Hemispherotomy in an infant with hemimegalencephaly and Ohtahara syndrome

We represent the case of a premature twin neonate born from uncomplicated pregnancy who developed seizures at the age of 24 h. Two-dimensional ultrasound and magnetic resonance imaging revealed left-sided hemimegalencephaly. Further extensive diagnostic evaluation revealed a diagnosis of Ohtahara syndrome. Resistance of the seizures to antiepileptic therapy led to hemispherotomy that was performed at the age of 10 months. Our patient is now a 4-year-old child, walking, eating without a nasogastric tube, still with right hemiparesis and lateral strabismus but without seizures.

Clinical characteristics and surgical management of facial infiltrating lipomatosis: a single center experience

BACKGROUND

Facial infiltrating lipomatosis (FIL) is a rare condition characterized by congenital facial enlargement. Beyond its impact on physical appearance, FIL can also impair essential facial functions such as swallowing, chewing, vision, and breathing, imposing a substantial physiological and psychological burden. Currently, fewer than 80 cases of FIL have been reported, and the characteristics and management strategies for FIL remain unclear.

METHODS

We reviewed the clinical, surgical, and radiological records of 39 FIL patients who were treated at our center. Of these, genetic testing was performed for 21 patients.

RESULTS

Aberrant overgrowth involves subcutaneous fat, bones, muscles, glands, tongue, lips, and teeth. Epidermal nevi could be observed in the dermatomes innervated by the three branches of the trigeminal nerve, with the highest frequency seen in the dermatome of the mandibular branch. Four patients exhibited concurrent hemimegalencephaly (HMEG), with one case presenting HMEG on the opposite side of the FIL. Nineteen patients were confirmed to harbor the PIK3CA mutation. Thirty-three patients underwent surgical procedures, with a post resection recurrence rate of approximately 25%.

CONCLUSIONS

A variety of maxillofacial structures may be involved in FIL. PIK3CA mutations are important pathogenic factors. Emerging targeted therapies could present an additional treatment avenue in the future. However, surgery currently remains the predominant treatment choice for FIL. The timing and modality of surgery should be individually customized, taking into account each patient's unique circumstances. Notably, there is a significant possibility of postoperative recurrence during childhood and adolescence, necessitating early strategic planning of disease management.

Predicting seizure outcomes and functional outcomes after hemispherotomy: are we any better?

INTRODUCTION

Present study attempted to analyze seizure freedom and detailed functional outcomes after functional hemispherotomy and utility of hemispherotomy outcome prediction scale (HOPS) scores in predicting outcomes.

METHODS

Patients who underwent functional hemispherotomy were analyzed for clinical presentation, neuroimaging, seizure outcomes, and functional outcomes.

RESULTS

A total of 76 procedures were performed on 69 patients. Mean age at the surgery was 8 ± 6.1 years. Fourteen patients were < 2 years. Age of onset epilepsy of the cohort was 2.0 ± 3.3 years. All had severe catastrophic epilepsy with multiple daily seizures. All patients had motor deficits with 36 (52%) patients had contralateral dysfunctional hand. Perinatal stroke (49%) was most common substrate followed by cortical malformations (21.7%). Eight patients had contralateral imaging abnormalities. Fifty-nine (86.76%) patients remained seizure free (Engle 1a) at 41 + -20.9 months. HOPS scores were available for 53 patients and lowest seizure outcome was 71% for HOPS score of 4. Lower HOPS scores predicted better seizure outcomes. Cortical malformations operated earlier than 2 years predicted poor seizure outcomes (66.6%). Positive functional outcomes are recorded in 80% of patients with 78% reporting improvement from the pre-surgical level. Five (7.2%) patients underwent shunt surgery. One mortality recorded.

CONCLUSIONS

Hemispherotomy has excellent seizure outcomes. Early surgery in cortical malformations appears to be predictor of poorer seizure outcomes. HOPS score is a good tool to predict the seizure outcomes. Hemispherotomy is perceived to improve the Cognitive and functional performance.

Neuroimaging Findings in Fetal Hemimegalencephaly: Case Study and Review

BACKGROUND

Limited information exists in the prenatal literature regarding the neuroimaging features of fetal hemimegalencephaly.

SUMMARY

This report describes ultrasound and magnetic resonance imaging (MRI) findings in a second-trimester fetus with an isolated, severe form of hemimegalencephaly. The most prominent imaging findings included unilateral enlarged cerebral hemisphere and ipsilateral ventriculomegaly causing cerebral asymmetry, midline shift, and macrocephaly. Abnormal cortical development imaging signs were also evident. A literature review encompassing 23 reports describing 36 cases, including ours, is presented.

KEY MESSAGES

Characteristic ultrasound findings for the diagnosis of hemimegalencephaly are not always apparent prenatally. Asymmetric ventriculomegaly emerges as the most common but nonspecific presenting feature during routine second- or third-trimester ultrasound scans. Subsequent high-resolution prenatal neurosonography and fetal MRI facilitate definitive prenatal diagnosis, showcasting associated features primarily related to cortical migration, differentiation, and maturation. Postnatally, the prognosis is poor due to intractable seizures, hemiplegia, and progressive neurodevelopmental delay.

Contralateral hippocampal sclerosis following functional hemispherectomy in children: A report of three cases

PURPOSE

Hippocampal Sclerosis (HS) may co-exist with temporal or extratemporal lesions (dual pathology) in children and is usually ipsilateral to the radiological lesion. Here were report three cases with extensive hemispheric cortical malformation and drug resistant epilepsy who had persistent seizures after functional hemispherectomy (FH) and developed contralateral HS after the surgery.

METHODS

This retrospective study enrolled children who underwent FH and developed contralateral HS after surgery. Their clinical, EEG, radiological and pathological data were reviewed and summarized.

