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

Ono, Yumie; Saito, Yoshiaki; Maegaki, Yoshihiro; Tohyama, Jun; Montassir, Hesham; Fujii, Shinya; Sugai, Kenji; Ohno, Kousaku

doi:10.1016/j.braindev.2015.09.005

Cited by 6 publications

(6 citation statements)

References 15 publications

(27 reference statements)

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“…Use of ketogenic diet and vagus nerve stimulation has been, at the most, partially effective in reducing the number of seizures (Tinkle et al, 2005). The early surgical intervention, anatomic or functional hemispherectomy results in hemispheric disconnection, thus improving seizure control, thereby preventing further intellectual disability and enabling psychomotor development (Bulteau et al, 2013; Ono et al, 2016). Functional hemispherectomy has gained popularity over anatomic hemispherectomy.…”

Section: Discussionmentioning

confidence: 99%

Hemimegalencephaly and intractable seizures associated with the NPRL3 gene variant in a newborn: A case report

Chandrasekar

Tourney

Loo

et al. 2021

American J of Med Genetics Pt A

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Hemimegalencephaly (HME) is a rare hamartomatous congenital malformation of the brain characterized by dysplastic overgrowth of either one of the cerebral hemispheres. HME is associated with early onset seizures, abnormal neurological findings, and with subsequent cognitive and behavioral disabilities. Seizures associated with HME are often refractory to antiepileptic medications. Hemispherectomy is usually necessary to provide effective seizure control. The exact etiology of HME is not fully understood, but involves a disturbance in early brain development and likely involves genes responsible for patterning and symmetry of the brain. We present a female newborn who had refractory seizures due to HME. Whole genome sequencing revealed a novel, likely pathogenic, maternally inherited, 3Kb deletion encompassing exon 5 of the NPRL3 gene (chr16:161898‐164745x1). The NPRL3 gene encodes for a nitrogen permease regulator 3‐like protein, a subunit of the GATOR complex, which regulates the mTOR signaling pathway. A trial of mTOR inhibitor drug, Sirolimus, did not improve her seizure control. Functional hemispherectomy at 3 months of age resulted in total abatement of clinical seizures.

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Section: Discussionmentioning

confidence: 99%

Hemimegalencephaly and intractable seizures associated with the NPRL3 gene variant in a newborn: A case report

Chandrasekar

Tourney

Loo

et al. 2021

American J of Med Genetics Pt A

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“…The age of epilepsy onset in our patient is similar to the mean age reported for FCD (nine years in our patient and eight years for patients with FCD) (Rácz et al ., 2018). It is slightly higher than the range (three to seven years) of the other three cases with frontal lobe HME (Ono et al ., 2016). Whereas the age spectrum is quite broad for patients with posterior cortex HME (one day to 10 years; mean: one year) (D’Agostino et al ., 2004), patients with classic HME notably tend to develop epilepsy earlier (the onset is in the neonatal period, sometimes from the first day of life) (Flores‐Sarnat, 2002).…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies provide evidence that HME and FCD type IIb are caused by mutations in the same mTOR pathway genes; the most important distinction between the two is their relative extent or the size/volume of the lesion, which reflect the progenitor cell and developmental time when the mutation occurred (Sarnat and Flores‐Sarnat, 2014; D’Gama et al ., 2017). Partial HME characteristically involves the posterior quadrant (D’Agostino et al ., 2004) and only three cases of limited frontal lobe malformation have been reported so far (Ono et al ., 2016).…”

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confidence: 99%

Widespread frontal lobe cortical dysplasia or partial hemimegalencephaly: a continuum of the spectrum

Cvetkovska

Kuzmanovski

Boskovski

et al. 2019

Epileptic Disorders

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Focal cortical dysplasia (FCD) type II and hemimegalencephaly (HME) are currently considered as a continuum of pathology, the most important distinction being the extent or the size/volume of the lesion. While partial HME involving the posterior cortex has been well described, we present an unusual case with a dysplastic lesion of the whole frontal lobe. A 17‐year‐old boy had focal seizures from the age of nine years. Apart from diminished right‐hand dexterity, his neurological and cognitive status were unremarkable. The course of his epilepsy exhibited a relapsing‐remitting pattern, with prolonged periods of remission. Imaging showed dysplastic left frontal lobe (including paracentral lobule) thickened cortex with an abnormal gyration pattern resembling polymicrogyria, as well as dystrophic calcifications and hypodensity scattered throughout the white matter. This patient represents an intermediate case within the FCD type II/HME spectrum. Localization of the lesion in the frontal lobe as well as clinical characteristics (childhood onset, relapsing‐remitting epilepsy, without hemiparesis and overt cognitive impairment) are more consistent with FCD type II, while a range of MRI features is shared between HME and FCD type II.

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“…Importantly, it has recently been discovered that dysplastic HMEG correspond indeed to large areas of focal cortical dysplasia Type II, with the size of the area dependent upon both the timing and the extent of the causative mutation (38). Midline abnormalities, involving the corpus callosum, septum pellucidum, and fornix are also common in this group of disorders (36,39,40) and aberrant midsagittal fibers can be also depicted on DTI running either intra or inter-hemispherically, especially on HMEG (41)(42)(43).…”

Section: Imaging Approach To Macrocephalymentioning

confidence: 99%

Diagnostic Approach to Macrocephaly in Children

et al. 2022

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Macrocephaly affects up to 5% of the pediatric population and is defined as an abnormally large head with an occipitofrontal circumference (OFC) >2 standard deviations (SD) above the mean for a given age and sex. Taking into account that about 2–3% of the healthy population has an OFC between 2 and 3 SD, macrocephaly is considered as “clinically relevant” when OFC is above 3 SD. This implies the urgent need for a diagnostic workflow to use in the clinical setting to dissect the several causes of increased OFC, from the benign form of familial macrocephaly and the Benign enlargement of subarachnoid spaces (BESS) to many pathological conditions, including genetic disorders. Moreover, macrocephaly should be differentiated by megalencephaly (MEG), which refers exclusively to brain overgrowth, exceeding twice the SD (3SD—“clinically relevant” megalencephaly). While macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, megalencephaly is most likely due to a genetic cause. Apart from the head size evaluation, a detailed family and personal history, neuroimaging, and a careful clinical evaluation are crucial to reach the correct diagnosis. In this review, we seek to underline the clinical aspects of macrocephaly and megalencephaly, emphasizing the main differential diagnosis with a major focus on common genetic disorders. We thus provide a clinico-radiological algorithm to guide pediatricians in the assessment of children with macrocephaly.

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

Cited by 6 publications

References 15 publications

Hemimegalencephaly and intractable seizures associated with the NPRL3 gene variant in a newborn: A case report

Hemimegalencephaly and intractable seizures associated with the NPRL3 gene variant in a newborn: A case report

Widespread frontal lobe cortical dysplasia or partial hemimegalencephaly: a continuum of the spectrum

Diagnostic Approach to Macrocephaly in Children

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