Procedure Coeliac Plexus Block

Position and anatomical landmarks

Posterior trans-aortic Technique

The patient lies prone on the operating table with a pillow under the abdomen to increase the kyphosis of the thoracic spine. In this way, the distance between the ribs and the iliac crest and the transverse processes of the adjacent vertebral bodies is enlarged. In order to enhance patient comfort the head is rotated sideways, with the arms hanging freely alongside the body or placed above the head. It may prove useful to mark anatomical landmarks on the skin.

 

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Figure 1. Neurolytic celiac plexus block: needle position in the anterior posterior view. The needles enter at level L2 and are directed obliquely upwards to L1.

Anatomical landmarks are: the iliac crests, 12th rib, dorsal midline, vertebral bodies, and lateral border of the paraspinal muscles. It is advisable to mark the crossing point of the 12th rib and the lateral border of the paraspinal muscle on the left side (this is generally consistent with level L2). Using a steel ruler, bilateral lines are drawn parallel to the underside of the12th rib. These lines, which cross the body of L1, are used to estimate the direction of the needles. The area is disinfected and covered with sterile drapes.

Procedure

The skin, subcutaneous tissues and muscles are anaesthetised using local anaesthetic at the site where the needles will be inserted. The comfort of the patient can be ensured by performing spinal anaesthesia with a short-acting local anaesthetic. A 20-

G or 22-G 15-cm stylet needle is inserted on the left side. Initially, the needle is directed 45º towards the midline and about 15° cranially in order to make contact with the vertebral body of L1. The moment there is contact with bone, the depth is recorded and the needle withdrawn to the subcutaneous tissue.

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Figure 2. Neurolytic coeliac plexus block: AP view with spreading of the contrast around Th12/L1, both pre- and retro-aortic.

Using fluoroscopy, the needle is reoriented slightly laterally (about 60° of the midline) in order to pass the lateral surface of the body of L. Consequently, the needle is carefully shifted until aortic pulsations are felt in the needle. The stylet is removed and the needle is further shifted until the aortic wall is perforated. As a sign of the intra-aortic position of the needle, blood will appear. The needle is further shifted until no further blood appears. The moment the aortic wall is perforated, a 'click' will be felt in the needle. It is important to take anterior posterior and lateral views in order to monitor the correct position of the needle.

When the needle is in the correct position, the stylet is removed and the hub controlled for CSF, blood and lymph. A small amount of contrast dye is injected bilaterally. The spreading of the contrast dye is checked by fluoroscopy with the C-arm. When the spread of the contrast dye is insufficient, it may be necessary to insert a second needle from right side before injecting the neurolytic solution. From the anterior posterior view, the contrast dye must be in the midline and concentrated around vertebral bodies Th12 and L1. The contrast dye should not spread beyond the contours of the vertebral bodies. From the lateral view, a smooth contour should be observed posteriorly and in front of the vertebral bodies. The contrast dye should not spread dorsally in the direction of the nerve roots.

Alternatively, during a CT-guided procedure, the contrast dye should be seen laterally and behind the aorta. If the contrast dye is only seen in the retrocrural space, the needle has to be shifted deeper in order to prevent the local anaesthetic composed of neurolytic solution flowing out towards the somatic nerves.

Paravertebral (retrocrural) approach

The vertebral body of Th12 is identified in the posterior anterior view and marked. The C-arm is rotated to an oblique position (about 45°) at the side where the needle is inserted. The diaphragm lateral to the vertebral body must be visible. The movements of the diaphragm during breathing are observed. If the diaphragm superpose Th12 vertebra and rib, at the same time the rib of Th11 rib should be identified.

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Figure 3. Neurolytic coeliac plexus block: anterior posterior view. Spread of the contrast dye within the contours of the spinal column. Characteristics are the vacuole-like brightening as a sign of the correct placement of the needles.

 

For both levels, the site of insertion in the skin is located at the point where the rib and the vertebral body cross.

The skin, subcutaneous tissues and muscles are anaesthetised using local anaesthetic. Using fluoroscopy a 14-G, 5cm extracath is inserted in such a way that the catheter approaches the target as a needle knob. After inserting two-third of the extracath, the stylet is removed and replaced by a 20-G or 22-G, 15 cm stylet needle. The C-arm is maintained in an oblique position. An extension tube is connected to the needle. The needle tip is shifted anteriorly with short pushes (0.5 cm), while all the time the needle tip glides along the vertebral body. Using fluoroscopy, both needles are shifted beyond Th12 and L1. Aspiration is performed in order to check for CSF and blood.In the lateral view, the final position of the needles is checked. In the lateral view, the injected contrast must be prevertebral and, in the anterior posterior view, within the contours of the spinal column. Thereafter, a neurolytic solution can be injected in a fractionated way.

Transdiscal technique

The intradiscal procedure is also performed using fluoroscopy or CT guidance. The patient lies prone on the operating table with a pillow under the iliac crests in order to increase the intradiscal space. Level Th12/L1 is identified by means of fluoroscopy. The C-arm is obliquely rotated to the left at an angle of 15º to 20°.

It is important to align the lower end plates in a cranial caudal projection. The insertion site is 5-7 cm from the median line. The skin and subcutaneous tissues are anaesthetised using local anaesthetic. The needle is shifted by means of tunnel vision towards the inferior aspect of the facet joint. If an intervertebral disc is punctured, 0.5 ml contrast (omnipaque) is injected in order to check the position of needle in the disc. The needle is further shifted until there is a feeling of 'loss of resistance'. It can then be concluded that the needle is outside the Th12/L1 disc. After checking the position of the needle, 10 ml phenol in 10% NaCl solution is injected. Thereafter, 2-3 ml is injected to prevent leakage of the neurolytic solution into the disc.

For diagnostic test blocks during retrocrural techniques, 2-15 ml lidocaine 1% or 0,25% ropivacaine is injected through both needles. During therapeutic blocks, after the injection of 10-16 ml local anaesthetic, it is also advisable to inject 10-16 ml 96% ethyl alcohol or a 10% solution of phenol in telebrex through both needles.  Many researchers inject contrast dye simultaneously in order to check the spread of the medication. Before injecting the neurolytic solution, the area of the needles is covered by wet sterile gauze in order to prevent the neurolytic solution spreading into the adjacent structures. The use of 10% phenol in telebrex is advised as a reference. After the neurolytic solution has been injected, each needle should be flushed with physiological serum, air or local anaesthetic in order to prevent fistula.

Complications

Transient hypotension, diarrhoea or local pain can occur. Percutaneous coeliac plexus block is a relatively safe technique. In a minority of cases, serious complications can occur, such as, pareses, paraesthesia (1%), haematuria, collapsed lung and shoulder pain (1%).  Cases of paraplegia due to coeliac blocks have also been reported. After the abdominal pain has decreased, other pain complaints can become clear. Therefore, is is not always possible to stop all pain medication. However, a significant reduction of previous pain medication should be possible.