In most pediatric surgical cases, epilepsy is caused by malformations of cortical development, perinatal insults, and encephalitis.1–3 When the epileptogenic area is large, the techniques of choice are disconnective surgeries (such as hemispherotomy) if the entire cerebral hemisphere is affected,4–8 or temporoparietooccipital (TPO) disconnection if the epileptogenic area affects only the posterior quadrant of the hemisphere and motor function is preserved.9–13
Our hospital is a national and European reference center (EpiCARE Network) for the treatment of pediatric patients with refractory epilepsy. Every year, 170 patients are evaluated and 60 patients are surgically treated in our epilepsy unit. Since 2007, 34 hemispherotomies and 17 TPO disconnections have been performed for refractory epilepsy in our pediatric hospital. Until 2019, our cohort of patients reached an ILAE class 1/Engel class I in 88% of hemispherotomies and 75% of TPO disconnections.35,36 Prior to this study, 6 of the patients who underwent hemispherotomy required reintervention due to incomplete disconnection to allow drug withdrawal or for persistent seizures. Reoperation is the most effective treatment for failed disconnective surgeries, although it is technically challenging and can result in severe complications.14–16
The technique of MRI-guided laser interstitial thermal therapy (MRIgLITT) has previously been used successfully in the treatment of epilepsy.17–26 This technology was initially incorporated into our hospital in 2019 to treat hypothalamic hamartomas (HHs) and had very promising outcomes.27 Other authors have used it to perform partial or complete callosotomy28–33 and even palliative hemispherotomy.34 This previous experience prompted us to apply MRIgLITT to complete other disconnective surgeries.
In this paper, we report our initial experience with laser ablation to complete hemispherotomy and TPO disconnection in pediatric patients, aiming to describe the surgical technique assisted by the robotic arm and its accuracy, safety, and efficacy.
Methods
Approval by the Research and Ethics Committees of the Sant Joan de Déu Barcelona Hospital was obtained before starting this study.
Patient Selection Criteria
Laser interstitial thermal therapy (LITT) was suggested for patients in whom reoperation was indicated to complete a hemispherotomy or TPO disconnection for seizure recurrence or persistence, or to allow antiepileptic drug (AED) withdrawal. After the initial disconnective surgery, patients were evaluated in the epilepsy surgery unit at 3, 6, and 12 months. The study included a video-electroencephalogram (VEEG), 3-T MRI with a specific epilepsy protocol, and neuropsychological assessments. In cases of seizure recurrence, seizure semiology, extended interictal and ictal VEEGs, and postoperative MRI were discussed. If the study findings were considered coherent, the team established a working hypothesis of which remnant connections were the most probable culprit of seizure propagation; therefore, those areas were defined as the MRIgLITT target.
Imaging Studies
Preoperative studies were performed using a 3-T MRI machine (Philips Healthcare). They included diffusion-weighted imaging (DWI), susceptibility weighted imaging (SWI), T2-weighted imaging, time-of-flight 3D volumetric FLAIR, and volumetric T1-weighted (1 mm3 isotropic) pre- and postcontrast images for neurosurgical navigation. Intraoperative MRIgLITT studies were performed using a 1.5-T MRI machine (Philips Ingenia, Philips Healthcare) located in the surgical area beside the neurosurgical theater. This equipment was used for spatial coregistration, intraoperative monitoring during laser ablation, and immediate postoperative imaging control.
Presurgical Plan
Preoperative 3D isotropic T1-weighted pre- and postcontrast MRI data sets were loaded into the planning workstation. The fiber trajectory was planned using Voxim software (Renishaw). The treatment aim was to ablate the connection or connections along its long axis, but in some cases a transverse trajectory was planned if it was considered safer. More than one laser fiber was planned if multiple connections were not included in one trajectory. Vessels were avoided during presurgical planning. Because of the size of the therapeutic window of the laser fiber, several pullouts were planned beforehand.
