Abnormal VNG Test and Balance Issues

[capot1948]

I woke up the morning of Dec 7th, 2013 not being able to keep my balance which continues 2 1/2yrs later that's why I'm posting this question in the stroke forum. I do not have vertigo nor am I dizzy. I can just be standing talking to my wife and suddenly I take several steps off to the right, backwards or at an angle. In Feb 2014 I had a VNG test administered, and the results were:

Occulomotor testing indicated results within normal limits for saccades and
gaze. Abnormal results were obtained during tracking and optokinetic (not
full visual field, therefore not true OKN). Tracking and optokinetic results
were abnormal at higher frequencies.
Dix-Hallpike positioning testing was negative for torsional nystagmus.
Significant down beating vertical nystagmus was noted in both the right and
left positions.
Positional testing indicated results within normal limits for the sitting and
head left positions. Down beating nystagmus was noted in the following
positions (normal  10 ?/sec)
Unilateral weakness: 15%, in the right ear (normal range < 25%)
Directional preponderance: 11%, to the left (normal range < 25%)
Fixation Index (FI): 46% to 86% (normal range < 60%)
A: Test results indicate abnormal tracking and fixation suppression which
suggests a central lesion. Fixation suppression and tracking mechanisms share
central pathways. Additionally significant down beating vertical nystagmus
was noted in the head hanging position which is also indicative of a central
lesion.

I've been trying for a long time to find out what this 'Central Lesion' is and still can't get a satisfactory answer.  The clinic who did the VNG test originally referred me to the ENT clinic however they said not their problem and I was referred to Neurology. I need to note here that I can't have an MRI done because I have implants in my back for pain and even though they no longer are used all the wiring is still connected to the nerves. An MRI would probably burn me up. I've had two CT scans of my head which according to my neurologist show nothing abnormal because they're just not good enough to pick any problems up according to him.  Besides seen a neurologist and eventually the ENT clinic where it was determined nothing was wrong with my vestibular system, I've also gone to 3 months of therapy on a system called a 'Balance Manager' http://www.natus.com/index.cfm?page=products_1&crid=271&contentid=397#balmaster the system the VA has is made up of the first two on this page. After 3 months of this I only increased my ability to balance by 5% overall. I've also gone through about 5 different medications to see if they'll help the balance issue. None of them worked (I could look in my records to see what they were).  My thoughts are that I had some kind of small stroke or something the night of 6 Dec, 2013 since on the 7th I had such difficulty standing it seemed as if I was drunk. However my VA neurologist will stand there and tell me no way you had a stroke and then throw his arms up and say 'I don't have anything else to try, we've done it all'.

I apologize for the long, meandering question however I wanted to get as much information into this as possible hoping that someone can either give me a definitive answer on this 'central lesion' thing or help me understand what it is.

Chris