RESULTS

Ninety-five children underwent FH during the study period; Three cases (3.2%) were eligible. They all had unilateral extensive hemispheric cortical malformation who underwent FH between 3 and 5 months of age with no clinical, EEG or radiological suggestion for involvement of contralateral hemisphere prior to FH. All three patients had persisting seizures after FH. Contralateral HS was detected between 2.2 to 3.7 years after FH in all three cases. Two of the patients showed pathogenic variants in GATOR1 pathway genes.

CONCLUSIONS

The genesis of contralateral HS in the reported patients remains unexplained. The presence and distribution of "second-hit" somatic mutations may play an important role in governing the seizure outcomes of epilepsy surgery in patients with apparently unilateral malformations of cortical development.

Technological and computational approaches to detect somatic mosaicism in epilepsy

Lesional epilepsy is a common and severe disease commonly associated with malformations of cortical development, including focal cortical dysplasia and hemimegalencephaly. Recent advances in sequencing and variant calling technologies have identified several genetic causes, including both short/single nucleotide and structural somatic variation. In this review, we aim to provide a comprehensive overview of the methodological advancements in this field while highlighting the unresolved technological and computational challenges that persist, including ultra-low variant allele fractions in bulk tissue, low availability of paired control samples, spatial variability of mutational burden within the lesion, and the issue of false-positive calls and validation procedures. Information from genetic testing in focal epilepsy may be integrated into clinical care to inform histopathological diagnosis, postoperative prognosis, and candidate precision therapies.

mTOR pathway: Insights into an established pathway for brain mosaicism in epilepsy

The mechanistic target of rapamycin (mTOR) signaling pathway is an essential regulator of numerous cellular activities such as metabolism, growth, proliferation, and survival. The mTOR cascade recently emerged as a critical player in the pathogenesis of focal epilepsies and cortical malformations. The 'mTORopathies' comprise a spectrum of cortical malformations that range from whole brain (megalencephaly) and hemispheric (hemimegalencephaly) abnormalities to focal abnormalities, such as focal cortical dysplasia type II (FCDII), which manifest with drug-resistant epilepsies. The spectrum of cortical dysplasia results from somatic brain mutations in the mTOR pathway activators AKT3, MTOR, PIK3CA, and RHEB and from germline and somatic mutations in mTOR pathway repressors, DEPDC5, NPRL2, NPRL3, TSC1 and TSC2. The mTORopathies are characterized by excessive mTOR pathway activation, leading to a broad range of structural and functional impairments. Here, we provide a comprehensive literature review of somatic mTOR-activating mutations linked to epilepsy and cortical malformations in 292 patients and discuss the perspectives of targeted therapeutics for personalized medicine.

Neuroimaging features of genetic syndromes associated with CNS overgrowth

Overgrowth syndromes can manifest with enlargement of the brain and other body parts and are associated with malignancy. Much of the current literature focuses on the imaging findings of the somatic overgrowth, while there is relatively little describing the overgrowth of the central nervous system. In this pictorial essay, we discuss common syndromes with central nervous system overgrowth, highlight key imaging features, and review the underlying genetics, including the PI3K-AKT-mTOR pathway as well as other syndromes from various genes.

Viral expression of constitutively active AKT3 induces CST axonal sprouting and regeneration, but also promotes seizures

Increasing the intrinsic growth potential of neurons after injury has repeatedly been shown to promote some level of axonal regeneration in rodent models. One of the most studied pathways involves the activation of the PI3K/AKT/mTOR pathways, primarily by reducing the levels of PTEN, a negative regulator of PI3K. Likewise, activation of signal transducer and activator of transcription 3 (STAT3) has previously been shown to boost axonal regeneration and sprouting within the injured nervous system. Here, we examined the regeneration of the corticospinal tract (CST) after cortical expression of constitutively active (ca) Akt3 and STAT3, both separately and in combination. Overexpression of caAkt3 induced regeneration of CST axons past the injury site independent of caSTAT3 overexpression. STAT3 demonstrated improved axon sprouting compared to controls and contributed to a synergistic improvement in effects when combined with Akt3 but failed to promote axonal regeneration as an individual therapy. Despite showing impressive axonal regeneration, animals expressing Akt3 failed to show any functional improvement and deteriorated with time. During this period, we observed progressive Akt3 dose-dependent increase in behavioral seizures. Histology revealed increased phosphorylation of ribosomal S6 protein within the unilateral cortex, increased neuronal size, microglia activation and hemispheric enlargement (hemimegalencephaly).

Role of epilepsy surgery in refractory status epilepticus in children

INTRODUCTION

Status epilepticus (SE) is one of the most common medical emergencies, requiring urgent treatment; nearly 30 % patients develop refractory SE. The role of epilepsy surgery (ES) for refractory SE however remains unclear with empirical evidence limited to single case reports and small case series. The aim of the present study was to determine the clinical presentation, imaging characteristics and outcome of children with refractory SE who underwent emergency ES for refractory SE.

MATERIAL AND METHOD

Patients who had SE, failed to respond to escalating medical treatment of SE with/ without pharmacological suppression therapy, and eventually underwent ES were included.

RESULTS

There were ten children, 7 boys and 3 girls (range 6 months to 14 years). The age of onset of epilepsy varied from day 2 of life to 12.8 years. The duration of SE prior to surgery was 2-6 days (mean 3.7 days). Four patients had hemimegalencephaly, 3 had focal cortical dysplasia, 2 had Rasmussen's encephalitis, and one had hemispheric porencephalic cyst. The time interval between onset of seizures and ES ranged from 2 months to 8 years (mean 3.1 year). Seven patients underwent hemispherotomy, resection of dysplasia in two and temporo-parieto-occipital disconnection in one. Nine had Engel I outcome and Engel IIIa in one, at follow up of 12-44 months (mean 31 months).