Laser Fiber Insertion
VIDEO 1. Clip showing completion of the disconnective surgical technique using MRIgLITT in a pediatric patient. © Santiago Candela-Cantó, published with permission. Click here to view.
Implantation of the laser fiber assisted by the Neuromate robotic arm. A: Preoperative MRI for coregistration and laser ablation are performed in the MRI facility located next door to the operating room. Spatial patient coregistration is performed through ultrasounds. The fiducial star-shaped array, with which the preoperative MRI is performed, is replaced by an ultrasound emitter, and an ultrasound receiver is attached to the robotic arm. In this way, the robot is able to locate the patient in the operating room space and achieve very precise coregistration. B: The drill bit is guided by the robotic arm through the 3.2-mm instrument holder. C: Fixation of the anchoring screw with a 1.7-mm stylet held by the robotic arm. D: Patient positioning in the MRI machine, using the soft coils to allow connection of the cooling catheter and laser fiber (or fibers) with the Visualase system without bending them. Figure is available in color online only.
Patients were transferred to the intraoperative MRI machine after fixation of a fiducial support to the skull for stereotactic spatial registration of the preoperative MRI. In the operating room, coregistration was based on fiducial location through ultrasound, and accuracy was checked by pointing a laser beam attached to the robotic arm at facial anatomical landmarks. The Medtronic 10-mm Visualase laser fiber was inserted with the Neuromate (Renishaw) robotic arm, and the skull was drilled with a 3.1-mm drill bit.
Transfer to the MRI Facility
After fiber insertion, an MRI safety checklist was reviewed and the patients were transferred to the MRI room. First, a standard MRI was performed to assess any possible complications, check the correct fiber placement, and determine which two planes would be more useful for treatment execution and monitoring.
Accuracy of the Laser Fiber Insertion Calculation
The accuracy of fiber insertion was calculated postoperatively using Voxim software, as reported previously in deep brain stimulation,37 stereo-electroencephalography,38 and laser ablation of HHs27 by the authors. The preoperative plan and initial intraoperative T1-weighted MRI localization were combined. Voxim measuring tools were used to calculate the distance between the tip of the laser fiber and the planned target point in different Cartesian planes. The “in-line” view of the trajectory was also used to calculate the total deviation.
Laser Ablation
The ablation was performed using the Visualase system, with the laser fiber connected to a 15-W, 980-nm laser diode and the cooling system. The procedure was performed using an intraoperative 1.5-T Philips Ingenia MRI machine.
The therapy was continuously monitored by real-time MRI thermography.40,41 We defined low-temperature markers (45°C) to protect the contralateral hemisphere, internal capsule, middle cerebral artery branches, insula, or basal ganglia, depending on the location of the laser ablation. During the cooling time after each treatment, real ablation extension was checked with DWI, FLAIR, and T2-weighted MRI. The laser fiber was pulled out as many times as needed to ablate the planned length. At the end of the procedure after removing the laser catheter, complete final MRI including volumetric T1-weighted, FLAIR, DWI, T2-weighted, and SWI was performed.
The Visualase system provided detailed power and time logs for every patient. The postoperative volume of the lesion was calculated with the “Smartbrush” tool of the Elements software (Brainlab) on the postoperative 3D FLAIR images.
Epilepsy Outcome
Epilepsy outcomes were evaluated using the International League Against Epilepsy (ILAE) and Engel (epilepsy surgery outcome) scales at 3, 6, and 12 months.35,36 Furthermore, all patients were contacted prior to manuscript submission to check the epilepsy outcomes. Intra- and postoperative complications were prospectively recorded during the hospital stay and outpatient follow-up.
In the 1 case with treatment failure, pathological analysis of the excised tissue was performed after the anatomical hemispherectomy was completed. Brain samples were processed following standard histological protocols.42
Results
Patient Demographics
Six patients with drug-resistant epilepsy, between 4 and 18 years of age (mean age 10 ± 4.4 years), who had previously undergone hemispherotomy (4 patients) or TPO disconnection (2 patients), were treated at our hospital. Seizures persisted in 5 of the 6 patients after open disconnective surgery. One patient relapsed and experienced seizures after the withdrawal of the AEDs, 4 years after hemispherotomy.
