] Neurosurgeons separating 29-year-old Iranian sisters
] joined at the head cut through brain tissue millimeter by
] millimeter Tuesday after rerouting a thick, shared vein
] and stitching in a new one.
]
] The team of doctors also contended with unstable pressure
] levels inside the twins' fused skulls as they began
] uncoupling the sisters' brains, a hospital official said.
] The risky, marathon procedure which could kill both women
] began about 10 p.m. EDT Saturday and could take four
] days.

ABCNEWS.com : Surgeons Work to Separate Conjoined Twins