Nisha Gadgil, Matthew Muir, Melissa A. Lopresti, Sandi K. Lam
  1. Department of Neurosurgery, Division of Pediatric Neurosurgery, Baylor College of Medicine/Texas Children’s Hospital, Houston, Texas,
  2. Department of Neurosurgery, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine/Ann and Robert H Lurie Children’s Hospital, Chicago, IL, USA.

Correspondence Address:
Sandi K. Lam
Department of Neurosurgery, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine/Ann and Robert H Lurie Children’s Hospital, Chicago, IL, USA.


Copyright: © 2019 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Nisha Gadgil, Matthew Muir, Melissa A. Lopresti, Sandi K. Lam. An update on pediatric surgical epilepsy: Part II. 27-Dec-2019;10:258

How to cite this URL: Nisha Gadgil, Matthew Muir, Melissa A. Lopresti, Sandi K. Lam. An update on pediatric surgical epilepsy: Part II. 27-Dec-2019;10:258. Available from:

Date of Submission

Date of Acceptance

Date of Web Publication


Background: Recent advances may allow surgical options for pediatric patients with refractory epilepsy not previously deemed surgical candidates. This review outlines major technological developments in the field of pediatric surgical epilepsy.

Methods: The literature was comprehensively reviewed and summarized pertaining to stereotactic electroencephalography (sEEG), laser ablation, focused ultrasound (FUS), responsive neurostimulation (RNS), and deep brain stimulation (DBS) in pediatric epilepsy patients.

Results: sEEG allows improved seizure localization in patients with widespread, bilateral, or deep-seated epileptic foci. Laser ablation may be used for destruction of deep-seated epileptic foci close to eloquent structures; FUS has a similar potential application. RNS is a palliative option for patients with eloquent, multiple, or broad epileptogenic foci. DBS is another palliative approach in children unsuitable for respective surgery.

Conclusion: The landscape of pediatric epilepsy is changing due to improved diagnostic and treatment options for patients with refractory seizures. These interventions may improve seizure outcomes and decrease surgical morbidity, though further research is needed to define the appropriate role for each modality.

Keywords: Epilepsy surgery, Innovation, Minimally invasive, Pediatric, Technology


Pediatric epilepsy has a worldwide prevalence of 1%, and 20–30% are diagnosed with drug-resistant epilepsy (DRE) (persistent seizures despite treatment with two first-line antiepileptic medications).[ 2 ] Conventionally, surgery was considered a last resort, though it is now advocated to provide long-term seizure control (control rate of 50–70%).[ 19 ] Minimally invasive approaches include stereotactic electroencephalography (sEEG), laser ablation, focused ultrasound (FUS), and responsive neurostimulation (RNS), summarized in Table 1 .

Table 1:

Minimally invasive options for drug-resistant epilepsy


Recent developments allow surgical options for patients previously not deemed candidates, such as those with bilateral, deep, eloquent, or poorly localizing epileptogenic foci. The American Academy of Neurology now recommends early surgery for select patients with DRE. Nevertheless, there is still substantial delay between diagnosis and surgical referral.[ 15 ]


Complete removal of the epileptogenic zone (EZ) is the most important factor associated with postsurgical seizure freedom. Accurate localization of the EZ is therefore critical, as is information obtained from semiology, EEG, structural magnetic resonance imaging (MRI), and other advanced testing.[ 15 ] Seizures localizable through scalp EEG or MRI are more amenable to surgical cure;[ 11 , 12 , 21 ] when noninvasive testing fails to localize epileptogenic focus, patients may require intracranial electrode recording.[ 15 ]

There are two main types of intracranial electrode monitoring: subdural strip/grid recordings, and stereotactically placed depth electrodes implanted through burr holes (sEEG). Robotic assistance has a 1–3 mm level of accuracy for placement of electrodes and allows safe trajectories with reduced operating time [ Figure 1 ].[ 14 ] Once placed, electrodes may remain for 1–2 weeks.[ 17 ]

Figure 1:

Axial, sagittal, and coronal views of a T2-weighted magnetic resonance imaging scan depicting depth electrode planning trajectories for stereotactic electroencephalography, Phase 2 epilepsy monitoring.


