Spinal anaesthesia

The Migraine And Headache Program

Natural Remedies for Migraine Headaches

Get Instant Access

Spinal (intrathecal) anaesthesia results from the injection of a local anaesthetic drug directly into the cerebrospinal fluid (CSF), within the subarachnoid space (Fig. 2.24b). The spinal needle can only be inserted below the second lumbar and above the first sacral vertebrae; the upper limit is determined by the termination of the spinal cord, and the lower limit by the fact that the sacral vertebrae are fused and access becomes virtually impossible. A single injection of local anaesthetic is usually used, thereby limiting the duration of the technique.

A fine, 22-29 gauge needle with a 'pencil point' or tapered point (for example Whitacre or Sprotte needle) is used (Fig. 2.25). The small diameter and shape are an attempt to reduce the incidence of postdural puncture headache (see below). To aid passage of this needle through the skin and inter-spinous ligament, a short, wide-bore needle is introduced initially and the spinal needle passed through its lumen.

Factors influencing the spread of the local anaesthetic drug within the CSF, and hence the extent of anaesthesia, include:

• Use of hyperbaric solutions (i.e. its specific gravity is greater than that of CSF), for example 'heavy' bupivacaine (0.5%). This is achieved by the addition of 8% dextrose. Posture is then used to control spread.

Figure 2.25 Photomicrograph showing shape of bevel needle (fop) and 'pencil point' needle (below). From Jones MJ, Selby IR, Gwinnutt CL & Hughes DG. Technical note: the influence of using an atraumatic needle on the incidence of post-myelography headache. British Journal of Radiology 1994; 67: 396-98.

Figure 2.25 Photomicrograph showing shape of bevel needle (fop) and 'pencil point' needle (below). From Jones MJ, Selby IR, Gwinnutt CL & Hughes DG. Technical note: the influence of using an atraumatic needle on the incidence of post-myelography headache. British Journal of Radiology 1994; 67: 396-98.

• Positioning of the patient either during or after the injection. Maintenance of the sitting position after injection results in a block of the low lumbar and sacral nerves. In the supine position, the block will extend to the thoracic nerves around T5-6, the point of maximum backwards curve (kyphosis) of the thoracic spine. Further extension can be obtained with a head-down tilt.

• Increasing the dose (volume and/or concentration) of local anaesthetic drug.

• The higher the placement of the spinal anaesthetic in the lumbar region, the higher the level of block obtained.

Small doses of an opioid, for example morphine 0.1-0.25 mg, may be injected with the local anaesthetic. This extends the duration of analgesia for up to 24 h postoperatively.

Was this article helpful?

0 0
101 Power Tips For Preventing and Treating Headaches

101 Power Tips For Preventing and Treating Headaches

Are you fed up with your frequent headache pain? 101 Simple Ways to Attack Your Headache BEFORE the Pain Starts Guaranteed No Pain, No Fear, Full Control Normal Life Again Headaches can stop you from doing all the things you love. Seeing friends, playing with the kids... even trying to watch your favorite television shows.

Get My Free Ebook


Post a comment