All patients in whom the initial disconnective surgery failed through persisting connections during the study period could be included in this series and only an open reoperation was performed in 1 patient after failed MRIgLITT. Persisting connections were identified through MRI in the posterior insula (2 cases), uncinate fasciculus (2 cases), superior temporal gyrus (2 cases), parietal and fronto-orbital cortices, and anterior corpus callosum. Figure 2 shows examples of the pre- and postoperative MR images. Table 1 summarizes the patient data.
Examples of planned trajectories (left column) and ablations (right column) using Voxim software: A: In-line coronal T1-weighted enhanced MR image showing a trajectory longitudinal to the posterior insular connection in patient 2. B: Postoperative in-line coronal FLAIR image showing complete ablation of the connection. C: Preoperative in-line sagittal T1-weighted enhanced trajectory including posterior insular and uncinate fasciculus connections in patient 3. D: Postoperative sagittal in-line FLAIR image in patient 3 corresponding to the insular trajectory, in which uncinate fasciculus ablation can also be seen. E: Preoperative in-line sagittal T1-weighted enhanced trajectory along the superior temporal gyrus in patient 5. F: Postoperative sagittal in-line FLAIR imaging in patient 5 showing the laser ablation of the superior temporal gyrus. G: Preoperative in-line coronal T1-weighted enhanced MR image showing a trajectory to complete a frontoorbital disconnection in patient 6. H: Postoperative in-line coronal FLAIR image showing the frontoorbital disconnection. Figure is available in color online only.
Patient description
| Pt No. | Disconnective Surgery | Etiology | Age (yrs) | Time Btwn Open Surgery & LITT | Seizure | Tx Received | Persisting Connections | |||
|---|---|---|---|---|---|---|---|---|---|---|
| At Ablation | At Onset | At Previous Surgeries | Type | Frequency | ||||||
| 1 | Lt hemi | Meningitis | 4 | 0.58 | 3 & 4 | 6 mos | Tonic-clonic, atonic | Daily | LEV, LEV + CLB, LEV + CLB + VGB, VPA + CLB + LCM, VPA + CLB + TPM, VPA + CLB + VGB, OXC + PER, VGB + CLB + BRV + VPA, VGB + CLB | Posterior insula |
| 2 | Rt hemi | Rasmussen encephalitis | 10 | 5 | 8 & 9 | 10 mos | Nonmotor, tonic | Daily | OXC, OXC + VPA, OXC + VPA + steroids + IGS, OXC + VPA + RITAB, OXC + LCM, OXC + ZNS + steroids + IGS + RITAB, OXC + ZNS + IGS ± CLB, PER, OXC + ZNS, OXC + TPM, OXC + TPM + CLB + ADAB, OXC + CLB + ADAB, OXC + BRV, OXC + CLB, OXC + LTG, OXC + ESL | |
| 3 | Rt TPO | Cortical dysplasia | 8 & 9 | 2 | 7 | 18 mos | Blinking, impaired awareness | Daily | VGB, VPA, VPA + LEV, VPA + LEV + CBZ, VPA + LEV + CBZ + steroids, LEV + LCM | UF, posterior insula/T1, parietal parisaggital |
| 4 | Lt hemi | Perinatal stroke | 18 | 10 | 17 | 20 mos | Tonic, hypermotor | Daily | PHT + PB + MDZ, PB + VPA, OXC, LEV, CZP, TPM + LCM + PER, LCM + CBZ, LCM + ESL + ZNS, LCM + ESL + VPA | UF |
| 5 | Rt TPO | Perinatal stroke | 7 | 1.66 | 6 | 5 mos | Motor, CSWS | Subclinical | OXC, OXC + VPA, OXC + VPA + LEV, VPA + LEV + CLB, VPA + LEV + CLB + steroids, OSP + CLB + BRV, OSP + CLB + ETO | UF, posterior insula |
