Doctors at Houston's TIRR Memorial Hermann said Thursday that congresswomen Gabrielle Giffords is recovering well after surgery to replace a part of her skull.

Arizona doctors removed a portion of her skull in January to deal with brain swelling after Giffords was shot in the head at point blank range at a public appearance in Tucson. The three-and-a-half hour surgery in Houston on Wednesday included both a cranioplasty, in which a synthetic hydroxyapatite ceramic implant was installed to replace the skull bone, and a shunt being placed in her brain to regulate and remove excess brain fluid.

Dr. Dong Kim, the director of the Mischer Neuroscience Institute at Memorial Hermann Hospital, said the surgery was an important step in Gifford's recovery, one which she had welcomed.

"Nobody is excited to go into surgery, but on Tuesday she was happy this step had come," Kim said. Giffords' chief of staff Pia Carusone said that the congresswoman is happy to finally get rid of the helmet she had been wearing to protect her brain during all activities, including rehab work and during her travel.

The surgery is expected to help Giffords' in her continuing rehabilitation, according to Dr. Gerard Francisco, chief medical officer at TIRR Memorial Hermann.

"After today or tomorrow we will continue and potentially upgrade the rehabilitation program," Dr. Francisco said. "Many patients do even better after surgery. The fluid has been pressing on parts of the brain, so there's more chance to heal with the shunt in place."

The shunt is a permanent tube that removes fluid from the brain cavity to outside the skull, then down the body under the skin to the abdomen, where it's absorbed. Dr. Kim says it is self-regulating, in the event that the brain begins to process the excess fluid on its own, and can be adjusted or turned off by doctors without additional surgery and is not noticeable to the patient or others.

That the surgery comes while Giffords' husband, Mark Kelly, is leading the current space shuttle mission was unplanned, according to doctors. Dr. Kim said the medical team had discussed the surgery with Kelly, and that all parties agreed that the schedule for her care would be performed at the optimal time, not based around the shuttle schedule.

In the long term, doctors were still unable to estimate when Giffords would move from in-patient to out-patient care or return to work, but they stressed that her recovery since January has been "almost miraculous."

"She's recovering very nicely, and her neurological condition has improved significantly," Dr. Francisco said. "Conversation is more interesting and in depth, and she has cracked me up a few times. She tells jokes and engages in social conversation."