timing and Clinical characteristics.

OBJECTIVE: To characterize the clinical course of patients with spinal epidural abscess (SEA) following an initial management decision and identify factors associated with failure of initial medical management.

SUMMARY OF BACKGROUND DATA: The optimal management of SEA remains controversial, particularly in patients without immediate indications for surgery. Delayed surgical intervention following failed medical management may result in neurological deterioration and worse outcomes, but factors associated with treatment failure remain incompletely defined.

METHODS: A retrospective chart review was performed across 11 institutions within a large health network. Patients diagnosed with SEA between 2017 and 2022 were identified using ICD-10 codes and categorized into Surgical (n=92), Medical (n=66), and Converted (n=22; initially managed non-operatively but later requiring surgery) groups. Demographic, clinical, microbiologic, neurologic, comorbidity, and treatment timing variables were collected and compared between groups.

RESULTS: Baseline demographics, gender, and arrival method did not differ significantly between groups. Approximately 25% of patients initially managed nonoperatively ultimately required surgery, most commonly because of neurologic deterioration (36%) and antibiotic failure (32%). Patients in the Converted group experienced significantly longer delays from neurosurgical recommendation to surgery compared with the Surgical group (5.7 vs. 1.7 d, P=0.0007). Generalized estimating equation analysis demonstrated lower rates of cervical and thoracic involvement among medically managed patients, while lumbar involvement was more common among converted patients. Among patients initially managed medically, cervical involvement was significantly associated with subsequent surgical conversion. Charlson Comorbidity Index differed significantly across groups, with the Surgical group demonstrating the lowest comorbidity burden.

CONCLUSION: A substantial proportion of patients initially managed nonoperatively ultimately required surgery and experienced significant delays in operative intervention. Cervical SEA was associated with a higher likelihood of failure of medical management. These findings may aid in risk stratification and guide decision-making regarding early surgical versus conservative treatment strategies.

STUDY DESIGN: Retrospective multicenter cohort study.