Infant Refusing To eat

My niece is 18 months old, 17 pounds, and has always refused to eat. She nurses, but always for a very short time.  (Her siblings and cousins nursed successfully, so don't blame that like one doctor did.) Nursing is what kept her alive this long.

Her upper GI, blood work, tests, all show normal.  She HAD a feeding tube for apx. 6 months, gained a little weight.  The tube came out--  tried a drastic move -- if she gets no nutrition maybe she'll eat.  She didn't.  But developmentally, after the tube was removed, she began moving more, turning her head, (The tape from the tube caused rashes and sores on her cheeks- she hesitated to move her head.)
After losing almost a pound, she is now on a feeding tube directly to her stomach.
The doctors rule out anything physical so far, her mother is very level headed, with 5 other great children,(so don't waste time there) so now we continue to search mental health.
Do you have any other cases or help?
(other than Failure to Thrive  from neglect or abuse -- since that does not apply here)

[HVM M.D. - EV]

Dear Ms. Holmes,
   I'm sorry your niece is having such difficulty with weight gain and feeding.  It is really hard to try and offer further advice.  But I do wonder if she has been seen by a Pediatric Gastroenterologist - and/or even been evaluated by a special "Feeding Team" - to see if something might be found to help her.  If not - I would encourage having her seen by these specialists.
She cerainly needs her calories for growth and development - so I would encourage use of the feeding tube until she is able to support herself with oral feedings.  Also - is her failure to grow a result of not enough calories and/or poor absorption?  Again - a Pediatric Gastroenterologist might be able to help assess the answers.   Good luck - Dr. EV.