Long-Term Motor Versus Sensory Lumbar Plexopathy Following Lateral Lumbar Interbody Fusion: Single-Center Experience, Intraoperative Neuromonitoring Results, and Multivariate Analysis of Patient-Level Predictors.

BACKGROUND: While lateral lumbar interbody fusion (LLIF) is an effective surgical option for lumbar arthrodesis, postoperative plexopathies are a common complication. We characterized post-LLIF plexopathies in a large cohort and analyzed potential risk factors for each.

METHODS: A single-institutional cohort who underwent LLIF between 05/2015 - 12/2019 was retrospectively reviewed for postoperative lumbar plexopathies. Plexopathies were divided based on sensory and motor symptoms and duration, as well as by laterality relative to the surgical approach. We assessed these subgroups for associations with patient and surgical characteristics as well as psoas dimensions. We then evaluated risk of developing plexopathies following intraoperative neuromonitoring observations.

RESULTS: A total of 127 patients were included. Broadly, the overall rate of LLIF-induced sensory or motor lumbar plexopathy was 37.8% (48/127). Of all cases, 42 were ipsilateral to the surgical approach (33.1%); conversely, 6 developed contralateral plexopathies (4.7%). Most (31/48, 64.6%) eventually resolved with a follow-up interval of 402 days in the plexopathy group. Of ipsilateral cases, 24 experienced persistent (>90 days) postoperative sensory symptoms (18.9%) while 20 experienced persistent weakness (15.7%). More levels fused predicted persistent sensory symptoms (OR = 1.714 [1.246, 2.359], p = 0.0085) while surgical duration predicted persistent weakness (OR = 1.004 [1.002, 1.006], p = 0.0382). Psoas anatomical variables were not significantly associated with plexopathy. Non-resolution of intraoperative evoked motor potential alerts was a significant risk factor for developing plexopathies (RR = 2.29 [1.17, 4.45]).

CONCLUSIONS: Post-LLIF plexopathies are common but usually resolve. Surgical complexity and unresolved neuromonitoring alerts are possible risk factors for persistent plexopathy.