Spinal disease and obstetric neuraxia analgesia

The most common issue I deal with in antenatal consultions is whether a woman's previous or current spinal disease complicates the use of neuraxial analgesia and anaesthesia for labour and delivery. Many cases are simply scoliosis or postural problems, and I often feel that other professionals such as chiropractors, physiotherapists, osteopaths and orthopaedic surgeons have made an unneccessary fuss over what should be fairly benign condtions. Such women may well have ongoing back pain, and are likely to still have it after delivery. And it may well be worse, particulary after the traivails of child-bearing and the subsequent child-carrying. Howell and others in BMJ 2002;325:357 conclude in their prospective study that low back pain commonly occurs after delivery, but epidural labour analgesia does not cause it. An epidural can be readily offered to such people, but it is prudent to discuss postpartum back pain and to suspect that the performance of the block may be hampered by posture and degenerative changes. Previous surgery, or clearly diagnosed spinal disease is a more complex matter. Sometimes a patient carries a warning from another practitioner "don't have an epidural or spinal", and of course this directive immediately excludes a way of providing anaesthesia with a low risk of airway crisis. Previous spinal surgery does not contraindicate the use of neuraxials, although it may make it more difficult to perform and to achieve a satisfactory block due to altered or obliterated anatomy. Intrathecal dosing may achieve a more satisfactory and reliable effect, and some use intrathecal catheters. I have avoided intrathecal catheters: case reports of inadvertant dosage and meningitis and my personal observations of hypotension, sedation and motor block in the labour ward have dulled my enthusiasm. I try to achieve labour analgesia with high-volume-low-concentration epidural bupivacaine and fentanyl, and use single shot intrathecal doses for operative delivery. If there is an abnormal spinal cord or spinal nerves (such as spina bifida or cord tethering) neuraxials are usually should be avoided because of the risk of intraneural injection. But often we are confronted with "I've got spina bifida occulta" after we have been called give epidural relief in active labour rather than an antenatal consultation. This is usually a diagnosis from Xrays done for low back pain.The books say 10% of the population have SBO, and nearly all have them have not been Xrayed, and are blissfully unaware of their disability. We have surely done many epidurals and spinals on such patients, without problems, and we can usually proceed with those with knowledge of SBO in a similar fashion. However, when the SBO is not really occulta -that is there is a lump, or hairy knot, or a dimple, or haemagioma- a neuraxial should be avoided unless there is reassuring imaging.