Timing of surgery in cauda equina syndrome with urinary retention: meta-analysis of observational studies

Object. The authors performed exploratory meta-analyses of observational cohort studies, evidence level III, examining whether earlier surgery makes a difference in outcome in terms of urinary function once cauda equina syndrome (CES) from a herniated lumbar disc has progressed to urinary retention (CESR). Methods. Literature search identified 27 studies of CESR patients with clear definition of surgical timing. Relative risk (RR) could not be calculated in 11 studies, leaving 16 for meta-analysis. Urinary retention related to surgical timing at 5 breakpoints: 12, 24, 36, 48, or 72 hours. Urinary outcome was classified as Normal, Fair, or Poor. Meta-analysis was performed for "Event = Fair/Poor" or "Event = Poor." Eight studies allowed separation into CESR and incomplete CES (CESI), and 5 of these had enough data for meta-analysis to compare CESR and CESI. A random effects meta-analysis model was used because of heterogeneity across the studies. A best-evidence synthesis was performed for the 4 largest studies that had 24- and 48-hour breakpoints. Results. For "Event = Fair/Poor," meta-analyses using the 5 breakpoints predicted a more likely Fair/Poor outcome for later surgery (RR range 1.77-2.19). The RR for later timing of surgery was statistically significant for 24- and 72-hour breakpoints and was elevated but not statistically significant for the other 3. For "Event = Poor," the RR range was 1.09-5.82, statistically significant for the 36 hour breakpoint only. Meta-analysis comparing CESR patients with CESI patients predicted a Fair/Poor result for CESR (RR 2.58, 95% confidence interval 0.59-11.31). The best-evidence synthesis did not disclose reasons for differences in the results of the 4 studies. Conclusions. This study supports early surgery for CES and indicates that CESR and CESI cases should not be analyzed together.