Patients with DRE may be considered for sEEG in the following situations: no structural lesion identified on MRI and scalp EEG nonlocalizing, suspected multifocal/multilesional epilepsy, conflicting noninvasive data, suspected widespread seizure network, or EZ in close proximity to eloquent structures.[ 32 ] Targets of sEEG are determined by the EZ hypothesis, localization by scalp EEG, abnormalities on magnetoencephalography (MEG), interictal positron emission tomography, and ictal single-photon emission computed tomography.[ 6 , 19 , 24 , 31 ]

sEEG is a minimally invasive approach for seizure localization that provides significant advantages over subdural electrodes such as sampling of extended regions, interrogation of deep structures not accessible to subdural electrodes,[ 6 ] bilateral sampling in cases of rapid generalization, and staged electrode placement. Several studies show the efficacy of sEEG in children for localizing the EZ and guiding surgical resection.[ 5 , 26 , 35 ] Nevertheless, subdural electrodes still provide robust diagnostic capabilities for superficial foci or when extensive cortical mapping is required.[ 26 ]


After the seizure focus has been appropriately localized, there are multiple surgical options, including open surgical resection and minimally invasive stereotactic techniques such as radiofrequency thermo-coagulation and stereotactic radiosurgery. However, radiofrequency thermo-coagulation does not allow real-time monitoring of tissue destruction and is less effective than open microsurgical resection.[ 10 ] Stereotactic radiosurgery has a delayed treatment effect (last seizure on average 11–19.7 months after treatment) and may result in complications such as radionecrosis (20% of patients).[ 8 , 28 , 33 ] MRI-guided laser interstitial thermal therapy (LITT) thermally ablates the epileptogenic focus while minimizing local tissue damage.[ 3 ] There is an approximate 23% complication rate following MR-guided LITT.[ 17 ]

MR-guided LITT is used to treat mesial temporal sclerosis, hypothalamic hamartoma, and deep periventricular lesions.[ 32 ] Approximately 50% of these patients are seizure-free at 1 year follow-up.[ 3 , 18 , 24 , 38 ] Although temporal lobectomy results in a higher rate of seizure freedom (60–80%), sparing the lateral temporal lobe structures may correlate with better neuropsychological outcomes, such as reduced naming and verbal/working memory deficits.[ 3 , 18 , 24 , 38 ] Therefore, some support laser ablation as first-line therapy for dominant mesial temporal lobe epilepsy.[ 3 ]

In pediatrics, hypothalamic hamartoma is the most frequently reported indication for LITT, allowing disconnection of these deep-seated lesions while avoiding damage to surrounding structures [ Figure 2 ].[ 17 ] There is a 73% rate of seizure freedom following LITT for these lesions.[ 7 , 17 ] MR-guided LITT is best suited for lesions difficult to access with open surgery and presumably results in improved cognitive function and reduced complications.[ 17 ]

Figure 2:

Intraoperative T2-weighted coronal magnetic resonance imaging of a child undergoing laser ablation for intractable gelastic epilepsy resulting from hypothalamic hamartoma. The laser cannula is in place with the tip terminating in the hamartoma, allowing focused delivery of heat that can be monitored in real-time using magnetic resonance thermography.



FUS is another minimally invasive modality used to create targeted tissue ablation by delivering high-intensity ultrasound waves through external transducer elements which cause irreversible coagulation. FUS creates a 2–6 mm diameter intracranial lesion with 1 mm precision. Tissue ablation can be monitored in real-time using MR thermography. FUS avoids the need for skin incision or burr holes and carries a reduced complication rate compared to open microsurgery or LITT.[ 1 ]

The current primary application of FUS is for treating essential tremor, Parkinson’s disease, and neuropathic pain, and more recently, deep brain tumors.[ 1 , 9 , 27 ] DRE is a potential application of FUS in patients with lesional epilepsy (hypothalamic hamartoma, deep-seated cortical dysplasia, or low-grade tumors).[ 23 ] While one mechanism of action of FUS is thermal tissue destruction, lower temperatures may alter neural activity without causing cell death.[ 4 , 37 ] FUS is a minimally invasive, targeted treatment that may potentially be used in the future to treat benign tumors and other deep-seated epileptogenic lesions with reduced morbidity.


