CT guided injections for spinal pain - a warning

There is an increasing number of patients being treated for spinal pain by radiologists on the request by general practitioners. Most commonly, these procedures are performed under CT guidance. Besides unnecessarily increasing costs, the use of CT may give a false sense of security. Here are the most common reasons:

1. It is rare that the injection needle can be placed perfectly parallel to the X-ray beams. Therefore, the precise position of the needle tip can rarely be identified. The claimed high precision of CT guided spinal procedures is thus a myth.

This patient has undergone a CT guided "epidural injection" of cortisone for radicular pain from the right L5 nerve root. The underlying cause was a disco-radicular conflict at the level of the L4/5 disc. The radiologist has introduced the needle at the L4/5 level (upper panel). The wrong nerve root (L4) was thus targeted. Injection of contrast shows that there is no spread to the nerve root at the site of conflict in the anterior epidural space (lower panel). Not surprisingly, there was no therapeutic effect of the intervention. 

2. For most spinal pain procedures, contrast should be injected to verify that the taget is reached and that the injection is not made into other compartments like blood vessels. This requires real-time acquisition of the spread of contrast, e.g. that contrast is injected during the exposure. With CT guided injections this is not the case; contrast is injected, the radiologist leaves the room and the exposure is made. In case of an intra-vascular injection, the contrast has disappeared when the exposure is made.

Injection of contrast around the L5 nerve root on the left side also documents a simultaneous appearane of contrast into blood vessels in the spinal canal. This would have gone by undetected if a CT guided injection had been made in stead of real-time imaging with fluoroscopy.

3. The injected contrast will only be visualized in the slices that are chosen for documentation of the procedure, and that are usually perpendicular to the spine. If contrast is injected into a blood vessel and spreads caudally or cranially from the site of injection it will not be observed even on retrospective analysis of the films. This is particularly dangerous in the cervical spine where several severe neurological complications following intravascular injections performed under CT guidance have been reported in the scientific literature. 

4. The indication for the the chosen procedure has not been validated by anybody with appropriate competence to manage patients with spinal pain. The combination of medical history, clinical examination and radiological findings has a diagnostic precision that rarely exceeds 50% to explain the cause of spinal pain. As an example, it is common to find that the CT-guided injections have been made at the inappropriate spinal level or have completely missed the target (see case report above).

5. Doing procedures on demand without in-depth knowledge of the patient's history and clinical examination is unacceptable and inevitably leads to bad results, a majority of which are unknown to the doctor who has performed the procedure. Patients with spinal pain conditions often have complex pathologies that require input from several specialists before deciding which minimal invasive diagnostic and therapeutic procedures should be undertaken.