Nerve Root / Facet Joint Block Injection

What is a nerve root / facet joint block injection?

A nerve root block or facet joint injection is a minimally invasive, image-guided procedure used to relieve back, neck, or radiating limb pain caused by inflammation or compression of spinal nerves or facet joints.

During the procedure, a combination of a local anaesthetic and corticosteroid is delivered precisely to the targeted nerve root or facet joint using either fluoroscopic (X-ray) or CT imaging guidance. This helps reduce inflammation and alleviate pain, and in some cases, can also help pinpoint the source of pain for future treatment planning.

Benefits of nerve root / facet joint block injections

• Temporary pain relief
• Temporary reduction of inflammation in the region of the spine causing pain
• Helps the doctor identify a more specific cause of pain
• Improved ability to function in daily life without the restrictions previously caused by pain

How it works

Facet joints are small joints located between the vertebrae that allow for movement of the spine. Nerve roots emerge from the spinal cord through openings next to these joints. When these joints or nerves become inflamed or compressed – due to injury, arthritis, or other spinal disorders – they can cause localised or radiating pain.

• A facet joint injection involves injecting medication directly into the joint capsule to reduce inflammation and pain.
• A nerve root block targets the area around the nerve root to “block” the transmission of pain signals and decrease nerve irritation.

Using real-time imaging, an interventional radiologist inserts a fine needle into the exact location and injects a small volume of corticosteroid (to reduce inflammation) and local anaesthetic (for temporary pain relief).

Why do you need a nerve root / facet joint block injection?

You may be recommended this procedure if:

• You have persistent neck, back, or radiating limb pain that has not responded to medication or physiotherapy.
• Imaging (e.g. MRI or CT) suggests nerve root compression or facet joint degeneration.
• Your doctor needs to confirm the source of your pain before planning further treatment, such as surgery or radiofrequency ablation.
• You are not a suitable candidate for more invasive procedures and need pain relief to improve daily function and quality of life.

What are the risks and complications of a nerve root / facet joint block injection?

While generally safe, this procedure carries some risks, including:

• Infection at the injection site
• Bleeding
• Accidental injection into a blood vessel, which may lead to side effects if medication enters the bloodstream
• Nerve injury or irritation if nearby nerves are inadvertently affected
• Temporary numbness or weakness if the anaesthetic spreads to adjacent nerves

Women who are pregnant or suspect they may be pregnant should inform their doctor beforehand, as imaging techniques like X-ray and CT involve exposure to ionising radiation.

How do you prepare for a nerve root / facet joint block injection?

• No special preparation, fasting, or sedation is typically required.
• Bring your latest spinal imaging (i.e. MRI, CT, or X-rays) to assist the radiologist in targeting the correct area.
• You will be asked to change into a gown to avoid metal artefacts from clothing obstructing the scan.
• Depending on the injection site, you may be positioned on your back or stomach for the procedure.

What can you expect during a nerve root / facet joint block injection?

Estimated duration

About 30–45 minutes, including preparation and post-procedure observation.

Before the procedure

• The injection site is cleaned and sterilised.
• A small area of skin is numbed with local anaesthetic.
• You may feel mild pressure but no significant pain during needle insertion.

During the procedure

• The radiologist uses fluoroscopy (live X-ray) or CT guidance to place a thin needle into the facet joint or adjacent to the nerve root.
• A contrast dye may be injected first to confirm the needle is in the correct position.
• A small amount of corticosteroid and local anaesthetic is then injected.
• More than one level may be treated if needed.

After the procedure

• You may feel immediate relief due to the anaesthetic, though this may wear off after a few hours.
• Mild soreness at the injection site is common and usually resolves within a day
• You will be monitored for 20–30 minutes in the recovery area.
• You may walk and eat normally, but you should not drive or operate machinery for the rest of the day.
• Arrange for someone to accompany you home.

Care and recovery after a nerve root / facet joint block injection

Expected recovery time

• Most patients experience immediate pain relief due to the local anaesthetic and are generally able to walk freely after the procedure
• You will be monitored for up to 30 minutes to ensure you are feeling well before discharge
• While the local anaesthetic wears off within hours, the full effect of the corticosteroid may take a few days to a week to become noticeable
• You may return to work and gradually increase your activities the following day

Recovery tips

• Avoid driving on the day of the procedure – arrange for someone to accompany you home
• Refrain from strenuous activity for the rest of the day
• Use ice packs if you experience mild discomfort at the injection site
• Observe for any unusual side effects (e.g. increased pain, fever, weakness) and inform your doctor if these occur
• Resume gentle movement and regular activity as tolerated the next day

What your recovery depends on

• The underlying spinal condition being treated
• The number and location of injections administered
• Your individual response to the medication
• Whether the procedure was done for diagnostic or therapeutic purposes

In some cases, repeat injections may be necessary, especially when the procedure forms part of a broader pain management strategy.