Brain tumor surgery calls to mind images of a shaved head and large incision. Traditionally, it is a major operation, with removal of a portion of the cranium and post-surgical concerns about cosmetics. But leading-edge procedures at Froedtert & the Medical College of Wisconsin Froedtert Hospital are changing both how skull base surgery is performed and perceived.

“By the mid-1990s, neurosurgeons were thinking there had to be a better way of doing brain surgery to minimize the morbidity, loss of structural integrity and wasting,” said Nathan Zwagerman, MD, neurosurgeon and MCW faculty member.

Advancement came in the form of a minimally invasive, endoscopic approach. “We started with the pituitary, which is done through the nose, and have now expanded to other areas, accessing the body’s natural corridors,” Dr. Zwagerman said.

In addition to the nostrils, Dr. Zwagerman reaches tumors through other access points on the skull: the corners of the eye, the creases of the eyebrow and behind the ear. When he has to create an opening, Dr. Zwagerman performs a craniotomy about the size of a quarter to accommodate the endoscope and surgical instruments.

Quarter-Size Opening, Wide-Angle View

This “keyhole” surgery, named for the small size of its opening, gives surgeons a wide-angle view of the tumor and its margins, as well as the structures around it. “The endoscope provides a much greater visualization of every sub-region, and the camera’s view is precise and broad,” Dr. Zwagerman said. High-definition monitors in upgraded surgical suites at Froedtert Hospital also aid visualization.

Dr. Zwagerman typically uses endonasal instruments, which are designed for long, narrow passageways. At least two instruments will usually be in the opening, and sometimes up to four. “It depends on the approach and what we need to accomplish to reach our goals,” he said.

While many keyhole procedures are designed for tumors outside the brain, Dr. Zwagerman can use a special dilator to reach tumors deep inside the brain. “The whole purpose is to avoid injury to the brain, so patients should not have any side effects in the brain afterward,” he said.

When the surgery is completed, Dr. Zwagerman seals the opening with bone cement. “It fills in that defect and reconstructs what the bone looked like and also reduces the risk of brain fluid leaking, which can lead to infection,” he said.

Seen and Unseen Benefits

Patients benefit from the minimally invasive surgery in ways that are obvious and not so obvious. “In most cases, the patient can go home in two to three days as opposed to seven, the pain is less, infection rates are low because there’s a smaller incision, and the cosmetic results are better,” Dr. Zwagerman said.

Most patients also avoid spending time in the ICU, going directly from surgery and recovery to a regular patient room. “We get people moving around a lot sooner, and they don’t feel like they had a big operation,” Dr. Zwagerman said.

Of the more than 120 different types of brain tumors, it is the tumor’s characteristics that dictate the surgical approach. Dr. Zwagerman listed meningiomas, schwannomas, metastases, pituitary tumors, pineal tumors, and lesions causing trigeminal neuralgia as among the tumors treatable with minimally invasive surgery.

Dr. Zwagerman estimates about half of the patients he sees are good candidates for the endoscopic approach. “A high percentage of the tumors are nonmalignant, and we don’t necessarily need to remove the whole tumor to relieve symptoms,” he said. “A nonmalignancy grows very slowly, and it’s not worth harming blood vessels and nerves or causing stroke or permanent deficits. It’s better to watch it over time.”

Malignant tumors are less amenable to a minimally invasive approach. “They’re a different scenario,” Dr. Zwagerman said. We may not be able to remove the whole tumor and need a bigger operation.” In these cases, he performs a traditional craniotomy.

Regardless of the surgical approach, Dr. Zwagerman gives patients a realistic perspective on what to expect. “I never tell patients that I can cure them,” he said. “All it takes is one bad cell, and I can’t see individual cells. Resection rates for keyhole procedures vs. open surgeries are about the same,” he said.

Like other surgical skills, there is a learning curve to minimally invasive brain surgery. Dr. Zwagerman dedicated a two-year fellowship to becoming more proficient and now teaches residents. In addition, he is helping to advance keyhole techniques and has pioneered the transorbital approach.

“The biggest challenge is working in a tight space,” he said. “It takes time to understand how to organize instruments around the opening and the ergonomics of performing surgery without injuring other tissues. I can see in two dimensions but have to rely on feel for depth perception.”

Putting Minds at Ease

Hearing that they are eligible for the minimally invasive approach understandably eases patients’ minds. “Everyone has seen someone who has had a surgery with big incisions,” Dr. Zwagerman said. “When I tell patients I can do this through a small incision or no incision at all, they usually react very favorably.”

Keyhole surgery may also aid healing because patients see no visible signs, which improves their attitude. “When they look in the mirror, they can scarcely believe they’ve had brain surgery,” he said.

Dr. Zwagerman coordinates closely with referring physicians to expedite their patients and report back to them. “We work very hard to get patients in to see us within five business days,” he said. “My number one goal is to take care of patients and send them back to their doctor better than when they came in.”

When patients who have had minimally invasive brain surgery do return to their doctors, it is likely an eye-opener for the physicians as well. “They’re surprised how they look —they can’t tell they’ve had surgery at all,” Dr. Zwagerman said.

For Our Referring Physicians:

Academic Advantage of Minimally Invasive Brain Surgery

The Froedtert & MCW health network gives patients and their referring physicians a distinct advantage.

Contact our physician liaison team for more information about our brain tumor treatments or if you would be interested in meeting with any of the Brain and Spine Tumor Program team members.


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