CT-Guided Steroid Injections

A Computerised Tomography or CT scanner is a type of x-ray machine that produces highly detailed images of the inside of the body. The images are taken as the patient moves on a bed through the hole in the middle of the scanner (see picture).The x-ray signals are read by a computer to form an image. The CT images guide the Radiologist (a Radiology doctor) to place the needle accurately and safely to target the spinal nerve root or facet joint thought to be causing symptoms before injecting the drugs. Often a series of injections performed weeks apart are necessary to identify which level is causing the problem. This treatment often avoids a full surgical operation or limits any subsequent operation to the minimum needed to provide relief. Sometimes repeat injections made to the same level (up to three times) can be very effective usually if there has been a partial or short-lived response.

Most commonly a nerve root or facet joint injection is used to relieve pain in the neck, shoulder, arm, back, or leg which is thought to be caused by irritation of nerves in the cervical spine region (neck) or lumbar spine region (lower back).

The injection is a mixture of local anaesthetic and a steroid drug. Local anaesthetic is used to temporarily block the nerves. This provides pain relief for 12-24 hours before gradually wearing off. The steroid drug works by reducing inflammation within the tissues. It usually takes between 24 and 72 hours to start working. The duration of pain relief can last from weeks to months, although this varies from patient to patient. Sometimes the injection allows more normal movement of the spine which we believe promotes the normal healing process.

All treatments and procedures have some risks and we will talk to you about the risks of CT guided injections.

Problems that may happen straight away

There is some stinging when the local anaesthetic is injected into the skin. During positioning of the spinal needle you may experience temporary pain in the same area that you have been feeling pain before.

Problems that may happen later

Immediately after the injection you may experience some worsening of your normal pain, numbness, tingling, clumsiness or even weakness into the affected limb. This will wear off within hours and is due to the effect of the local anaesthetic. If the treatment is unsuccessful – usually because the level injected is not the source of the symptoms – there may be no improvement. This ‘negative’ information is often very useful for the surgeon who then knows that operating at this level is unlikely to relieve symptoms.

Problems that are rare, but serious

Like all x-ray machines, a CT scanner produces x-rays which can potentially be harmful and may cause some cancers to develop in the future. Modern CT equipment and techniques are designed to keep the x-ray exposure as low as possible

whilst producing some exceptionally clear images of your body. In addition, your doctor will have made a judgement about your risk and benefit before agreeing to the scan (including the risk to your health of not having the scan). The dose of radiation for each procedure can be compared to the amount of background radiation that you will receive just by living in the UK. The amount you receive will depend on the type of scan you are having. For example, a CT scan of the head will be the same as receiving an additional 12 months of natural background radiation.

People between 12 and 55 years of age and of child bearing capacity who are, or think they may be pregnant, must inform the Neuroradiology Department as soon as possible. In some urgent cases the procedure may still go ahead but with additional precautions in place. In other cases, an alternative date or form of imaging (such as ultrasound) may be booked for you instead.

The use of CT guidance provides the Radiologist with highly detailed images which significantly decreases the risk of injecting drugs into vessels or nerves. Whilst such a complication remains very unlikely (we estimate much rarer than one in 1000 patients), the consequences are potentially serious, at worst causing permanent damage to the brain or spinal cord tissue, resulting in disability.

During some CT procedures a dye is used which can cause an allergic reaction (not routinely used for CT-guided injections).

Your referring consultant will discuss alternative treatments with you. These may include physiotherapy, surgical interventions or other types of pain relieving injections.

You must tell us about all of the medicines you are taking, especially anticoagulants such as warfarin or heparin, or antiplatelet agents such as aspirin, clopidogrel or dipyridamole. Sometimes some medications would interact with the steroid injection, and these would need to be stopped for your procedure. Neuroradiology staff will advise you about this.

On the day of the procedure you can eat and drink normally and take all of your usual medications (except for those mentioned above). You should take the remainder of the day off work and resume normal activities on the following day. Please ensure

you are accompanied by a responsible adult who can help you home (you may, for example, develop a leg weakness). You should not drive a vehicle home after the procedure.

