Hi bead, i know what you mean, but i also think you already know the answer to this yourself.  If you don't have more tests, which on one hand would be good and would stop the fuel to the fire as it were, you would always be thinking about it.  I know that because i am finding it hard not to do an ecg on myself, my comfort zone, as i'm off work at the moment.  And if you have the tests and they come back negative, your'e back to square one!  I know how fed up of all this you are as so am i.  I am going to be referred again to a neurologist to have more tests as they don't know what is wrong but think that something is, ?muscular or ?menieres disease.  I dread more tests and more of the anxious waiting and everything but i will have them and if they are negative then that's that, nothing i can do.  
Now, i have had hundreds of ecg's and a 3 day holter monitor and not once did it show anything.  The cardiologist thinks that i'm having ectopics beats, benign and i will be fine.  But i would just like to catch them on something, see it in black and white so that it can be properly looked at and then they can say, oh yes, i see them, this is what it is and it is fine.  But after a very long time trying, still never caught anything.  I know that is good and it shows that there is nothing wrong but it doesn't feel like there is nothing wrong when they happen, does it?  
Anyway, you have to do what you feel is the best thing to do.  You could have the tests and when they are negative or showing something that is benign and fine then you could say, right, that's that, they show nothing and i'm fine and you will have to accept that fact.  You will eventually have to accept it anyway when every single test comes back ok.  As we all will have too when nothing is wrong physically.  But i know this is hard.  If you follow your gp's advise and say enough is enough and i won't bother then will you always be wondering what if?  If the tests have been asked for by a cardiologist for confirmation then there is no reason why you shouldn't have the tests and then maybe you will be able to put something to rest and concentrate on possibly a different root of the problem, as with me is PTSD and anxiety.x

I agree that the additional tests are really just another attempt at reassurance and are unlikely to tell you anything you don't know. If it were me? I would have them - and then try to say, "That's it". No more tests. I accept I'm fine.

Addison's disease????

Okay, you need to take a breath and slow way down. Your fears and worries are running away with you. Medicine is about one of the most deceptively complex sciences known. Many people wander the internet and intuitively try to match their symptoms to one of many disorders or diseases. If it were somehow this easy, why would it take an average of 12 years to learn the skills associated with the practice of medicine? You are are attempting to employ your own brand of logic into a situation that unavoidably requires formal training and experience. Whether you realize it or not, you are trusting your own intuition over and above the mounting series of diagnostic tests that continuously reveal no presence of physical disease or disorder. At some point, you are going to have to question whether this is a plausible approach.

I'm afraid it's not your cardiologist who is "clutching at straws." To read your statement, you're actually pitting the opinions of the specialists you've gathered to search for a cause you believe to be present.

As for the presence of nystagmus, there is actually a small degree of horizontal nystagmus in perfectly normal people. Any ENT worth his salt would know that. And just what "neurological deficit" did the ENT elucidate that prompted them to return you to neurology?

Your neurologist does not wish to re-evaulate you for a very good reason. His likely professional opinion is that there's nothing physically present that would explain your symptoms and therefore, nothing capable of being provided in the way of treatment.

Again, my suggestion is to explore whether your symptoms are the expression of intense anxiety disorder and seek treatment. Surely your true goal must be to reduce symptoms and experience relief. You can continue to press the medical community to locate a physical cause for your symptoms, but I'm constrained to point out here that I've spent more than 40 years in practice examining people with symptoms quite similar to your own and they also have no underlying physical cause. We're not speaking of something rare or unique here.

This doesn't mean that your crazy or that you have a brain disease or any other extreme. It merely means you are suffering from somatic features of an anxiety disorder, which is very treatable. All you have to do is wrap your head around the growing evidence that nothing physically is wrong with you which would otherwise explain your symptoms. Have you paused to consider that your perceptions are altogether incorrect about your symptoms? The fact that you are escalating your search for a physical cause as the evidence to the contrary continues to grow is a very good indication that you need to reflect upon what is actually taking place.

