There are two types of partial seizures: simple and complex. Simple means a person retains awareness; complex is when awareness is lost and the person may make movements such as blinking, chewing or hand gestures.
Then – in 2011, behind the wheel of her car on a highway in Alexandria, Louisiana – 26-year-old Hernandez had a “tonic-clonic” seizure which led to a crash. During a tonic-clonic seizure, a person’s muscles stiffen, and they typically lose posture and consciousness, may bite their cheek, turn blue and experience jerking movements of their limbs.
“I could feel it coming on. I tried to pull to the side of the road, but my foot hit the accelerator instead of the brake,” said Hernandez. “I flipped my car three times. I remember waking up in the trauma unit. They told me they had lost me at the scene and in the ambulance.”
Following that near-fatal wreck, Hernandez’s neurologist in Alexandria referred her to Giridhar Kalamangalam, M.D., a neurologist with UT Physicians and associate professor at McGovern Medical School at UTHealth.
“Michelle had what we call refractory focal epilepsy which are seizures starting in a particular part of the brain that were resistant to high doses of multiple drugs,” explained Dr. Kalamangalam. “When seizures are resistant to drugs, several types of treatment need to be considered including brain surgery.”
In Hernandez’s case, the seizures were due to a rare condition called periventricular nodular heterotopia (PVNH), in which gray matter gets “trapped” deep within the brain of a developing embryo.
“Typically, as in Michelle’s case, there is trapped brain on the right and left sides,” said Dr. Kalamangalam. “PVNH patients can be very difficult to treat with brain surgery due to the deep location of the abnormal gray matter, and the fact that the gray matter is not located in one place, but is present in multiple areas. However, we noticed evidence on brain scans and EEG analysis that only one cluster of abnormal gray matter in Michelle’s brain appeared to be active in causing seizures. Though there was some uncertainty, it was possible that surgically removing that one area along with the surrounding seizure-scarred brain might help her.”
Dr. Kalamangalam consulted with his team that makes up the Texas Comprehensive Epilepsy Program at the Mischer Neuroscience Institute. Nitin Tandon, M.D., director of epilepsy surgery and professor of neurosurgery at McGovern Medical School at UTHealth reviewed Hernandez’s case.
“Patients with PVNH represent a particular challenge as the abnormal tissue responsible for generating seizures is located deep in the brain, often surrounded by important brain pathways,” said Dr. Tandon.
“In Michelle’s case, the PVNH was associated with scarring and damage to the medial temporal lobe structures as well. Seizures in her case resulted from a deranged network involving the PVNH, and the rest of the temporal lobe. Crafting a resection strategy that allowed us to target both the abnormal cluster of cells and the scarring in the hippocampus to disrupt the network was critical in trying to stop her seizures,” explained Dr. Tandon.