| 6 | Lt hemi | Perinatal stroke | 15 | 4 | 10 | 5 yrs | Motor | Occasional | VPA + CBZ, LEV + CBZ, CBZ, TPM + CBZ, CBZ + LTG, LTG + CLB, CLB + PER, CLB + CBZ, CLB + CBZ + LCM, CBZ + LCM, ESL + LCM, ESL + LTG | Frontoorbital cortex, anterior corpus callosum |
| Mean | 10 | 3.8 | 8 | 1.6 yrs | ||||||
ADAB = adalimumab; BRV = brivaracetam; CBZ = carbazepine; CLB = clobazam; CSWS = epileptic encephalopathy with continuous spike and wave during sleep; CZP = clonazepam; ESL = eslicarbamazepine; ETO = etosuximide; hemi = hemispherotomy; IGS = immunoglobulins; LCM = lacosamide; LEV = levetiracetam; LTG = lamotrigine; MDZ = midazolam; OSP = ospolot; OXC = oxcarbazepine; PB = phenobarbital; PER = perampanel; PHT = phenytoin; pt = patient; RITAB = rituximab; TPM = topiromate; Tx = treatment; UF = uncinate fasciculus; VGB = vigabatrin; VPA = valproic acid; ZNS = zonisamide.
Presurgical Plan
We intended to plan trajectories longitudinally along the persisting connections: a longitudinal transparietal trajectory was planned for the posterior insula and the posterior part of the superior temporal gyrus, and a longitudinal transoccipital trajectory for the superior temporal gyrus. However, in 2 cases (for the uncinate fasciculus and to disconnect the frontoorbital cortex), a perpendicular trajectory was considered safer. In all cases, the entry point was planned through the disconnected brain tissue. Examples of planned trajectories are shown in Fig. 2.
Laser Ablation
VIDEO 2. Clip showing real-time MRI thermographies of disconnective surgery using MRIgLITT. CSWS = continuous spike and wave during sleep; sz = seizures. © Santiago Candela-Cantó, published with permission. Click here to view.
Ablation details and seizure outcome
| Pt No. | Ablated Area | Trajectory | TPLE (mm) | Mean Power (W) | Time (sec) | Energy Delivered (J) | Vol Ablated (mm3) | Max Ablation Diameter (mm) | Surgical Time (hrs) | Postop Hospital Stay (days) | Seizure Outcome | FU | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Engel Class | ILAE Class | ||||||||||||
| 1 | Post insula | Long | 0 | 2.93 | 908 | 2658 | 660 | 14 | 8.5 | 4 | IA | 1 | 29 mos |
| 2 | Post insula | Long | 0.4 | 6.19 | 4085 | 25,277 | 5555 | 23 | 6.7 | 3 | IA | 1 | 22 mos |
| 3 | 1st LITT | ||||||||||||
| F1 | 9.5 | IA | 1 | 3 mos* | |||||||||
| UF | Perp | 3 | 6.58 | 2567 | 16,885 | 6320 | 21 | ||||||
| F2 | |||||||||||||
| Post T1 | Long | 2.3 | 5.71 | 2279 | 13,024 | 6670 | 20 | ||||||
| 2nd LITT | |||||||||||||
| F1 | 6.9 | 3 | IA | 1 | 19 mos | ||||||||
| Post insula | Long | 0 | 7.42 | 2200 | 16,330 | 3090 | 25 | ||||||
| F2 | |||||||||||||
| Parietal | Long | 1.5 | 7.50 | 1488 | 11,166 | 5050 | 23 | ||||||
| 4 | 1st LITT | IVA | 5 | ||||||||||
| UF | Perp | 3 | 7.04 | 2658 | 18,712 | 4350 | 18 | 6.75 | 3 | 4 days* | |||
| 2nd LITT | |||||||||||||
| UF | Long | 4.2 | 8.67 | 2480 | 21,509 | 8130 | 22 | 6.5 | 2 | 0 days* | |||
| 5 | Temporal pole–T1 | Long | 1.75 | 6.40 | 3670 | 23,500 | 5220 | 13 | 7.5 | 3 | IA | 1 | 16 mos |
| 6 | Frontoorbital cortex | Perp | 1.2 | 7.43 | 1574 | 11,694 | 3360 | 15 | 5.5 | 3 | IA | 1 | 15 mos |
| Mean | 1.7 | 6.58 | 2391 | 16,075 | 4840 | 19.4 | 7.2 | 3.1 | |||||
FU = follow-up; Long = longitudinal; Perp = perpendicular.
