[Spinal anesthesia in a patient with SMON disease].

We report a patient with subacute myelo-optico-neuropathy (SMON) in whom spinal anesthesia was employed to treat fracture of the femur neck. An 87-year-old woman was diagnosed as having SMON at the age of 45. The patient was admitted to our hospital with fracture of the femur neck. Aspiration pneumonia was also suspected with shadow in the right lung on the chest X-P The percutaneous oxygen saturation (Spo2) with room air was 77%. Spinal anesthesia with 5 mg of 0.5% hyperbaric bupivacaine and 20 mcg of fentanyl was performed at L3-4. The level of anesthesia was T4. During surgery, no severe pain in the lower limbs was observed. Three hours after the end of surgery, the level of anesthesia was T9. On the day after surgery, the extent of dysesthesia and reflex were similar to those before surgery. General anesthesia has been chosen in SMON patients, because there was a report of severe pain of the lower limbs after spinal anesthesia with dibucaine. In our patient, general anesthesia was considered inappropriate due to hypoxemia. We used a mixture of bupivacaine and fentanyl for spinal anesthesia, because the neurotoxicity of bupivacaine is weaker than that of dibucaine.