Medial Branch Nerve Blocks

A medial branch nerve block is a minimally invasive injection procedure that involves injecting a small amount of a local anesthetic, with or without a corticosteroid, near the medial branch nerves – the small nerves near the facet joints of the spine that carry pain signals from the joints to the brain.¹Said N, Amrhein TJ, Joshi AB, N NCN, Kranz PG. Facets of facet joint interventions. Skeletal Radiology. Published online October 17, 2022. doi: 10.1007/s00256-022-04184-5^,2Kaiser JT, Lugo-Pico JG. Neuroanatomy, Spinal Nerves. [Updated 2023 Aug 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542218/

The injection aims to block the pain signals transmitted through the medial branch nerves and produce targeted pain relief.¹Said N, Amrhein TJ, Joshi AB, N NCN, Kranz PG. Facets of facet joint interventions. Skeletal Radiology. Published online October 17, 2022. doi: 10.1007/s00256-022-04184-5^,2Kaiser JT, Lugo-Pico JG. Neuroanatomy, Spinal Nerves. [Updated 2023 Aug 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542218/

Goals of Medial Branch Blocks

The primary purpose of medial branch blocks is to diagnose or pinpoint pain originating from a facet joint(s) and guide further treatment if a positive response is seen.¹Said N, Amrhein TJ, Joshi AB, N NCN, Kranz PG. Facets of facet joint interventions. Skeletal Radiology. Published online October 17, 2022. doi: 10.1007/s00256-022-04184-5^,3Bartleson JD, Maus TP. Diagnostic and therapeutic spinal interventions: Facet joint interventions. Neurol Clin Pract. 2014;4(4):342-346. doi:10.1212/CPJ.0000000000000044

• Diagnostic: Significant pain relief following the anesthetic injection suggests that the facet joints are involved, while lack of pain improvement indicates they are likely not the main contributor to pain.¹Said N, Amrhein TJ, Joshi AB, N NCN, Kranz PG. Facets of facet joint interventions. Skeletal Radiology. Published online October 17, 2022. doi: 10.1007/s00256-022-04184-5^,3Bartleson JD, Maus TP. Diagnostic and therapeutic spinal interventions: Facet joint interventions. Neurol Clin Pract. 2014;4(4):342-346. doi:10.1212/CPJ.0000000000000044
• Treatment planning: A positive response to medial branch block injections also indicates that a patient will likely benefit from medial branch radiofrequency ablation (RFA) treatments that involve creating heat lesions on the nerves to prevent long-term pain signaling.¹Said N, Amrhein TJ, Joshi AB, N NCN, Kranz PG. Facets of facet joint interventions. Skeletal Radiology. Published online October 17, 2022. doi: 10.1007/s00256-022-04184-5^,3Bartleson JD, Maus TP. Diagnostic and therapeutic spinal interventions: Facet joint interventions. Neurol Clin Pract. 2014;4(4):342-346. doi:10.1212/CPJ.0000000000000044

RFA treatments are preferred as they offer longer pain relief (6 to 12 months) and are not associated with the potential risks linked to repeated corticosteroid use.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274

See Radiofrequency Ablation (RFA) Side Effects and Risks

Less commonly, medial branch block injections are used therapeutically after a positive diagnosis and involve injecting a combination of an anesthetic and a corticosteroid for sustained pain relief (2-4 months).⁵Manchikanti L. Comprehensive Evidence-Based Guidelines for Facet Joint Interventions in the Management of Chronic Spinal Pain: American Society of Interventional Pain Physicians (ASIPP) Guidelines. Pain Physician. 2020;3S;23(5;3S):S1-S127. doi: 10.36076/ppj.2020/23/s1^,6Lee DG, Ahn SH, Cho YW, Do KH, Kwak SG, Chang MC. Comparison of Intra-articular Thoracic Facet Joint Steroid Injection and Thoracic Medial Branch Block for the Management of Thoracic Facet Joint Pain. Spine (Phila Pa 1976). 2018;43(2):76-80. doi:10.1097/BRS.0000000000002269

When Medial Branch Blocks are Recommended

Medial branch blocks are used in the diagnosis of injuries and/or medical conditions that are known to cause inflammation of the facet joints, including⁶Lee DG, Ahn SH, Cho YW, Do KH, Kwak SG, Chang MC. Comparison of Intra-articular Thoracic Facet Joint Steroid Injection and Thoracic Medial Branch Block for the Management of Thoracic Facet Joint Pain. Spine (Phila Pa 1976). 2018;43(2):76-80. doi:10.1097/BRS.0000000000002269^,7Zhou KL, Dong S, Ji W, et al. Effects of massage therapy for patients with thoracic facet joint disorders: A protocol for systematic review and meta-analysis. Medicine (Baltimore). 2020;99(49):e23480. doi:10.1097/MD.0000000000023480:

