Guided Laser Surgery Offers Novel Treatment for Epilepsy

Magnetic resonance imaging (MRI) thermal imaging is being used to guide stereotactic lasers in real-time, destroying lesions in the brain that cause epilepsy and uncontrollable seizures.

Developed by researchers at Texas Children's Hospital (Houston, USA), the new surgical approach offers a significantly less invasive alternative to craniotomy, which is currently the most commonly used surgical treatment for epilepsy. For high-risk patients with deep brain lesions, the new technique can be particularly life changing, since a MRI-guided laser probe utilizes a much smaller pathway through the brain to reach the lesion; this reduces the risk of patient complications related to contact with surrounding brain tissue. In addition, the MRI-guided laser probe is inserted through a hole in the skull that is only 3.2 mm in diameter, compared to the removal of a larger area of skull bone for a craniotomy; and since it is a less invasive procedure, recovery time is shorter.

The optical system is based on a continuous-wave 980-nm diode laser delivered through a fiber-optic with a one-cm diffusing tip. The fiber is housed within a coaxial cooling catheter circulating room-temperature saline to cool the applicator, with the whole procedure taking place within a conventional 1.5 Tesla MRI scanner to provide real-time thermal imaging. The MRI confirms probe placement in the target, and also allows the surgeon to see the ablation of the lesion by the laser heat as it actually happens, with an automatic feedback system that shuts the laser off when the heat approaches nearby critical brain structures.

“The main use of the MRI guidance is to actually be able to observe the target lesion before the ablation is made, and the position of the laser catheter tip can be exactly imaged by heating up it up by just a couple of degrees,” said Angus Wilfong, MD, director of Texas Children's comprehensive epilepsy program. “This confirms the position [of the catheter tip] before continuing on with the ablation. We can also place safety markers on the MRI image to protect sensitive structures from reaching a predefined temperature to avoid damage.”

Five surgeries using the MRI-guided laser probe procedure have been successfully performed at the Texas Children's Hospital on pediatric epilepsy patients ranging in age from 5 to 15 years old, with widely varied types of brain lesions. In all cases, patients have been seizure-free since surgery and most were released within one to five days.

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