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Unilateral Megalencephaly


  • Our case is the first autopsied report on fetal hemimegalencephaly and confirms that the key pathogenic changes may present as early as 20-22 weeks gestation.[ncbi.nlm.nih.gov]
  • […] definition Hemimegalencephaly is a rare cerebral malformation characterized by overgrowth of all or part of a cerebral hemisphere, often with ipsilateral severe cortical dysplasia or dysgenesis, white matter hypertrophy and dilated lateral ventricle, presenting[orpha.net]
Low Set Ears
  • He had craniofacial asymmetry with left frontal bossing, midface hypoplasia, proptosis, and low-set ears.[ncbi.nlm.nih.gov]
  • All three have significant developmental delay and demonstrate other manifestations of the condition: macrocephaly in two, contralateral hemiparesis in one and one boy has ipsilateral facial hemihypertrophy and linear naevus.[semanticscholar.org]
  • He later showed macrocephaly, developmental delay, athetotic quadriplegic cerebral palsy, and neuromuscular scoliosis.[ncbi.nlm.nih.gov]
  • Sometimes it is associated with macrocephaly or cranial bone hemihypertrophy. Hemimegalencephaly has been observed in several genetic syndromes including TS, NF1, Proteus and Linear Sebaceous Nevus.[peds.ufl.edu]
Facial Hemihypertrophy
  • However, it was an unusual variant of this syndrome because the patient had left facial hemihypertrophy, left hemimegalencephaly and ipsilateral ventriculomegaly.[ncbi.nlm.nih.gov]
  • All three have significant developmental delay and demonstrate other manifestations of the condition: macrocephaly in two, contralateral hemiparesis in one and one boy has ipsilateral facial hemihypertrophy and linear naevus.[semanticscholar.org]
  • Pavone L , Curarolo P , Rizzo R Epidermal nevus syndrome: a neurologic variant with hemimegalencephaly, gyral malformation, mental retardation, seizures and facial hemihypertrophy Neurology 1991 41 266–271 11.[nature.com]
Facial Swelling
  • We present a case of unilateral facial swelling in a 1.5-year-old boy in whom magnetic resonance imaging and computed tomography revealed CILF associated with unilateral megalencephaly.[ncbi.nlm.nih.gov]
  • A boy with epilepsy of neonatal onset was diagnosed with hemimegalencephaly (HME) based on the finding of an enlarged left cerebral hemisphere with dysplastic cortex over the frontal, parietal, and temporal lobes.[ncbi.nlm.nih.gov]
  • Hemispherectomy should be performed as soon as possible when medical treatment fails to control seizures.[ncbi.nlm.nih.gov]
  • Seizures In most cases, hemimegalencephaly will cause the child to have seizures. Seizures can begin in very early infancy and are often drug-resistant. Some children may not have any seizures associated with hemimegalencephaly.[brainrecoveryproject.org]
Motor Disturbances
  • Both patients had moderate mental and motor disturbances with persistence of seizures. Hemiplegia was progressive during early childhood.[ncbi.nlm.nih.gov]


  • Initial workup included EEG, which showed excessive sharp EEG transients more over the right hemisphere, and MRI of the brain, which showed asymmetric enlargement of the right cerebral hemisphere and diffuse thickening of cortical gray matter with increased[pediatricneurosciences.com]
Focal Spikes
  • In the non-HME hemisphere, presurgery CBF was abnormal in 60% of the patients, increased and related mostly to diffuse interictal spikes on the same side, whereas normal CBF cases had focal spikes.[ncbi.nlm.nih.gov]
  • In patients with diffuse MRI abnormalities and multi-focal spikes on EEG, focal resection may not lead to a good seizure outcome, since the definitions of only one epileptogenic region is not easy.[scielo.br]
Cortical Tubers
  • The white-matter lesions were better seen in the neonatal period, whereas cortical tubers were better detected at a later age.[ncbi.nlm.nih.gov]
  • The non HME hemisphere may be normal or have cortical tubers (8,9) .[scielo.br]
White Matter Lesions
  • The white-matter lesions were better seen in the neonatal period, whereas cortical tubers were better detected at a later age.[ncbi.nlm.nih.gov]
Lymphocytic Infiltrate
  • Occasional perivascular and leptomentingeal lymphocytic infiltrates were present. No viral inclusions were identifiable. Polymerase chain reaction on multiple specimens showed unequivocal CMV positivity. In intrauterine CMV infection.[ncbi.nlm.nih.gov]


