Image: Sick child © Bananastock, age fotostock

Millions of Americans suffer from illnesses that add insult to injury by being virtually uninsurable.

Patients with controversial or poorly understood conditions often can't get coverage, even if they have robust employer plans. Many with diagnoses such as temporomandibular joint disorders or autism are left to pay significant out-of-pocket costs to treat their conditions.

Take TMJ disorders, which typically involve pain around the jaw and difficulty chewing and speaking. Some 35 million Americans, or 12% of the population, suffer from it. For some people, it's mild and intermittent, while others have unrelenting pain that precludes them from eating solid food.

Yet labeling the complex condition TMJ can be the "kiss of death" in terms of getting insurers to cover it and dentists and doctors to see patients, said Terrie Cowley, the president of the TMJ Association, a patient-advocacy group in Milwaukee.

"It's unconscionable this mess we are in," she said.

Sometimes employers and insurers don't want to pay for medical treatments that don't help or, worse, harm people further. By refusing to cover treatments that aren't proved to be effective, health insurers say they can hold down premiums for the broader pool of their members.

But it's not always so straightforward. If you have a diagnosis that insurers don't want to touch, you should investigate your options, health care advocates say.

How to fight back

Here are eight tips to protect yourself.

1. Talk with your doctor or health care provider about your treatment options. Ask whether the ones he or she recommends are supported by scientific evidence, said Dr. John Santa, the director of Consumer Reports' Health Ratings Center in Yonkers, N.Y. Or are the recommended treatments based on the doctor's expert opinion or perhaps something more speculative?

2. Contact nonprofit patient-advocacy and support organizations. These groups can help you determine whether your state has any coverage mandates and give you a sense of their treatment priorities. (Some groups are research-oriented and don't assist individuals.) You may be surprised at how conservative their approach is.

The TMJ Association, for example, suggests patients stick with therapies that are reversible and the least invasive, whenever possible, including pain medications and palliative treatments. The reason is that there are little data on what works for TMJ disorders.

Surgery and implants have caused some TMJ patients even worse pain and dysfunction over the years, Cowley said. "Coverage is extremely haphazard," she notes. "It boggles the mind to think (health plans) won't pay for a heating pad, but they will pay for a surgical procedure."

Applying hot and cold compresses to the jaw, the most common therapy, was deemed the most effective of 46 treatments, including splints, physical therapy and cortisone injections, according to a survey of 1,511 TMJ sufferers published last year in The Clinical Journal of Pain.

For severely autistic children, intensive treatment called applied behavior analysis is a standard of care, said Lorri Unumb, the Lexington, S.C.-based vice president of state government affairs for Autism Speaks, a nonprofit research and advocacy group. Even so, only 28 states require insurers to offer it. Families who don't benefit from such mandates sometimes find recourse through the group's efforts, she said. "We routinely help families petition their (human resources) department to try to get this benefit added."

3. Visit your insurer's website. Look for any policy statements related to your condition, and review the services your individual plan covers. Learn your rights and responsibilities for requesting coverage.

4. Engage someone at your health plan. It could be a nurse case manager or the medical director. And insist that the insurer follow its own rules. "Oftentimes, an insurer may have a legitimate reason for being concerned about a test or a treatment, but they have to follow a specific process" for denying a claim or pre-authorizing a service, Santa said. "Your request may or may not be covered, but the insurer has an obligation to provide due process."

5. Appeal. If you're not satisfied with your plan's response, don't be afraid to go through the appeals process. "The track record on appeals is favorable," Santa said. "There's a good chance you could win." In the case of autism, make sure your treatment plan is medically focused and targets deficits in social interaction, communication and repetitive or restrictive behaviors, said Kristin Jacobson, the president of Autism Deserves Equal Coverage, an advocacy group in Burlingame, Calif. "Health plans make it very hard for families," she said. "They count on families giving up. The ones who don't give up are the ones who eventually will prevail."

6. Beware of signing long-term contracts. Some TMJ patients have gotten locked into multiyear contracts with health care providers and continue having to pay long after they've stopped treatment, Cowley said. "In the event that the treatment doesn't work or you are worse, you are still obligated to pay that contract."

7. Maximize your benefits. If you have another medical condition that overlaps with the one you can't get coverage for, treat the one that is covered. Children with autism whose family health plans exclude that diagnosis, for instance, might find some relief by pursuing coverage for related conditions such as speech or motor-skills delays, Jacobson said. Your health plan also may have a separate disease-management program, for which you might qualify, that could help you with pain management or diabetes, should you need it.

Click here to become a fan of MSN Money on Facebook

8. Consider hiring a private health care advocate. Choose someone who has handled many cases similar to yours. You can search for professional advocates near you at AdvoConnection.com and the database of the National Association of Healthcare Advocacy Consultants.