CONCLUSION

Emergency ES is an effective treatment option for termination of refractory SE in children with structural pathology, after failure of medical treatment. Patients with refractory SE with focal or hemispheric structural abnormality on MRI, and concordant semiology with/without concordant EEG can be surgical candidates with or without invasive monitoring.

Postoperative seizure and developmental outcomes of children with hemimegalencephaly and drug-resistant epilepsy

OBJECTIVE

To evaluate seizure and developmental outcomes in the short and long term in children with hemimegalencephaly (HMEG) after surgery.

METHODS

This is a cohort study of 36 children who underwent surgery for HMEG were followed up for at least 1 year postoperatively. The Griffiths Mental Development Scales, Ages and Stages Questionnaire version 3, and Peabody Developmental Motor Scales were used to assess development.

RESULTS

The median postoperative follow-up duration was 2.7 (1.0-5.0) years, and median age at surgery was 1.9 years (5.8 months-5.9 years). At the last follow-up, 83% of children were seizure-free. the predicted probability of being seizure-free three years after surgery was 79%. The proportion of patients who were moderate to severe delay declined from 97% preoperatively to 76% at least 1 year after surgery. Catch-up, stabilization, and regression of developmental quotient (DQ) was observed in 41%, 35%, and 24% of children 3 months after surgery, respectively. The corresponding proportions during long-term follow-up were 40%, 33%, and 27%, respectively. Change of DQ shortly after surgery was negatively correlated with age at seizure onset and age at surgery. The long-term DQ was positively correlated with the preoperative DQ. Long-term change of DQ was positively correlated with change of DQ shortly after surgery.

CONCLUSIONS

Most of patients with HMEG could achieve seizure free after surgery. After surgery, the proportion of catch-up, stabilization, and regression in both short- and long-term DQ was approximately 40%, 35%, and 25%, respectively. The change of DQ shortly after surgery may be a predictor for long-term developmental change.

Epileptic children with hemispheres' asymmetry. Quantitative brain magnetic resonance-based analysis of apparently unaffected hemisphere. Case-control study

OBJECTIVE

We performed a quantitative hemispheres analysis in epileptic children with hemispheres' asymmetry -due to unilateral dysplastic malformation- in order to recognize subtle volumetric changes of the contralateral and apparently unaffected hemisphere.

METHODS

13 children with Hemimegalencephaly (HME) and 20 with Hemimicrencephaly (Hme) were clustered in subgroups according to underlying hemispheric cortical dysplastic malformation and epilepsy pattern. 3D FSPGR T1weighted images were used to assess white and grey matter volumes for both hemispheres. Each volumetric parameter was compared with the average of an age-matched healthy control group.

RESULTS

HME subgroups: HME with pachygyria and focal (HME-PG-F; n 6) or multifocal epilepsy (HME-PG-MF; n.7). In both subgroups affected hemisphere (AH) volume was increased and contralateral hemisphere (CH) showed white matter volume reduction; in HME-PG-MF grey matter volume of CH was more reduced than HME-PG-F. Hme subgroups: Hme with polimicrogyria and focal epilepsy (Hme-PMG-F; n.8), Hme with giant subcortical nodular heterotopia and focal (Hme-SCH-F; n.6) or multifocal epilepsy (Hme-SCH-MF; n.6). In all subgroups AH volume was reduced; the volume of CH was significantly increased in Hme-PMG-F and Hme-SCH-MF while it was not significantly increased in Hme-SCH-F compared to affected hemisphere.

CONCLUSIONS

In patients with hemispheres' asymmetry, quantitative high-resolution MRI offers a more objective assessment of brain structures volume. The type of hemispheric dysplastic malformation together with the age of epilepsy onset and epileptic pattern may contribute to changes in contralateral and apparently unaffected hemisphere. Future studies are warranted to evaluate whether the early identification of these changes might help in planning future antiepileptic treatments.

Neurite Outgrowth Inhibitor (NogoA) Is Upregulated in White Matter Lesions of Complex Cortical Malformations

Complex cortical malformations (CCMs), such as hemimegalencephaly and polymicrogyria, are associated with drug-resistant epilepsy and developmental impairment. They share certain neuropathological characteristics including mammalian target of rapamycin (mTOR) activation and an atypical number of white matter neurons. To get a better understanding of the pathobiology of the lesion architecture, we investigated the role of neurite outgrowth inhibitor A (NogoA), a known regulator of neuronal migration. Epilepsy surgery specimens from 16 CCM patients were analyzed and compared with sections of focal cortical dysplasia IIB (FCD IIB, n = 22), tuberous sclerosis complex (TSC, n = 8) as well as healthy controls (n = 15). Immunohistochemistry was used to characterize NogoA, myelination, and mTOR signaling. Digital slides were evaluated automatically with ImageJ. NogoA staining showed a significantly higher expression within the white matter of CCM and FCD IIB, whereas cortical tubers presented levels similar to controls. Further analysis of possible associations of NogoA with other factors revealed a positive correlation with mTOR and seizure frequency. To identify the main expressing NogoA cell type, double staining revealed dysmorphic neuronal white matter cells. Increased NogoA expression is associated with profound inhibition of neuritic sprouting and therefore contributes to a decrease in neuronal network complexity in CCM patients.

Hemimegalencephaly and tuberous sclerosis complex: A rare yet challenging association

Hemimegalencephaly is a rare malformation of cortical development characterised by enlargement of one cerebral hemisphere. The association between hemimegalencephaly and tuberous sclerosis complex, an autosomal dominant genetic disorder, is uncommon and has so far been reported only in a few cases. Intractable epilepsy and severe developmental delay are typical clinical manifestations. Aberrant activation of the mTOR signalling pathway is considered to be the hallmark of the pathogenesis of these two disorders. Thus, mTOR inhibitors such as everolimus represent a promising therapeutic approach to mTOR-associated manifestations. We present a thorough literature review of the association between hemimegaloencephaly and tuberous sclerosis complex.

