I have small fiber neuropathy. i had an isolated positive ana titer of 1:160 with a homogenous pattern. lupus, rheumatoid arthritis and sjogrens were negative. is it still possible i have an autoimmune disease causing small fiber neuropathy?

Assuming you have well documented Small Fiber Neuropathy, confirmed on skin punch biopsy, there is a standard blood and urine testing protocol to uncover causation. It is best that you work with an experienced neurologist at a nearby medical school to achieve thorough and successful management. The most common cause in the USA is diabetes or pre-diabetes, but other causes may be considered.