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CT guided nerve root injection

Patient information A-Z

What is a nerve root injection?

In this procedure a local anaesthetic and steroid are injected into the area around one of the nerves as they exit the spine in your neck or lower back. This is generally done as a diagnostic test, to see if your symptoms are relieved by the injection. This will indicate to your referring doctor or surgeon whether the nerve injected is the cause of your symptoms. The procedure may also be performed to relieve pain.

Risk vs benefit

You have been referred for a CT guided procedure to help deliver your treatment. A specialist in radiology agrees that this is the best procedure to treat your clinical condition and that the benefit of the examination is greater than the risk. The CT scan involves a dose of ionising radiation equivalent to a few months or years of natural background radiation which we are all exposed to every day. Ionising radiation can cause cell damage that may turn cancerous; however, the risk of this happening from your examination is considered low. The dose delivered will be kept as low as is practicable.


  • If you are taking aspirin, you can continue without restriction.
  • If you are taking clopidogrel/ prasugrel/ ticagrelor, these should be stopped five days prior to examination.
  • If you are taking apixaban/ edoxaban/ rivaroxaban/ dabigatran, these should be stopped 48 hours prior to examination.
  • If you are on low molecular weight heparin (LMWH), this should be stopped for one dose prior to examination.
  • If you are taking warfarin, please contact the Radiology Day Unit (RDU) on 01223 274287 for further advice.


The procedure takes place in the CT Scanning Department and generally lasts around 20 minutes.

You will be given a questionnaire to record your pain levels and symptoms prior to the injection.

You may be asked to change into a backless gown if necessary.

The radiologist will discuss the procedure with you, ask you to sign a consent form and will then position you on the CT scanning table. You will probably be lying face down; part of your back will be exposed and a plastic marker placed on it.

A CT scan will be taken and a pen mark will be made on your skin.

The doctor will clean your back with antiseptic solution, and then inject local anaesthetic to numb your skin. A needle will then be positioned, using CT scans for guidance, and the longer lasting local anaesthetic and steroid will be injected.

You may feel a pushing sensation and some minor discomfort. A plaster will be put on your back after the needle has been removed.

After the procedure

You will be given a questionnaire to record your pain levels and symptoms one to two weeks after the injection. Please bring the questionnaires with you to your next appointment with your referrer.

You are allowed to leave the department as soon as the procedure has finished.

You are not permitted to drive yourself afterwards as you may experience some temporary numbness down a leg, so you need to arrange for someone to take you home. You may resume driving on the day after the injection.

Contact information

If you require more information or have any questions, please contact our team in CT Scanning on 01223 217427.

Please note: Staff are unable to look after children whilst an examination or treatment is taking place. Patients should make suitable arrangements for the care of their children.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151