There were no complications in any patient.
Time to epilepsy relapse.
Summary of descriptive and outcome statistics
| Variable | Mean | SD | Min | Q1 | Median | Q3 | Max |
|---|---|---|---|---|---|---|---|
| Age at laser ablation (yrs) | 10.14 | 4.41 | 4 | 7.5 | 9 | 12.5 | 18 |
| Age at epilepsy onset (yrs) | 3.87 | 3.40 | 0.58 | 1.74 | 3 | 4.75 | 10 |
| Age at previous open surgeries (yrs) | 8 | 4.34 | 3 | 5.5 | 7.6 | 9.25 | 17 |
| Time btwn open surgery & LITT (mos) | 19.83 | 20.61 | 5 | 7 | 4 | 19.5 | 60 |
| TPLE (mm) | 1.73 | 1.40 | 0 | 0.6 | 1.62 | 2.82 | 4.2 |
| Mean power (W) | 6.58 | 1.53 | 2.93 | 6.24 | 6.81 | 7.42 | 8.67 |
| Duration of ablation (sec) | 2390.9 | 963.03 | 908 | 1730.5 | 2379.5 | 2635.25 | 4085 |
| Energy delivered (J) | 16,075.5 | 6746.11 | 2658 | 12,026.5 | 16,607.5 | 20,809.75 | 25,277 |
| Surgical time (hrs) | 7.23 | 1.25 | 5.5 | 6.65 | 6.82 | 7.75 | 9.5 |
| Vol ablated (mm3) | 4840.5 | 2108.94 | 660 | 3607.5 | 5135 | 6128.75 | 8130 |
| Max diameter ablated (mm) | 19.4 | 4.19 | 13 | 15.75 | 20.5 | 22.75 | 25 |
| FU (mos) | 20.2 | 5.6 | 15 | 16 | 19 | 22 | 23 |
Q1, Q3 = quartile 1, quartile 3.
Five (83%) of 6 patients attained seizure freedom after LITT: 4 (66%) of 6 after the first LITT, and 1 (50%) of 2 after the second LITT.
Duration of Surgical Procedure and Hospital Stay
The mean duration of the complete procedure was 7 hours 15 minutes (range 5 hours 30 minutes to 9 hours 30 minutes), from the fiducial support insertion to the final MRI control (both included). The mean postoperative hospital stay was 3 days, including 1 night in the intensive care unit.
Epilepsy Outcome
Five (83%) of the 6 patients were seizure free (ILAE class 1, Engel class IA) after a mean of 20.2 ± 5.6 months of follow-up. Four patients (66%) were seizure free after a first MRIgLITT; 2 patients with initial MRIgLITT failure (1 TPO disconnection and 1 hemispherotomy) underwent reoperation.
Patient 3 (TPO disconnection) did not present with clinical seizures after the first MRIgLITT, but the VEEG showed a pseudoperiodic pattern originating in the disconnected parenchyma and diffusing to the rest of the cerebral hemisphere, which improved after the second laser ablation. The VEEG changes are shown in Fig. 3. The seizures persisted in patient 4 (hemispherotomy) after two MRIgLITT procedures. The patient underwent an open reintervention (anatomical hemispherectomy) 8 months after the initial procedure without improvement (ILAE class 5, Engel class IVB). Figure 4 shows the MR images corresponding to the first and second MRIgLITT, the MR image after hemispherectomy, and current VEEG.
