DO NOT listen to this "dr logan". The website that he is stating is just a generic drug sales site. I did report his comment.
I'm not a neurologist, but am an early Medical student. Just had a read of your post and I'm learning about neuroanatomy at the moment. Using my minimal knowledge...
The postural hypotension could be due to an enormous range of things, but, as you say an enlarged pituitary. Among other hormones, the posterior part of the pituitary produces ADH (Anti Diuretic hormone), which serves to retain body water and maintain the volume in the blood (i.e. keep blood pressure up). Innervation of posterior pituitary may be comprimised.
Tingling/Numbness in face - Trying to relate this to the constant headache in the back of the skull - the corticobulbar fibers (involved in facial innervation, jaw movements and swallowing) - runs through the superior cerebral peduncles, which exist on the anterior side of the mid-brain of the brain stem.
Ask your neurologist to look at the neuroanatomy surrounding the cerebral peduncles and innervations of the posterior pituitary. They're all generally on the anterior (front) side of the brainstem.
Oh, a blood test looking at oxytocin levels (also produced by posterior pituitary). If they're reduced, then possible clue that posterior pituitary is not functioning right.
Pituitary lesions...something to bug your neurologist about...especially the description of Empty sella syndrome.
Thank you for your comment. We just left another pediatric Endocrynologist and he said the same as the others: If hormones are okay then she does not have an endo problem. Her ACTH level is very high, but he said that because she is VERY slim this could not be the problem. (She has a barbie doll figure). He is sending her to another pediatric Neurologists. I am just about to give up. No one will look at the whole issue. Each doctor deals with only the symptoms that may be related to their field. Thanks for the input. I will try to get the info to her new Neuro when she sees her in July.