Woojin Nam, Kyeongyoon Woo
Neurologic complications after spinal anesthesia are uncommon but remain a major concern because of their potential severity. Distinguishing anesthesia-related neurologic injury from preexisting spinal pathology is often challenging. A 70-year-old man with hypertension, hyperlipidemia, and known lumbar degenerative disease underwent elective bilateral inguinal hernia repair under spinal anesthesia. Spinal anesthesia was performed via a paramedian approach at the L3-4 interspace using a 25-gauge Quincke needle and 2.6 mL (13 mg) of 0.5% hyperbaric bupivacaine without paresthesia or technical difficulty. Sensory block reached the T6 dermatome level. The intraoperative course was uneventful, with stable hemodynamics throughout the procedure. Approximately two hours after surgery, motor function had recovered in all extremities except the right lower limb. The neurologic deficits persisted despite completion of the standard six-hour postoperative bed rest, with continued sensory loss, paresthesia, and motor weakness in the right lower extremity, whereas the left lower extremity recovered completely. Lumbar magnetic resonance imaging demonstrated severe degenerative lumbar disease, including marked L5-S1 spondylolisthesis, epidural fat hypertrophy, and central canal narrowing, without evidence of neuraxial hematoma, abscess, or other compressive lesions. Serial neurologic examinations demonstrated gradual improvement. Electrodiagnostic studies subsequently revealed findings consistent with right sciatic neuropathy with predominant tibial division involvement. Although a causal relationship between spinal anesthesia and postoperative neuropathy could not be definitively established, perioperative positioning-related sciatic neuropathy was also considered in the differential diagnosis but was regarded as less likely based on the operative course.