Treatment of seizures in subcortical laminar heterotopia with corpus callosotomy and lamotrigine

Non-pharmacological treatment options of drug-resistant epilepsy in subcortical band heterotopia: systematic review and illustrative case

OBJECTIVE

Subcortical band heterotopia is a rare X-linked neuronal migration disorder primarily in females often associated with drug-resistant epilepsy. The aim of this study is to review the literature for non-pharmacological treatment options of drug-resistant epilepsy in subcortical band heterotopia.

MATERIAL AND METHODS

In accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we performed a systematic review. Entering the keywords "double cortex," "subcortical band heterotopia," and "subcortical laminar heterotopia," we searched Scopus and PubMed databases. We paid particular attention to type of invasive and non-invasive treatment, radiological presentation, and outcome. We also describe a related case report, managed at Alder Hey Children's Hospital, Liverpool.

RESULTS

The systematic literature review yielded 25 patients with subcortical band heterotopia and drug-resistant epilepsy who underwent non-pharmacological treatment. Including our patient, 26 patients were reported. The patients' mean age at seizure onset was 6.5 years (range 0.2-23) with a female sex predilection (5.25:1). The patients' mean age at invasive or non-invasive treatment was 21.5 years (range 6.5-51). The 26 patients underwent 29 non-pharmacological treatments. Ten patients underwent corpus callosotomy; 8 patients had a formal temporal lobectomy. Three patients had focal cortical resection. Two patients respectively had multiple subpial transections, insertion of a vagal nerve stimulator, or deep brain stimulation of the bilateral anterior nuclei of the thalamus. One patient underwent responsive focal neurostimulation. Another patient had transcutaneous stimulation of the vagal nerve. Sixteen patients reported a reduction or the disappearance of the seizures; 1 patient had no improvement. The outcome of 2 patients was classified class I, of 1 patient class II, of 1 patient class III, and of 5 patients class IV according to the Engel Epilepsy Surgery Outcome Scale.

CONCLUSION

Mainly corpus callosotomy and formal temporal lobectomy have been performed as non-pharmacological treatment with few cases published overall. Several other invasive procedures and one non-invasive technique are based on case reports. The small number of reported cases prevents drawing a firm conclusion as to which non-pharmacological treatment is the best treatment option for refractive epilepsy in patients with subcortical band heterotopia.

Incremental changes in interhemispheric functional connectivity after two-stage corpus callosotomy in a patient with subcortical band heterotopia

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Coherence calculated from scalp EEG may be utilized to evaluate functional connectivity.

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Functional connectivity decreased stepwise after anterior/posterior callosotomy.

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Correlation was seen between functional connectivity and seizure frequency change.

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Functional connectivity may reflect seizure outcome of callosotomy.

Corpus callosotomy (CC) has been reported to be effective in reducing generalized seizures in patients with drug-resistant epilepsies. However, efficacy is measured only by seizure frequency, without any electrophysiological guidance. Herein, we conducted a quantitative analysis of interhemispheric functional connectivity using inter-electrode coherence of scalp electroencephalogram (EEG) in a clinical case of subcortical band heterotopia to evaluate its relationship with seizure frequency. In our case, seizure frequency decreased significantly after posterior CC but not after anterior CC. Inter-electrode coherence also decreased after posterior CC, suggesting it correlated with seizure frequency. This case study supports the use of inter-electrode coherence as an electrophysiological tool that is useful as predictive factor in evaluating the effectiveness of CC.

Hypothalamic Hamartoma, Gray Matter Heterotopia, and Polymicrogyria in a Boy: Case Report and Literature Review

BACKGROUND

Hypothalamic hamartomas (HHs) are rare, and it is even rarer when combined with gray matter heterotopia (GMH) and polymicrogyria (PMG).

CASE DESCRIPTION

A 5-year-old boy with HH, GMH, and PMG was retrospectively evaluated. The clinical data, including the symptoms, examinations, diagnosis, and treatment, were collected. The patient had a chief complaint of gelastic seizures and intellectual deficiency. Brain magnetic resonance imaging showed HH, paraventricular nodular heterotopia, and PMG. Video electroencephalographs were normal. The patient underwent resection of the HH via transcallosal transseptal interforniceal approach. Seizures disappeared immediately after complete resection of HH, and the intellectual development improved.