Pre- and postoperative VEEGs 6 months after the second MRIgLITT in patient 3 (bipolar; high-pass filter 0.4 Hz, low-pass filter 70 Hz, gain 150 μV/cm). A: Preoperative awake VEEG showing asymmetrical basal activity and subcontinuous slowing over the right cerebral hemisphere due to interference of the anomalies (spike and polyspike wave activity over T4TP10 [arrow]). B: Preoperative no REM sleep (NREMS) VEEG with significant activation of epileptiform abnormalities in the posterior region of the right cerebral hemisphere (arrow) and contralateral diffusion (asterisks). C: Postoperative awake VEEG with asymmetrical basal activity. Spikes/spikes and wave over O2T6 (arrows), posterior alpha rhythm reactive to ocular opening (OA) and closing (OC; asterisk), subcontinuous slowing over the right cerebral hemisphere. D: NREMS VEEG showing spikes/spikes and wave (arrows) plus beta activity (18 Hz/30–40 mV) over O2T6 (β) plus contralateral diffusion at O1T5 (asterisks). Figure is available in color online only.
Images from the case with treatment failure (patient 4). A: Planned transverse trajectory through the uncinate fasciculus viewed in an in-line T1-weighted MR image using the Voxim software for the first MRIgLITT. B: Postoperative in-line FLAIR image showing the ablation of this connection. C: Preoperative in-line coronal TI-weighted enhanced MR image showing the planned longitudinal trajectory for the uncinate ablation in the second MRIgLITT. D: Postoperative in-line coronal FLAIR image showing the complete ablation of the uncinate fasciculus. E: Coronal T1-weighted enhanced MR image showing anatomical hemispherectomy after the failed second MRIgLITT. F: Axial T1-weighted enhanced MR image showing the anatomical hemispherectomy. G: Awake VEEG with right frontal epileptiform abnormalities (arrow) and contralateral diffusion (asterisks) after the anatomic hemispherectomy. H: NREMS VEEG after anatomical hemispherectomy showing right frontal epileptiform abnormalities (arrow) and contralateral diffusion (asterisk). Figure is available in color online only.
No complications were reported in any patient. Neuropathological findings for patient 4 are shown in Fig. 5.
Photomicrographs showing histopathological findings in patient 4. A and B: Cavity in the cerebral cortex and white matter in the area of laser ablation. H&E. C and D: Reactive astrogliosis at the periphery of the laser ablation tract (C) with aggregates of foamy macrophages (D). Glial fibrillary acidic protein (C), CD68 (D). E and F: Marked depletion of the axons in the vicinity of the cavity (E) compared with white matter without laser ablation (F). Neurofilament. G and H: Rarefaction in the subcortical white matter with spongiosis at the periphery of the cavity (G) with numerous aggregates of lipofuscin with calcified neurons (H) is identified. H&E. Figure is available in color online only.
Discussion
The most frequent cause of surgical failure in disconnective surgeries is incomplete disconnection, and reoperation is the treatment of choice.14–16 Usually, persisting connections are deep-seated and small and are particularly suited to being disrupted by MRIgLITT.
Previous experience disrupting white matter pathways has been described, using partial or complete callosotomy, with a decrease in drop attacks and improvement of epilepsy outcome,28–33 and palliative hemispherotomy, with minimal morbidity and good results as well.34 We have observed different persisting connections in our patients depending on the surgical technique chosen for the hemispherotomy. When the perisylvian technique5,7 was used, there was more risk of leaving small connections at the posterior insula, and when the vertical technique6 was used, connections could persist at the uncinate fasciculus. Because of the risk of hypothalamic damage, we are always very cautious in the frontoorbital disconnection, and it can lead to a connection at this level. For the TPO procedure, we performed the temporal disconnection through the middle temporal gyrus in some cases, and it led to a persisting connection along the superior temporal gyrus.