RNS adapts therapeutic stimulation in response to a continuous feedback loop. Depth or strip electrodes within the ictal onset zone continuously monitor electrocorticography activity; the device uses a programmed algorithm to detect incipient seizures. Once an abnormal activity is detected, the device supplies responsive therapeutic electrical stimulation designed to reduce or abort the seizures.[ 4 , 20 , 36 ] This may be used as a palliative approach for patients with eloquent, multiple, or broad epileptogenic foci.[ 23 ] Intracranial monitoring may be performed before RNS implantation to guide electrode placement.[ 23 ]

NeuroPace RNS (Neuropace, Mountain View, CA) is the first and only FDA-approved RNS device available to patients aged 18 years or older.[ 34 ] Most studies have focused on adult patients with mesial temporal (particularly bilateral mesial temporal) seizure onset or neocortical seizure onset in the eloquent cortex (such as language or sensorimotor). Studies have demonstrated long-term seizure reduction in almost two-thirds of patients, but few patients showed complete seizure freedom.[ 16 , 29 ] However, there were improvements in quality of life, though those undergoing temporal lobectomy may have had better results.[ 29 ] RNS is primarily advocated as a palliative option in patients who have no further treatment options. Patients with bitemporal epilepsy or those with epileptogenic foci in eloquent areas of the brain may have the most benefit from this procedure.[ 30 , 36 ]

RNS has been used off-label in pediatric patients with DRE in those with no surgical resection options (bilateral or eloquent epileptogenic foci).[ 22 , 34 ] Limited studies show promise for its use in children; shortcomings include performing a craniectomy for device implantation in a growing skull, and as well as the inability to obtain future MRI studies. Karsy et al. speculated that NeuroPace would be useful as an ambulatory Eastern Cooperative Oncology Group modality for pediatric patients who might not tolerate intracranial monitoring as well as adults.[ 19 ]

An example of RNS placement is demonstrated in Figure 3 , which depicts a 16-year old male with refractory complex partial seizures consisting of staring and pacing without responsiveness. Despite using three first-line antiepileptic medications, seizures occurred 3 times daily. MRI demonstrated no abnormality, and long-term scalp EEG demonstrated interictal discharges of the left frontal region with occasional bifrontal and right frontal discharges. MEG demonstrated spikes in the left inferior frontal and superior frontal gyri. Positron-emission tomography demonstrated decreased metabolic activity throughout the left frontal lobe, and a possible second metabolic focus in the left temporal lobe. The patient underwent Phase 2 monitoring with placement of subdural electrodes; events were captured with onset from multiple regions spanning a large area of the left frontal lobe involving eloquent speech and motor cortices. The patient underwent NeuroPace placement with strip electrodes on the left frontal motor and opercular regions. Electrocorticography noted seizure activity arising from all areas, and RNS therapy initiated. The patient has been seizure-free at 1-year follow-up and is being weaned off his antiepileptic medications.

Figure 3:

Lateral skull radiograph of a 16-year-old male after NeuroPace device implantation. Subdural electrode strips are connected to the device, which is seated in the patient’s skull.



DBS is an open-loop neuromodulatory program that involves the delivery of electrical stimulation to deep brain structures through implanted electrodes connected to a pulse generator. The safety profile is similar to DBS for movement disorders.[ 25 ] The landmark SANTE multicenter randomized trial enrolled adults with refractory epilepsy who underwent bilateral stimulation of the anterior nuclei of the thalamus; this reduced seizure frequency for up to 2 years.[ 13 ] Other noncontrolled studies have explored targets such as the hippocampus, centromedian nucleus of the thalamus, cerebellum, and nucleus accumbens.[ 25 ] There are, however, few pediatric studies. A recent systematic review of 40 pediatric DBS patients with DRE showed a reduction in seizures, but only small percentage was seizure free.[ 39 ] The centromedian nucleus of the thalamus and anterior thalamic nucleus were the most common targets. In the future, DBS may be considered as a palliative measure in children with DRE.