CONCLUSIONS

In this extremely rare case, resection of the HH eliminated the symptoms. Nonetheless, we still need to be cautious about the possible epilepsy that may be caused by GMH and PMG.

Spontaneous epileptiform activity in a rat model of bilateral subcortical band heterotopia

OBJECTIVE

Malformations of cortical development are common causes of intellectual disability and epilepsy, yet there is a crucial lack of relevant preclinical models associating seizures and cortical malformations. Here, we describe a novel rat model with bilateral subcortical band heterotopia (SBH) and examine whether this model develops spontaneous epileptic seizures.

METHODS

To generate bilateral SBH in rats, we combined RNAi-mediated knockdown of Dcx and in utero electroporation with a tripolar electrode configuration enabling simultaneous transfection of the two brain hemispheres. To determine whether bilateral SBH leads to epileptiform activity, rats of various ages were implanted for telemetric electrocorticographic recordings and histopathological examination was carried out at the end of the recording sessions.

RESULTS

By 2 months, rats with bilateral SBH showed nonconvulsive spontaneous seizures consisting of spike-and-wave discharges (SWDs) with dominant frequencies in the alpha and theta bands and secondarily in higher-frequency bands. SWDs occurred during both the dark and the light period, but were more frequent during quiet awake state than during sleep. Also, SWDs were more frequent and lasted longer at older ages. No sex differences were found. Although frequencies and durations of SWDs were found to be uncorrelated with the size of SBH, SWDs were initiated in some occasions from brain hemispheres comprising a larger SBH. Lastly, SWDs exhibited absence-like pharmacological properties, being temporarily alleviated by ethosuximide administration.

SIGNIFICANCE

This novel model of bilateral SBH with spontaneous epilepsy may potentially provide valuable new insights into causality between cortical malformations and seizures, and help translational research aiming at designing novel treatment strategies for epilepsy.

Management of Status Epilepticus in Children

Status epilepticus is a common pediatric neurological emergency. Management includes prompt administration of appropriately selected anti-seizure medications, identification and treatment of seizure precipitant(s), as well as identification and management of associated systemic complications. This review discusses the definitions, classification, epidemiology and management of status epilepticus and refractory status epilepticus in children.

Corpus callosum and epilepsies

Introduction.Corpus callosum (CC) is the largest forebrain commissure. Structural anomalies and accompanying clinical symptoms are not in the focus of neurologists, epileptologists or neurosurgeons.

Aim and method.Anatomy, embryological development, normal functions, structural abnormalities, additional malformations, clinical symptoms and seizure disorders with CC anomalies are reviewed from the literature.

Review.The detection of callosal anomalies increased rapidly with widespread use of brain imaging methods. Agenesis or dysgenesis of corpus callosum (AgCC) might be considered an accidental finding. Epileptic seizures occur in up to 89% of patients with AgCC. The causal relationship correctly is questioned. However, additional causative malformations of midline and/or telencephalic structures can be demonstrated in most seizure patients. The interruption of bilateral spread of seizure activities acts as the concept for callosotomy as epilepsy surgery. Indications are drug-resistant generalized, diffuse, or multifocal epilepsies. A resectable seizure onset zone should be excluded. Most treated patients are diagnosed as Lennox-Gastaut or Lennox-like syndrome.

Conclusions.In cases with callosal abnormalities and clinical symptoms additional malformations are frequently observed, especially with seizure disorders. Callosotomy is the most effective option against drop attacks. The method probably is underused. After callosotomy a circumscript seizure focus might be unveiled and a second step of resective epilepsy surgery can be successful.

Corpus callosotomy for treatment of pediatric refractory status epilepticus

Medically refractory status epilepticus (RSE) causes high morbidity and mortality in children. There are no evidence-based guidelines for treatment. Epilepsy surgery is a treatment option for RSE. We describe a 9-year-old boy treated successfully for RSE with complete corpus callosotomy (CC). Epilepsy surgery should be considered for prolonged RSE. In the absence of evidence of focal epileptogenesis, complete corpus callosotomy may be effective in select cases.

