Medical branch block is an injection of a local anesthetic near the medial branch nerves to temporarily block the pain signal carried from the facet joints of the spine to the brain. It is used to assist your physician in diagnosing the cause of your back pain.
Facet joints are the joints connecting the different vertebrae of the spine to each other. Medial branch nerves are small nerves that supply the facet joints of the spine.
If a medial branch block is successful in confirming the patient’s back pain is originating from the facet joints, Radiofrequency Rhizotomy is indicated to provide longer pain relief.
Indications and contraindications
Medial branch block injections are usually indicated in patients with back pain originating from arthritic changes in the facet joints or from mechanical stress to the back. A medial branch block can be performed for the diagnosis or treatment of pain arising from the facet joints.
The procedure cannot be performed on patients taking blood-thinning medications or who have an active infection. Also inform your doctor if you are allergic to medications used for the procedure. Be sure to discuss these situations with your physician before the procedure.
A medial branch block procedure is performed under fluoroscopy ( X-ray) guidance for accurate placement of the needles and to avoid nerve injuries. The basic steps involved in the injection procedure include:
- The patient lays on their stomach on an x-ray table. The area of the skin to be injected is cleansed properly and a local anesthetic is administered to numb the skin. A stinging or burning sensation may be felt for a few seconds.
- A small needle is then directed into the medial branch nerve area, under X-ray (fluoroscopy) guidance.
- Contrast dye is used to confirm the location of the needle over the medial branch nerves.
- Following this, a small mixture of the numbing agent and steroid medication, is then slowly injected over the targeted nerves.
The whole procedure takes about 20-30 minutes and patients can go home on the same day.
After the medial branch block, your pain may either
- go away for a few hours
- go away for a few days or
- not reduce at all
If the pain is relieved after the medial branch block, this indicates that the origin of the pain is the medial branch nerves supplying the facet joints.
Based on the amount of pain relief observed during the first 6-12 hours after the injection, the patient may be considered suitable for a Radiofrequency Neurotomy procedure to relieve the pain for a longer period of time. In Radiofrequency Neurotomy, an electrical current is passed through a needle to the selected medial branch nerves causing pain in order to interrupt the pain signals.
Patients are advised to avoid driving and doing any vigorous activities on the day of the injection. You should arrange for someone to drive you home after the procedure.
The patient may experience localized pain at the injection site in the first 2-3 days for which ice packs can be applied to ease the discomfort. Patients may continue their routine prescribed medications after a gap of 4-6 hours following the procedure, in order to avoid incorrect assessment of diagnostic results related with pain relief.
Patients can return to their regular activities, a day after the procedure. In cases where improvement in the pain is seen, patients are advised to perform moderate activities, with regular exercises.
Risks and complications
Although medial branch block injection is a safe procedure, the possible risks and complications associated with the procedure include:
- Allergic reaction, usually with x-ray contrast dye
- Bleeding from the site of injection
- Infection at the site of injection
- Discomfort at the site of injection
- Increased pain
- Nerve or spinal cord damage and rarely, paralysis