The number of persisting connections and their diameters are the most important data points for considering LITT for completing a disconnective surgery. In our series, we used a maximum of two laser fibers per patient to cover one or two persisting connections. The reason for this limit is merely financial, based on the cost of the laser fibers and the budget per patient provided by our public health system. We used the Neuromate robotic arm for laser fiber insertion; specific considerations for treating pediatric patients have been previously discussed.27,37,38 In this cohort study, we were aware that the entry point did not coincide with the previous craniotomy performed.
The TPLE calculated for these patients was comparable to the TPLE described in our previous reports for other stereotactic techniques.27,37,38 The major deviation was 4.2 mm in the second ablation in patient 4. This was a very long trajectory along the persisting connection in the uncinate fasciculus, and it passed through the postsurgical cavity. In fact, during the first treatment of this patient, we performed a perpendicular (transverse) trajectory to avoid a long trajectory. This strategy did not prevent us from accomplishing the ablation. No fibers needed to be relocated.
The amount of energy delivered in our patients was relatively large compared to the energy needed in HHs, for example.27 The energy delivered in HHs was 11,615 ± 6887 J, while in these surgeries it was 16,075 ± 6746 J. This difference could be explained because the connections were widely surrounded by freely circulating CSF that cooled the targeted area during the treatment. Additionally, as our targets were bordered by disconnected brain tissue, we considered it safe to use high-energy ablations. In fact, our patients did not experience any complications. As in HHs, it is desirable to lower the amount of energy.27 More selective ablations could contribute to this purpose and shorten the surgical time.
The maximum ablation diameter obtained in our series was 25 mm. Larger, persisting connections should be excluded or approached with more than one laser fiber. Laser ablation was effective in 5 of our 6 patients after more than 1 year of follow-up. The method was only unsuccessful in 1 patient, who required reintervention by MRIgLITT and later open surgery to complete the anatomical hemispherectomy, also without success. Neuropathological examination of the excised tissue revealed changes attributable to the white matter disruption by MRIgLITT. This patient has epilepsy secondary to a perinatal infarction, and we believe that there could be a contralateral parasagittal epileptic focus.
This technique was minimally invasive. There is no need to reopen the cranium to address major anatomical distortions, previous scars, or adhesions between the brain and meninges. Blood loss was negligible; therefore, none of our patients required blood transfusions, which is especially important in younger patients. None of the patients developed hydrocephalus, which is a risk factor for open reoperations in disconnective surgery.43 Two of the 6 patients who had previously undergone a hemispherotomy reoperation through a craniotomy developed hydrocephalus (33%), compared with only 4 (12%) of 34 patients after the first hemispherotomy surgery in our series. Furthermore, the hospital stay was much shorter.
Considering these theoretical advantages of MRIgLITT over open reoperation, this technique has become our institution’s first choice for completing disconnective surgeries. Because this is a complex and expensive technique, specialized centers should be defined to increase safety and efficacy.
Conclusions
In our limited experience, MRIgLITT has been deemed safe and effective in its ability to complete hemispherotomies and TPO disconnections, resulting in 5 of 6 patients with Engel class IA after this procedure. However, studies with a larger sample size and longer follow-up periods need to be conducted to better assess the safety and efficacy of MRIgLITT in completing disconnective surgeries.
Acknowledgments
We thank Lucia Bentabol for her technical support. We thank Manel Gomez Ponce, Fernando Borreguero, Sonia Acero, Miriam Álamo, and Rosa Aguilar for their professional and personal involvement. We thank Carles Fàbrega and Gemma Fernández for figure and video editing. We are indebted to the "Biobanc de l’Hospital Infantil Sant Joan de Déu per a la Investigació," part of the Spanish Biobank Network of ISCIII, for the sample and data procurement.
Disclosures
Dr. Candela-Cantó reports having a teaching and education contract with Medtronic.
Author Contributions
Conception and design: Candela-Cantó. Acquisition of data: Candela-Cantó, Muchart, Valera, Jou. Analysis and interpretation of data: Candela-Cantó, Muchart, Valera, Jou. Drafting the article: Candela-Cantó. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Candela-Cantó. Study supervision: Aparicio, Hinojosa, Rumià.
Supplemental Information
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