Dr. Dino Terzic got lucky the other day. In his seventh and final year as a neurosurgery resident at the University of Minnesota, the 32-year-old Bosnian got to operate on a rare type of brain aneurysm that required a special approach through the patient's forehead.

As Terzic prepared to slice into the patient's scalp, he was asked if he'd ever seen this type of flaw in an artery, which occurs in just 2 to 3 percent of aneurysm cases.

"On a video," Terzic replied with a chuckle.

Terzic's hands-on experience shows why the nation's medical schools are beset by a nagging controversy over rules that limit the number of hours residents can work. The rules were adopted a decade ago to avoid the sort of fatigue and medication errors that contributed to the death of 18-year-old Libby Zion in New York in 1984. But now, some medical educators say the rules may be undercutting the training of some U.S. doctors by reducing the number of procedures they perform.

"While we're in residency our goal is to do as many cases as possible," Terzic said.

"It has been a very controversial thing from the beginning, particularly among surgical specialties, because it was unclear to us what the impact would be," said Dr. Stephen J. Haines, director of the U's neurosurgery department. "Would it really have a benefit to training? Or would the … decrease in experience of the residents overcome any value of just having a less intense time and sleeping more?"

Haines directed a study, published in August in the Journal of Neurosurgery, which found that regulations barring residents from working more than 80 hours a week made no measurable improvement in major outcomes. He and his colleagues focused on neurosurgery residents because they had among the longest hours before the rules took effect — often more than 120 hours a week — and because they routinely deal with high-risk procedures in which a mistake may kill the patient or cause lasting damage.

"Interestingly, the [duty hour] regulations appear to be associated with an increase in the frequency of postoperative complications and discharge to long-term care facilities," the study says. It's unclear why.

Even so, the accreditation council that oversees physician training in the United States has considered reducing resident duty hours even more, prompting pushback from training departments.

An analysis of 135 studies published in June in the Annals of Surgery concluded that "one-size-fits-all" duty hour restrictions may not fit all specialties. While the restrictions have improved the lives of surgery residents, the authors wrote, their scores on board exams have declined. Worse, the analysts found that limits on duty hours appear to be harming more seriously ill patients, possibly by increasing the number of "handoffs" that take place.

"As soon as you start introducing more people into your care team … you're not only handing off the patient to someone else to care for, you're handing off the responsibility," said Dr. Andrew Grande, a vascular neurosurgeon and assistant professor at the U. "So that drive to really dig down deep and go that extra mile for that patient — I don't think it's the same.''

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The U, like nearly all neurosurgery training programs, accepts just two new interns a year for its grueling, seven-year program.

"They are the hardest-working people in the hospital," said Dr. Matthew Hunt, director of the U's neurosurgery residency program.

Rounds usually begin around 5:30 a.m., after a thorough review of what the interns call "The List." It's a digest of the demographics, conditions, medications, lab results, images and strategies for individual patients.

Second-year residents Coridon Quinn, 36, and David Darrow, 28, spend much of their time updating The List. One recent morning, it covered 20 patients, though Quinn said he's seen as many as 40. It must remain perfectly accurate as the other physicians — and their patients' lives — depend on it.

At the U, first-year residents, known as interns, spend five months on neurosurgery, seven months on neurology, general surgery, trauma and ICU training. They spend much of their time in the clinic, learning to make diagnoses and to interact with patients and their loved ones facing dire health problems.

Interns can work no more than 16 hours straight, while other residents must stop at 24. Those restrictions can be tricky in a field in which some operations last 20 hours or more.

The second year of training is particularly difficult: Residents alternate, one month at a time, working the 12-hour overnight shift alone. Although the shift technically starts at 7 p.m., they often start an hour early, sign out at 8 a.m., and continue working a while longer. They visit patients and field often urgent questions from nurses and physicians. When in doubt, they phone the chief resident for advice.

"The first several months we bug the heck out of him," Quinn said.

The residents also conduct research, prepare and attend presentations on current cases, and attend mandatory weekly, three-hour classes on topics such as neuropathology and neuroradiology.

Darrow said nothing can prepare new residents for the heavy responsibilities and long hours.

"Not even close," he said between gulps of coffee. "You're just running all the time."

