Good information. Based on what I've read and heard, I disagree a little bit with one comment made by your doctor. Those who have genetic based EM have primary EM, but those who seem to have primary EM are not all suffering from EM from a genetic defect. It seems only a small subset of primary EM suffering patients have the genetic version of it. But it could be that medical terms defining primary EM have changed and now only refer to genetic based EM. This would leave those who previously had spontaneous EM with no known cause, in a undefined category perhaps. Should we call it spontaneous EM now?
BY THE OLDER DEFINITION
Primary EM is EM with no known source.
A secondary EM is one that is caused by another disease and when you treat the other disease, and resolve the other disease the cause of EM, and the EM symptoms are relieved.
If I have EM from cancer for example. The EM might be relieved when I cured of cancer, if that happens. If I have EM from cancer treatment, and that cancer treatment damaged my nerves, I might have EM from nerve damage and it might be a kind of permanent EM, with a known cause. Still perhaps referred to by some as primary EM but we know the cause. If I have EM from a drug reaction to psychotropic drugs for depression. Perhaps that was damage from those drugs. I don't have a classic source of my EM, being cancer, lupus, diabetes EM flares. So I am labelled with primary EM. As the cause becomes more known, I may know the cause, but many still may refer to this as primary EM because the damage isn't secondary from another treatable disease. It's my primary problem and I'm treating it alone.
All EM symptoms without a known source are considered primary EM.
At least that is the case in the old days.
Statements of Primary EM being defined as the genetic defect are now being made as patients with primary EM have tested positive for the genetic defect.
Think of primary EM in the traditional sense and EM with a mysterious cause. It's not caused by something that can be treated or found. Perhaps it's due to a nerve damage condition or autoimmune disease, but they just can't figure it out for your EM, so it's called primary EM, or an EM that seems to just appear.
Genetic based EM (my term) or primary EM from a genetic defect is a flaw in the sodium NAV 1.7 channel defect. This is a primary EM that develops from the genetic defect and the patient is tested positive for the defect. There are many who have the Nav 1.7 gene defect and may not get EM at all. It affected something like 20% of those who have the genetic defect.
Pain travels down nerve channels. Think of the sodium nerve channels like EQ bands of sound in your stereo system. Pain in your nerves can travel down different channels like different bands of EQ from my sound sound system. With a narrow band EQ you can perhaps turn down one band of sound in your stereo. A broad band sodium channel blocker is turning down all the EQ channels and it will reduce the volume on all channels, including the NAV 1.7 specific EQ band we would want to target. If I turned down all or many of the EQ's with a broad band EQ, then a wider range of sound would be reduced. With a broad band channel blocker other pain signals besides Nav 1.7 are turned down as well.
If one takes a broad band sodium channel blocker like oral lidocaine or uses lidocaine, it's turning down all the channels of pain. Which can help for EM symptoms if you have the Nav 1.7 channel defect. If you have the nav 1.7 sodium channel defect and have EM pain and you can turn down just the noise from that channel, then you are targeting the pain from EM more specifically. This is what they are working on a narrow target of the Nav 1.7 pain channel.
About two years ago I heard that there were only 30 known family groups in the world that had the genetic defect. So there were apparently many people who have primary EM or something like that, who didn't have the Nav 1.7 defect. Those people may not be helped by the sodium channel blocker approach, but some may still be helped. So there are those who seem to have primary EM, but can't be linked to the genetic defect. They may have some other mystery illness or perhaps just some kind of strange nerve damage which is unknown.
We can likely state that if you have the Nav 1.7 genetic defect and EM, then it's definately primary EM that you have. But I don't think we can say every person that has Primary EM, has the genetic defect.
In either case, with the genetic defect or without, a sodium channel blocker may help the EM sufferer, so it's worth a try.