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[Functional Neurosurgery]
MGH Functional Neurosurgical Service
mGH Neurosurgical Service
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The Functional and Stereotactic Neurosurgery Center provides comprehensive evaluation and care for patients with movement disorders, epilepsy, obsessive-compulsive disorder, and certain chronic pain syndromes. The center works closely with the Partners Parkinson and Movement Disorders Treatment Center, and the MGH Epilepsy Unit.
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Used with pernission:
[MGH News] December 1993
Epilepsy Surgery
Makes 'A Little Miracle'

(Jump to a description of the Images used to create a Road Map for Surgery)

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When the ambulance braked at the doors of the MGH in the early-morning hours of March 13, the medical team on board sighed in relief. Throughout the night, as they raced back to Boston from northern Vermont, they knew that one of the biggest snowstorms in recent years was marching up the coast toward New England.

But while one storm had been beaten, another waited to challenge a team of MGH specialists. The patient who arrived in that ambulance was a five-month-old child whose brain was wracked by the electrical storms of severe, uncontrolled epilepsy.

Little Ian Pelkey appeared perfectly fine when he was born in October 1992. Although he seemed rather fussy at times and rarely slept through the night, generally he was an alert, happy baby.

[Ian] Now freed from almost constant seizures, Ian Pelkey is learning how to walk. The helmet protects his healing brain fron the usual bumps and bruises oftoddler hood.

But when he was about four months old, Ian began to 'space out,' recalled his mother, Lynn Pelkey. 'At first we thought he was just starting to notice things, to focus on them. But then we realized it was more like he was going into a trance.'

The episodes became more frequent and severe. The child's eyes rolled back in his head, his muscles became rigid -- characteristic symptoms of epileptic seizures. By now Ian's parents knew that something was seriously wrong. On the advice of their pediatrician, they took the child to the Medical Center Hospital of Vermont in Burlington, 40 miles from their home in St. Albans.

The MCHV neurologists gave Ian a complete examination and prescribed standard anti-seizure drugs, which initially appeared effective. But the day after the child came home, the seizures returned.

Back in the hospital, Ian's condition became increasingly uncontrollable. Despite large doses of medication, he was soon having literally hundreds of seizures a day -- sometimes without a stop.

'We knew we had to find a hospital better equipped to handle Ian's problem,' Ms. Pelkey said. The Vermont doctors agreed and arranged Ian's transfer to the MGH.

Once Ian had safely arrived, the MGH specialists began a lengthy search for a cause of his seizures. Infantile epilepsy sometimes results from a brain injury occurring either before or during birth. In other instances, seizures are traced to abnormally developed brain tissue. Often no specific cause can be found.

Some seizures appear to involve the entire brain simultaneously, while others -- called focal seizures -- emanate from a specific area. The difference is important, as the generalized seizures respond better to medication.

The MGH team first conducted a 24-hour electroencephalogram (EEG). This measurement of the brain's electrical activity usually takes place over a couple of hours. But in cases like Ian's, specialists make readings over a full day with simultaneous video recording of physical activity. This allows neurologists to correlate overt symptoms with what actually happens in the brain.

Ian's readings showed the numerous, almost constant seizures, but the source of the problem was unclear. 'At first it appeared that the seizures were very broad, rather diffuse throughout his brain,' said MGH neurologist Daniel B. Hoch, MD.

'But there also was evidence suggesting a focus of epileptic activity in the left frontal lobe [the part of the brain right above the eyes]. EEG readings taken in between seizures indicated a possible structural abnormality in the same area.'

Following up this observation, the MGH team ordered a PET (positron emission tomography) scan, an advanced imaging technique -- pioneered at the MGH and other institutions-- that reveals activity within the brain.

'We were fortunate enough to get what's called an ictal PET -- a PET image taken while he was in seizure -- which clearly showed an area of overactivity in the left frontal lobe,' MGH neurosurgeon G. Rees Cosgrove, MD , explained. 'This led us to take another look at the MRI [magnetic resonance imaging] studies, which initially had appeared normal.'

[Dr Cosgrove] Dr. Rees Cosgrove

Close examination of the MRI, which gives a detailed look at the brain's structure, revealed a subtle area of abnormal tissue, also in the left frontal lobe. Additional MRI studies, specially processed to enhance the images, clearly identified the structural flaw.

The largest part of the brain, called the cerebrum, consists of a thin, outer layer of grey matter surrounding internal white matter. The grey matter contains the brain cells involved in thought, movement, and sensation; the white matter contains fibers that carry signals from one part of the brain to another.

Within the suspect portion of Ian's brain was an area of grey matter that was up to five times thicker than it should have been. This kind of abnormality -- called cortical dysplasia -- is known to be associated with epileptic seizures.

Identifying this structural flaw held out the possiblility that surgery to remove the tissue could relieve Ian's symptoms. But because the child was so young and because of the risks associated with any brain surgery, the MGH team first tried different medication-based strategies to control the seizures.

'You always exhaust the medical options before you go to surgery,' said Elizabeth C. Dooling, MD, the MGH pediatric neurologist who oversaw Ian's care.

