Numbing the supply lines
Each facet joint is served by small medial branch nerves. Anaesthetising those nerves silences the joint without entering it.
Diagnostics · Invasive
Medial Branch Block
A diagnostic block of the small nerves supplying the facet joints, used to identify a pain source.
What it is
Test the wiring, not the joint
Since facet pain travels along the medial branch nerves, silencing those nerves temporarily is one of the most specific tests in spine diagnostics. It is the standard gatekeeper before any longer-term treatment of facet-mediated pain.
Relief as the readout
If your typical pain eases substantially while the block is active, the blocked facet joints are confirmed as contributors.
Gateway, not therapy
The numbness wears off within hours. A positive block qualifies the painful levels for longer-term treatment of those nerves.
False positives respected
A single block can mislead, so results are interpreted cautiously — sometimes confirmed with a second, comparative block.
Invasive diagnostics are used only when the result will change the plan. Suitability is assessed individually.
Common questions
Things patients ask us
How is this different from a facet joint injection?
The injection numbs inside the joint; the block numbs the nerves carrying that joint's pain signals. Both are diagnostic, and the choice depends on the question being asked.
Will it hurt?
The skin is numbed first and the needles are fine. Most people feel brief pressure at each site.
What must I disclose beforehand?
Blood thinners, infections, allergies, diabetes and pregnancy all matter. Bring a full medication list so the team can plan safely.
What happens after a positive block?
The team explains the options for the confirmed levels — which may include radiofrequency treatment of the same nerves — including benefits, limits and alternatives.
Start with your case.
Send your history and any imaging you already have. The ProSpine team will review your case and respond with the next steps.
Free · No obligation · Reviewed by the ProSpine team