NBC reports that Karanam was surprised to learn of the "teratoma" -- her embryonic twin, a rarity in modern medicine, complete with bone, hair and teeth after surgery.
Her twin wasn't a good companion - causing all sorts of problems for the Indiana woman.
"Problems with reading comprehension, listening comprehension. If a couple people were talking in a room, I wouldn't understand what was happening," Karanam said.
Dr. Hrayr Shahinian at the Skullbase Institute in Los Angeles performed the surgery that removed the twin - using fibre optics to guide an endoscope though a half-inch incision into the brain to reach in to slowly, delicately chisel away at the tumour.
"Unlike traditional brain surgery where you open the skull and use metal retractors and you bring a microscope to see in the depths of the brain, what we're doing is keyhole surgery," he said.