While the paramedian approach is the favoured epidural technique of many anaesthetists, it tends to be used less than the midline approach (1) (Chapter 1).
Some of the claimed advantages of the paramedian route are:
1. reduced incidence of technical and catheter-related problems - extreme flexion of the back to open up the interlaminar space is not required;
2. reduced risk of trauma to the epidural veins;
3. lower incidence of epidural vein cannulation;
4. easier catheter insertion - the needle is angulated substantially more cephalad resulting in less "tenting" of the dura and a straighter catheter path;
5. lower incidence of dural puncture with a reduced incidence of headache after dural puncture (2) (Chapter 97);
6. less paraesthesiae on catheter insertion;
7. less trauma to the ligaments of the back, with fewer complaints of postpartum backache (Chapter 84);
8. less incidence of initial failure;
9. the technique is said to be easier to teach.
It should be stressed that many of the claimed advantages are unconfirmed. The approach may be extremely useful for patients with a midline scar or for those with a rigid spine (eg following back trauma, ankylosing spondylitis).
References:
48.1. GAYNOR A. The epidural region: anatomy and approach. In; Reynolds F, ed. Epidural and spinal blockade in obstetrics. London: Balliere Tindall,1990: 3-18.
48.2. HATFALVI BI. The dynamics of post-spinal headache. Headache 1977; 17:64-67