You should expect to be in the hospital for at least two hours.

We want to involve you in all the decisions about your care and treatment. If you decide to go ahead with treatment, by law we must ask for your consent and will ask you to sign a consent form. This confirms that you agree to have the procedure and understand what it involves. Staff will explain all the risks, benefits and alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please don’t hesitate to speak with a senior member of staff again.

You will be asked to come to the Lysholm Department of Neuroradiology located on the lower ground floor of Chandler Wing, National Hospital for Neurology and Neurosurgery. A nurse will ask you some questions and put an identity bracelet on your wrist which you must wear for the duration of your stay. You will be asked to wear a hospital gown, or you can bring your own loose comfortable clothing if you prefer. The nurse will take you to the CT scanner where you will meet the radiology team. A Radiologist will explain the procedure and answer any questions you may have.

A Radiographer will ask you to lie on the table on your back (for a cervical injection) or front (for thoracic or lumbar). We will make you as comfortable as possible.

It is very important to lie still while scans are performed and the radiologist accurately locates the area for injection.

The skin over the area is cleaned and a local anaesthetic is injected to numb the area. This will sting a little.

The Radiologist will then insert a needle. Several small scans will be taken to confirm the position of the needle tip before the injection. You may be aware of numbness or tingling in your leg or arm at this time. The whole procedure takes about 20 minutes.

You will remain in the department for up to an hour after the injection, and a nurse will check if there have been any changes in your level of pain or other symptoms. After about an hour you can leave the department. Immediately after the procedure your leg or arm may be numb and weak. This is unlikely to persist more than 18 hours or so, but caution is required in walking, and driving should not be attempted. It is quite common for the pain relieving effects of the injection to be delayed for up to seven to ten days. This is the usual time taken for any irritation of the nerve to settle.

In the few days following the injection, moderate activity is fine. Usually you will be aware of your own limitations. The Radiologist will advise you about going back to work.

You should continue to take your pain killing drugs as before, but may find you need them less.

The Radiologist who performed the procedure will write a report to your referring Consultant. Your Consultant will review you in the outpatient clinic (usually around four to six weeks afterwards) to see if things have improved. If you have not heard from your Consultant’s team within this time, please contact the team directly via your Consultant’s secretary.

The NHS Clinical Knowledge Summaries website is a useful source of information. NHS Direct is also another very useful source of health information.

UCLH cannot accept responsibility for information provided by other organisations.

• Cyteval C, Thomas T, Decoux E, Sarrabere MP, Cottin A, Blotman F, Taourel P. (2004). “Cervical Radiculopathy: Open Study on Percutaneous Periradicular Foraminal Steroid Infiltration Performed under CT Control in 30 Patients.” American Journal of Neuroradiology 25: pp 441-445.
• Anderberg, L, Saveland H, Annertz M. (2006). “Distribution patterns of transforaminal injections in the cervical spine evaluated by multi-slice computed tomography.” European Spine Journal 15: pp 14651471.
• Silbergleit R, Mehta BA, Sanders WP, Talati SJ 2001. “Imaging- Guided Injection Techniques with Fluoroscopy and CT for Spinal Pain Management.” Radiographics 21: pp 927-942.
• Wagner AL 2008. “Paraspinal Injections – Facet Joint and Nerve Root Blocks.” American Journal of Neuroradiology 26: pp 43-

Lysholm Department of Neuroradiology

The National Hospital for Neurology and Neurosurgery

Queen Square

London

WC1N 3BG

Email: uclh.enquiry.nhnmrapp@nhs.net

Reception Direct line: 020 344 84744

Appointment queries: 020 344 83103 / 83106 / 83107

Fax: 020 344 84723

Switchboard: 0845 155 5000

Website: www.uclh.nhs.uk/nhnn

The Lysholm Department of Neuroradiology Reception is located in Chandler Wing, on the lower ground floor of the National Hospital for Neurology & Neurosurgery, Queen Square.

Please turn left when you exit the Chandler Wing lifts on the lower ground floor to find our main departmental reception.