We present a unique case of a 16-year-old patient who underwent lumbar decompression surgery (L4–S1), low-grade spondylolisthesis reduction surgery at L5–S1, and posterior instrumented fusion from L4 to the pelvis. Neurologic monitoring did not show any sustained changes throughout the operation. The patient was awoken from endotracheal anesthesia with grade 0 muscle function of the left extensor hallucis longus and tibialis anterior muscles resulting in left-sided foot drop. At the last follow-up 12 months after surgery, the patient had partial recovery, with grade 4 muscle function of the left extensor hallucis longus and tibialis anterior muscles. We suggest that early identification with direct nerve root stimulation and wake-up test immediately after reduction of spondylolisthesis will allow prompt release of the reduction and further foramen exploration, and increase the possibility of good postoperative nerve root recovery.