What is an intervertebral disc test block?
An intervertebral disc is located in between two vertebrae (numbers 1 and 2 in Figure 1). This intervertebral disc is found in front of the vertebral canal (number 3 in the Figure) behind which is found the spinous process of the vertebra. The intervertebral disc is like a car tyre with an outer tyre and an inner tube. The inner tube is the inner part of the intervertebral disc (the core) that keeps the car tyre under pressure (number 1 in the Figure). Around this core there is an outer part with fibres that run in various directions that form a kind of outer tyre (number 2 in the Figure).
This outer fibrous area is also supplied with small nerves for registering pain (number 4 in the figure). These nerves are found both at the front and the back of the intervertebral disc (number 5 in the Figure) and they enter a little way into the disc. By anaesthetising these nerves in a test block we can see whether or not a certain intervertebral disc is causing your back pain.
Figure 1: Bird's-eye view of a vertebra showing the intervertebral disc, and the nerves that register pain in the intervertebral disc (see text).
What should I be aware of before undergoing an intervertebral disc test block?
Any of the following situations should be reported to your pain specialist if he proposes a intervertebral disc test block:
- If you are pregnant: since X-ray equipment is used, pregnant women may not undergo an intervertebral disc test block and a new appointment has to be made.
- If you are ill or have a fever on the day of treatment you cannot undergo an intervertebral disc test block, in which case a new appointment will have to be made.
- If you are allergic to iodine, bandages, anaesthetics or contrast fluids, you should notify your pain specialist before the appointment for treatment is made.
- If you are taking blood thinners, you should notify that your pain specialist before the appointment for treatment is made. He will then consider whether the use of certain medications should be ceased temporarily.
How should I prepare for an intervertebral disc test block?
- No special preparations, such as an overnight bag, are necessary because the treatment is carried out on an outpatient basis.
- You may eat before treatment and take your normal medication.
- N.B.: this does not include blood thinners, as mentioned above.
- Make sure you have someone to take you home, because you may not drive for 24 hours.
- The treatment will be performed in the surgical day-care centre, where you will be asked to change into a surgical gown. This gown closes at the back.
- A nurse will escort you to the treatment room, where there is a treatment table, an X-ray machine and television monitors
- You will be positioned on the treatment table with your stomach on the top of a cushion.
- The blood pressure and the amount of oxygen in your blood will be controlled during the treatment.
- The right place of the block is estimated with aid of fluoroscopy.
- This place is marked on the skin with a felt pen.
- The area around this site is then disinfected with a cold, red liquid.
- The pain specialist covers the area with sterile drapes.
- After a local anesthetic has been applied to the skin, the pain specialist, by means of fluoroscopy (via the television monitor), will insert the needles in the correct place.
- Some contrast fluid is also injected to enable the position of the needle to be clearly visible.
- If the needle is in the right place the intervertebral disc test block is performed.
- In intervertebral disc test blocks small amount of local anaesthetics are injected around the nerves of the intervertebral disc to block them temporarily.
- This numbness may take several hours, and then get back again the same pain as before the test block.
- You will then be asked to get dressed and return to the waiting room.
- After half an hour, your pain specialist will inquire whether the intervertebral disc test block clearly reduced your pain.
- If this is not the case, you will have to make a new appointment with your own pain specialist to discuss further possible treatment options.
- If the intervertebral disc test block clearly reduced your pain, then an appointment will immediately be made at the day centre for a permanent intervertebral disc block.
How should I prepare for an intervertebral disc test block?
- No special preparations, such as an overnight bag, are necessary because the treatment is carried out on an outpatient basis.
- You may eat before treatment and take your normal medication.
- N.B.: this does not include blood thinners, as mentioned above.
- Make sure you have someone to take you home, because you may not drive for 24 hours.
How does an intervertebral disc test block work?
- The treatment will be performed in the surgical day-care centre, where you will be asked to change into a surgical gown. This gown closes at the back.
- A nurse will escort you to the treatment room, where there is a treatment table, an X-ray machine and television monitors
- You will be positioned on the treatment table with your stomach on the top of a cushion.
- The blood pressure and the amount of oxygen in your blood will be controlled during the treatment.
- The right place of the block is estimated with aid of fluoroscopy.
- This place is marked on the skin with a felt pen.
- The area around this site is then disinfected with a cold, red liquid.
- The pain specialist covers the area with sterile drapes.
- After a local anesthetic has been applied to the skin, the pain specialist, by means of fluoroscopy (via the television monitor), will insert the needles in the correct place.
- Some contrast fluid is also injected to enable the position of the needle to be clearly visible.
- If the needle is in the right place the intervertebral disc test block is performed.
- In intervertebral disc test blocks small amount of local anaesthetics are injected around the nerves of the intervertebral disc to block them temporarily.
- This numbness may take several hours, and then get back again the same pain as before the test block.
- You will then be asked to get dressed and return to the waiting room.
- After half an hour, your pain specialist will inquire whether the intervertebral disc test block clearly reduced your pain.
- If this is not the case, you will have to make a new appointment with your own pain specialist to discuss further possible treatment options.
- If the intervertebral disc test block clearly reduced your pain, then an appointment will immediately be made at the day centre for a permanent intervertebral disc block.
What are dangers and side effects of an intervertebral disc test block?
After an intervertebral disc test block, the following complications or side effects can occur:
- Sometimes an allergic reaction for the injected substances such as contrast fluid can occur.
- Sometimes a nerve has been hit resulting in a prolonged pain.
- You have to contact pain specialist for additional pain medication.
When can I expect pain relief after the treatment?
- Afterpains can occur following an intervertebral disc test block. This may last a week but will eventually disappear.