I have posted a number of times under Spine Health as I was diagnosed almost 2 years ago with NMOSD (neuromyelitis optica spectrum disorder). I am not sure this is the correct group to post, but the symptoms of this disease often mimic those of MS and makes it difficult to accurately diagnose. Here is my question: Is there a test for MS? According to several neurologists, you can be tested for NMOSD with a blood test called AQP4-lgG+ that looks for antibodies called AQP4. If these antibodies are found in your blood, it will confirm that you have NMOSP and not MS. If the test comes back negative, you are quite likely to have MS. Any validity to this? I have had numerous blood tests over the last 4 years since my symptoms began to appear: numbness in lower extremities, balance and walking problems, foot drop on my right foot, muscle and joint stiffness, spasms in legs, etc. I do not recall having this specific blood test nor do I recall my neurologists ever telling me my diagnosis of NMOSD resulted from this test. How do I know if my current diagnosis is truly NMOSD and not MS? I am 73 years old and currently in my third go round with infusions of Rituxen, with no decrease in symptoms, only worsening of above symptoms to date.