"IMR upheld the denial."

Why appealing the IMR itself rarely works

The grounds for appealing an IMR determination are narrow and mostly procedural — fraud, conflict of interest, a plainly erroneous finding of fact, or the reviewer acting outside their authority.

Disagreeing with the medical conclusion is not a ground. The California Supreme Court has upheld the framework, and the practical reality is that the medical result stands.

So the useful question is not "how do I appeal this." It is "what else works."

The four things that still work

1. Check whether the UR decision was defective in the first place

A procedurally defective utilization review decision is not properly resolved through IMR at all — it goes to a judge, which is a materially better forum.

Check: Was the UR decision timely from receipt of the request? Was it made by a physician competent in the relevant field — only a physician may modify or deny for medical necessity? Was it served on everyone required, within the required time? Did it actually address what was requested?

This has to be raised as a defect, not as a disagreement. How to check a UR denial.

2. A new request, with new information

An IMR determination resolves the request that was made. A new request supported by new clinical information — a failed conservative trial, a new diagnostic finding, a change in your condition, a specialist's opinion addressing the guideline directly — is a new request.

What wins is responding to the guideline the reviewer cited, specifically, rather than resubmitting the original request. Most guideline pathways require documented failure of something less invasive first — and that documentation is frequently in the chart but not in the request.

3. Check whether the guidelines changed

They did, recently, and repeatedly:

• The utilization review regulations were restructured effective April 1, 2026.
• Four MTUS guidelines were replaced effective January 2, 2026 — shoulder, elbow, hand, wrist and forearm, and traumatic brain injury — and a further set took effect June 1, 2026: initial approaches to treatment, chronic pain and eye disorders.

A denial resting on a superseded guideline is resting on something that no longer exists.

4. The MPN route, which is a different system

If the dispute is really about which physician's opinion governs rather than whether a specific treatment is necessary, the MPN process applies instead — second opinion, third opinion, then MPN independent medical review under § 4616.4.

And that route has an exit that IMR does not: where the MPN reviewer agrees with you, "the injured employee may seek the disputed treatment or diagnostic service from a physician of his or her choice from within or outside the medical provider network," and the employer is liable for the cost.

How the MPN process works.

And in the meantime

Do not stop treating. A gap in treatment is used against you on causation, on credibility, and on permanent disability.

Document what the denial cost you — increased symptoms, lost function, a worsened condition. Where a denial made you worse, that is relevant to your permanent disability, and where industrial treatment (or its denial) caused disability, apportionment arguments get harder for the defense. More.