Lateral Lumbar Interbody Fusion (LLIF) is a widely used minimally invasive approach providing access to the disc space for interbody fusion via a lateral approach to the spine. The benefits of this procedure include shorter hospital stay and recovery time with minimal blood loss. As the approach for this procedure involves cutting through the psoas muscle, the greatest risk is to the lumbar plexus and femoral nerve which pass through the muscle. The most common post op deficits are hip flexion weakness due to quadriceps weakness and decrease in anterior thigh sensation. 

To provide the best protection, a multi-modality approach with SSEP, MEP, EMG, Triggered EMG is needed for lateral lumbar procedures. Saphenous nerve SSEP from the surgical side provides more significant sensory information pertaining to the surgery site as it is the sensory branch of the femoral nerve. Peroneal nerve SSEP are to be recorded from the non-surgical side to prevent peroneal nerve compression due to the lateral decubitus position. EMG and MEP from the Quadriceps (VM, VL, RF), Adductor longus should be monitored in addition to Tibialis Anterior, Gastrocnemius muscles. EMG and triggered EMG help in identifying a safe pathway to the disc space. EMG can identify blunt nerve injury but is non-specific and cannot help in identifying developing nerve root dysfunction. MEP is more specific in identifying developing nerve root dysfunction. A high-grade femoral nerve injury is more debilitating than a single nerve root injury and MEP responses from the quadriceps help significantly in preventing transient as well as permanent neural injury.

Though Free run or Spontaneous Electromyography (SpEMG)and triggered EMG are commonly used during these procedures, the IONM protocol must be expanded to include Somatosensory evoked potentials (SSEP) from Saphenous nerve on the surgical side, Peroneal nerve on the non-surgical side in addition to Ulnar and Posterior Tibial Nerve SSEP, Motor Evoked Potentials (MEP) from at least two muscles of the quadriceps and adductors in addition to the other lower lumbar muscles.