One of our readers, whom we will call “Jay,” was looking for some medical information about pain-relieving spinal injections.
Jay began her quest by asking an artificial “intelligence” (“AI”) program, and, in her words, “the most extraordinary conversation with the Claude AI tool” ensued.
Claude is Anthropic’s AI program, “built for problem solvers.”
Jay sent us a copy of the “conversation” between herself and Claude. “I have attached a copy of the conversation and highlighted parts of the text in yellow,” she told us.
Adding, “In a nutshell, the tool stated that it does not search for evidence before it makes statements and that it favours a comfortable mainstream medical narrative over high-quality conflicting evidence.
“This should be a wake-up call for everyone who believes the rubbish that AI is churning out. What a scary future we face.”
Conversation with Claude Opus 5 on 06 September 2026
Note from The Exposé: The following exchange was sent to us by Jay. We have made no edits except to add subtitles and a Table of Contents to help readers navigate through it. “Q” are the questions Jay posed, and “A” is the response from Claude. Instead of yellow highlights as Jay used, we have used orange.
Table of Contents
- Can RFA Cause Muscle Weakness?
- Show Me The Evidence
- Why Did You Lie About “The Evidence”?
- Why Do You Make Things Up?
- How Do You Form An Answer Without Using a Source Text?
- Where Do You Source Your “General Knowledge”?
- Who Decides Which Pattern Forms Your “General Knowledge”?
- Does Anthropic Program Biases To Suit The Acceptable Narrative?
- Has AI Been Trained to Suppress the Truth?
- Will You Ever Be Able to Independently Distinguish Between True and False?
- How Can I Ensure That You Have Fact-Checked Your Responses?
Can RFA Cause Muscle Weakness?
Q. If you have a RFA nerve ablation at S1, L5, Ll4 or SI joints can it also cause muscle weakness or atrophy because I thought the procedure only targeted pain nerves not motor nerves that innervate muscles?
(Thought for 16s)
A. Your understanding is the standard explanation given to patients, but it’s a simplification. The nerves targeted in lumbar facet RFA are not purely sensory.
Lumbar medial branches are mixed nerves. The medial branch of the dorsal ramus supplies the facet joint capsule and some skin, but it also carries motor fibers to the multifidus — the deep segmental stabilizer muscle running alongside the spine. Ablating it denervates the multifidus at that level. The L5 target is slightly different (you’re lesioning the L5 dorsal ramus itself as it crosses the sacral ala rather than a discrete medial branch), but it too supplies multifidus.
This shows up on imaging. Studies looking at MRI before and after lumbar RFA have found measurable reduction in multifidus cross-sectional area and increased fatty infiltration at the treated levels. Dreyfuss and colleagues documented this fairly clearly, and it’s been replicated.
Why most people don’t notice it. Multifidus has overlapping segmental innervation, so neighboring levels partially cover the denervated segment. The longissimus, iliocostalis, and other paraspinals also compensate, and they’re supplied by different branches. Most patients have no detectable functional weakness on exam. There’s also a confounder: people with chronic facet-mediated back pain usually already have multifidus atrophy before the procedure from pain inhibition and disuse, so it’s hard to attribute all of it to the RFA. Whether the additional denervation matters for long-term spinal stability is genuinely unsettled — it’s one of the open criticisms of repeated RFA.
SI joint (S1–S3 lateral branches) is different. Lateral branches are essentially sensory to the posterior SI ligaments and joint. There’s no established motor target there, so muscle atrophy isn’t an expected consequence of properly placed sacral lateral branch lesions.
True limb weakness is a separate issue. Weakness in the leg — foot drop, quad weakness, difficulty with plantarflexion — would mean the ventral ramus or exiting spinal nerve was affected, which is a complication rather than an expected effect. This is rare, and it’s exactly why motor stimulation testing (usually 2 Hz) is done before lesioning: if the leg twitches, the needle is too close to something it shouldn’t be near and gets repositioned. Post-procedure neuritis can also cause temporary discomfort and reflexive guarding that feels like weakness without being true motor loss.
If you’re actually experiencing new weakness or visible muscle wasting after a procedure, that’s worth reporting to the physician who did it rather than filing under expected side effects — the distinction between segmental multifidus denervation and a nerve injury is one that needs an exam, and possibly EMG.
Core and paraspinal strengthening afterward is reasonable regardless, and is often recommended partly for this reason.