Failed Hemispherotomy: Insights from Our Early Experience in 40 Patients

OBJECTIVE

To study the factors responsible for failure of hemispherotomy and outcomes of revision surgery. The effect of the surgeon's learning curve on failures was also analyzed.

METHODS

Forty consecutive patients, who underwent functional hemispherotomy through a 4-year period, from the inception of the single-surgeon epilepsy surgery program, were analyzed.

RESULTS

A total of 47 functional hemispherotomies were performed in the study period in 40 patients (7 revision surgeries on 6 patients). Mean age of the cohort was 9.45 ± 14.84 years and it included 7 infants (<2 years). Of the 9 patients (23.5%) who failed the first procedure, 6 qualified for revision surgery, all of whom belonged to the cohort of the first 15 patients treated during the first 2 years of the program. Hemimegalencephaly was the most common disease (n = 4). Ipsilateral temporal stem (n = 3), frontobasal connections (n = 2), splenium of corpus callosum (n = 2), and posterior insula (n = 2) were residual undisconnected substrates identified for revision on imaging. The substrates for failure were obvious in 5/6 patients and resulted from incomplete disconnection, implying surgical inadequacy. At the mean follow-up of 30 ± 13.17 months (range, 13-55 months), 35 of 40 patients (87.5%) remained seizure free (Engel class Ia), including 4/6 patients who underwent redo surgery. Revision did not benefit the remaining 2 patients (Engel class III). There was no mortality.

CONCLUSIONS

Surgical revision is more common in hemimegalencephaly and in the early days of a surgical program. Affirmative neuroimaging improves the outcomes of subsequent revision surgery.

Structural MRI and tract-based spatial statistical analysis of diffusion tensor imaging in children with hemimegalencephaly

PURPOSE

To investigate the gross white matter abnormalities in the structural brain MR imaging as well as white matter microstructural alterations using tract-based spatial statistics (TBSS) analysis of diffusion tensor imaging (DTI) in both affected and contralateral cerebral hemispheres of children with hemimegalencephaly (HMEG).

METHODS

From 2003 to 2019, we retrospectively reviewed brain MR images in 20 children (11 boys, 2 days-16.5 years) with HMEG, focusing on gross white matter abnormalities. DTI was evaluated in 12 patients (8 boys, 3 months-16.5 years) with HMEG and 12 age-, sex-, and magnetic field strength-matched control subjects. TBSS analysis was performed to analyze main white matter tracts. Regions of significant differences in fractional anisotropy (FA) were determined between HMEG and control subjects and between affected and contralateral hemispheres of HMEG.

RESULTS

Gross white matter abnormalities were noted in both affected (n = 20, 100%) and contralateral hemisphere (n = 4, 20%) of HMEG. FA values were significantly decreased in both hemispheres of HMEG, compared with control subjects (P < 0.05). Contralateral hemispheres of HMEG showed regions with significantly decreased FA values compared with affected hemispheres (P < 0.05).

CONCLUSIONS

In addition to gross white matter abnormalities particularly evident in affected hemispheres, DTI analysis detected widespread microstructural alterations in both affected and contralateral hemispheres in HMEG suggesting HMEG may involve broader abnormalities in neuronal networks.

Transient water-electrolyte disturbance after hemispherotomy in young infants with epileptic encephalopathy

PURPOSE

This study aimed to elucidate the clinical features of water-electrolyte disturbance (WED) as a sequela of hemispherotomy.

METHODS

We performed a retrospective chart review to identify the clinical features of diabetes insipidus (DI) as a complication in < 12-month-old patients who underwent hemispherectomy or hemispherotomy for severe epilepsy between 2007 and 2018. Central DI was diagnosed if a patient developed polyuria (urine output > 5 mL/kg/h), abnormally high serum osmolality (> 300 mOsm/kg), high serum sodium level (> 150 mEq/L), either abnormally low urine specific gravity (< 1.005) or low urine osmolality (< 300 mOsm/kg) or both, and effective control of polyuria with arginine vasopressin (AVP). The clinical course of post-hemispherotomy WED, complications other than WED, and seizure outcomes were analyzed.

RESULTS

The review identified that 3 of 23 infants developed WED. All patients developed polyuria within 2 days after surgery, with high serum osmolality and hypotonic urine; AVP was effective in treating these symptoms. The clinical course was compatible with central DI. Two patients subsequently developed hyponatremia in a biphasic or triphasic manner. All patients had multiple seizures that were probably related to WED. Two patients developed asymptomatic cerebral sinovenous thrombosis, possibly because of the surgical procedure and dehydration; anticoagulant treatment was provided. All patients were treated for WED for up to 2 months and had no residual pituitary dysfunction.

CONCLUSION

Systemic complications other than intracranial ones can occur in patients who have undergone hemispherotomy. Perioperative systemic management of young infants undergoing this procedure should include careful water and electrolyte balance monitoring.

Minimizing blood loss in hemispherectomy for hemimegalencephaly in low-weight infants: technical note

INTRODUCTION

Drug-resistant seizures due to hemimegalencephaly in neonates and infants are a unique surgical and anesthesia challenge. While early surgery in these patients may predict a better seizure control, a lower body weight, limited blood volume, and surgical blood loss may make hemispherectomy prohibitive.

METHODS

Two infants (weight, 8.7 kg and 3.7 kg) underwent interhemispheric vertical hemispherotomy with endoscope assistance. In the first case, during the lateral disconnection, excessive bleeding prompted the surgeon to coagulate the lenticulostriate arteries at the origin from the middle cerebral artery to reduce bleeding. In the second infant, the lenticulostriate arteries were coagulated before initiating the lateral disconnection.

RESULTS

In both infants, the blood loss from lateral dissection was reduced by coagulation of lenticulostriate arteries.

