One of the most common questions I hear from patients who come in with imaging results in hand: “I have a bulging disc. Can VAX-D fix that?”
It’s a fair question, and the answer is more nuanced than a simple yes or no. What I want to do in this post is explain exactly what’s happening inside the disc during treatment — because once you understand the mechanism, you’ll understand both why decompression works and what its realistic limits are.
First: What Is a Bulging Disc, Exactly?
Your lumbar discs are fibrocartilaginous structures that sit between each vertebral body, acting as shock absorbers and spacers that allow movement. Each disc has two main components: an outer ring of tough, layered fibrous tissue called the annulus fibrosus, and a soft, gel-like center called the nucleus pulposus.
A bulging disc means the disc has deformed outward — the outer wall hasn’t ruptured, but the disc wall is expanding beyond its normal boundary. It’s like pressing your thumb into a water balloon: the balloon doesn’t pop, but it distorts.
A herniated disc goes further: the outer wall has torn, and the inner nucleus material is extruding through the tear. This is often more acutely painful because the extruded material can directly compress nerve tissue.
Both conditions can cause pain, but they have different structural implications for treatment.
What Causes Disc Pressure to Build Up
The nucleus pulposus is mostly water — about 70-80% when healthy. It’s designed to be hydraulic: when you compress the spine, the nucleus distributes load in all directions and then rebounds when pressure is released.
The problem is that the nucleus depends on movement and alternating pressure to stay hydrated. A compressed disc under continuous load — the daily load of sitting, standing, poor mechanics, or chronic muscle tension — gradually loses fluid. As the nucleus dehydrates, it loses its ability to distribute load evenly. The annulus compensates, gets stressed, and begins to bulge or tear.
Here’s the key number: intradiscal pressure in a healthy disc is positive, around +90 mmHg when standing. Under certain loading conditions (bending forward while lifting, for example), it can exceed 200 mmHg. This sustained positive pressure is what drives fluid out of the disc over time.
What VAX-D Does to Intradiscal Pressure
The foundational research on VAX-D — conducted by Dr. Allan Dyer and published in the 1990s — measured intradiscal pressure directly during decompression using intradiscal pressure sensors. The findings were significant: VAX-D treatment produces intradiscal pressures in the range of -100 to -160 mmHg.
That’s not just low pressure — that’s genuinely negative pressure, below atmospheric. And that negative pressure differential does two things:
1. It creates a retraction force on herniated or bulging disc material. The negative pressure inside the disc pulls inward, which can draw nucleus material back toward the center, away from nerve tissue. This is the mechanism behind the clinical observation that many patients experience significant nerve pain relief after a course of decompression — the disc material that was pressing on a nerve root has retracted.
2. It drives fluid, nutrients, and oxygen back into the disc. Think of the disc as a sponge. Sustained pressure squeezes fluid out; negative pressure draws it back in. The nucleus needs water to function. It also needs the glucose and oxygen that arrive via that fluid, since adult discs are avascular — they don’t have a direct blood supply. The negative pressure during VAX-D treatment creates an imbibition effect: fluid is drawn in through the endplate margins, re-hydrating nucleus tissue that had become desiccated.
What Actually Changes in the Disc
When a full course of decompression is completed — typically 15-20 sessions over 5-6 weeks — we see three categories of change in well-responding patients:
Structural retraction: Some patients with documented herniations or bulges show measurable reduction in disc protrusion on follow-up MRI. This isn’t universal, and the extent varies significantly by patient and the severity of the initial finding. But it does happen, and it’s the reason patients with nerve-compression symptoms sometimes experience near-complete resolution of radiating pain after treatment.
Disc rehydration: Follow-up MRI can show increased T2 signal in the nucleus — the radiological marker of increased water content. A desiccated disc on pre-treatment MRI sometimes shows improved hydration on post-treatment imaging, particularly in patients under 60.
Pain and functional improvement independent of structural change: Some patients improve significantly without demonstrable structural change on imaging. This likely reflects the reduction in inflammatory mediators that occurs when disc pressure normalizes, and possibly changes in pain sensitization. Not every good outcome requires a visible structural change — disc pain has both mechanical and neurochemical components.
The Honest Answer: Who This Actually Works For
VAX-D is most likely to produce meaningful improvement in patients with:
- Contained disc herniations or bulges at L3-L4, L4-L5, or L5-S1 with corresponding nerve root compression symptoms (pain, numbness, or tingling into the buttock, thigh, or leg)
- Discogenic low back pain without significant herniation — primarily disc degeneration and loss of disc height
- Symptoms that have not responded to conservative care (physical therapy, chiropractic manipulation, anti-inflammatories) but are not severe enough to be considered for surgery
- Patients who are not surgical candidates due to age, health status, or patient preference
VAX-D is not appropriate for:
- Spinal instability, fracture, or severe spondylolisthesis
- Severe osteoporosis
- Active cancer in the spine
- Certain types of surgical hardware that contraindicate traction forces
- Very large, sequestered disc herniations that have separated from the disc (these may require surgical consultation)
This is why we insist on reviewing your MRI before beginning any decompression protocol. The list above isn’t boilerplate — it’s a clinical checklist we take seriously on every patient evaluation.
A Note on Expectations
I want to be direct about something: VAX-D is not a cure. For some patients, it produces dramatic and lasting improvement. For others, it provides partial relief that needs to be maintained with periodic treatment and home exercise. For a subset — maybe 20-25% based on our experience — it doesn’t produce clinically meaningful improvement.
What I can tell you, having used this technology since 1997, is that the patients who do best are the ones who commit to the full protocol, follow through on home instructions, and are realistic about the recovery timeline. Disc pathology doesn’t develop overnight. Meaningful structural repair doesn’t happen in two sessions.
But for the right patient, with the right disc condition, at the right stage of their problem — the mechanism is real, the research is real, and the outcomes are real.
Want to Find Out If Your Disc Is a Candidate?
Bring your MRI to your evaluation. We’ll review the imaging, take a full history, and give you a straight answer about whether decompression is likely to help your specific disc condition — and if not, what the better options are.
Call us at 631-659-2980 or schedule your evaluation online. West Hills Chiropractic Pain Center, 400 W Jericho Turnpike, Huntington, NY 11743.
— Dr. Tom Oddo, DC CSCS CEAS, West Hills Chiropractic Pain Center