The director of the electromyography laboratory and a professor of neurology at Cedars-Sinai discussed the misdiagnosis of the rare condition.
Richard A. Lewis, MD
Treating rare neurologic disorders, such as chronic inflammatory demyelinating polyneuropathy (CIDP), can come along with challenges to treatment.
For physicians that treat CIDP, like Richard A. Lewis, MD, the director of the electromyography laboratory and a professor of neurology at Cedars-Sinai, that can cause confusion for the general neurologist during attempts to identify the condition. The ensuing misperceptions can then lead to poor or even improper treatment.
To clear up the muddied waters, Lewis spoke with NeurologyLive in an exclusive interview. He also noted how far the disease has come, and what physicians in this field need to improve the state of care.
Richard A. Lewis, MD: Jeff Allen, MD, and I have written on this a bit in the last few years on the misdiagnosis of CIDP. CIDP, in a sense, is a syndrome. It’s not one particular disease entity. Everything in the syndrome has certain commonalities, but we don’t really know whether each of the variations on that disease are just per chance or whether there’s actually a different disease mechanism. It’s probably a different disease mechanism. Classic CIDP of symmetrical proximal and distal weakness with loss of reflexes—most people when they see that and recognize it as a neuropathy, recognize that as being CIDP. Studies that I was involved in showed that if you have that classic presentation, the nerve conduction test helped confirm it, but you almost don’t need it to make the diagnosis.
Where people have trouble is trying to deal with people who don’t have that phenotype of the classic symmetric proximal and distal weakness, and try to say this is inflammatory, and try to treat it as CIDP. There’s a tremendous confusion about that, and although there are some very good criteria and guidelines developed in the diagnosis, most clinicians are not using those guidelines. If I had any appeal to clinicians, it would be: Please look at the guidelines and the ones that have been the most used are the EFNS/PNF from 2010, but almost any guidelines would be better than not using any guidelines.
The other part that gets confusing is people give intravenous immunoglobulin (IVIG), typically, to these patients, and the patient says, “I’m feeling better,” and the doctor then accepts that as this is treating the disease and therefore they must have CIDP. But that feeling better doesn’t mean they’re actually treating the disease. Using that subjective response to treatment is not an adequate way of saying the patients are actually responding to an expensive and somewhat risky treatment, and it doesn’t mean they have the disease.
The disease was essentially identified in the late 1970s, so it’s a relatively new disease. The variants have come out over the last 40 years, and some of them make sense and some of them are a little bit of a stretch. The biggest issue was actually recognizing when the disease occurred. The second thing was to recognize that there are treatments available including the IVIG, and I didn’t mention plasma exchange. The fact that plasma exchange helps a number of these patients—where you’re actually taking out the plasma and something in the plasma constituency obviously has a major effect on the disease because people have a direct response to it—tells us that we’re hitting factors instrumentally hitting the disease. The fact that there are these circulating antibodies complementing the disease was a major factor.
We do pretty well in controlling this disease, I would say over three-quarters of patients respond to first- and maybe second-line treatment, so we do pretty well. That’s encouraging. It’s also one of the neuropathies that we can treat, so it’s exciting, which is one of the reasons people want to make this diagnosis—because it’s treatable.
What we need in the next 5 to 10 years is something that you can use and don’t have to keep giving indefinitely to control the disease. Now, there are a lot of diseases, like diabetes, where you need ongoing treatment for most of or the rest of your life. Now, they’re looking for other things to try and reverse that. We in the neuropathy world are still looking for that curative agent.
The development of monoclonal antibodies and targeting different constituents of the immune system as well as the central nervous system is in its infancy. I’m optimistic that we’re going to come up with different approaches, but at this point, we still don’t know. We need to know the physiology of the disease to a better extent that we know. We need research, support money, and scientists to go into the field. We have a nice core group, but scientists go into the field most supported by funding. We have a little bit of a struggle in the CIDP world. There is no funding for agents and we can’t get investment in this rare disease.
Transcript edited for clarity.