CONCLUSION

The authors suggest that early coagulation of the lenticulostriate arteries is a useful strategy to minimize blood loss in low-weight infants undergoing hemispherotomy.

Physical Growth of the Contralateral Cerebrum is Preserved After Hemispherotomy in Childhood

BACKGROUND

Hemispherotomy can be an effective treatment for refractory childhood epilepsy. However, the extent of postoperative brain development after hemispherotomy remains incompletely understood. This study aims to provide an anatomic foundation in assessing development of the contralateral hemisphere, by measuring volumetric growth after hemispherotomy.

METHODS

Eleven patients with hemimegalencephaly, Rasmussen's encephalitis, and cerebral infarction who underwent hemispherotomy before age 12 years, an immediate preoperative magnetic resonance imaging, and at least three years of follow-up magnetic resonance imagings were retrospectively analyzed. The volume of the contralateral hemisphere was measured before and after surgery. Growth curves were compared with those of healthy individuals from an open database. The growth rate relative to the healthy individuals ("catch-up rate") was calculated.

RESULTS

A positive volumetric growth of the contralateral hemisphere was observed across all pathologies. The hemimegalencephaly subgroup underwent hemispherotomy at the earliest time and had the largest postoperative growth rate, which exceeded that of healthy individuals. The Rasmussen subgroup underwent surgery at the second earliest time and had an intermediate growth rate, which was similar to that of healthy individuals. The infarction subgroup underwent surgery at the latest time and had the slowest growth rate, which was less than that of healthy individuals.

CONCLUSIONS

The contralateral hemisphere continues to increase in volume after hemispherotomy in childhood. Further studies with a larger sample size and correlation with cognitive outcomes may aid in characterizing the prognosis after hemispherotomy.

Disrupted cortico-ponto-cerebellar pathway in patients with hemimegalencephaly

OBJECTIVE

Cerebellar dysmaturation and injury is associated with a wide range of neuromotor, neurocognitive and behavioral disorders as well as with preterm birth. We used diffusion tensor MR imaging to investigate a disruption in structural cortico-ponto-cerebellar (CPC) connectivity in children with infantile-onset severe epilepsy.

METHODS

We performed CPC tract reconstructions in 24 hemimegalencephaly (HME) patients, 28 West syndrome (WS) of unknown etiology patients, and 25 pediatric disease control subjects without a history of epilepsy nor brain abnormality on MRI. To identify the CPC tract, we placed a seeding ROI separately in each right and left cerebral peduncle. We evaluated the distribution patterns of the CPC tracts to the cerebellum and their correlation with clinical findings.

RESULTS

In control and WS of unknown etiology groups, both sides' CPC tracts descended to bilateral hemispheres in 20 (80.0%) and 21 (75.0%); mixed (bilateral on one side and unilateral on the other side) in five (20.0%) and five (17.9%); and unilateral in zero (0.0%) and two (7.1%), respectively. However, in the HME, both sides' CPC tracts descended to bilateral hemispheres in four (16.7%); mixed in 13 (54.1%); and unilateral in seven (29.2%). These CPC patterns differed significantly between the HME and other groups (p < 0.001). Among HME patients, those with a unilateral cerebellar distribution on both sides had significantly earlier seizure onset (p = 0.049) and more frequent seizures (p = 0.052) at a trend level compared to those with bilateral and mixed distributions.

CONCLUSION

Disrupted CPC tracts were observed more frequently in HME patients than in WS of unknown etiology patients and controls, and they may be correlated with earlier seizure onset and more frequent seizures in HME patients. DTI is a useful and non-invasive method for speculating the pathology in the developing brain.

Posterior Quadrantic Dysplasia: MRI Diagnosis of a Lesser Known Cause of Pediatric Intractable Epilepsy

Posterior quadrantic dysplasia (PQD) is a rare cause of pediatric intractable epilepsy. It is a sporadic cortical development malformation that involves the posterior three lobes of a single hemisphere and spares the frontal cortex. Very few cases have been reported in the literature, mostly as anecdotal reports or as a part of large series of refractory epilepsy. It is essential to know about this lesser known entity and differentiate it from other more common similar anomalies such as multilobar cortical dysplasia and hemimegalencephaly as new motor-sparing neurosurgical disconnective procedures have led to dramatically reduced mortality and morbidity rates, apart from gifting the affected children a better quality of life. Magnetic resonance imaging (MRI) is pivotal in astute diagnosis of the condition and accurate delineation of boundaries of the lesion to aid in neurosurgical management. We report one such case of PQD presenting with refractory epilepsy, which was diagnosed on MRI.

Delayed diagnosis of shunt overdrainage following functional hemispherotomy and ventriculoperitoneal shunt placement in a hemimegalencephaly patient

Shunt overdrainage represents a nebulous condition of variable clinical and imaging presentations, where the diagnosis is primarily clinical. The condition presents a diagnostic challenge particularly in patients with cognitive impairment and developmental delays. Here we present a 3-year-old boy with drug-resistant focal onset seizures due to hemimegalencephaly who previously underwent functional hemispherotomy followed by ventriculoperitoneal shunt placement for postoperative hydrocephalus. The subsequent clinical course was complicated by delayed diagnosis of shunt overdrainage in the absence of significant image findings. Maintaining a high index of suspicion for the possibility of shunt overdrainage is critical even in the face of unremarkable imaging findings.

"Endovascular embolic hemispherectomy": a strategy for the initial management of catastrophic holohemispheric epilepsy in the neonate

PURPOSE

Conflicting challenges abound in the management of the newborn with intractable epilepsy related to hemimegalencephaly. Early hemispherectomy to stop seizures and prevent deleterious consequences to future neurocognitive development must be weighed against the technical and anesthetic challenges of performing major hemispheric surgery in the neonate.

