There are some disease in which there are no available "objective" tests, such as Parkinson's. The diagnosis of such an illness depends entirely on the clinical picture, course, response to treatment etc. Only a good therapuetic dialogue between the patient and the physician can be used in this setting.

On the other side of the spectrum there are diseases in which the diagnosis relies entirely on "objective" tests. cancer of any type would be under that category. no physician in his/her right mind is going to give chemotherapy to a patient without a pathologist signing a report of the diagnosis. even then, mistakes can happen both ways, but it is extermely rare.

And there are many diseases that fall in-between. There are pretty good tests to diagnose them, but those tests are not essential for the diagnosis. They are also not positive in all the patients with the disease, and not negative in all those that don't have it. If the clinical picture is very clear, then you can rely on it (just like in Parkinson's disease). The "objective" tests are required in order to suppport the diagnosis, but don't make the diagnosis.

such tests have a given sensitivity (what percent of patients with the disease are going to have a diagnostic test), specificity (what percent of the patients who do not have the disease, are going to have a diagnostic test), positive predictive value ( how likely is the disease, given a diagnostic test is present), negative predictive value (how likely it is that the disease is not present given a diagostic test is not present).

In myasthenia there is a somewhat ridiculous (forgive me for using this word) situation. In reality it belongs to the third group. there is no pathological specimen that you can have that shows without doubt that the illness is or is not there. There are multiple diagnostic tests- antibodies, SFEMG, ice-pack, tensilon test etc. but all have relatively poor sensitivity, specificity and negative predictive value. in the range of 70-80% and no where near the 100% that they atribute to it.

This means that given a negative test, the likelihood of having myasthenia is still in the range of 20-30%. even if you combine a few tests, you will at the most reach a likelihood of 5%, with all tests being negative.

Now if you have a disease that belongs to the third group. you have a very high pretest probability (which means that before doing the test, based on the clinical picture, course of illness etc, the disease is very likely, say in the range of 80%), and you do not have any alternative/more likely diagnosis, then for all practical reasons this is the diagnosis, even if all the tests are negative.

obviously, your degree of certainty will never be as it is for the diagnosis of cancer, in which you have a pathological specimen that actually shows the malignant cells, yet this is accepted in medicine, by physicians and patients as a legitimate way to diagnose an illness.

Maybe one day we will have "objective" tests for every possible illness, and maybe this will never happen, but as things are now, we really don't.

The problem with myasthenia is that when it is written in almost every text book, that a SFEMG done properly in a weak muscle rules out the diagnosis of Myasthenia, it gives this test an accuracy that does not exist, and a negative predictive value of 100%, when in fact it is much more near 80% (which is a very low negative predictive value for a test).

As long as this mistake is not corrected (and there are a few neurologists and scientists around the world that do realize it, and have even written about it in good medical journals, but they do not seem to be able to convince the rest), there will be a non-negligible number of patients around the world that are going to have clinically diagnsed myasthenia which will then be "ruled out" by a normal SFEMG.

As there is no real alternative diagnosis (apart from very rare cases of mitochondrial myopathy or other obscure and extremely rare diseases), such patients remain with "no diagnosis" and their illness just doesn't exist.

when their symptoms become severe/potentially life-threatening, they will be treated, but then no one is going to take full responsibility for that, and questioning their diagnosis, and sometimes even their sanity is a good way to go, for their treating physicians, who are at loss.

If you had a clear diagnosis of myasthenia, your management now would have been very different. you would not be left with partial treatment, which is started and stopped, on order to get tests that may or may not give the "objective" evidence they are looking for.

But all this doesn't really help you and I am trying to think what you should practically do, and as this is a very hard situation, I am not sure how good my advice is going to be, so just think about it, and see if it seems reasonable to you.

I think what you need to do is go to your neurologist, ask him what he thinks your diagnosis is. If he says that clinically it can only be mysthenia, tell him that you trust his clinical judgement and don't need any further proofs. you can also tell him that you have read about those tests, and realized that it is possible that even if you do have myasthenia they will all be negative.

If he says that there are other possibilities, ask him what they are, and how in practice he is going to persue their diagnosis, and what would be the management for them.

Don't let him get away with vague answers, and maybe, possibly, could be. tell him that after a fairly traumatic hospitalization and a few more weeks at home, in which you followed his advice, you think you deserve to know. Force him to stop sitting on the fence, and have him decide one way or the other.

And if he keeps on avoiding giving you reasonable answers, you proably need to find another neurologist.

I hope any of this can somehow help,

all the best,

alice