It is not common for pain to get worse after a medial branch block (MBB). However, this could happen if there are complications during the procedure that result in nerve damage.

It is also possible that the procedure may not work. Depending on the cause, the pain could continue or get worse than it was before.

An MBB is a diagnostic procedure to determine whether pain comes from damage to the spine’s facet joints, which connect the bones of the spine together. A surgeon injects numbing medication around the nerves coming from a specific vertebrae to determine the origin of the pain.

An MBB can provide some short-term pain relief. If it is successful, a doctor may also perform an ablative nerve block, which can offer longer-term relief. This procedure can also cause complications, such as nerve pain.

Read on to learn more about whether pain can get worse after an MBB.

A person's spine with a red scribble signifying pain after a medial branch block.Share on Pinterest
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It is possible for an MBB to make pain worse, but it is not common.

An MBB involves injecting numbing medication around nerves in the spine to disrupt their ability to send pain signals. If successful, it will provide temporary pain relief.

However, if the procedure goes wrong or does not work, it could make the pain worse. Because it does not happen often, though, no recent studies have looked at how common worsening pain is after this procedure.

An older 2009 prospective study followed 911 people who had various types of nerve blocks. Of the procedures studied, 95% were successful, and 8.2% of study participants reported new nerve pain 1 month after the procedure. At 6 months, this figure fell to 0.6%.

A person may still experience pain for several reasons:

No ablation

A 2019 study found that about half of MBB procedures were effective a month after the procedure. However, for a person to have long-term relief, they may also need ablation to kill the nerve causing the pain.

People who have an MBB with no ablation will eventually begin experiencing pain again after the procedure. This is because MBBs are not a long-term solution to pain — they are a tool doctors use to diagnose the source of the pain.

As a result, any pain relief a person does experience could be temporary without this second treatment.

Unsuccessful procedure

If a person’s pain comes from a damaged facet joint in the spine, an MBB should improve the pain. However, if it does not improve the pain at all, even briefly, then this could suggest that the facet joint is not the source of the pain.

Alternatively, the injection may not have targeted the right location. During an MBB, a surgeon has to inject the medication with precision into a specific area. If the location is not correct, the test may not work, and it could provide incorrect information about the source of the pain.

Progressive condition

Even if an MBB is successful and identifies the origin of a person’s pain, it could continue to worsen if they have a progressive condition.

Progressive conditions get worse over time. Some examples of progressive conditions that can damage the facet joints include:

A person may mistake worsening pain after an MBB to the procedure, when it may be that the numbing drug is wearing off. This can happen fairly suddenly, and if the progressive condition has gotten worse, the pain may be worse than it was before the MBB.

Nerve pain

Damage to the medial branch nerves, or surrounding nerves, may cause new or worsening pain following an MBB. This could happen if the doctor makes a mistake and injects the medication into a nerve instead of around the nerves.

Pain that occurs due to a nerve injury may have a different intensity or pattern than what a person experienced before the procedure.

It is unclear what the risk of nerve injury is from an MBB, but an older 2009 study found that 8.2% of people who underwent any type of nerve block had nerve pain at 1 month, with 0.6% reporting pain at 6 months. This suggests the risk is low.

It is typical for MBBs to wear off, so if the pain goes away and then comes back later on, this is a sign the procedure worked. The doctor will know the origin of the pain and may offer nerve ablation to stop the pain long term.

If there was no relief from the pain at all, this suggests the pain originates elsewhere. A person will need to undergo additional testing before a doctor can recommend an effective treatment.

In the meantime, the doctor may recommend pain management with medications.

A 2019 study found that 55% of people who underwent MBB had pain reduction 1 month following the procedure. This was higher than those who had only a placebo treatment.

However, it is important to note that MBBs are not a medical treatment for pain. A small number of people will experience long-term pain relief afterward, but that is not the goal. The aim of the procedure is to find where the pain is coming from.

That said, the temporary success of MBB may predict how well a person will respond to ablation.

Numerous medical conditions can cause low back pain. If an MBB or ablation does not entirely work, there are other treatments that may help.

Some potential back pain treatments include:

  • pain medication
  • complementary therapies, such as acupuncture
  • physical therapy
  • weight management, if body weight could be contributing to the pain
  • corticosteroid injections
  • surgery to treat damage from degenerative conditions
  • management of underlying conditions causing the pain

Pain can get worse after an MBB, but this is not common. While it is typical for the medication doctors use during an MBB to eventually wear off, the pain should not be worse than it was before the procedure.

If the pain is worse, there may be another explanation, such as an underlying progressive condition or a potential nerve injury. People who experience new or worsening pain following the procedure should tell their doctor.

MBBs are not treatments that offer long-term pain relief. If an MBB works temporarily, though, a person may be able to get ablation, which permanently kills the nerve causing the pain.