METHODS

We hereby present our experience with two neonates with hemimegalencephaly and intractable seizures who were managed using a strategy of initial minimally invasive embolization of the cerebral blood supply to the involved hemisphere.

RESULTS

Immediate significant seizure control was achieved after embolization of the cerebral blood supply to the involved hemisphere followed by delayed ipsilateral hemispheric resection at a later optimal age.

CONCLUSION

The considerations and challenges encountered in the course of the management of these patients are discussed, and a literature review is presented.

Evolution of epilepsy in hemimegalencephaly from infancy to adulthood: Case report and review of the literature

Hemimegalencephaly (HME) is a rare disorder of cortical development with overgrowth of one cerebral hemisphere. Patients have intellectual delay, hemiparesis and severe epilepsy. Drug-resistant epilepsy is often treated with a hemispherectomy. We review the literature on HME natural history and report a 26-year-old man with HME who did not undergo hemispherectomy in childhood with recurrent focal convulsive or non-convulsive status epilepticus.

Few patients with HME have been followed into adulthood. Reported adult cases have milder epilepsy or underwent hemispherectomy in childhood. Patients surviving to adulthood have poor outcomes, regardless of treatment method, although seizure burden is improved with hemispherectomy.

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Hemimegalencephaly is a rare disorder of neuronal migration characterized by epilepsy, developmental delay and hemiparesis.

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Outcomes of hemimegalencephaly are generally poor; however, this is typically reported in pediatric populations, not adults.

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Hemispherectomy is beneficial in reducing seizure burden; however, most do not obtain seizure-freedom.

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Seizures are typically focal onset; however, the epileptogenic area may increase with poor seizure control.

Complex observation of scalp fast (40-150 Hz) oscillations in West syndrome and related disorders with structural brain pathology

We investigated the relationship between the scalp distribution of fast (40-150 Hz) oscillations (FOs) and epileptogenic lesions in West syndrome (WS) and related disorders. Subjects were 9 pediatric patients with surgically confirmed structural epileptogenic pathology (age at initial electroencephalogram [EEG] recording: mean 7.1 months, range 1-22 months). The diagnosis was WS in 7 patients, Ohtahara syndrome in 1, and a transitional state from Ohtahara syndrome to WS in the other. In the scalp EEG data of these patients, we conservatively detected FOs, and then examined the distribution of FOs. In five patients, the scalp distribution of FOs was consistent and concordant with the lateralization of cerebral pathology. In another patient, FOs were consistently dominant over the healthy cerebral hemisphere, and the EEG was relatively low in amplitude over the pathological atrophic hemisphere. In the remaining 3 patients, the dominance of FOs was inconsistent and, in 2 of these patients, the epileptogenic hemisphere was reduced in volume, which may result from atrophy or hypoplasia. The correspondence between the scalp distribution of FOs and the epileptogenic lesion should be studied, taking the type of lesion into account. The factors affecting scalp FOs remain to be elucidated.

Three cases of right frontal megalencephaly: Clinical characteristics and long-term outcome

AIM

To delineate the clinical and neuroimaging characteristics of localized megalencephaly involving the right frontal lobe.

METHOD

Data from three patients aged 14-16 years at the last follow-up were retrospectively reviewed.

RESULTS

All the patients were normal on neurological examination with no signs of hemiparesis. Enlargement of the right frontal lobe with increased volume of subcortical and deep white matter, as well as thickening of the ipsilateral genu of the corpus callosum was common. The onset of epilepsy was 4-7 years of age, with seizure types of massive myoclonus in two and generalized tonic-clonic in two, which could be eventually controlled by antiepileptics. Interictal electroencephalography showed frontal alpha-like activity in one, and abundant spike-wave complexes resulting in diffuse continuous spike-wave activity during sleep in two patients even after suppression of clinical seizures. Psychomotor development appeared unaffected or slightly delayed before the onset of epilepsy, but became mildly disturbed during follow-up period of 7-11 years.

CONCLUSION

Certain patients with right frontal megalencephaly can present with a milder epileptic and intellectual phenotype among those with localized megalencephaly and holohemispheric hemimegalencephaly, whose characteristic as epileptic encephalopathy was assumed from this study.

Hemispherectomy Procedure in Proteus Syndrome

Objective Proteus syndrome is a rare overgrowth disorder including bone, soft tissue, and skin. Central nervous system manifestations were reported in about 40% of the patients including hemimegalencephaly and the resultant hemicranial hyperplasia, convulsions and mental deficiency. We report a 1-month-old male baby referred to Pediatric Neurology Clinic Soetomo Hospital, Surabaya, Indonesia in 2014 presented recurrent seizures since birth with asymmetric dysmorphic face with the right side larger than the left, subcutaneous mass and linear nevi. Craniocervical MRI revealed hemimegalencephaly right cerebral hemisphere. Triple antiepileptic drugs were already given as well as the ketogenic diet, but the seizures persisted. The seizure then was resolved after hemispherectomy procedure.

Surgical management of medically refractory epilepsy in patients with polymicrogyria

OBJECTIVE

Polymicrogyria (PMG) is a malformation of cortical development characterized by formation of an excessive number of small gyri. Sixty percent to 85% of patients with PMG have epilepsy that is refractory to medication, but surgical options are usually limited. We characterize a cohort of patient with polymicrogyria who underwent epilepsy surgery and document seizure outcomes.

METHODS

A retrospective study of all patients with PMG who underwent epilepsy surgery (focal seizure foci resection and/or hemispherectomy) at our center was performed by review of all clinical data related to their treatment.

