Remember last week's story about the brain surgeon who was AWOL from North Shore University Hospital when he was supposed to be operating on a prepped, anesthetized patient? It gets worse. At least four families are suing Dr. Paolo Bolognese (pictured) and his colleague Thomas Milhorat, who has just stepped down as chairman of the department and, at age 73, will no longer be operating. The plaintiffs in one case are the parents of a five-year-old girl with Chiari malformation, a rare defect where the lower part of the brain descends into the spinal canal, as well as 'tethered cord syndrome." Their lawyers argue that Dr. Bolognese's $100,000 operation to treat the tethered cord "was unnecessary and experimental," and that the girl "was being used as a human research subject." They say she didn't even have tethered cord to begin with, and that the surgery made her problems incredibly worse. Her grandfather tells the Daily News, "These doctors must be stopped. I have cried a thousand tears over her. They must be shut down." A hospital attorney insists that the two surgeons are "expert in this area, and when all the facts come forth, they will be vindicated."