• Facet joint osteoarthritis
• Spinal osteoarthritis
• Degenerative spondylolisthesis
• Rheumatoid arthritis
• Ankylosing spondylitis
• Scoliosis

As a treatment, medial branch blocks are typically considered after first-line therapies such as oral medications, primarily non-steroidal inflammatory drugs (NSAIDs), and physical therapy are tried for at least 3 months.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274

When Medial Branch Blocks May Not Be Recommended

Due to an increased risk of complications, medial branch blocks are contraindicated in the following circumstances¹Said N, Amrhein TJ, Joshi AB, N NCN, Kranz PG. Facets of facet joint interventions. Skeletal Radiology. Published online October 17, 2022. doi: 10.1007/s00256-022-04184-5^,3Bartleson JD, Maus TP. Diagnostic and therapeutic spinal interventions: Facet joint interventions. Neurol Clin Pract. 2014;4(4):342-346. doi:10.1212/CPJ.0000000000000044:

• Active systemic infection
• Local infection around the procedure site
• Bleeding disorders
• Pregnancy

Additionally, patients are advised to communicate any known allergies or sensitivities to the drugs used in medial branch block procedures with their doctor, and to discuss possible alternative medications or interventions.³Bartleson JD, Maus TP. Diagnostic and therapeutic spinal interventions: Facet joint interventions. Neurol Clin Pract. 2014;4(4):342-346. doi:10.1212/CPJ.0000000000000044

How Medial Branch Blocks Treat Facet Joint Pain

Two medial branch nerves innervate each facet joint, and they communicate pain signals originating from the spine to the brain.⁸Le DT, Alem N. Facet Joint Injection. [Updated 2023 Jun 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572125/

These nerves are enclosed by a fibro-osseous canal (a canal formed by bone and soft tissue), and injecting medication into this canal allows the drug to adequately surround the nerve, blocking the pain signals transmitted by the nerve.⁹Shuang F, Hou SX, Zhu JL, et al. Clinical Anatomy and Measurement of the Medial Branch of the Spinal Dorsal Ramus. Medicine (Baltimore). 2015;94(52):e2367. doi:10.1097/MD.0000000000002367

Number of Medial Branch Injections Needed

It is recommended that patients undergo two diagnostic medial branch block procedures due to the high potential for false-positive (placebo) responses from a single block. The second injection should be performed 2-3 weeks later to provide sufficient time for the effects of the first block to dissipate.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274

Effectiveness of Medial Branch Blocks

Multiple studies have demonstrated significant pain reduction after diagnostic medial branch blocks in patients with spinal pain.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274 The outcomes of these studies show:

• More than half of the patients experience at least 80% improvement in pain after a successful diagnostic medial branch block.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274  
• If two medial branch blocks independently confirm facet joint pain at the same spinal level, there is approximately a 60% chance of achieving significant and lasting pain relief with RFA treatment of those medial branch nerves.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274

Therapeutic medial branch blocks that combine an anesthetic and a corticosteroid are generally not considered effective because studies have shown that they do not provide more pain relief than a placebo injection.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274  

Differences Between Medial Branch Blocks, Facet Joint Injections, and Epidural Steroid Injections

Epidural, facet, and medial branch injections share a common goal of alleviating inflammation and spinal pain. However, the type of injection used depends on the specific nature of the pain.

The following table lists the similarities and primary differences between these 3 common injection techniques.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274^,10Chou R, Hashimoto R, Friedly J, et al. Epidural Corticosteroid Injections for Radiculopathy and Spinal Stenosis: A Systematic Review and Meta-analysis. Ann Intern Med. 2015;163(5):373-381. doi:10.7326/M15-0934

In general, medial branch blocks are primarily diagnostic, and facet joint injections and epidural steroid injections are therapeutic interventions.⁴Cohen SP, Doshi TL, Constantinescu OC, et al. Effectiveness of Lumbar Facet Joint Blocks and Predictive Value before Radiofrequency Denervation: The Facet Treatment Study (FACTS), a Randomized, Controlled Clinical Trial [published correction appears in Anesthesiology. 2018 Sep;129(3):618]. Anesthesiology. 2018;129(3):517-535. doi:10.1097/ALN.0000000000002274^,8Le DT, Alem N. Facet Joint Injection. [Updated 2023 Jun 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK572125/