RESULTS

We identified 12 patients (7 males and 5 female) with mean age of 18 (ranging from 3 months to 44 years) at time of surgery. Mean age at seizure onset was 8 years, with the majority (83%) having childhood onset. Six patients had focal, five had multifocal, and one patient had diffuse PMG. Perisylvian PMG was the most common pattern seen on magnetic resonance imaging (MRI). Eight patients had other cortical malformations including hemimegalencephaly and cortical dysplasia. Scalp electroencephalography (EEG) often showed diffuse epileptic discharges that poorly lateralized but were focal on intracranial electrocorticography (ECoG). Eight patients underwent seizure foci resection and four underwent hemispherectomy. Mean follow-up was 7 years (ranging from one to 19 years). Six patients (50%) were seizure-free at last follow-up. One patient had rare seizures (Engel class II). Three patients were Engel class III, having either decreased seizure frequency or severity, and two patients were Engel class IV. Gross total resection of the PMG cortex trended toward good seizure control.

SIGNIFICANCE

Our study shows that even in patients with extensive or bilateral PMG malformations, some may still be good candidates for surgery because the epileptogenic zone may involve only a portion of the malformation. Intracranial ECoG can provide additional localizing information compared to scalp EEG in guiding resection of epileptogenic foci.

Utility of diffusion tensor imaging parameters for diagnosis of hemimegalencephaly

BACKGROUND

Hemimegalencephaly is a rare hamartomatous entity characterised by enlargement of all or part of the cerebral hemisphere ipsilaterally with cortical dysgenesis, large lateral ventricle and white matter hypertrophy with or without advanced myelination. Although conventional magnetic resonance imaging (MRI) is useful for detecting these diagnostic features, hemimegalencephaly is not always easily distinguished from other entities, especially when hemimegalencephaly shows blurring between the grey and white matter. Diffusion tensor imaging (DTI) is a functional MRI technique commonly used to assess the integrity of white matter. The usefulness of DTI in assessing hemimegalencephaly has not been fully elucidated. In this study, we clarified the characteristics of hemimegalencephaly with regard to DTI and its parameters including fractional anisotropy and apparent diffusion coefficient.

METHODS

Three patients with hemimegalencephaly underwent MRI including DTI. We first visually compared fractional anisotropy mapping and conventional MRI. Next, we quantitatively measured the fractional anisotropy and apparent diffusion coefficient values in the subcortical white matter of the hemisphere with hemimegalencephaly and corresponding normal-appearing contralateral regions and analysed the values using the Mann-Whitney U test.

RESULTS

On fractional anisotropy mapping, we could clearly distinguish the junction of grey and white matter and observed thicker white matter in the hemisphere with hemimegalencephaly, which was unclear on conventional MRI. The white matter in the hemisphere with hemimegalencephaly showed significantly higher fractional anisotropy (P<0.0001) and lower apparent diffusion coefficient (P=0.0022) values than the normal contralateral side.

CONCLUSION

DTI parameters showed salient hemimegalencephaly features and could be useful in its assessment.

Ohtahara syndrome associated with hemimegalencephaly and intracranial lipoma

Hemimegalencephaly is a disorder of cortical malformation and is associated with various disorders including various neurocutaneous syndromes and many seizure types. We present a case of hemimegalencephaly associated with Ohtahara syndrome and intracranial and facial lipoma.

Infantile tauopathies: Hemimegalencephaly; tuberous sclerosis complex; focal cortical dysplasia 2; ganglioglioma

Tau is a normal microtubule-associated protein; mutations to phosphorylated or acetylated forms are neurotoxic. In many dementias of adult life tauopathies cause neuronal degeneration. Four developmental disorders of the fetal and infant brain are presented, each of which exhibits up-regulation of tau. Microtubules are cytoskeletal structures that provide the strands of mitotic spindles and specify cellular polarity, growth, lineage, differentiation, migration and axonal transport of molecules. Phosphorylated tau is abnormal in immature as in mature neurons. Several malformations are demonstrated in which upregulated tau may be important in pathogenesis. All produce highly epileptogenic cortical foci. The prototype infantile tauopathy is (1) hemimegalencephaly (HME); normal tau is degraded by a mutant AKT3 or AKT1 gene as the aetiology of focal somatic mosaicism in the periventricular neuroepithelium. HME may be isolated or associated with neurocutaneous syndromes, particularly epidermal naevus syndromes, also due to somatic mutations. Other tauopathies of early life include: (2) tuberous sclerosis complex; (3) focal cortical dysplasia type 2b (FCD2b); and (4) ganglioglioma, a tumor with dysplastic neurons and neoplastic glial cells. Pathological tau in these infantile cases alters cellular growth and architecture, synaptic function and tissue organization, but does not cause neuronal loss. All infantile tauopathies are defined neuropathologically as a tetrad of (1) dysmorphic and megalocytic neurons; (2) activation of the mTOR signaling pathway; (3) post-zygotic somatic mosaicism; and (4) upregulation of phosphorylated tau. HME and FCD2b may be the same disorder with different timing of the somatic mutation in the mitotic cycles of the neuroepithelium. HME and FCD2b may be the same disorder with different timing of the somatic mutation in the mitotic cycles of the neuroepithelium. Tauopathies must be considered in infantile neurological disease and no longer restricted to adult dementias. The mTOR inhibitor everolimus, already demonstrated to be effective in TSC, also may be a potential treatment in other infantile tauopathies.

Happle-Tinschert syndrome: report of a case with hemimegalencephaly

Happle-Tinschert syndrome is a disorder causing unilateral segmentally arranged basaloid follicular hamartomas of the skin associated with ipsilateral osseous, dental and cerebral abnormalities including tumors. Although a case with hemimegalencephaly was previously described, this is the first report of Happle-Tinschert syndrome with discrepant short left leg, ipsilateral skin lesions, hemimegalencephaly and frontal polymicrogyria.

