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CASE REPORT
Year : 2011  |  Volume : 59  |  Issue : 5  |  Page : 748-752

Multimodal approach in the surgical treatment of refractory epilepsy associated with tuberous sclerosis complex: A series of three cases


Department of Neurosurgery, West China Hospital of Sichuan University, Chengdu, China

Date of Submission01-May-2011
Date of Decision16-May-2011
Date of Acceptance28-Jul-2011
Date of Web Publication22-Oct-2011

Correspondence Address:
Jianguo Xu
Department of Neurosurgery, West China Hospital of Sichuan University, No. 37 Guoxue Road, Chengdu - 610 041
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.86553

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 » Abstract 

We describe the surgical treatment of tuberous sclerosis complex (TSC)-related refractory epilepsy in three patients. All three had multiple daily seizures, and each had more than three cortical tubers. High-resolution magnetic resonance imaging, ictal and interictal scalp electroencephalogram (EEG), positron emission tomography, magnetoencephalography as well as acute and intracranial video-EEG were used to identify the epileptogenic tubers. After localization, five cortical tubers (two in the right temporal lobe in patient 1; one each in the left frontal and temporal lobes in patient 2; and one in the right frontal lobe in patient 3) were resected. At minimum follow-up of 13 months (range, 13-35 months), patient 3 had seizure remission; patient 2 had only rare seizures; while patient 1 had 60% reduction in seizure frequency. Successful epilepsy surgery is possible in patients of TSC with multiple tubers using the multimodal approach.


Keywords: Electroencephalogram, epilepsy, surgical treatment, tuberous sclerosis complex


How to cite this article:
Li Q, You C, Fang Y, Xu J. Multimodal approach in the surgical treatment of refractory epilepsy associated with tuberous sclerosis complex: A series of three cases. Neurol India 2011;59:748-52

How to cite this URL:
Li Q, You C, Fang Y, Xu J. Multimodal approach in the surgical treatment of refractory epilepsy associated with tuberous sclerosis complex: A series of three cases. Neurol India [serial online] 2011 [cited 2019 Jul 19];59:748-52. Available from: http://www.neurologyindia.com/text.asp?2011/59/5/748/86553



 » Introduction Top


Tuberous sclerosis complex (TSC) is a genetic disorder and affects multiple systems, and is associated with medically refractory seizures in children, often leading to neuropsychological impairments. Reports of surgical treatment in TSC-related refractory epilepsy have been limited. [1] Because most patients harbor multiple epileptogenic tubers, it is difficult to localize them with non-lateralizing electroencephalogram (EEG), and novel approaches have been adopted. [1],[2],[3] Pre-operative evaluation using multiple modalities may define target tuber better and improve outcomes. We report three patients with TSC-related refractory epilepsy, with special focus on the multimodal approach in the surgical management.


 » Case Reports Top


Pre-operative evaluation

In the period between 2006 and 2008, five patients with TSC were considered as candidates for surgical treatment, and three of them had pre-surgical workup [Table 1]. All the three patients had regular scalp EEG and magnetic resonance imaging (MRI) in an outpatient clinic. Patients were admitted for scalp video-EEG (VEEG) for 24-72 h (mean, 43 h). These patients were subjected to stage 2 evaluation when the baseline evaluation showed concordant information, which included intracranial VEEG monitoring, [18F]-FDG-positron emission tomography 18F-FDG-PET and magnetoencephalogram (MEG). Based on scalp VEEG recordings, 24-channel intracranial VEEG was performed with intracranial electrodes positioned on the bilateral frontal and temporal lobes. The recordings lasted 72-96 h (mean, 80 h). The data, clinical symptoms, intracranial VEEG recordings, localization of tuber, PET and MEG results were analyzed together, and only patients with concordant data were finally selected for operation under general anesthesia. During operation, EEG monitoring was done before and after each tuber resection. When residual discharge was recorded after target tuber resection, cortex surrounding the tubers was cauterized at 4-6 watts and 1-2 s, followed by repeat EEG until no abnormal discharge was recorded.
Table 1: Clinical data of patients

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All the patients had medically refractory seizures with skin pigmentation or facial angiofibroma. MRI showed hypointense sub-ependymal nodules and hyperintense cortical tubers on T2-weighted imaging [Figure 1]. MEG showed focal discharge in regions near the epileptogenic lesions. All resected tubers were at least 1 cm away from the eloquent areas. Pathological diagnosis was confirmed as loss of normal six layers, disorganized large pyramidal or "giant" cells in reactive gliosis with eosinophilic neurofibrils. Follow-up was through outpatient clinic visits [Table 2]. The study was approved by the Ethics Committee of the West China Hospital, and parents of the patients gave informed consent.
Figure 1: Pre-operative magnetic resonance imaging of all three patients. Panel 1 - images of Patient 1. Arrows indicated two target tubers in the right temporal lobe (a), and tubers can also be found in the subependyma of the bilateral ventricles (b). Panel 2 - images of Patient 2. Arrows indicated target tubers near the left hippocampus in and in the left frontal lobe in (b). Panel 3 - images of Patient 3. Subependymal tubers could be found in the bilateral ventricles in and the arrow in (b) indicated one target tuber in the right frontal lobe