Modified Atkins diet for the treatment of nonconvulsive status epilepticus in children

The authors describe the use of a modified Atkins diet for the treatment of 2 children with nonconvulsive status epilepticus. Patient 1 was a 4-year-and-11-month-old girl diagnosed with frontal lobe epilepsy. Since the age of 3 years and 10 months, she had daily nonconvulsive status epilepticus resistant to antiepileptic agents. Patient 2 was a 5-year-and-5-month-old girl with subcortical band heterotopia. She had nonconvulsive status epilepticus daily since the age of 5 years. They were treated with the modified Atkins diet, in which carbohydrate intake was restricted to 10 g/d without restriction on protein, caloric, or fluid intake. The nonconvulsive status epilepticus disappeared 5 and 10 days after the initiation of the diet treatment, respectively. They have been on the diet treatment and free from nonconvulsive status epilepticus for 19 and 4 months, respectively. The modified Atkins diet appears to be very effective for the treatment of nonconvulsive status epilepticus.

Treatment of refractory status epilepticus: literature review and a proposed protocol

Refractory status epilepticus describes continuing seizures despite adequate initial pharmacologic treatment. This situation is common in children, but few data are available to guide management. We review the literature related to the pharmacologic treatment and overall management of refractory status epilepticus, including midazolam, pentobarbital, phenobarbital, propofol, inhaled anesthetics, ketamine, valproic acid, topiramate, levetiracetam, pyridoxine, corticosteroids, the ketogenic diet, and electroconvulsive therapy. Based on the available data, we present a sample treatment algorithm that emphasizes the need for rapid therapeutic intervention, employs consecutive medications with different mechanisms of action, and attempts to minimize the risk of hypotension. The initial steps suggest using benzodiazepines and phenytoin. Second steps suggest using levetiracetam or valproic acid, which exert few hemodynamic adverse effects and have multiple mechanisms of action. Additional management strategies that could be employed in tertiary-care settings, such as coma induction guided by continuous electroencephalogram monitoring and surgical options, are also discussed.

Ictal/interictal EEG patterns and functional neuroimaging findings in subcortical band heterotopia: report of three cases and review of the literature

Subcortical band heterotopia (SBH) is a rare, genetic disorder of neuronal migration, which is seen almost exclusively in females. Little is known about the functionality of the band heterotopia, in terms of both physiology and pathology, in this malformation. Patients are reported to have several different types of seizures, which are usually drug resistant. Interictal EEG findings are known to correlate with the type of seizures, however less is known about the ictal EEG patterns. We present 3 female patients who were investigated at our center with video-scalp EEG monitoring, interictal single photon emission computed tomography (SPECT), functional magnetic resonance (MR) imaging (fMRI) and MR spectroscopy (MRS) besides routine MR imaging. They had several different types of seizures, and one of them reported also having circling seizures that have not been reported previously in patients with SBH. Ictal EEG recordings were remarkable for their unusual patterns of propagation. The findings in structural and functional neuroradiological investigations are discussed in light of the literature.

Brief Report: The Impact of Subcortical Band Heterotopia and Associated Complications on the Neuropsychological Functioning of a 13-year-old Child

Motor impairment in children with Asperger syndrome (AS) or high functioning autism (HFA) has been reported previously. This study presents results of a quantitative assessment of neuromotor skills in 14-22 year old HFA/AS. Sixteen HFA/AS and 16 IQ-matched controls were assessed by the Zurich Neuromotor Assessment (ZNA). The HFA/AS group showed strongest impairments of dynamic balance skills and diadochokinesis. Motor abilities were associated with degree of social withdrawal in the full sample and severity of current autistic symptoms in the HFA/AS group. Similar motor patterns as in younger children were found in the older adolescents. The association of autistic symptoms with motor performance points towards an essential role of motor impairment in autism spectrum disorders.

Refractory status epilepticus

PURPOSE OF REVIEW

Although conventional anticonvulsant agents can terminate status epilepticus in most cases, a substantial minority of patients develops medically refractory status and requires more aggressive care. This review explores the options available.

RECENT FINDINGS

Increasing numbers of previously unexpected etiologies for refractory status epilepticus continue to be reported. There are also some promising new therapies on the horizon, both for the short and the longer terms.