Initially the drugs reduced Ian's seizures to one or two per day -- enough that he was able to return home for several months. But it was not long before the seizures again became more frequent.

'He just kept getting worse,' Mrs. Pelkey recalled. 'The doctors were trying different drugs, and he was in and out of the hospital up here. We really felt like we were grasping at straws.'

One day before Ian was scheduled to return for a follow-up visit, he was again brought to the MGH by ambulance. 'I knew he wouldn't leave without the surgery,' his mother said.

'Of course my husband and I were scared to death,' she added. 'We knew that removing a portion of his brain had real risks -- paralysis, loss of function -- but we also knew that he wouldn't stand a chance if the surgery was not done.'

In preparing to operate on Ian, Dr. Cosgrove and his colleagues turned to one of the most recent developments in imaging -- computer technology that allows information from different kinds of images to be fused into a single picture.

A sophisticated MRI study provided a detailed three-dimensional image of Ian's brain that could be reproduced from any angle or cross-section. Then that information was combined with data on brain activity from the PET scan. (see images below)

'Fusing these two data sets gives you a representation of both the anatomy and function of the individual patient's brain. And we found that the area of overactivity from the PET scan correlated precisely with the anatomic abnormality from the MRI,' Dr. Cosgrove said.

The picture created from the fused images also showed the pattern of folds and furrows on Ian's brain -- a pattern that is slightly different for each individual. This information helped Dr. Cosgrove map the location of key areas controlling movement, areas to avoid in the operation.

'During the operation, we were able to recognize the features we'd seen in the images,' he added. 'What the computers were showing us was what we actually found during surgery.'

Before removing the abnormal tissue, Dr. Cosgrove placed EEG electrodes directly on the surface of Ian's brain. Even though the child was under anesthesia with no evidence of seizures, the electrodes showed that cells in the abnormal area were firing in an epileptic pattern. The area was then carefully removed using standard neurosurgical techniques.

Since the operation in July, Ian has not had a single seizure and appears to be developing normally. Dr. Dooling noted that the child now wears a special helmet to protect his head as he is learning navigate the world as any toddler does. He also continues to take antiseizure medications. 'After getting those seizures under control, we don't want to take any chances,' she said.

Although the operation removed a significant portion of Ian's brain, his future prospects are quite good. 'This was not normal brain tissue. It really did not have any function except to give rise to seizures,' explained Dr. Cosgrove, who is also an assistant professor of neurosurgery at Harvard Medical School.

He added that in young children the brain is very adaptable. If an area controlling a particular function must be removed, that activity can be taken over by the corresponding area on the opposite side of the brain. 'The younger the child is, the less likely there will be any deficit.'

[Ian & Mom] Lynn Pelkey helps her son Ian celebrate his first birthday.

Andrew J. Cole, MD, chief of the MGH Epilepsy Service, pointed out that Ian's story shows how important it is to search for a potential structural cause of seizures.

'Right now we don't know how many cases of severe childhood epilepsy are associated with a structural abnormality, because doctors haven't always looked for one. In Ian's case, the standard MRI exam didn't allow us to diagnose him. We needed information from the more sophisticated techniques.'

A few weeks after Ian's first birthdayr, his mother reported, 'He's pulling himself up to his feet, trying to walk, and getting into everything. Sometimes I look at him and think, 'What a little miracle!'

Images Create a Road Map for Surgery

[Road Map]

While none of the imaging techniques used to plan Ian Pelkey's surgery were unique to the MGH, his treatment represented one of the first combined uses of these methods in treating a patient.

The two types of imaging used -- MRI and PET -- both have advantages and disadvantages. MRI produces highly detailed images of the structure of bodily organs, but standard MRIs do not reflect how an organ is functioning. PET images show function but cannot pinpoint the activity's exact location.

Combining the great wealth of information produced by both methods required an intricate and powerful computer program, developed in the MGH Radiology Department.

Bradley R. Buchbinder, MD, an MGH neuroradiologist, explained that most previous work integrating structural and functional brain imaging (some of which has been done at the MGH) focused on locating the sites of various activities -- vision, hearing, thought -- in the normal brain. Ian Pelkey's treatment may have been the first in which these techniques were used to create a map to guide an operation.

Neurosurgeon G. Rees Cosgrove, MD, said, 'Most decisions about how you're going to do a procedure should be made before you enter the operating room. This kind of imaging helps the surgeon perform very detailed and individualized preoperative planning. When this gets integrated with other techniques we're using, we hope to be able to do smaller, more precise, and safer operations.'

Dr. Buchbinder adds that the MGH researchers -- including Drs. Cosgrove-- are also investigating the use of such integrated imaging in planning treatment of tumors, abnormal blood vessels, and other problems within the brain.

They also will be comparing the merits of PET to new MRI techniques that can show brain function. 'If we could do all of this with MR, these techniques could have broader application, because only a few institutions are able to conduct PET scans,' said Dr. Buchbinder. 'But we have to investigate that question scientifically.'
[Functional and Stereotactic Neurosurgery]

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