Lateral Lumbar Interbody Fusion without Muscle Relaxants: Early Experience with Adverse Events Technical Considerations

Presented at SMISS Annual Forum 2016
By Guy Fogel MD
With Laurence Rosen MD,

Disclosures: Guy Fogel MD None Laurence Rosen MD None,


The surgical technique for lateral transpsoas lumbar interbody fusion (LLIF) 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 how use of muscle-relaxants impacts neurological adverse events (AE) in lateral interbody fusion. The most common AE is thigh dysthetic pain and hip flexor weakness attributed to irritation of the lumbar plexus. 


The purpose of this study was to present an early experience series of patients treated with LLIF without the use of muscle relaxants (NMR). The NMR group will be compared to patients treated with low doses of Non-depolarizing muscle relaxants prior to intubation (MR). 


A retrospective review of 38 consecutive patients (79 levels) of LLIF (NMR) were compared to a retrospective group of 124 consecutive patients (238 levels) (MR). All patients had LLIF at L3-4, L4-5, or both levels. Perioperative variables were collected, including evoked and free-run EMG readings and posterior neural and muscular side effects. Hospital records including progress notes describing post-operative 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. 


NMR patients reported a perfect twitch test immediately. MR patients had slower arrival of the twitch and often settled at a lower level (80-92%). NMR group had 11% and MR 28% thigh AE at one month. None of the NMR patients treated at L4-5 experienced any thigh AE. Two MR patients had lower extremity weakness. All NMR group thigh AE cleared by 3 months and MR group thigh AE was 12% at 3 months. MR had 5.4% persistent thigh AE at 6 months. Two femoral nerve injuries occurred in the MR group and persisted at least one year. 


In this series, eliminating muscle relaxants altogether allowed the evoked and free running EMG to be more reliable and accurate. Alert-level EMG feedback when targeting the posterior disc space was 96%. Neurological AE in NMR were limited and eliminated by the 3rd month. MR group had persistent AE 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, neural AE may be able to be limited or eliminated.