Long-term developmental outcome after early hemispherotomy for hemimegalencephaly in infants with epileptic encephalopathy

This study aimed to identify the effect of early hemispherotomy on development in a consecutive series of 12 infants with hemimegalencephaly (HME) demonstrating epileptic encephalopathy. Mean age at onset was 20.4 days (range, 1-140), mean age at surgery was 4.3 months (range, 2-9), and mean follow-up time was 78.8 months (range, 36-121). Eleven patients had a history of early infantile epileptic encephalopathy. Vertical parasagittal hemispherotomy was performed without mortality or severe morbidities. At follow-up, seizure freedom was obtained in 8 patients (66.7%), who showed significantly higher postoperative developmental quotient (DQ) (mean, 31.3; range, 7-61) than those with seizures (mean, 5.5; range, 3-8) (p=0.02). Within the seizure-free group, postoperative DQ correlated with preoperative seizure duration (r=-0.811, p=0.01). Our results showed that shorter seizure duration during early infancy could provide better postoperative DQ in infants with HME and epileptic encephalopathy.

Surgical management of cortical dysplasia in infancy and early childhood

PURPOSE

To describe operative procedures, seizure control and complications of surgery for cortical dysplasia (CD) causing intractable epilepsy in infancy and early childhood.

METHODS

Fifty-six consecutive children (less than 6years old) underwent resective epilepsy surgery for CD from December 2000 to August 2011. Age at surgery ranged from 2 to 69months (mean 23months) and the follow-up was from 1 to 11years (mean 4years 4months).

RESULTS

Half of the children underwent surgery during infancy at an age less than 10months, and the majority (80%) of these infants needed extensive surgical procedures, such as hemispherotomy and multi-lobar disconnection. Seizure free (ILAE class 1) outcome was obtained in 66% of the cases (class 1a; 55%): 85% with focal resection (n=13), 50% with lobar resection (n=18), 71% with multilobar disconnection (n=7) and 67% with hemispherotomy (n=18). Peri-ventricular and insular structures were resected in 23% of focal and 61% of lobar resections. Repeated surgery was performed in 9 children and 5 (56%) became seizure free. Histological subtypes included hemimegalencephaly (16 patients), polymicrogyria (5 patients), and FCD type I (6 patients), type IIA (19 patients), type IIB (10 patients). Polymicrogyria had the worst seizure outcome compared to other pathologies. Surgical complications included 1 post-operative hydrocephalus, 1 chronic subdural hematoma, 2 intracranial cysts, and 1 case of meningitis. No mortality or severe morbidities occurred.

CONCLUSIONS

Early surgical intervention in children with CD and intractable seizures in infancy and early childhood can yield favorable seizure outcome without mortality or severe morbidities although younger children often need extensive surgical procedures.

Epilepsy surgery for hemispheric syndromes in infants: hemimegalencepahly and hemispheric cortical dysplasia

OBJECTIVE

Hemimegalencepahly (HME) and Hemispheric Cortical Dysplasia (HCD) are rare congenital diseases that occur with intractable epilepsy. They manifest by early epilepsy, mental retardation, hemianopsia and contralateral hemiplegia. Hemispheric disconnection (mainly anatomical hemispherectomy, peri-insular hemispherotomy, modified lateral hemispherotomy and vertical parasagittal hemispherotomy) have been reported to be efficient on seizures and also to prevent additional cognitive injury and developmental delay.

METHOD

We reviewed literature about clinical presentation, predictors of outcome and expectation about epileptic seizures and cognitive outcome.

RESULTS

Clinical presentation and seizures outcome have been described in almost 600 children for the last thirty years. Epilepsy improved in most cases depending on the series and the follow-up duration. Percentage of seizure-free patients with HME or HCD was lower than in other groups (Rasmussen Encephalitis, Vascular Sequellae). Post-operative complications decreased with the hemispherotomy surgical procedures. EEG abnormalities on the "save" hemisphere did not negatively influence postsurgical outcome. Seizure free outcome did not seem to depend on the surgical procedure but the presence of residual insular cortex seemed to be associated with persistent postoperative seizures. Contralateral MRI abnormalities seemed to be associated with poorer prognosis for seizure free outcome and lack of cognitive improvement.

CONCLUSION

Hemispheric disconnection remains the best treatment in order to control epileptic seizures. Hemispheric surgical procedures are safe and can be performed from the first month of life. Prospective studies of cognition are needed to emphasize benefits on long term outcome.

Increased Ki-67 immunoreactivity in the white matter in hemimegalencephaly

Hemimegalencephaly (HMG) is a developmental brain disorder characterized by an enlarged unilateral hemisphere with cortical malformation comprising abnormal hypertrophic cells. To address the proliferative status of HMG, Ki-67 immunoreactivity was investigated in HMG specimens obtained during epilepsy surgery. Nine HMG tissues were stained with a Ki-67 antibody and Ki-67 labeling index in the malformed cortex, and the underlying white matter was measured separately and compared with tissues from focal cortical dysplasias and normal brains from autopsy. In HMG tissues, Ki-67-positive cells were scattered in both the gray and white matter, with a significantly higher Ki-67 labeling index in the white matter compared with gray matter. No dysmorphic neuron or balloon cell was stained for Ki-67. As Ki-67 immunoreactivity overlapped with that of ionized calcium-binding adaptor protein-1, Ki-67-positive cells were identified as microglia. In HMG, microglia were activated and entered into a proliferative status with higher distribution in the white matter, implying an ongoing neuroinflammatory process involving the white matter.

Klippel-trenaunay-weber syndrome with hemimegalencephaly; report of a pediatric case

BACKGROUND

Klippel-Trenaunay-Weber Syndrome (KTWS) is a rare neurocutaneous syndrome. Hemimegalencephaly (HME) and seizure episodes have been reported previously in a few cases with KTWS.

CASE PRESENTATION

We report here a 3 day-old girl with partial motor seizures, extensive port-wine staining and mild structural deformities in the feet, and a hemimegalencephaly.

CONCLUSION

Occurrence of partial motor seizures in addition to bilateral lower extremities extensive port-wine staining is a unique feature seen in our case.