Stereotactic Laser Ablation for Brain Tumors
Seth F. Oliveria, M.D., Ph.D.
Medical Director, Functional Neurosurgery, Providence Brain and Spine Institute
Stereotactic laser ablation, also known as laser interstitial thermal therapy (LITT), is a minimally-invasive neurosurgical technique that expands treatment options for patients with brain tumors. Fiber optic laser probes are precisely implanted in the brain to ablate tumors using heat generated by high intensity light at the tip of the laser fiber. Heat-sensitive, real-time MRI thermography is used for guidance during the procedure to monitor damage to the tumor, while protecting nearby brain tissue. Brain tumors can be treated with LITT via a 3 mm skull opening and similarly sized skin incision. This eliminates the need for a traditional open craniotomy. Most patients are observed overnight and discharged the next morning after the procedure with minimal discomfort. At Providence St. Vincent Medical Center, we use state of the art stereotaxy—typically including dual intraoperative CT and MR imaging performed in the same operating room without moving the patient—to maximize the safety and efficacy of the procedure.
LITT has several applications in surgical neuro-oncology. First, this technique is particularly useful for deeply located tumors where open resection carries high risk to surrounding brain structures, or as a second stage after open surgical debulking to reach residual tumor that could not be removed safely via an open approach. Second, it can be combined with stereotactic biopsy to diagnose and provide focal control at the earliest sign of recurrence for malignant brain tumors including glioblastoma. For malignant tumors, LITT is performed palliatively but has similar cytoreductive benefit to open re-resection with more rapid recovery and reduced surgical risk. Finally, LITT can also be used for patients with metastatic brain tumors that grow after radiation therapy and/or develop treatment-related radiation necrosis. In this clinical situation, LITT can help to reduce steroid-dependence for patients with persistent cerebral edema. Also, interruption of systemic chemotherapy treatment is greatly reduced compared to open craniotomy, since wound healing complications are much less of a concern.
LITT is generally limited to small tumors with relatively simple geometry: the laser probes create a sphere of tissue ablation with a maximal diameter of 2 cm. By retracting the catheters, cylindrical ablations can be achieved and multiple stereotactic trajectories can be combined to create complex shapes within the confines of the surrounding brain anatomy. Additionally, since the ablation is performed within the strong magnetic field of an MRI scanner, neither standard intraoperative neuromonitoring nor awake neurologic testing can be readily performed to monitor eloquent brain function during the procedure. Despite these limitations, LITT is a promising innovation that not only improves surgical safety, efficacy and comfort, but also represents a new approach to treat tumors that were previously considered surgically inaccessible.
Photo credit: Medtronic Visualase