Best regards and Good Health

Hand eye coordination tests are generalizations that are coupled with a great deal of other examination factors and diagnostic testing. Alone, they do not represent neurological deficit by any means whatsoever.  

Whenever these tests are utilized, I'm constantly having to remind physician residents and medical students that "handedness" plays a major role in the outcome. If you happen to be right-handed, you will perform far better with your dominant right hand than you will with your left and some people are far more affected by handedness than others to the extent that it can dramatically affect their coordination and performance. Surely you've heard of people with "two left feet."

There are actually very specific signs that are evaluated with hand/eye coordination tests that have far more to do with whether you can simply touch your own nose or the examiner's finger as a target or not. The same holds true for proprioceptive testing and general balance/coordination. Practitioners who use these tests without experience of knowing the parameters of what we in neurology consider to be normal, will most often interpret performance and results strictly as either pass or fail.

Incidentally, although I certainly haven't examined you, I would consider your description of your performance to be entirely unremarkable in the absence of other supporting diagnostic criteria, definitely not a "neurological deficit."

Somatic features of anxiety disorder are most often the result of changes to the nervous system, causing muscular tension, altered performance to sensory and organ systems, even changes to the immune system. Unwarranted stimulation produces changes that can either be mild or dramatic in nature. It's very important for you to realize that the state of the nervous system produced by anxiety and panic disorders, commonly described as fight or flight phenomenon, is entirely normal for certain environmental circumstances. People who experience this phenomenon in the proper context do not reflect upon the sensations as abnormal. It is only when the body adopts such a posture for prolonged periods in the absence of warranted environmental circumstances that "symptoms" begin to appear and construed by the affected person as physical in nature. Subsequent fear often accentuates the symptoms and a growing fear that something is dreadfully wrong begins to develop in the mind of the person afflicted, quickly leading to the assumption that the underlying cause is physical in nature.  

So what we're really speaking about here is the perceived circumstances rather than actual circumstances that are capable of producing change to a person's level of anxiety in such cases. This is true to such an extent that most all patients falling under my care often state "but I don't feel anxious" or "If there's nothing physically wrong with me, then why do I feel so sick?" It is a contradiction in the way the circumstances are being perceived by the affected individual by comparison to situations wherein they might feel it warranted based upon previous experience. They are unable to identify the causal factors due to a failure to make the logical connection between the intangible source of their anxiety and its subsequent effects upon the body from a symptomatic standpoint. See how that works?

What I'm trying to communicate to you here is that the brain and nervous system have no checks or balances to determine whether your perceptions are correct or not. In fact, the world around us can often deceive the senses. So If you feel that your preservation or safety in other ways is in imminent danger (even when no actual danger is present), the brain responds to your perception and not the actual circumstances. It invokes the fight or flight phenomenon that causes changes to the body to physically prepare for either combat or escape. Note here that I said physically prepare. Does that make any relevant sense where the appearance of physical symptoms is concerned? Fight or flight is autonomic in nature, meaning that it is engaged without conscious effort. So now what do you think about a system that both reacts to perceptions whether accurate or not and can also be induced in the absence of the conscious mind's will or desire?

The key lies in discovering what perceptions have caused you to believe that your safety is in jeopardy in some way, sufficient enough for your brain to believe the threat actually exists and therefore has responded by inducing the fight or flight phenomenon. Anxiety is produced because you are unable to identify the threat. If you happen to be a person who has a habit of constantly preparing in advance, emotionally or otherwise, imagine how this might affect you if you are unable to make such preparation because you do not know what, when where or how this unknown threat may approach and confront you and yet, you feel it is nevertheless imminent.

You're going to be fine. You simply have a lot of introspection to perform and gain a far better understanding of how the brain responds physically to psychological manifestations. Work closely with your therapist on these issues. They are very adept at helping you to decifer your emotions, perceptions and patterns construed as faulty.

As for brain chemistry, I'm grounded in behavioral neurology so in my world, all psychological phenomenon has its roots in neurochemistry.

Best regards and Good Health