Date Published: April 23, 2018
Author(s): Ashwin Sankar, Minou Behboudi, Faraj W. Abdallah, Alan Macfarlane, Richard Brull.
Transient neurologic symptoms (TNSs) can be distressing for patients and providers following uneventful spinal anesthesia. Spinal mepivacaine may be less commonly associated with TNS than lidocaine; however, reported rates of TNS with intrathecal mepivacaine vary considerably.
We conducted a retrospective cohort study reviewing the internal medical records of surgical patients who underwent mepivacaine spinal anesthesia at Toronto Western Hospital over the last decade to determine the rate of TNS. We defined TNS as new onset back pain that radiated to the buttocks or legs bilaterally.
We found one documented occurrence of TNS among a total of 679 mepivacaine spinal anesthetics (0.14%; CI: 0.02–1.04%) that were performed in 654 patients.
Our retrospective data suggest that the rate of TNS associated with mepivacaine spinal anesthesia is lower than that previously reported in the literature.
Transient neurologic symptoms (TNSs), characterized by low back pain that radiates to the buttocks or legs after recovering from spinal anesthesia [1, 2], can be distressing to patients and providers. TNS typically appears within 24 hours of spinal anesthesia, lasts 2–5 days, and resolves completely without sequelae . Because TNS is traditionally associated with intrathecal lidocaine, mepivacaine has been the local anesthetic of choice for short-acting spinal anesthesia at our institution for over a decade. While TNS following mepivacaine occurs less frequently compared to similar doses of lidocaine [3, 4], varied rates of TNS have been reported following mepivacaine spinal anesthesia. Previous small randomized trials examining patients undergoing isobaric intrathecal mepivacaine anesthesia for knee arthroscopy surgery have reported rates of TNS as high as 7.5% [3, 5–8]; however, intraoperative positioning for this procedure has been associated with an increased risk of TNS [1, 9]. It is our anecdotal experience that TNS following intrathecal mepivacaine is rare, occurring far less than the 6.4% incidence reported in one large prospective cohort of knee arthroscopy patients . Therefore, we undertook this retrospective cohort study to understand the rate of TNS reported among surgical patients who underwent spinal anesthesia with isobaric mepivacaine at Toronto Western Hospital (TWH) over the last 10 years. We hypothesized that TNS following isobaric mepivacaine spinal anesthesia is rare.
Following the University Health Network ethics approval, we conducted a retrospective cohort study of consecutive patients who received spinal anesthesia with 1.5% or 2% isobaric mepivacaine for elective surgery at TWH between January 1, 2006 and March 31, 2017. We adhered to the STROBE recommendations for the design and reporting of observational studies .
A total of 679 mepivacaine spinal anesthetics were performed in 654 patients. Twenty-two patients (3.3%) underwent multiple mepivacaine spinal anesthetics, among whom 19 (2.9%) received two mepivacaine spinal anesthetics and 3 (0.4%) received three mepivacaine spinal anesthetics, each in separate encounters. Twenty-four patients (3.6%) received a rescue spinal anesthetic using isobaric mepivacaine following a failed spinal anesthetic with isobaric bupivacaine (5–15 mg) during the same encounter. Figure 1 details the identification process for the present cohort.
Our single-institution retrospective cohort study suggests that the reported rate of TNS following spinal anesthesia with isobaric mepivacaine is very low. Our large cohort of mepivacaine spinal anesthetics allowed for addressing some important shortcomings in previous small randomized trials, wherein a wide range of 0–7.5% rates of TNS have been observed [3, 5–8]. The majority of previously published studies were small, each including less than 100 patients [3, 5–8]; and several of these studies employed a combined spinal-epidural technique which may have obscured the relationship between spinal mepivacaine and TNS [6–9]. Further, almost all previous studies investigating the association between spinal mepivacaine and TNS were conducted in patients undergoing arthroscopic knee surgery [3, 5–9], the intraoperative surgical position for which has been associated with an increased risk of TNS . In our study, 38% of mepivacaine spinal anesthetics were performed for knee arthroscopy procedures; the remaining spinal anesthetics were performed for lower extremity orthopedic and lower abdominal procedures. This variety of surgical procedures may have contributed to the low rate of TNS observed herein. Our low rate of TNS may also have been impacted by contemporary anesthetic practice, including the adoption of multimodal analgesia and prophylactic antiemetic medications as evidence supporting their use became available. It is possible that the increasingly routine use of nonsteroidal antiinflammatory drugs such as ketorolac administered for preventive analgesia and the inherent antiinflammatory properties of dexamethasone administered for postoperative nausea and vomiting may prevent and/or mask symptoms of TNS, and at least partially account for our low reported rates of TNS. The latter notwithstanding, the results of this retrospective review underscore that TNS following mepivacaine spinal anesthesia has not posed a clinical challenge to our regional anesthesia teaching program over the last decade.
A large cohort comprising a decade of experience with isobaric mepivacaine for short-acting spinal anesthesia at our institution suggests that the rate of TNS is lower than that previously reported in the literature. Practically, TNS following mepivacaine spinal anesthesia has not posed a clinical challenge to our regional anesthesia teaching program over the last decade.