Did Mary Lincoln Suffer from Pernicious Anemia?

[RJNorton]

I have read about many of her symptoms, but Mary having the Lhermitte symptom was a totally new one to me. I had never heard of it before. I looked it up in Wikipedia, and there it says, "Lhermitte's phenomenon or the Lhermitte phenomenon, sometimes called the barber chair phenomenon, is an electrical sensation that runs down the back and into the limbs. The sensation can feel like it goes up or down the spine. It is generally considered uncomfortable. In many patients, it is elicited by bending the head forward. It can also be evoked when a practitioner pounds on the posterior cervical spine while the neck is flexed; this is caused by involvement of the posterior columns."