SUMMARY

Refractory status epilepticus, while a challenge to the intensivist, can be treated with drugs that are commonly used by intensivists. The cooperation of an interested electroencephalographer is vital.

[Heterotopic gray matter. Report of four pediatric cases]

Severe infant epilepsy is included within difficult etiologic diagnosis. Gray matter heterotopias are an uncommon cause. The authors report four observations of gray matter heteropias concerning three-, six-, seven- and nine-year-old girls, presenting no particular antecedents. No consanguinity was noted. The first occurrence of epilepsy ranged from the age of nine months to the age of four years. A mild mental retardation was found in three cases, and mental regression in one case. A status epilepticus was noted in three children. Magnetic resonance imaging scans showed subependymal heterotopias in one case and diffuse cortical heterotopias in three cases associated to a partial agenesis of corpus calloseum in one case and pachygyria in two cases.

Effects of antiepileptic drugs on induced epileptiform activity in a rat model of dysplasia

Seizure activity associated with cortical dysplasia (CD) is often resistant to standard pharmacologic treatments. Although several animal models exhibit CD, virtually nothing is known about antiepileptic drug (AED) responses in these animals. Here we have used rats exposed to methylazoxymethanol acetate (MAM) in utero, an animal model featuring nodular heterotopia, to investigate the effects of AEDs in the dysplastic brain. 4-aminopyridine (100 microM), a K(+) channel blocker, was used to induce interictal epileptiform bursting in acute hippocampal slices from MAM-exposed and age-matched vehicle-injected control animals. Extracellular field recordings were used to monitor seizure activity in vitro. Five commonly used AEDs were tested: phenobarbital, 25-400 microM; carbamazepine, 25-200 microM; valproate (VPA), 0.19-4 mM; ethosuximide (ESM), 0.5-8 mM; and lamotrigine (LTG), 49-390 microM. 4-AP-induced bursting occurred with shorter latencies in slices from MAM-exposed rats in comparison with slices from controls, confirming the intrinsic hyperexcitability of dysplastic tissue. Each AED tested demonstrated significant burst suppression in control slices, but interictal epileptiform bursting in MAM-exposed slices was resistant to these treatments. Even at the highest concentrations, VPA, ESM and LTG had no effect on burst amplitude in slices from MAM-exposed rats. Pharmaco-resistance was further tested by measuring seizure latencies in awake, freely-moving rats after kainate administration (15 mg/kg, i.p.) with and without pre-treatment with VPA (400 mg/kg i.p.). Pre-treatment with VPA prolonged seizure latency in control rats, but had no effect in MAM-exposed animals. These results suggest MAM-exposed rats exhibit a dramatically reduced sensitivity to commonly prescribed AEDs.

Surgical resection for intractable epilepsy in "double cortex" syndrome yields inadequate results

PURPOSE

To analyze the results of surgical treatment of intractable epilepsy in patients with subcortical band heterotopia, or double cortex syndrome, a diffuse neuronal migration disorder.

METHODS

We studied eight patients (five women) with double cortex syndrome and intractable epilepsy. All had a comprehensive presurgical evaluation including prolonged video-EEG recordings and magnetic resonance imaging (MRI).

RESULTS

All patients had partial seizures, with secondary generalization in six of them. Neurologic examination was normal in all. Three were of normal intelligence, and five were mildly retarded. Six patients underwent invasive EEG recordings, three of them with subdural grids and three with stereotactic implanted depth electrodes (SEEG). Although EEG recordings showed multilobar epileptic abnormalities in most patients, regional or focal seizure onset was recorded in all. MRI showed bilateral subcortical band heterotopia, asymmetric in thickness in three. An additional area of cortical thickening in the left frontal lobe was found in one patient. Surgical procedures included multiple subpial transections in two patients, frontal lesionectomy in one, temporal lobectomy with amygdalohippocampectomy in five, and an additional anterior callosotomy in one. Five patients had no significant improvement, two had some improvement, and one was greatly improved.

CONCLUSION

Our results do not support focal surgical removal of epileptogenic tissue in patients with double cortex syndrome, even in the presence of a relatively localized epileptogenic area.