Oral Posters: Adult Spinal Deformity

Presented by: G. Fogel - View Audio/Video Presentation (Members Only)

Author(s):

G. Fogel(1), L. Rosen(2), I. Cheng(3)

(1) Spinepainbegone, San Antonio, TX, United States
(2) Star Anesthesia, San Antonio, TX, United States
(3) Stanford U, Orthopedics, Las Angeles, CA, United States

Abstract

Introduction: The surgical technique for the eXtreme Lateral Interbody Fusion (XLIF ) allows for the use of fast-metabolizing, short-acting muscle relaxants such as succinyl choline but not the longer acting non-depolarizing muscle relaxants. It is not known, however, how use of any muscle-relaxants impacts neurological adverse events (AE) in lateral interbody fusion. The most common AEs following XLIF are thigh dysesthetic pain and hip flexor weakness attributed to irritation of the sensory nerves of the lumbar plexus and direct muscle trauma to the iliopsoas muscle during the procedure, respectively. The purpose of this study was to present an early experience series of patients treated with XLIF without the use of relaxants (NMR) and to compare those XLIF patients with a sample of patients treated with a low dose of non-depolarizing muscle relaxants prior to intubation (MR).

Methods: A retrospective review of 38 consecutive patients treated at 79 levels with NMR XLIF were compared to a group of 124 consecutive MR XLIF patients treated at a total of 238 levels. All patients had XLIF at L3-4, L4-5, or both levels. Perioperative variables were collected, including evoked and free-run EMG readings and postoperative neural and muscular side effects. Hospital records including progress notes describing postoperative symptoms and anesthesia records describing the drugs, dosages, and timing were studied. Clinical records were reviewed for 1 month, 3 months, and 6 months complaints of neurologic AE.

Results: NMR patients reported a perfect twitch test (>99%) immediately. MR patients had slower arrival of the twitch and often settled at a lower level (80-92%). No surgery was attempted until the twitch test was at least 80%. Alert-level (< 4.5 mA response threshold) triggered electromyographic (EMG) feedback was observed in 96% of NMR group. NMR group had 11% and MR 28% thigh AE (thigh dysthetic pain) at one month. Total neuro AE at one month was significantly greater in the MR vs NMR (p=0.030). Two MR patients had lower extremity weakness (femoral nerve injury) which were persistent at one year postoperative, while none were observed in the NMR group. All NMR group thigh AEs resolved by the 3 months postoperative visit compared with a 12% incidence remaining in the MR group at 3 months. MR patients had 5.4% persistent thigh AEs at 6 months.

Conclusion: In this series, eliminating muscle relaxants altogether appears to have allowed the evoked and free running EMG to be more reliable and accurate. AEs peripherally related to neural and muscular integrity in NMR patients were limited and eliminated by the 3rd month. The MR group had persistent AEs in 5.4% at 6 months. The MR group reported 2 (1.6%) distal weaknesses not seen in NMR group. These results are encouraging that by eliminating muscle relaxants altogether, AEs may be able to be limited or eliminated.