  • Five of the six patients who underwent early surgical treatment showed this kind of perfusion/metabolism discrepancy.[ncbi.nlm.nih.gov]
  • Nonetheless, the researchers have begun investigating potential treatments that address the known gene mutations, with the clear goal of finding a way to avoid the need for surgery.[health.ucsd.edu]
  • Direct in style but comprehensive in content, with ample tables and summaries, the Handbook of Epilepsy Treatment covers: Treatment of the different forms and causes of epilepsy Treatment in the different commonly encountered clinical situations Treatment[books.google.com]
  • Anatomic hemispherectomy (AH) was first introduced by Dandy in 1928 for the treatment of malignant gliomas and was expanded for the treatment of seizures by McKenzie in 1938 ( Bahuleyan et al 2013 ).[medlink.com]


  • Prognosis The prognosis for children with hemimegalencephaly is poor. Sources 1. Satoa N, Yagishitac A, Obad H, et al. Hemimegalencephaly: A Study of Abnormalities Occurring Outside the Involved Hemisphere.[cmcdfoundation.org]
  • Mild, moderate, and severe grades of severity can be recognized, providing a functional neurologic prognosis and therapeutic plan.[ncbi.nlm.nih.gov]
  • ", keywords "Hemimegalencephaly, MRI, Neurofibromatosis, Prognosis", author "R. Cusmai and P. Curatolo and S. Mangano and R. Cheminal and B.[moh-it.pure.elsevier.com]


  • Although the etiology of HME is not known, it provides an opportunity to study anomalous development of the brain and neuronal developmental abnormalities.[ncbi.nlm.nih.gov]
  • The etiology of hemimegalencephaly is not clear. Some authors consider abnormal neuroepithelial cell lineage as the primary cause.[genome.jp]


  • Epidemiology of hemimegalencephaly: a case series and review. Am J Med Genet A. 2005;15:204-11. Sasaki M, Hashimoto T, Furushima W, et al. Clinical aspects of hemimegalencephaly by means of a nationwide survey. J Child Neurol. 2005;20:337-41.[rarediseases.org]
Sex distribution
Age distribution


  • As this update demonstrates, hemimegalencephaly is likely a heterogeneous group of disorders with distinct pathophysiologic characteristics resulting in a shared clinical presentation.[medlink.com]
  • PATHOPHYSIOLOGY Histopathologic changes include abnormal gyrification, with loss of cortical lamination, neuronal heterotopia, marked gliosis, large bizarre neurons and non-neuronal large cells, called balloon-cells (5,27) .[scielo.br]
  • Pathophysiology [ edit ] One impact of megalencephaly is the complete lack of motor development.[en.wikipedia.org]


  • Wouldn’t it be wonderful if our results could prevent the need for such radical procedures in these children?”[health.ucsd.edu]
  • Currently, Hemimegalencephaly may not be preventable, since it may be genetic disorder.[dovemed.com]
  • […] information 1 Department of Pediatrics, Tohoku University School of Medicine, Aoba-ku, Sendai 980-8574, Japan. uematsu@bk9.so-net.ne.jp Abstract Hemimegalencephaly (HME) presents as severe refractory seizures and requires early surgical treatment to prevent[ncbi.nlm.nih.gov]
  • Treatments may prevent seizures and improve the quality of life. The first line of treatment for seizures would be medication, although early consideration with regard to surgery should be given.[contact.org.uk]

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