Diagnostic nerve blocks are targeted injections of local anesthetic to specific nerves or joints, used to identify the source of a patient's pain. When imaging shows multiple potential pain generators, diagnostic blocks isolate which one is actually responsible. Information that often changes the treatment plan substantially.
Why diagnostic blocks matter
Patients with chronic back or neck pain often have multiple imaging findings: a disc bulge at one level, foraminal narrowing at another, facet arthritis at a third. Which of these is actually causing the patient’s pain? Without targeted testing, the answer is often a guess.Diagnostic blocks remove the guess. Anesthetizing a specific structure and observing whether the patient’s pain disappears confirms (or rules out) that structure as the source. The information is actionable in a way that imaging alone often isn’t.
Types of diagnostic blocks
Selective nerve root blocks — anesthetizing a specific nerve root to confirm radicular pain source. Medial branch blocks — anesthetizing the small nerves serving suspected facet joints to confirm facet-mediated pain. Sacroiliac joint blocks — anesthetizing the SI joint to confirm SI as the pain source. Provocation discography — assessing whether a disc is the source of axial pain (more limited current role).Each block has specific indications and interpretation criteria. The right block depends on the clinical question being asked.
How they work procedurally
Performed under fluoroscopic guidance — image-guided positioning ensures the local anesthetic reaches the targeted structure. The patient lies on a table; the procedure typically takes 15-30 minutes; mild sedation may be used for comfort.Local anesthetic with or without contrast dye is injected at the target. The patient then describes whether their typical pain has decreased, and by how much. A positive block — significant reduction during the anesthetic period — confirms the target as the pain source. The patient typically goes home shortly after.
Send your MRI for a free review
Dr. McMillan reviews each scan personally. You get a candid answer about candidacy before any travel or scheduling.
What we suggest doing first
If you are weighing this decision, the most useful single action is sending your MRI for a free review. The review costs nothing and produces a candid written assessment from Dr. McMillan — including the answer that you are not a candidate, when that is the honest answer. We do not ask patients to travel for a procedure that will not help them.
When the review indicates that the endoscopic approach fits, the next step is a $250 consultation. The fee covers Dr. McMillan’s time to review the imaging in detail and discuss what the procedure would involve for your specific situation. If you decide to proceed, the $250 is credited toward the procedure bundle. If you decide not to proceed, you owe the consultation fee and nothing further.
From there, scheduling moves at a pace that fits your situation. The procedure is outpatient, takes about an hour, and most patients are home the same day. Post-procedure follow-up is part of the bundle. For patients coming from out of town, the office coordinates lodging guidance, transportation considerations, and handoff with your local providers — this is a routine part of how we work, not an exception. The goal throughout is to make a complicated decision more navigable, with the actual numbers and the actual options in front of you.
What changes after a diagnostic block
A confirmed pain source guides treatment selection. Confirmed facet-mediated pain → consider rhizotomy. Confirmed radicular source → discectomy or decompression of that specific level. Confirmed SI joint pain → targeted SI treatment rather than lumbar spine intervention.A negative block — no significant pain reduction — is equally informative. It rules out the tested source and redirects the search. Knowing what isn’t causing the pain is sometimes as useful as knowing what is.
Bottom line
Diagnostic nerve blocks are targeted injections of local anesthetic to specific nerves or joints, used to identify the source of a patient's pain. When imaging shows multiple potential pain generators, diagnostic blocks isolate which one is actually responsible. Information that often changes the treatment plan substantially.
If you’ve been told you need a fusion — or you’re trying to avoid one — a free MRI review is the most useful next step. Dr. McMillan reviews each scan personally and tells you candidly whether the endoscopic approach fits your specific anatomy.
For patients dealing with diagnostic nerve block, the conversation comes down to specifics: what your imaging actually shows, what your symptoms are actually telling us, and which procedure (if any) genuinely matches that pattern. The candid answer is sometimes that you do not need surgery yet; the candid answer is sometimes that you do, but a smaller operation than the one you have been quoted. A second-opinion MRI review separates those cases and gives you the information you need to make the decision well.
