# Comparing the Effect of Spinal Versus General Anesthesia on Postoperative Opioid Use in Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Patient Matched Study

## TL;DR

This study found that spinal anesthesia leads to less opioid use and shorter hospital stays after a specific type of back surgery compared to general anesthesia.

## Contribution

The study demonstrates that spinal anesthesia reduces postoperative opioid consumption and hospital length of stay in minimally invasive lumbar fusion surgery.

## Key findings

- Patients under spinal anesthesia used fewer opioids post-surgery compared to those under general anesthesia.
- Spinal anesthesia was associated with shorter operating room time and shorter hospital stays.
- Multivariate analysis confirmed reduced opioid use and hospital length of stay with spinal anesthesia.

## Abstract

Background/Objectives: Postoperative opioid exposure after lumbar fusion remains a key clinical concern. Understanding which perioperative factors are associated with lower postoperative opioid use may help optimize recovery after minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF). This study aimed to determine if patients undergoing MIS-TLIF under spinal anesthesia (SA) showed lower postoperative opioid use compared to those undergoing MIS-TLIF under general anesthesia (GA). Methods: We retrospectively studied all adult patients (>18 years) undergoing 1- and contiguous 2-level MIS-TLIFs performed by a single surgeon. Patients undergoing the procedure under GA were compared to those undergoing the procedure under SA. Postoperative oral opioid use, up to 3 months post discharge, was collected. A 1:1 propensity score matching (PSM) protocol was implemented. Each outcome variable was initially assessed using univariate regression. Predictor variables with a p-value < 0.2 were included in the multivariate regression model. This was a retrospective, non-randomized study, and residual confounding cannot be excluded despite PSM. Results: The matched groups (n = 50 in each group) did not differ significantly depending on demographics or levels fused. Before regression, mean number of postoperative opioid prescriptions (p = 0.03), mean total operating room (OR) time in minutes (p < 0.01), and median length of stay (LOS) in days (p = 0.03) were significantly different. Multivariate regression showed that the GA group received 216.5 more total morphine milligram equivalents than the SA group (95% CI = 0.7–432.2, p = 0.049). The days of opioid use were higher in the GA group by 3.8 days (95% CI = 0.5 to 7.1, p = 0.025). On multivariate regression, LOS in hours was greater in the GA group by 14.1 h (p = 0.042). Conclusions: SA is an effective anesthetic modality for spinal surgery with the advantages of reduced postoperative opioid use, reduced OR time, and shorter LOS compared to GA.