To most parents, a child’s laughter is music to their ears, but when 8-year-old Keagan Dysart laughed, it meant he was having a gelastic seizure — a rare convulsion that caused him to laugh uncontrollably two to three times an hour. But now, thanks to a real-time MRI-guided imaging and laser technology that corrects epilepsy-causing lesions in the brain, Keagan’s parents have finally heard his “real” laugh. Keagan’s case, which also included tonic seizures with generalized body stiffness and loss of awareness that would cause him to fall asleep for sometimes up to an hour afterward, was considered high risk because the lesion was in the hypothalamus, near the brain stem. In this highly sensitive region, there are myriad potential serious complications from surgery, including loss of sight, damage to the pituitary gland, stroke from artery damage or development of diabetes insipidus, a potentially fatal condition where the kidneys cannot conserve water because of disruption to the area of the brain that releases the body’s antidiuretic hormone. Keagan Dysart. (Images: Texas Children’s Hospital) The location, size and complexity of Keagan’s brain lesion made him an ideal candidate for the new surgical procedure, which was performed at Texas Children’s Hospital in March 2011 without any surgical complications. He is now living a normal, seizure-free life. “Knowing the complexity of Keagan’s case, the decision to go forward with this surgery was the toughest decision and the best decision we ever made,” said Khris Dysart, Keagan’s father. The surgical approach offers a safer and significantly less invasive alternative to craniotomy, currently the most commonly used cranial surgical treatment for epilepsy. For high-risk patients with deep brain lesions, this new technique is particularly significant because the MRI-guided laser probe uses a much smaller pathway through the brain to reach a deep lesion. This reduces the risk of patient complications related to contact with surrounding brain tissue. Instead of removing a larger area of skull bone for a craniotomy, the surgeon inserts a probe through a hole in the skull that is only 3.2 mm. Because it is a less invasive procedure, patient recovery time is much shorter. An artist’s rendition of the craniotomy technique. “We believe the use of MRI-guided laser surgery will change the face of epilepsy treatment and provide a life-changing option for many epilepsy surgery candidates — both children and adults,” said Dr. Angus Wilfong, director of Texas Children’s comprehensive epilepsy program and associate professor of pediatrics and neurology at Baylor College of Medicine. The surgery is performed by first mapping the area of the brain where the lesion is located using MRI. The catheter is inserted through the skull in the operating room, and then the patient is transferred to an MRI unit, where the ablation of the lesion is performed. The MRI confirms probe placement in the target, and the magnetic resonance thermal imaging allows the surgeon to see the ablation of the lesion by the laser heat as it happens with an automatic feedback system that shuts the laser off when the heat approaches nearby critical brain structures. An artist’s rendition of the new laser ablation technique. Five surgeries using this MRI-guided laser procedure have been successfully performed at Texas Children’s Hospital on pediatric epilepsy patients ranging in age from 5 to 15, 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. The reduced risk and invasiveness of the procedure could encourage more epilepsy patients to see surgery as a viable option, said Dr. Daniel Curry, Texas Children’s director of pediatric surgical epilepsy and functional neurosurgery, who worked alongside Wilfong. For more information, visit: www.texaschildrens.org