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

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.

Hemimegalencephaly with Bannayan-Riley-Ruvalcaba syndrome.

Hemimegalencephaly is known to occur in Proteus syndrome, but has not been reported, to our knowledge, in the other PTEN mutation-related syndrome of Bannayan-Riley-Ruvalcaba. Here, we report a patient with Bannayan-Riley-Ruvalcaba syndrome who also had hemimegalencephaly and in whom the hemimegalencephaly was evident well before presentation of the characteristic manifestations of Bannayan-Riley-Ruvalcaba syndrome. An 11-year-old boy developed drug-resistant focal seizures on the fifth day of life. MRI revealed left hemimegalencephaly. He later showed macrocephaly, developmental delay, athetotic quadriplegic cerebral palsy, and neuromuscular scoliosis. Freckling of the penis, which is characteristic of Bannayan-Riley-Ruvalcaba syndrome, was not present at birth but was observed at 9 years of age. Gene analysis revealed a c.510 T>G PTEN mutation. This patient and his other affected family members, his father and two siblings, were started on the tumour screening procedures recommended for patients with PTEN mutations. This case highlights the importance of early screening for PTEN mutations in cases of hemimegalencephaly not otherwise explained by another disorder, even in the absence of signs of Proteus syndrome or the full manifestations of Bannayan-Riley Ruvalcaba syndrome.

Hemimegalencephaly with intractable epilepsy: A case report.

Isolated Hemimegalencephaly (iHME) is a rare form of congenital malformation of cortical development.It is characterized by enlargement of all or part of one cerebral hemisphere. It typically presents with intractable seizures, mental retardation, developmental delay, contralateral hemiparesis and hemianopia. The patient was a five and half month's old baby girl who presented first with focal seizures at 10th day of life. No other physical or behavioral abnormality was noted. However, Initial EEG showed excessive sharp EEG transients more over the right hemisphere, repeated EEG showed spikes, polyspikes, sharps and slow wave discharges predominately over right hemisphere. MRI brain showed asymmetric enlargement of the right cerebral hemisphere, suggestive of hemimegalencephaly. Initial treatment with anti-epileptics was successful in controlling the seizures but later on the seizures became intractable even on polytherapy. Identification of this and similar cases of iHME can help us better understand this disorder and its associated symptoms and eventually help us develop better treatment options for it.

Early modified functional hemispherectomy in a young infant with Ohtahara syndrome and hemimegalencephaly.

We report on the youngest infant treated with modified functional hemispherectomy at the age of 5 months for Ohtahara syndrome and hemimegalencephaly as underlying pathology, and we depict the favorable outcome regarding seizure control and psychomotor development. These results highlight the potential usefulness of early surgery in such conditions.

Unilateral holohemispheric central nervous system lesions associated with medically refractory epilepsy in the pediatric population: a retrospective series of hemimegalencephaly and Rasmussen's encephalitis.

OBJECT: Cortical malformations and inflammatory encephalopathy are among common etiologies for medically refractory epilepsy in children. On rare occasions, lesions can affect an entire cerebral hemisphere while sparing the other; the 2 processes that can manifest in this manner are hemimegalencephaly (HME) and Rasmussen's encephalitis (RE). Although the clinical course and radiological appearance between the 2 disorders are distinct, there is occasional overlapping pathology between RE and cortical migration disorders. One question that arises from these observations is whether RE and HME, diseases with holohemispheric involvement but apparently different etiologies, have any overlapping characteristics. METHODS: The authors performed a retrospective review of all patients with presumed diagnosis of HME or RE who underwent hemispherectomy at University of California, San Francisco, and reviewed their clinical presentation, imaging, and pathology data. RESULTS: The authors present the clinicopathological features of 14 pediatric patients with unilateral holohemispheric lesions associated with medically refractory epilepsy. Radiological and pathological assessment classified 7 of the patients as having hemimegalencephaly, while the other 7 were diagnosed as having RE. Four of the patients had unusual features suggestive of overlapping developmental and inflammatory (dual) pathology. All patients underwent hemispherectomies. Eight patients (57%) became seizure free (Engel Class I), 5 patients (36%) had rare seizures (Engel Class II), and 1 patient had significant seizure reduction (Engel Class III). CONCLUSIONS: Based on this case series, HME and RE can be distinguished on the basis of their radiological and histological appearance, even though some cases may have overlapping features. Hemispherectomy was effective at eliminating seizures for both HME and RE.

Hemimegalencephaly without epilepsy: case report.

Hemimegalencephaly is a rare sporadic brain malformation characterized by enlargement of one cerebral hemisphere. The classical clinical triad consists of intractable epilepsy, severe psychomotor delay and hemiparesis. In this report, we describe a case of a 3-year-old girl, with all the radiological features of severe hemimegalencephaly but with a comparatively benign clinical course. She had no hemiparesis, mild delay and no seizures. An extensive literature review reveals only one previously reported case of hemimegalencephaly with the absence of seizures, as part of case series. This is the first dedicated case report, with clinical description and radiological images, of this entity.