FAQs on Medial Branch Blocks – What are They?

A medial branch block is a procedure that is used primarily as a diagnostic tool, although it may also be used therapeutically to treat chronic pain. It involves injecting numbing medications (a mixture of a local anesthetic and a corticosteroid) into an area near the spine intended to target the medial branch nerves in order to determine if these nerves are the source of a patients’ pain.

Diagnostically, these injections are used to determine if the patient is a candidate for RFA (radiofrequency ablation), which is a procedure that essentially burns off the nerve to prevent it from sending pain signals to the brain.

What conditions are treatable with a medial branch block?

A medial branch block can be used to treat pain caused by conditions of the spine affecting the facet joint of a vertebra. It is similar to a facet joint injection but in a medial branch block the medication is injected outside of the facet joint to target the medial branch nerves while in a facet joint injection the medication is injected directly into the facet joint.

A medial branch block may be used to treat pain, but it is also used as a diagnostic tool to determine the patient would benefit from a procedure called RFA. An RFA is a procedure where high frequency radio waves are introduced to the nerve via an electrode probe in order to in effect burn the nerve to prevent it from sending pain signals to the brain.

What are expectations when a patient gets a medial branch block?

If the procedure is successful the patient can expect to experience some level of pain relief. If the correct nerve has been targeted the patient often experiences immediate relief from the local anesthetic medication used. This is temporary however and generally wears off within 24 hours. The corticosteroid medication in the injection can take from 2 to 4 days to begin to take effect but then may provide lasting relief for several days to several weeks.

How is a medial branch block performed?

This is an outpatient procedure and generally takes only about a half an hour, depending on the number of locations being treated, (several injections may be performed in one visit). Often the patient will be sedated and their vital signs monitored. The area(s) to be injected are cleansed with antiseptic solution to prevent infection and then numbed with a topical anesthetic to ease the sensation of the insertion of the needle.

The doctor then inserts the needle(s) into the appropriate locations using a fluoroscope (a type of real time x-ray machine) to guide them to ensure proper needle placement. The medication is then slowly injected, afterwards the needles are withdrawn and the injection site(s) covered with a sterile bandage.

How long do the effects from the procedure last?

The first time the procedure is performed the effects may last from several days to several weeks. But with subsequent procedures the duration of the benefit is often extended to several months.

What risk or side effects are possible with this procedure?

The procedure is relatively safe but there are a few minor side effects that are possible. The least of these are localized swelling, slight bruising and bleeding at the injection site. Temporary increased pain, this is usually from the swelling and is caused by the steroid medication, it generally subsides within a couple days as the medication is absorbed and the swelling goes down. The most serious risk is also the rarest, nerve damage from a misplaced needle. This is virtually impossible however when the fluoroscope is used.

How successful are they for the relief of pain?

When properly diagnosed, the majority of patients who receive a medial nerve block experiences relief from pain. The level of relief depends on how well the patient responds to the medications and how many injections have been performed. The level of relief usually rises as more injections are given.

What is the bottom line on this procedure?

If you suffer from chronic pain that is being caused by a medial nerve this procedure can be very effective in lessening or halting that pain. Discuss your condition with your doctor to determine if you could benefit from the procedure.