Spinal Anesthesia Failure Following Wasp Envenomation: A Case Series of Two Patients.

Spinal anesthesia is highly effective, and complete failure in healthy patients is rare. Wasp venom contains neuroactive peptides capable of modifying sodium-channel function and inducing neuroinflammation, but its impact on neuraxial anesthesia has not been previously reported. We describe two healthy ASA I males who developed complete spinal anesthesia failure months after separate wasp stings. Despite correct technique, confirmed CSF flow, and standard doses of hyperbaric bupivacaine, no sensory or motor block occurred in either case, necessitating conversion to general anesthesia. Postoperative evaluations revealed no technical, anatomical, or pharmacologic explanation. The temporal association and biological plausibility raise the possibility that prior wasp envenomation may influence neural sensitivity to local anesthetics through sodium-channel modulation or inflammatory mechanisms; however, causality cannot be established from these observations. Clinicians should consider recent insect stings when planning neuraxial anesthesia. Further investigation is needed to clarify this potential association.