I had a MRI done where they found demyelinating disease and thinks that it's multiple sclerosis I have several of the symptoms for MS I have to get a spinal tap done.What other diseases is associated with demyelinating disease besides MS?
Besides MS, there are several other demyelinating diseases, such as the leukodystrophies (Adrenoleukodystrophy, Canavan Disease, Krabbe Disease, Pelizaeus-Merzbacher Disease, Cockayne Syndrome, and Alexander's Disease), Marchiafava-Bignami Disease, Central pontine myelinolysis, and Progressive Multifocal Leukoencephalopathy (PML). Among other things, the spinal tap will help to rule out some of the other demyelinating diseases. Some of these are fairly unlikely (for example, Adrenoleukodystrophy occurs when more than 90% of the adrenal cortex is destroyed, and is a very rare condition, so you'd likely have far more symptoms without a functioning adrenal cortex).
The "white spots" visible on an MRI are generally pretty specific for MS; in other words, for certain white spot patterns, only MS produces such patterns on an MRI. That, along with the other tests (blood tests and lumbar puncture) can rule out the other causes of white spots on an MRI.
The referenced site has loads of (mostly medical) information about all of these diseases, but it may be helpful to you. You can look up each disease individually and find some information on them.