When is hemispherotomy offered?
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.
Experts at hemispherotomy
The Epilepsy Management 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 nearly 100 hemispherotomies, and about 90% of patients experience complete or near-complete resolution of their seizures.
The hemispherotomy procedure
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 a hemispherotomy
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.
Axial and coronal MRI images following a right-sided peri-insular hemispherotomy
Publications related to hemispherotomy from our team:
1. Hemispherotomy in children with electrical status epilepticus of sleep.
Jeong A, Strahle J, Vellimana AK, Limbrick DD Jr, Smyth MD, Bertrand M.
J Neurosurg Pediatr. 2017 Jan;19(1):56-62. doi: 10.3171/2016.8.PEDS16319. Epub 2016 Oct 28.
2. Characterization of postoperative fevers after hemispherotomy.
Kamath AA, Limbrick DL, Smyth MD.
Childs Nerv Syst. 2015 Feb;31(2):291-6. doi: 10.1007/s00381-014-2572-7. Epub 2014 Oct 21.
3. Palliative hemispherotomy in children with bilateral seizure onset.
Ciliberto MA, Limbrick D, Powers A, Titus JB, Munro R, Smyth MD.
J Neurosurg Pediatr. 2012 Apr;9(4):381-8. doi: 10.3171/2011.12.PEDS11334.
4. Hemispherotomy: efficacy and analysis of seizure recurrence.
Limbrick DD, Narayan P, Powers AK, Ojemann JG, Park TS, Bertrand M, Smyth MD.
J Neurosurg Pediatr. 2009 Oct;4(4):323-32. doi: 10.3171/2009.5.PEDS0942.