Hemispherotomy may be offered to children with refractory seizures arising from one hemisphere of the brain, particularly if there is already a suggestion of impaired function of that hemisphere (such as weakness of the opposite side of the body).
In some instances, hemispherotomy may be offered to treat life-threatening seizures, such as status epilepticus, or those causing significant ongoing neurological damage, even if the opposite side is not entirely normal.
The Epilepsy Managment Team at St. Louis Children’s Hospital has extensive experience with hemispherotomy. In fact, our experience has been highlighted at several national and international meetings and medical journal publications (see below). We have performed over 50 hemispherotomies, and almost 90% of patients experience complete or near-complete resolution of their seizures.
In technical terms, our current operative technique for hemispherotomy is described as a modified “peri-insular hemispherotomy”. The steps of the procedure are as follows:
- A small question-mark-shaped incision is made above the ear on the affected side.
- A window of bone is removed which will provide access for the remainder of the operation.
- A natural division between the frontal and temporal lobes is opened, and a small amount of each of these lobes is then removed.
- Using the guidance of special MRI scans and a navigation computer, the cerebrospinal fluid cavity (ventricle) is opened, exposing the deeper structures of the brain.
- The amygdala and hippocampus are removed from the temporal lobe, and a division is made in the corpus callosum, a band of fibers connecting the two hemispheres.
- The disconnection is then completed in the frontal area, and tissue is removed from another region called the insula.
- At the end of the operation, a silastic drain is left within the ventricle and the bone is replaced and secured with titanium plates and screws.
- The scalp is closed with absorbable stitches and a head wrap is applied.
- The endotracheal breathing tube may be removed, or it may remain in overnight.
After the operation, the child will be monitored in the pediatric ICU for 1-2 days, and an MRI will be performed to verify that all areas were disconnected appropriately. Over the course of the next few days, he or she will move to a normal neurosurgery room and undergo physical and occupational therapy.
The ventricular drain may be removed 5-7 days after surgery; a permanent shunting device is rarely required. Anticonvulsant medications are continued as seen fit by the treating neurologist, although it is often several months until medications are tapered.
- Limbrick DD, Narayan P, Johnston JM, Ojemann JG, Park TS, Smyth MD: Outcomes following hemispherotomy: the St. Louis Children’s Hospital experience. (Abstract) Child’s Nervous System, 23(9) 1062, 2007.
- Limbrick DD, Narayan P, Ojemann JG, Park TS, Smyth MD. Functional Hemispherotomy: Rates of Seizure-Freedom and Analysis of Seizure Recurrence. In preparation for submission to Child’s Nervous System, 2008.
- Narayan P, Isik U, Trevathan E, Fitzgerald RT, Arnold ST, Smyth MD, Leonard JR, Ojemann JG, Park TS. Functional hemispherectomy for epilepsy in childhood: Institutional experience. Platform presentation, Joint Pediatric Section, Salt Lake City, UT, 2003.
- Limbrick DD, Narayan P, Johnston JM, Ojemann JG, Park TS, Smyth MD: Outcomes following hemispherotomy: the St. Louis Children’s Hospital experience. Platform presentation to the International Society of Pediatric Neurosurgeons, Liverpool UK 2007.
- Limbrick DD, Narayan P, Johnston JM, Ojemann JG, Park TS, Smyth MD: Seizure-freedom and complications following functional hemispherotomy. Platform presentation, AANS/CNS Joint Pediatric Section, Miami, FL 2007.
- Limbrick DD, Narayan P, Johnston JM, Ojemann JG, Park TS, Smyth MD: Functional Hemispherotomy: Rates of Seizure-Freedom and Analysis of Seizure Recurrence. Platform presentation at the 21st Annual Neurosurgery in the Rockies conference, Beaver Creek CO, 2008.
- Powers AK, Limbrick DD, Smyth MD. Palliative hemispherotomy in patients with bilateral seizure onset. Presentation to the AANS/CNS Joint Pediatric Section, Spokane WA, 2008.