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Table 2: Clinical data of patients

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Case 1

A 6-year-old boy with a 3-year history of seizures had daily episodes of atypical absence and weekly generalized tonic-clonic seizures (GTCS) and no family history of TSC. His intelligent quotient (IQ) was 83. Pre-operative MRI showed two subcortical tubers in the right temporal lobe and others in the subependyma [Figure 1]a and b. Intracranial ictal VEEG showed generalized irregular spikes and waves in the right temporal lobe and PET scan showed hypometabolism in the corresponding region [Table 1]. Tubers in the right temporal lobe were identified as epileptogenic, and the patient underwent total resection and cortex cauterization under EEG surveillance. Follow-up was 13 months, and he had 60% reduction in seizure frequency (Engel class III).

Case 2

A 8-year-old girl with a 4.5-year history of seizures had simple and complex partial motor seizures and drop attacks almost every day and GTCS every week. She had a family history of TSC and her IQ was 79. MRI showed one tuber each in the left frontal and temporal lobes, and other tubers in the right frontal lobe [Figure 1]c, d. Intracranial VEEG showed generalized irregular spikes and waves in the left frontal and temporal lobes and PET scan revealed hypometabolism in the corresponding regions [Table 1]. Tubers in the left frontal and temporal lobes were identified as epileptogenic and were resected under EEG surveillance. She also underwent cortex cauterization. She had only four seizures during 35 months follow-up after operation, with significantly reduced severity and duration (Engel class II).

Case 3

An 11-year-old boy with a 5-year history of seizures had simple and complex partial seizures and absence seizures everyday and no GTCS. His IQ was 75 [Table 1]. Pre-operative MRI revealed one tuber in the right frontal lobe and others in the subependyma [Figure 1]e, f. Interictal scalp EEG showed high sharp waves in the right frontal lobe [Figure 2]a and VEEG showed sharp and slow waves in the right frontal lobe [Figure 2]c and d. Intracranial ictal VEEG showed 2.5-4 Hz-high spike waves in the right frontal lobe [Figure 3]. PET scan revealed hypometabolism in the right fontal and temporal lobes [Figure 2]b. Because there was no identifiable tuber in MRI and VEEG showed no primary ictal discharge in the right temporal lobe, the tuber in the right frontal lobe was identified as epileptogenic and was resected. The patient did not undergo cortex cauterization and had no seizure relapse after operation (Engel class I).
Figure 2: Non-invasive electroencephalogram (EEG) and positron emission tomography (PET) of Patient 3. (a) Inter-ictal regular scalp EEG showed high sharp waves in the right frontal lobe. Reference voltage was 100 μV/cm. (b) PET scan revealed marked hypometabolism in the right frontal lobe. (c and d) 18-channel scalp video EEG recordings. The patient experienced no seizure attack during the recording period, but sharp waves and slow waves can be found in the right frontal lobe, which was concordant with findings in the regular scalp EEG and PET scan. Reference voltage was 150 μV/cm. Electrodes were positioned according to the 10-20 system

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Figure 3: 24-channel cortex surface video electroencephalogram (EEG) recordings of Patient 3. (a and b) Position of the cortex surface electrodes. Arrows showed electrodes on the bilateral frontal and temporal lobes. (c) Inter-ictal EEG recordings were similar to those in the scalp video EEG. (d) Ictal EEG showed epileptic discharge started in the right frontal lobe, and spread to the left frontal lobe. Reference voltage was 300 ìV/cm

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 » Discussion Top


TSC-related seizures when uncontrolled cause neuropsychological impairments and are critical problems for such patients. [4] Thus, seizure control is a cardinal issue in the management of TSC. However, TSC-related seizures are often medically refractory, and surgical treatment is a treatment option.

Identification of epileptogenic tuber is of utmost importance in the surgical management of TSC-related seizures. However, most often, patients with TSC may have more than one epileptogenic tuber, and localization of epileptogenic tuber is quite challenging. Nevertheless, several novel approaches have been described to facilitate this process. [1],[2],[3] Wu et al. [1] reported a non-invasive approach using magnetic source imaging (MSI) and PET/MRI co-registration for localization of epileptogenic tuber. In their study of the 28 patients, 18 (64%) patients had surgery based on the concordant data and 12 (67%) had seizure freedom post-operatively. MEG with synthetic aperture magnetometry (SAM) has been shown to be useful in localizing complex epileptogenic zones; of the seven patients in this study, six were seizure-free after resection. [2] For better localization of the epileptogenic zone, invasive surgical approach including 3-staged epilepsy surgery has been proposed. [3] More than 68% of the patients undergoing multistage epilepsy surgery were in Engel class I at mean follow-up of 28 months. Four of the five patients who were earlier considered as not candidates for surgery because of the multifocal epileptogenic zones were seizure-free when operated by this novel approach. However, with the advancement of technology, non-invasive methods may be the future for pre-operative evaluation of epileptogenic tubers in patients with TSC.

