Spinal Injections

 

About Spinal Injections

There are different types of injections used in the spine. These differ mainly in the target they are aimed at. Most injections contain a mixture of long-lasting local anaesthetic drug (i.e.Bupivacain) and Steroid (i.e. Triamcinolone). None of these injections provide a long term solution for any spinal condition but may be very helpful for acute pain or specific conditions. If the effects are short lived one should look for other treatment options rather than simply continue with further injections except in a very few exceptions. All injections should have a specific target and confirmation of this target by x-ray or CT is important. There should be no ‘blind’ injections.
Spinal injections should be given in strictly aseptic conditions either in the operating theatre or angiography room (a special treatment room in the x-ray department).

Some are mainly for diagnostic purposes. It is not always possible to say exactly where the pain comes from. A ‘test’ injection can be a diagnostic tool to see how much it improves the pain or not. 

Epidural injection

This is an injection into the so-called epidural space. This is a space between the sac containing the nerves (dural sac) and the bony part of the vertebra forming the spinal canal (see ‘The Normal Structure of the Spine’). Most commonly it is given in the lower spine but can be given in the neck, too. In the lower spine the injection can be administered either through a small opening in the base of the spine (sacrum). This is called a caudal epidural (‘cauda latin’ for ‘tail’). It can also be give directly into the back or neck (direct epidural). Although some doctors give caudal epidurals without x-ray control, the latter should always be x-ray guided. This is to avoid injection too deep into the cerebrospinal fluid. The same technique is used in women delivering a baby under a ‘spinal block’. However, patients having a epidural for back problems do not get any numbness or leg weakness unless there are complications and can walk immediately afterwards. How long the epidural lasts varies considerably. The local anaesthetic lasts only a few hours but the pain killing effect it has can last from days to several months. The drugs will reach all nerve roots in the lower spine. Therefore pain due to pressure at different level and both side can be treated with one injection.

The main indication is pain from pressure on a nerve root (radiculopathy). In some cases it can relief back pain from a central disc bulge with a tear. As most disc protrusions improve with time it can be a useful painkiller whilst waiting for the nerve irritation to settle. Spinal claudication due to lumbar canal stenosis is another good indication and often improves the pain and walking. Although it is clearly not a long term solution, many patients with spinal claudication are elderly and might not be fit for surgery. In these patients repeat injection (x2-3/year) can be very effective.

Complications include bleeding, infection (epidual abcess), leg numbness or paralysis (this is usually transient but can be permanent in extremely rare cases), no improvement of symptoms and cerebrospinal fluid (CSF) leak. A CSF leak is usually asymptomatic. However, some patients can develop headache if the leak continues. This is due to the change in pressure in the head (so-called low pressure headache) which improves with lying down. In cases of persisting headache a ‘blood patch’ can be administered to seal the tiny whole in the dura.

Patients are able to gome afterwards but should arrange for somebody to pick the up.

Facet joint injection

This is an injection into the facet joint (see ‘The normal Structure of the Spine’) It can be given in the neck and lower back. and should always be give under x-ray control to ensure optimal placement of the needle. Some doctors administer a small does of contrast to see whether this fills the joint. The facet joins are on either side of the spine and in the majority of cases injections are give to both joints of a level. It is often difficult to say exactly which facet joint is causing the pain. Therefore most doctors will inject two or three levels at the same time.

The main indication is low back pain due to facet joint arthritis. This should be carefully assessed and the injection should not be given just for low back pain. The effect can last several months.  In some cases a facet joint injection can be helpful in finding the source for the pain or knowing the exact level. This can be a useful tool befor a spinal fusion if it is clinically or radiologically not clear which level is mainly causing the pain.

Discography or intra-discal injection

This is an injection directly into the intervertebral disc with local anaesthetic. It is usually given for diagnostic purposes before a spinal fusion or disc replacement. The aim is to reproduce the pain the patient is complaining about to identify the correct level. Usually a ‘healthy’ level is also injected as a test. This injection can only be given under x-ray or CT control. In my opinion, it should not be given as a treatment for patients with low back pain. For complications see epidural injection. In addition a direct nerve root injury from the needle is possible leading to numbness, paralysis or chronic nerve pain.

Sacro-iliac injection

This injection is given if the sacro-iliac joint (this is the joint connecting the base of the spine to the pelvis) is the source of the pain.

CT/x-ray guided root block

This injection can be done for treatment or diagnosic purpose. If it is clinically and radiologically (on MRI) clear that one specific nerve is causing the pain a targeted root block is indicated. In contrast to epidural injections it will have no effect on any other nerve. Sometimes it is not clear, which nerve root is causing the pain in particular if there is nerve entrappment at different levels. A root block can help to identify the correct level. Obviously, only one level should be done at a time.

Lumbar punture

A lumbar puncture involves aspiration of cerebrospinal fluid through a needle. It is usually done in the lumbar spine. As the cerebrospinal fluid is flowing freely between the brain and the spine it is a common diagnostic procedure for suspected infections (meningitis) or a certain type of brain haemorrhage (subarachnoid haemorrhage). It is also used to investigate other neurological conditions.  Initially, some local anaesthetic is administred to numb the skin. The needle is inserted in the midline of the spine until CSF starts draining. This injection normally does not require x-ray control unless it is not possible to drain CSF. In rare cases, drugs can be administered. One side effect is low pressure headach due to continuous leakage of CSF into the epidural space after the needle is withdrawn.