The Synergy approach to diagnostic nerve block
At Synergy Spine Center, diagnostic nerve block is performed by Dr. Marion McMillan personally — the same surgeon who reviews your imaging, plans the operation, and handles your post-operative care. This single-surgeon model isn’t unusual for boutique surgical practices; it’s structural at Synergy because the spine literature shows volume-outcome relationships for individual operators. Patients pursuing this procedure most often arrive with a diagnosis of radiculopathy or facet joint syndrome after being told elsewhere that more invasive surgery — typically fusion — is their only path forward.
Candidacy is established before any travel commitment through the free MRI review process. Patients submit recent imaging and a brief clinical history; the review identifies whether the specific pathology shown on imaging would respond to diagnostic nerve block or whether a different intervention would be more appropriate. If you’re a candidate, you’ll receive a written assessment along with transparent bundled pricing for the procedure. If you’re not a candidate, you’ll be told that directly, often with a referral to the appropriate specialty — the review is screening, not sales.
Recovery from diagnostic nerve block is intentionally faster than from traditional open spine surgery or fusion. Most patients return to office work within one to two weeks; manual labor takes four to six weeks. Routine post-operative follow-up is included in the bundled price, and for out-of-town patients much of the follow-up happens remotely through phone or secure video — the 3-day plan documents typical visit cadence. Authoritative clinical background on this procedure is also available at Cleveland Clinic — Nerve Block for patients who want to read more about the underlying evidence.
Frequently asked
Do diagnostic blocks treat pain or just diagnose?
Their primary purpose is diagnostic. Some have therapeutic effect from accompanying corticosteroid, but the diagnostic value is what makes them important. Transparent bundled pricing for diagnostic nerve block is published openly at /spine-surgery-cost-transparent-pricing/, so you can plan financially before scheduling and avoid surprise bills.
How long does pain relief last after a block?
Diagnostic-only blocks with just local anesthetic — relief during the anesthetic period (hours). Blocks with steroid added — relief can extend for weeks. To find out whether you’re a candidate for diagnostic nerve block, submit your imaging through the free MRI review — Dr. McMillan reviews each scan personally and provides candid candidacy assessment within several business days.
Are diagnostic blocks accurate?
When properly performed under image guidance, generally accurate. Both false positives and false negatives exist but are uncommon. To find out whether you’re a candidate for diagnostic nerve block, submit your imaging through the free MRI review — Dr. McMillan reviews each scan personally and provides candid candidacy assessment within several business days.
Will my insurance cover them?
Diagnostic blocks for appropriate indications are typically covered. The office verifies specifics. Transparent bundled pricing for diagnostic nerve block is published openly at /spine-surgery-cost-transparent-pricing/, so you can plan financially before scheduling and avoid surprise bills.
How is a diagnostic block different from an epidural injection?
Epidural injections place medication in the epidural space (around multiple nerve roots). Selective blocks target specific structures. To find out whether you’re a candidate for diagnostic nerve block, submit your imaging through the free MRI review — Dr. McMillan reviews each scan personally and provides candid candidacy assessment within several business days.
Can blocks be done on multiple structures in one session?
Sometimes, but interpreting the results becomes more difficult. Often blocks are sequenced over visits to clarify findings. Patients who travel for care typically combine consultation and procedure into a single trip — the 3-day plan documents the standard cadence and lodging logistics for out-of-town patients.
How this page was prepared
This page summarizes the clinical approach taken at Synergy Spine Center for the topic above. It is based on peer-reviewed literature, professional society guidelines (NASS, AAOS), federal patient education resources (NIH, AHRQ, CMS), and Dr. McMillan’s experience as Director of Spinal Medicine and Endoscopic Spinal Surgery. Outcome language is qualified. Individual results vary. Pricing where shown is current for 2026 and may change.
References
- NASS — diagnostic block resources. — source
- PubMed — diagnostic block literature. — source
- OrthoInfo — injection procedures. — source
- Cleveland Clinic — Nerve Block — clinical reference relevant to diagnostic nerve block.
- NIH NCBI — Nerve Block — clinical reference relevant to diagnostic nerve block.
Synergy Spine Center publishes patient education content for general information only; it is not medical advice and does not establish a physician-patient relationship. For specific medical guidance, schedule a consultation. No identifiable patient information is included on this page.