Do neurologists follow checklists when diagnosing symptoms? Will this case change their procedures going forward?
Often times there are symptoms overlap. A patient may not display or disclose the symptoms that makes it stand out from the others.
Many diseases are diagnosed by physical examination only as lab results can't pinpoint many diseases. This makes it difficult as the doctors you are seeing may not have any/enough experience with the disease to properly diagnose.
In my case it took over six years to get a correct diagnosis and treatment. My doctor is quite humble which served me well as other doctors might have misdiagnosed and treated me incorrectly. In my case the doctor said to me after several months of testing and examinations, "There is clearly something serious wrong with you, but I'm not smart enough to figure out what." After that he became more of a puppet master sending me to different specialists until finally, after 6 years I found one who was familiar with my illness.
It is extremely rare and occurs in only about 1 in 1 million people.
https://en.m.wikipedia.org/wiki/Stiff_person_syndrome
For this particular illness, 6 years is the average amount of time it takes to diagnose. Just to help put it in perspective.