Spina bifida occulta: a challenge for obstetric anaesthesia?
Background: Spina bifida occulta (SBO) is part of a spectrum of congenital abnormalities resulting from failure closure of the neural tube. It's incidence is between 10-25% of the population. It is frequently diagnosed by chance, on radiologic tests performed for other reasons. Neuraxial anesthesia might be challenging in these patients, due to changes in sacrolumbar anatomy and the increased risk of dural puncture when performing epidurals.
Case report: 33 years old women, 1.63m and 80kg, ASA II, GIP0, admitted for caesarean section at 40w due to fetal pelvic position. On her past medical history, she was diagnosed 3 years ago with SBO at the L5-S1 level, with sporadic episodes of lumbar pain, treated with NSAIDS. After ASA standard monitorization, regional anaesthesia was the approach of choice. We performed a combined spinal-epidural technique at the L3-L4 level, with the patient in the sitting position, using 18G Tuohy and 27G Quinck needles for catheter placement and spinal anaesthesia, respectively.The technique was uneventful and 7,5mg of levobupivacaine + 2,5 mcg sufentanil was administered, reaching sensitive blockage at he T4 level after 15 minutes. The parturient had an episode of hypotension treated with 200 mcg of phenylephrine, and remain otherwise stable. No need for dose adjustment. No complications reported. Effective analgesia achieved through epidural
boluses of 16mg ropivacaine 0,2% + 1mg morfine every 8h. NRS 0 at rest and 2 with movements. The catheter removed after 48h, uneventfully.
Discussion: There are very few cases in literature describing the anaesthetic approach of obstetric patients with SBO. Spinal approach is not contraindicated in these patients, keeping in mind that they frequently have associated spinal deformities, altered dural permeability and reduced epidural spaces, which makes local anaesthetic spread unpredictable. Spina bifida is also associated with difficult intubation and restrictive respiratory disease, so general anaesthesia should be avoided in there patients whenever possible. Finally, spina bifida patients might have an increased risk of latex allergy.
Learning points: SBO is a congenital spinal column defect, usually diagnosed by chance; Very few reports of anaesthetic management of these patients; Regional anaesthesia is the approach of choice in these patients; Changes in the sacrolumbar anatomy, increased dural puncture risk and unpredictable anaesthetic spread are its main challenges.