BALTIMORE -- Doctors at Johns Hopkins Hospital say for the first time that they are "delighted" with the progress of Siamese twins separated in a pioneering 22-hour operation last month.

The 9-month-old West German boys, Benjamin and Patrick Binder, were born sharing the major veins and blood drainage systems behind their brains. Both have been in critical but stable condition since the operation, and doctors said Friday that their recovery in the last 10 days has been remarkable.

At first, the twins were plagued with infections, digestion problems and trouble with their lungs and hearts. They lost so much weight during the surgery that each needed constant infusions of intravenous nutrients.

"After the surgery, we knew how fragile they were and we knew it would be a tough road," said Dr. Mark Rogers, director of pediatric intensive care at Hopkins. "But even we were surprised by what a monumental struggle it has been."

Rogers said that, while the twins are not in the type of immediate danger they have endured for six weeks, doctors cannot predict whether they can lead normal lives.

"It's really going to be several months before we can get any specific sense of how far they might progress," he said.

Doctors continue to express concern that the twins may show brain damage from the lengthy surgery, during which their oxygen supply was sharply reduced. The twins respond to pain and to their parents, but the status of their muscles and reflexes has not been determined, doctors said.

Benjamin was weaned from a mechanical ventilator last week, and Patrick's is expected to come off in the next week or two.

"They are still sick . . . but more and more they look like healthy little babies," said Dr. Benjamin Carson, director of pediatric neurosurgery at Hopkins. "Ben cries, they both wiggle their arms and legs and they are getting kind of plump."

The boys' hearts, lungs, immune systems and digestive systems have been constant problems. Intensive-care doctors and nurses have responded to daily threats significant enough to kill the children.

Their father, Josef Binder, returned home to Ulm, West Germany, recently because his leave time had expired. Their mother, Theresia, visits the boys daily.

The twins require several more operations, including skull reconstruction. Doctors had intended to cover their brains with a shield of titanium at the end of the original surgery Sept. 5, but swelling forced a postponement.

To separate the twins, a team of more than 70 doctors and nurses drained the blood from both bodies and stopped their heartbeats while new blood vessels were made for each from the one they shared.

Doctors lowered the twins' body temperature to provide more time for the delicate surgery. It is believed to be the first time that twins sharing the same major blood systems have been separated successfully.

Since the operation, doctors at Hopkins have received inquiries from doctors in several countries about performing similar operations.

"We are consulting with everyone who calls," Carson said. "But we are not planning to carry out a similar operation here in the near future. We learned a lot, but it is not something you can carry out every other week."