The principle of epileptogenic zone localization is concordance of data from different modalities. High-resolution MRI provides precise anatomical location and structural evidence for sclerotic tubers in TSC, and is essential in surgical planning. Intericatal scalp EEG may seldom catch ictal discharges, but may help in hemispherical lateralization if not lobar localization. Scalp VEEG is very useful in documenting the clinical events and the associated ictal discharge patterns. Based on this data, the next stage of pre-surgical workup, including intracranial VEEG, PET and MEG, could be planned. If scalp VEEG fails to localize the epileptogenic zone, intracranial VEEG would be necessary for accurate localization. Intracranial electrodes can be placed in a relatively pre-defined area based on the scalp VEEG information thus avoiding large craniotomy. Intraoperative electrocorticography determines the exact location of the epileptogenic and may also guide and determine cortex cauterization. PET and MEG are accessory investigative modalities for better localization of epileptogenic tubers. However, in our view, surgical indications should adhere to the classical triad of clinical seizure semiology, MRI and VEEG, and PET or MEG provides extra data in surgical management of TSC-related seizures.

There is growing consensus that TSC-related epilepsy may be treated surgically. [5] However, resection of epileptogenic tubers in the eloquent region often results in neurological deficits, and low-power cauterization with bipolar on this region may be used to reduce seizure frequency. [6] If epileptogenic tuber is not suitable for surgical resection, stereotactic radiosurgery could be an alternative to craniotomy surgery, [7] and its effect is more of irradiation in the epileptogenic zone than radiation dose to the tubers. [8] In the report by Romanelli et al., a 40% reduction of seizure frequency was observed in one patient who had little benefit from subtotal tuber resection. [7]

Based on our experience and review of the literature, multiple epileptogenic tubers are not necessarily a contraindication for surgical resection, and the outcome is not related to the number of tubers. In the series by Weiner et al., [3] 92% of the patients, even with multiple epileptogenic foci, had Engel Class I and II outcome in both short- and long-term follow-up. One of our patients had Class III outcome, and it is quite possible in him that one of the other tubers might have evolved to epileptogenic tuber, thus, emphasizing the need for long term follow-up of these patients. When seizures relapse or the seizure frequency increases, these patients may require re-evaluation for possible second surgery.


 » Acknowledgments Top


We would like to thank D Zhou for pre-operative evaluation and Q Zhou for defining the pathological characteristics of the resected lesions.

 
 » References Top

1.Wu JY, Salamon N, Kirsch HE, Mantle MM, Nagarajan SS, Kurelowech L, et al. Noninvasive testing, early surgery, and seizure freedom in tuberous sclerosis complex. Neurology 2010;74:392-8.  Back to cited text no. 1
[PUBMED]  [FULLTEXT]  
2.Sugiyama I, Imai K, Yamaguchi Y, Ochi A, Akizuki Y, Go C, et al. Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis. J Neurosurg Pediatr 2009;4:515-22.  Back to cited text no. 2
[PUBMED]  [FULLTEXT]  
3.Weiner HL, Carlson C, Ridgway EB, Zaroff CM, Miles D, LaJoie J, et al. Epilepsy surgery in young children with tuberous sclerosis: Results of a novel approach. Pediatrics 2006;117:1494-502.  Back to cited text no. 3
[PUBMED]  [FULLTEXT]  
4.Ess KC. Treatment of infantile spasms in tuberous sclerosis complex: Dismal outcomes but future hope? Nat Clin Pract Neurol 2009;5:72-3.  Back to cited text no. 4
[PUBMED]  [FULLTEXT]  
5.Hemb M, Velasco TR, Parnes MS, Wu JY, Lerner JT, Matsumoto JH, et al. Improved outcomes in pediatric epilepsy surgery: The ucla experience, 1986-2008. Neurology 2010;74:1768-75.  Back to cited text no. 5
[PUBMED]  [FULLTEXT]  
6.Luan G, Sun Z, Bai Q, Wang C. Surgical treatment of intractable epilepsy combined with bipolar electrocoagulation on functional cortex. Stereotact Funct Neurosurg 2001;77:233-8.  Back to cited text no. 6
[PUBMED]  [FULLTEXT]  
7.Romanelli P, Verdecchia M, Rodas R, Seri S, Curatolo P. Epilepsy surgery for tuberous sclerosis. Pediatr Neurol 2004;31:239-47.  Back to cited text no. 7
[PUBMED]  [FULLTEXT]  
8.Regis J, Bartolomei F, de Toffol B, Genton P, Kobayashi T, Mori Y, et al. Gamma knife surgery for epilepsy related to hypothalamic hamartomas. Neurosurgery 2000;47:1343-52.  Back to cited text no. 8
    


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    Tables

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