Advances in diagnostic capabilities and minimally invasive treatments, including stereotaxy, surgical robotics, laser ablation, and neurostimulation may improve seizure outcomes while minimizing surgical morbidity.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


1. Abe K, Taira T. Focused ultrasound treatment, present and future. Neurol Med Chir (Tokyo). 2017. 57: 386-91

2. Berg AT, Jallon P, Preux PM. The epidemiology of seizure disorders in infancy and childhood: Definitions and classifications. Handb Clin Neurol. 2013. 111: 391-8

3. Buckley R, Estronza-Ojeda S, Ojemann JG. Laser ablation in pediatric epilepsy. Neurosurg Clin N Am. 2016. 27: 69-78

4. Bystritsky A, Korb AS, Douglas PK, Cohen MS, Melega WP, Mulgaonkar AP. A review of low-intensity focused ultrasound pulsation. Brain Stimul. 2011. 4: 125-36

5. Cossu M, Cardinale F, Castana L, Citterio A, Francione S, Tassi L. Stereoelectroencephalography in the presurgical evaluation of focal epilepsy: A retrospective analysis of 215 procedures. Neurosurgery. 2005. 57: 706-18

6. Cossu M, Cardinale F, Castana L, Nobili L, Sartori I, Lo Russo G. Stereo-EEG in children. Childs Nerv Syst. 2006. 22: 766-78

7. Curry DJ, Raskin J, Ali I, Wilfong AA. MR-guided laser ablation for the treatment of hypothalamic hamartomas. Epilepsy Res. 2018. 142: 131-4

8. Eekers DB, Pijnappel EN, Schijns OE, Colon A, Hoeben A, Zindler JD. Evidence on the efficacy of primary radiosurgery or stereotactic radiotherapy for drug-resistant non-neoplastic focal epilepsy in adults: A systematic review. Seizzure. 2018. 55: 83-92

9. Elias WJ, Lipsman N, Ondo WG, Ghanouni P, Kim YG, Lee W. A randomized trial of focused ultrasound thalamotomy for essential tremor. N Engl J Med. 2016. 375: 730-9

10. Englot DJ, Birk H, Chang EF. Seizure outcomes in nonresective epilepsy surgery: An update. Neurosurg Rev. 2017. 40: 181-94

11. Englot DJ, Breshears JD, Sun PP, Chang EF, Auguste KI. Seizure outcomes after resective surgery for extra-temporal lobe epilepsy in pediatric patients. J Neurosurg Pediatr. 2013. 12: 126-33

12. Englot DJ, Rolston JD, Wang DD, Sun PP, Chang EF, Auguste KI. Seizure outcomes after temporal lobectomy in pediatric patients. J Neurosurg Pediatr. 2013. 12: 134-41

13. Fisher R, Salanova V, Witt T, Worth R, Henry T, Gross R. Electrical stimulation of the anterior nucleus of thalamus for treatment of refractory epilepsy. Epilepsia. 2010. 51: 899-908

14. Foley JL, Little JW, Vaezy S. Effects of high-intensity focused ultrasound on nerve conduction. Muscle Nerve. 2008. 37: 241-50

15. Guan J, Karsy M, Ducis K, Bollo RJ. Surgical strategies for pediatric epilepsy. Transl Pediatr. 2016. 5: 55-66

16. Heck CN, King-Stephens D, Massey AD, Nair DR, Jobst BC, Barkley GL. Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive neurostimulation: Final results of the RNS system pivotal trial. Epilepsia. 2014. 55: 432-41

17. Hoppe C, Helmstaedter C. Laser interstitial thermotherapy (LiTT) in pediatric epilepsy surgery. Seizure. 2018. 18: S1059-311

18. Kang JY, Wu C, Tracy J, Lorenzo M, Evans J, Nei M. Laser interstitial thermal therapy for medically intractable mesial temporal lobe epilepsy. Epilepsia. 2016. 57: 325-34

19. Karsy M, Guan J, Ducis K, Bollo RJ. Emerging surgical therapies in the treatment of pediatric epilepsy. Transl Pediatr. 2016. 5: 67-78

20. Kinnear KM, Warner NM, Gersappe A, Doherty MJ. Pilot data on responsive epilepsy neurostimulation, measures of sleep apnea and continuous glucose measurements. Epilepsy Behav Case Rep. 2018. 9: 33-6

21. Knake S, Triantafyllou C, Wald LL, Wiggins G, Kirk GP, Larsson PG. 3T phased array MRI improves the presurgical evaluation in focal epilepsies: A prospective study. Neurology. 2005. 65: 1026-31

