Title comparison of primary and secondary spinal epidural abscesses: a retrospective analysis of 29 cases.

Background: Spinal epidural abscesses (SEA) are uncommon. In certain regions their incidence is rising. Vague initial presentation may result in delayed diagnosis. Familiarity with SEA is imperative because if not treated expeditiously, they can have devastating neurologic sequelae.

Methods: A retrospective analysis using analysis of variance (ANOVA) was performed on patients diagnosed with SEA between 1980 through 2000. The patients were assigned to one of the two defined groups: primary (PSEA) consisted of SEA alone; secondary (SSEA) included SEAs with vertebral osteomyelitis. Both groups were compared for factors including survival, age, diagnostic accuracy, etiology, hospitalization, management, and outcome.

Results: Twenty-nine cases were identified. Four (23.7%) were PSEAs and 25 (86.2%) were SSEAs. Mean age (52.7 vs. 53.2 years) and mean duration of hospitalization (39.2 vs. 38.6 days) were comparable in both groups (p = 0.9). The admitting diagnosis was correct in 75% of PSEA and 20% of SSEA cases (p = 0.1). Staphylococcus aureus was present in 75% and 68%, respectively. In SSEA cases, 24% (n = 6) of the infections were consequent to spinal surgery. PSEA did not show a predilection for any level. Most (56%) cases of SSEA occurred at the lumbar levels. The entire PSEA group and 58.3% of the SSEA group underwent surgery (p = 0.06), 75% versus 40.9% had a good outcome for PSEA and SSEA, respectively.

Conclusions: PSEAs are very rare. Both groups have similar characteristics. Staphylococci remain the predominant etiologic agent. PSEAs are treated by surgery; SSEAs are managed surgically or conservatively.