Mayor Bob O'Connor, who was downgraded to serious condition on Monday, continued treatment for seizure activity and infection in the intensive care unit yesterday.

According to a hospital spokeswoman, his medical team at UPMC Shadyside will no longer be issuing daily updates about his condition or ongoing treatment for his rare cancer, called primary central nervous system T-cell lymphoma.

The doctors would not elaborate as to the scope of the seizures, status of the infection or extent of the symptoms that led to Mr. O'Connor's downturn.

Yesterday morning, he was expected to have another electroencephalogram, or EEG, and repeat spinal fluid testing. Hospital spokeswoman Clare Collins said the team was trying to determine both the type and cause of his infection, and that doctors also were working to assess whether his brain was continuing to experience seizure activity.

But "we don't at this time have anything further to add," she said later in the day.

On Monday, the mayor's medical team performed a 30-minute procedure to put in a new, antibiotic-coated drain to replace one that had been inserted three weeks ago. The device removes excess fluid bathing the brain and spinal cord.

Earlier that day, doctors downgraded his condition to serious and said that tests indicated that infection may have involved his brain and spinal fluid. His EEG exams showed seizure activity.

The infection and seizures have added more bumps to an already rocky road, according to outside experts who have no direct knowledge of the mayor's case or treatment.

About two weeks ago, his doctors shifted from chemotherapy, which was not working, to focused radiation, called intensity-modulated radiation therapy, or IMRT. Those treatments are now on hold.

The mayor should respond to radiation therapy if his latest problems with infection and seizures are brought under control, "but it sounds touch and go," said Dr. Jeff Bradley, a radiation oncologist and associate professor at the Alvin J. Siteman Cancer Center at Washington University in St. Louis.

"It's not looking particularly good," said Dr. Virginia Stark-Vance, a neuro-oncologist in the Dallas-Fort Worth area who has treated and researched central nervous system lymphoma. "Any time you have to deviate from the treatment plan because of infection, that throws a wrench into things."

"We all have patients who, when things are looking grim, are able to turn around," said Dr. Paul Zeltzer, a professor of neurosurgery at the University of California, Los Angeles and author of the book "Brain Tumors: Leaving the Garden of Eden."

The mayor could turn the corner as well, he said, "but it sounds like he's in a tough situation."

First Published: August 30, 2006, 4:00 a.m.