22. Kokoszka MA, Panov F, La Vega-Talbott M, McGoldrick PE, Wolf SM, Ghatan S. Treatment of medically refractory seizures with responsive neurostimulation: 2 pediatric cases. J Neurosurg Pediatr. 2018. 21: 421-7

23. Krishna V, Sammartino F, Rezai A. A review of the current therapies, challenges, and future directions of transcranial focused ultrasound technology: Advances in diagnosis and treatment. JAMA Neurol. 2018. 75: 246-54

24. Lang M, Chitale A, Sharan A, Wu C. Advancements in stereotactic epilepsy surgery: Stereo-EEG, laser interstitial thermotherapy, and responsive neurostimulation. JHN J. 2016. 11: 32-6

25. Li MC, Cook MJ. Deep brain stimulation for drug-resistant epilepsy. Epilepsia. 2018. 59: 273-90

26. Liava A, Mai R, Tassi L, Cossu M, Sartori I, Nobili L. Paediatric epilepsy surgery in the posterior cortex: A study of 62 cases. Epileptic Disord. 2014. 16: 141-64

27. MacDonell J, Patel N, Rubino S, Ghoshal G, Fischer G, Burdette EC. Magnetic resonance-guided interstitial high-intensity focused ultrasound for brain tumor ablation. Neurosurg Focus. 2018. 44: E11-

28. McGonigal A, Sahgal A, De Salles A, Hayashi M, Levivier M, Ma L. Radiosurgery for epilepsy: Systematic review and International Stereotactic Radiosurgery Society (ISRS) practice guideline. Epilepsy Res. 2017. 137: 123-31

29. Meador KJ, Kapur R, Loring DW, Kanner AM, Morrell MJ, RNS® System Pivotal Trial Investigators. Quality of life and mood in patients with medically intractable epilepsy treated with targeted responsive neurostimulation. Epilepsy Behav. 2015. 45: 242-7

30. Morrell MJ, RNS System in Epilepsy Study Group. Responsive cortical stimulation for the treatment of medically intractable partial epilepsy. Neurology. 2011. 77: 1295-304

31. Pestana Knight EM, Schiltz NK, Bakaki PM, Koroukian SM, Lhatoo SD, Kaiboriboon K. Increasing utilization of pediatric epilepsy surgery in the United States between 1997 and 2009. Epilepsia. 2015. 56: 375-81

32. Ravindra VM, Sweney MT, Bollo RJ. Recent developments in the surgical management of paediatric epilepsy. Arch Dis Child. 2017. 102: 760-6

33. Rheims S, Fischer C, Ryvlin P, Isnard J, Guenot M, Tamura M. Long-term outcome of gamma-knife surgery in temporal lobe epilepsy. Epilepsy Res. 2008. 80: 23-9

34. Singhal NS, Numis AL, Lee MB, Chang EF, Sullivan JE, Auguste KI. Responsive neurostimulation for treatment of pediatric drug-resistant epilepsy. Epilepsy Behav Case Rep. 2018. 10: 21-4

35. Taussig D, Lebas A, Chipaux M, Jan M, Fohlen M, Bulteau C. Stereo-electroencephalography (SEEG) in children surgically cured of their epilepsy. Neurophysiol Clin. 2016. 46: 3-15

36. Thomas GP, Jobst BC. Critical review of the responsive neurostimulator system for epilepsy. Med Devices (Auckl). 2015. 8: 405-11

37. Tufail Y, Matyushov A, Baldwin N, Tauchmann ML, Georges J, Yoshihiro A. Transcranial pulsed ultrasound stimulates intact brain circuits. Neuron. 2010. 66: 681-94

38. Willie JT, Laxpati NG, Drane DL, Gowda A, Appin C, Hao C. Real-time magnetic resonance-guided stereotactic laser amygdalohippocampotomy for mesial temporal lobe epilepsy. Neurosurgery. 2014. 74: 569-84

39. Yan H, Toyota E, Anderson M, Abel TJ, Donner E, Kalia SK. A systematic review of deep brain stimulation for the treatment of drug-resistant epilepsy in childhood. J Neurosurg Pediatr. 2018. 23: 274-84

Leave a Reply

Your email address will not be published. Required fields are marked *