Nationally, 10 to 20 percent of neurosurgery residents quit in their first two years.

"You can't really tell if this is your thing until you're into it," Terzic said.

Neurosurgery residents ride an emotional roller coaster. One recent patient, a student close to finishing his degree at the U, had hit his head in a fall and came in with a few spots of blood in his brain. The residents were initially optimistic, but the bleeding and swelling increased rapidly.

"The surgery we do for this is to remove the entire top part of the skull for six months," Darrow said. He said the patient faces a year or more of rehabilitation and may never work in his field of study.

Darrow said although neurologists can keep patients alive despite severe brain damage, "at the end of the day if it doesn't make a difference, you're just prolonging the pain. Then you have to have the discussion with the family — and that's hard."

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Dr. Ciro Vasquez, a sixth-year senior resident, spent more than an hour on a recent day adjusting a surgical table and myriad instruments he would use to remove a "vascular abnormality" from the side of a patient's brain.

"Sixty percent of brain surgery happens before the operation," Vasquez said.

Dr. Cornelius Lam, a neurosurgery professor, supervised the operation and quietly suggested how to cut through the muscle over the bone in one pass to minimize damage.

"Beautiful," Lam said as Ciro worked. "We've got a pretty good resident here."

Once you open the brain, Lam explained, it's easy to get lost. So neurosurgeons rely heavily on live imaging technology to establish landmarks that guide their work. Vasquez and Lam sat side by side, peering into the patient's brain with a dual microscope. Vasquez used tiny, electrified tongs to simultaneously cut and cauterize tissue until he found the damaged clump of blood vessels causing the patient's seizures.

"Buzz, buzz, buzz, go all the way round it," Lam said. "Cut the brain," he said. "Keep going. You're on it!"

In an adjoining operating room, Terzic finished removing a group of blood tumors known as lymphoma from a woman's spine, then took a quick lunch break before launching into a "straightforward case" — the removal of a tumor causing another patient's splitting headaches.

Terzic peeled back the patient's scalp, then carefully cut a window in the frontal bones revealing an egg-sized mass the color of grape jelly. A couple of days later, Terzic was back in the operating room with surgeon Grande to work on a woman with trigeminal neuralgia, a nerve condition so painful it's nicknamed the "suicide disease" because patients sometimes kill themselves seeking relief. This operation would be relatively simple. It involved threading a slender metal probe through a patient's cheek into the base of the skull, then inflating a balloon at its tip to crush the nerve that enervates the face. More than 9 out of 10 patients emerge pain-free, Grande said.

But things can go seriously wrong. The probe must pass by the carotid artery. Pierce it, and you can kill the patient. In one such procedure, Quinn said, blood started spewing out as he withdrew the probe. He feared the worst, but he had just nicked a small branch of the artery.

"I was terrified," Quinn said. He said Haines, an expert in the procedure, told him he needed to get back to work.

"He said, 'Tell me what you're going to do different,' " Quinn recalled. He determined that the way he had draped the patient had concealed some important landmarks. He did two similar cases that day, shaken but better for the experience.

"Now, every time I do that procedure, I see red," Quinn said.

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As Grande, Terzic and Vasquez went to work on the patient with the rare aneurysm, several visitors stopped by to watch the lengthy procedure. Terzic painstakingly cut through the arachnoid, a weblike membrane that holds the brain tissue together.

"Just enjoy it," Grande said. "Before you know it, it just falls open and you're there."

Terzic continued making tiny cuts, probing with his electrified tongs and a suction device, but he couldn't find the aneurysm. The room fell silent as everyone watched his progress on an HDTV monitor. Then Terzic nicked a vessel, filling the cavern with blood. He tried unsuccessfully for a few moments to repair it, and Grande stepped in to seal it up and continue the operation.

The residents watched Grande closely as he cut and prodded his way deeper into the patient's brain.

"There it is!" Terzic called out.

Grande clamped off the aneurysm and returned the patient to Terzic.

"This case went well. Now I've got to got talk to a family about lab tests on a malignant brain tumor in a woman 26 years old," Grande said. "So, the highs and the lows of neurosurgery."

Dan Browning • 612-673-4493