Preparing for Surgery and Making it More Accurate
Most brain and spinal cord tumors, regardless of type, will require surgery. Surgery may be a stand-alone treatment, but often for best results, it may be part of a combined treatment, including radiation therapy or drug therapy, depending on your individual tumor.
To treat each tumor effectively, specific diagnosis and grading are of the utmost importance. Depending on the biology and genetics of the tumor, patients may be advised to have radiation and/or chemotherapy before surgery. Determining the need for neoadjuvant (before surgery) treatment involves careful treatment planning. There are parts of the tumor that may not be amenable to surgery, so a combined approach is needed. Advance planning helps surgeons determine ahead of time: if they remove a tumor in a certain way, the patient might be eligible for a vaccine trial.
When surgery is required, advanced brain mapping allows extremely precise surgery to excise a tumor without damaging adjacent sensitive structures for the best long-term outcomes. There is enough variation in functional anatomy for speech and motor sites among different individuals that precisely delineating their locations requires careful mapping using electrophysiological techniques.
For many years, neurosurgeons have done that using a time-intensive approach called functional magnetic resonance imaging (fMRI). Patients perform several simple tasks—saying their name or moving an arm, for example—while their brain is repeatedly scanned. Surgeons look for areas of increased blood flow during tasks to pinpoint the brain regions involved. Some patients were not able to cooperate to the extent needed because of the length and distraction of the prolonged procedure. Now, Washington University neurosurgeons have shown that the same information can be gathered faster and at less cost by looking at the brain at rest. They now use resting-state fMRI to map a patient’s brain prior to surgery to precisely map all an individual patient’s critical brain networks for speech, motor control and others. The surgeon gets all the information he needs in one 15-minute session, during which the patients just lies in the scanner and rests.
With the data from the genetic tumor map and the functional MRI, the surgery can commence. However, as tumor is removed and cerebrospinal fluid drained, the map becomes inaccurate for tumor margins. That’s where real-time intraoperative MRI (iMRI) comes in to give the surgeons the updated information to complete the surgery accurately. They have done well over 1000 iMRI cases, a significant portion of which are gliomas, pituitary skull base tumors, and spinal tumors, including metastases from lung and breast cancers. After most of the tumor is removed and before surgery is completed, surgeons can use a special MRI machine adjacent to the surgical suite to give them the information they need to avoid healthy tissue and remove the remainder of the diseased portions of the brain.
Innovative Types of Surgery
Combining this advanced technology and surgical expertise accumulated by seasoned neurosurgeons in a coordinated, multidisciplinary approach to treatment gives the greatest benefit to our patients. The specialized expertise of physicians representing the fields of neurosurgery, neurology, medical oncology, radiation oncology, neuropathology, neuroradiology, nuclear medicine, otolaryngology, ophthalmology and plastic surgery are available to consult on individual cases. Open surgery with robotic assist may be called for. Most skull-based surgery uses a more minimally invasive approach, like MRI-Guided laser interstitial therapy, Gamma Knife or endonasal endoscopy to get to inaccessible tumors.
MRI-Guided Laser Interstitial Therapy
Washington University neurosurgeons are among the first in the nation to use an MRI-guided, high-intensity laser probe designed especially for the treatment of inoperable brain tumors in hard-to-reach areas.
The MRI-guided laser is used to “cook” cancer cells deep within the brain while leaving surrounding brain tissue undamaged. Patients who are candidates for this procedure have only a small hole the diameter of a pencil drilled through their skull, instead of a larger skull flap that is replaced after surgery. Using real-time MR imaging, the neurosurgeon guides the probe through the brain and into the tumor, avoiding sensitive brain structures along the way. Once inside the tumor, the laser discharges highly focused heat to coagulate and kill cancer cells.
An added benefit of this therapy is that heat-treating the tumor opens the blood-brain barrier that normally keeps chemotherapy from reach brain cancer cells. During a window of time after the treatment, novel chemotherapies can be used systemically to kill remaining cancer cells.
Types of brain tumors that can be treated this way include: gliomas, anaplastic astrocytomas, glioblastoma multiforme, metastatic cancers from other regions of the body, pituitary tumors, some radiation-resistant tumors, and radiation necrosis due to prior radiation therapy.
MRI studies of the tumor after treatment show evidence of tumor death immediately after the surgery. The patient’s recovery usually takes several days but is generally much quicker than with open surgery.
Although Gamma Knife is a form of radiation, it is considered a surgical intervention because it can replace surgery. Some patients could have either, so the treatment is based on lifestyle and impact to the patient’s life. Learn more about Gamma Knife in the radiation therapy section.
Minimally Invasive Endoscopy:
Many diseases of the skull base can now be treated with endoscopic endonasal skull-base surgery. Traditionally, the surgical approach for these diseases was through facial incisions or through an opening of the scalp and then removal of a piece of the skull. In endoscopic endonasal skull-base surgery, however, the surgical team advances an endoscope through the nasal cavity to view the anatomy and perform the surgery. The approach eliminates the need to make incisions in the scalp and/or face. Endoscopic endonasal surgery can be done for the treatment of: pituitary tumors, chordomas, chondrosarcomas, craniopharyngiomas, cysts, meningiomas and other types of skull base brain tumors.
The surgeon can also access tumors through small incisions behind or in front of the ear as an alternative minimally invasive approach.