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Diagnostic Injections
Medial Branch Block
Numbing the tiny nerves that supply a facet joint to confirm the joint as a pain source.
For information only — not medical advice. The content on this page is patient education to help you understand a condition or treatment. It is not a substitute for personalised assessment by a qualified clinician. Always consult your doctor or specialist about your own symptoms, diagnosis, and treatment decisions.
What it is
A medial branch block is an injection of local anaesthetic around the small nerves — the medial branches — that carry pain signals from the facet joints at the back of the spine. Rather than injecting the joint itself, it numbs its nerve supply. It is used as a precise diagnostic test to confirm whether specific facet joints are the source of back or neck pain, particularly when a nerve-deactivation treatment is being considered.
How it works
Each facet joint receives sensation from a pair of medial branch nerves. If numbing these nerves reliably and temporarily removes the pain, it confirms that the joint they supply is responsible. Under X-ray guidance, small amounts of anaesthetic are placed precisely at the bony points where these nerves run. Because a single positive test can occasionally be misleading, the block is sometimes repeated on a separate occasion to be confident before proceeding to longer-lasting treatment.
What to expect
You lie face down while the skin is numbed and imaging guides the needles to the exact nerve points. You may feel brief pressure or aching. The procedure is short. As with other diagnostic blocks, you will be asked to monitor your pain carefully over the following hours and to keep a record, because the pattern of relief is what makes the test meaningful. After-care advice is given and transport home may be needed.
Why it matters for spinal investigations
The medial branch block is the standard way of confirming facet joint pain before a radiofrequency procedure, which works by deactivating these same nerves for a longer period. Getting the diagnosis right first — ideally with a clear, reproducible response — makes that subsequent treatment much more likely to succeed. It is a targeted, logical step in working up mechanical spinal pain.
References & further reading
- —NICE — Low Back Pain and Sciatica in Over 16s (NG59)
- —Faculty of Pain Medicine, Royal College of Anaesthetists — Standards
- —British Association of Spine Surgeons (BASS)
This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.
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