Discogenic Pain & Basivertebral Nerve (BVN) Ablation

Intracept (BVN Ablation) Procedure

The Intracept procedure (Relievant Medsystems / Boston Scientific) uses radiofrequency energy to ablate the basivertebral nerve within the vertebral body, interrupting pain signal transmission from inflamed endplates.

Basivertebral Nerve Anatomy

Understanding the BVN is essential:

• Course: The basivertebral nerve enters the vertebral body through the posterior cortex (basivertebral foramen) and branches anteriorly to innervate the vertebral endplates
• Function: Sensory nerve carrying nociceptive signals from the endplates to the spinal cord
• Key concept: The BVN is the final common pathway for endplate-mediated nociception — ablating it interrupts pain signal transmission from inflamed endplates
• Pain mechanism: In degenerative disc disease with endplate changes, inflammatory mediators (TNF-alpha, IL-1, IL-6) sensitize endplate nociceptors, which transmit signals via the BVN

Step-by-Step Procedure

1. Pre-procedure MRI review: Confirm Modic type 1 or type 2 changes at the target levels
2. Patient positioning: Prone on fluoroscopy table
3. Transpedicular approach: A curved introducer is advanced through the pedicle into the vertebral body under fluoroscopic guidance
4. RF probe deployment: The probe is deployed to the midline of the vertebral body where the BVN is located
5. Ablation: RF energy is applied to create a lesion that ablates the BVN
6. Bilateral treatment: Typically both the superior and inferior vertebral bodies flanking the pathologic disc are treated (e.g., for L4-5 disc disease, L4 and L5 BVNs are ablated)
7. Multi-level: Indicated for up to two levels (three vertebral bodies)

Understanding Modic Changes

Modic changes on MRI are the key imaging finding that identifies BVN ablation candidates:

| Type | T1 Signal | T2 Signal | Pathology | Clinical Significance | |------|-----------|-----------|-----------|----------------------| | Modic 1 | Hypointense | Hyperintense | Active inflammation/edema | Best predictor of treatment response | | Modic 2 | Hyperintense | Hyperintense/iso | Fatty infiltration | More chronic/stable; may still respond | | Modic 3 | Hypointense | Hypointense | Sclerosis | Least common; not an indication |

• Modic 1 changes represent active inflammatory endplate disease and are the strongest predictor of response to BVN ablation
• Prevalence: ~6% of general population; 35-40% of patients with chronic low back pain
• Natural history: Modic 1 can progress to Modic 2 over 1-3 years, or may persist or fluctuate

IPSIS BVNRFN Procedural Details

The IPSIS Technical Manual provides detailed step-by-step guidance for basivertebral nerve radiofrequency neurotomy:

Target Zone:

• Posterior limit: 1 cm anterior to the posterior vertebral body wall (to allow heat dissipation and protect the epidural space)
• Anterior limit: the anterior terminus of the basivertebral foramen
• At L3-L5, the basivertebral foramen terminus is typically 30-50% of the distance from the posterior to anterior vertebral body wall
• Target zone is midway between the superior and inferior endplates at lumbar levels
• At S1, the target zone is closer to the superior endplate (approximately 40% from superior to inferior)

Transpedicular Approach:

• The introducer needle (typically 8G) enters at the superior-lateral aspect of the pedicle and advances toward the inferior-medial aspect
• Frequent alternating between true AP and true lateral imaging is essential to avoid breaching the pedicle cortex
• Goal: reach the posterior vertebral body in the lateral view before reaching the medial or inferior pedicle walls in the AP view
• The L5 pedicle is undercut by the lateral recess — the inferomedial quadrant should be avoided
• At L3, narrower pedicles may require a coaxial trajectory through the center rather than a superior-lateral to inferior-medial angle
• The iliac crest may obstruct S1 pedicle access; additional cephalad tilt can help

Channeling Through Bone:

• A critical distinction from soft-tissue procedures: bone channeling is not forgiving — each advancement creates a permanent channel
• The curved nitinol channeling stylet is advanced in approximately 2 mm increments with measured mallet taps
• Direction is adjusted by rotating the cannula hub and curved channeling assembly as a single unit
• If the curved stylet progresses too posteriorly (within 1 cm of the posterior wall), switch to the straight channeling stylet

Bipolar RF Lesion:

• The bipolar RF electrode is positioned so its midpoint is at the center of the target zone
• Standard lesion protocol: 85 degrees C for 15 minutes, or targeted coagulation at 75 degrees C for 7 minutes
• Venous bleeding through open instruments is common (cancellous bone is densely vascularized); minimize time that instrument lumens remain open
• Access to the next vertebral body can begin on the contralateral side while the RF lesion is in process

Safety Considerations:

• Because of the convex posterior wall of L5, insufficient trochar advancement before placing the curved stylet risks breaching the central canal
• Medial branch of the dorsal ramus may be unavoidably disrupted during transpedicular access (located at the junction of the transverse process and superior articular process)
• Pre-medication with IV antibiotics is standard; monitored anesthesia care or general anesthesia is often used for patient comfort

IPSIS Provocation Discography Overview

The IPSIS manual covers cervical provocation discography in detail, which provides relevant context for understanding discogenic pain diagnosis:

Key Principles of Disc Provocation:

• The purpose is to determine whether a specific disc is the source of a patient's pain by reproducing concordant pain with controlled disc pressurization
• Internal disc morphology (as shown by contrast medium spread) is not diagnostic — only whether concordant pain is reproduced matters
• A negative control disc is required; without it, a disc cannot be deemed the pain source
• The initial nonreproducible pain response during injection (startle response) must be distinguished from true concordant provocation

Diagnostic Criteria (IPSIS/SIS Standards):

• Correct technical performance
• Facet joint pain excluded at studied segments (medial branch blocks should be performed first)
• Concordant pain reproduced with disc stimulation
• Pain intensity of 7/10 or greater on NRS
• Stimulation of adjacent discs does not produce concordant pain

Infection Prevention:

• Full sterile preparation (surgical mask, cap, gown) is required
• Intradiscal and/or IV antibiotic prophylaxis is indicated
• Fresh needles for each disc accessed; no-touch technique for needle tip bends

CPT Coding

• CPT 64628: Thermal destruction of intraosseous basivertebral nerve, first two vertebral bodies, including fluoroscopic guidance
• CPT 64629: Each additional vertebral body