Lori Dreher said doctors had tried “everything” to control her daughter Andi’s severe epilepsy — a laundry list of medications, a special diet and a couple of attempted surgical interventions. But none halted the seizures that have left the nine-year-old unable to walk unaided and have stolen her ability to speak more than a few words at a time.
“She essentially can’t be left alone,” Dreher said of the youngest of her four children, who can suffer up to 150 seizures a day. “She can’t walk from A to B even if it’s two feet in front of you because she’ll have one and she’ll fall to the ground.”
With no standard options left for treating Andi, doctors at Toronto’s Hospital for Sick Children decided to take a bolder approach, suggesting to her family that she undergo a procedure known as deep brain stimulation, or DBS.
The intervention is increasingly being used in adults to treat movement disorders like Parkinson’s disease, as well as epilepsy and chronic pain. But only about 40 children worldwide have had DBS — and this would be the first pediatric case in Canada.
“This can be thought of as a pacemaker for the brain,” said Sick Kids neurosurgeon Dr. George Ibrahim, explaining that DBS involves burying electrodes deep in the brain, which then transmit electrical pulses aimed at stopping seizures, controlled by a battery-operated device implanted in the chest.
So on Oct. 1, Ibrahim and a neurosurgical team performed the delicate six-hour operation, drilling nickel-sized channels through Andi’s skull on both sides of her head, then carefully inserting four electrodes in the thalamus in each hemisphere of her brain. Wires from the electrodes were then fed down through her neck and into her chest, where they were attached to the device that triggers the electrical impulses.
“The electrical stimulation can alter the brain circuitry. Some brain activity can be dialled up or it can be dialled down,” he said, calling deep-brain stimulation a much-needed potential option for the one-third of children with treatment-resistant epilepsy.
“The true effects of the DBS can only be known once the device has been turned on for several months. However, when we turned it on as a test during surgery, it completely silenced the electrical activity that’s causing Andi’s seizures, which is what we were hoping to target.”
Andi’s case was particularly tricky because of the physiology of her brain.
While in her mother’s womb, Andi had a mass in her brain detected on ultrasound that subsequently disappeared during the course of the pregnancy. But her daughter at some point also developed a venous anomaly in her left cerebral hemisphere, a tangled clump of veins that made the DBS surgery potentially dangerous. Next to this cluster of blood vessels was an extensive region that spontaneously generated seizures.
But because her epilepsy had been occurring for a long time — she had her first seizures at age three — different parts of her brain in both hemispheres began to independently produce the electrical malfunctions.
“So her epilepsy was actually quite complex,” said Ibrahim, stressing that the operation’s success rested on the surgical team precisely mapping out a pathway through Andi’s brain to implant the electrodes without damaging key neurological structures.
“The electrodes need to be implanted with sub-millimetre accuracy,” he said, a feat achieved with the use of sophisticated brain imaging scans and other tests. “So even before Andi (came) into the operating room, our team had spent hours and hours carefully planning the safest way to approach the area.”
A few days after the surgery, Andi was sent home to Kitchener, Ont., and given time to recover. On Nov. 15, the DBS device was switched on and Dreher has since been testing different combinations of electrical pulses within set parameters she was taught by Andi’s doctors — a process of fine-tuning aimed at determining which will work best for diminishing her seizures.
Still, Dreher said the process involves some trial and error. One of the combinations of electrical impulses she tested left Andi “not good, like a zombie, with Jell-O legs.”
“It’s tough,” she admitted. “She’s still having some of her seizures and still frequently, but we can see that she’s alert at least and able to maybe say four or five words in a sentence.”
But the family wants so much more for Andi, who was able to keep up in school, be independent and even played soccer up until about two years ago, when her seizures dramatically worsened.
They’re pinning their hopes on DBS.
“You want the girl to be able to walk from A to B without someone holding her hand,” said Dreher. “You just want her to be able to get her personality back. She used to be a sassy, fun little girl.
“And if this can do what they think, ideally it will control the seizures,” she said. “I would love just to see her talking and walking on her own again. We’re hoping DBS can give Andi somewhat of a normal life.”
That’s Ibrahim’s hope as well, though he said it’s too early to predict to what extent Andi will be helped by DBS.
“My hope is that over the coming weeks with optimization of the parameters we’ll see that her seizure frequency is decreasing and she will be able to engage in the activities that children should be engaging in.”