A previously healthy 10-year-old girl presented for 10 months of dystonic painful left limb posturing followed by transient left hemiplegia. Events occurred in the mornings upon awakening, consisting of 3 minutes of dystonic posturing of her left limbs and hemiface, followed by left-sided weakness. There was no impairment of awareness, although mild dyslalia was present during and a few seconds after the events. She also complained of intermittent pain in the left lower limb. Physical examination was otherwise normal.

EEG: showed normal background activity with frequent spikes and sharp waves over the left centro-temporal-frontal head regions (maximal amplitude at electrodes T7-C3-F3), at times with bilateral synchronic activity including centro-frontal areas (F4-C4) ( Fig. 17.1 ).

Sleep EEG shows normal background activity with paroxysmal interictal discharges as spikes, sharps, and subsequent slow waves over the left central-temporal areas with an electrical field over the frontal and parietal areas ( arrows ) and occasional bilateral synchronous discharges ( arrowheads ). EEG, Electroencephalography.

MRI with contrast ( Fig. 17.2 ) showed a right frontal mass with T2-hyperintense signal and bubbly appearance. Multivoxel spectroscopy showed decreased N-acetylaspartate (neuronal marker) without an increase in the choline peak (cell membrane marker) in the area of ​​interest. No other abnormal metabolites were present.

DNET. Brain MRI, (A) axial T2 shows hyperintense, well-circumscribed, rounded lesion in the right lateral precentral gyrus cortex and subcortical white matter ( arrow ). (B) Axial T1 shows corresponding hypointense signal ( arrow ). (C) Axial FLAIR shows internal signal suppression with bubbly cysts and surrounding hyperintense rim ( arrow ). (D) Multivoxel spectroscopy shows decreased NAA ( arrows ) within the lesion ( right box ) compared with contralateral normal brain tissue ( left box ). DNET , Dysembryoplastic neuro-epithelial tumor; FLAIR , fluid-attenuated inversion recovery; NAA , N-acetylaspartate.

Electroencephalogram (EEG) showed focal epilepsy in the left centro-temporo-frontal region and treatment with levetiracetam was initiated.

The patient went to surgery, and the resected tissue showed a nodular lesion consisting of neuronal cells with mucoid matrix. Immunohistochemistry showed positive results for synaptophysin and glial fibrillary acidic protein (GFAP) (in astrocytes) and negative neurofilament, CD34, and p53. Proliferative index (Ki-67 Ventana, clone 30-9) was 2% to 3%.

Focal epilepsies in children are often due to focal cortical dysplasia (FCD). FCD manifests with seizures earlier in life that are highly refractory to antiseizure medications (ASMs) and can be often complicated by status epilepticus. FCDs can be associated with mesial temporal sclerosis, vascular malformations, low-grade neoplasms, and neurocutaneous syndromes.

Hemiplegic migraine is an epilepsy mimic that can occur familially or sporadically. Patients experience transient episodes of hemiplegia that can last hours or even days, often in association with chronic headaches. Genetic testing can reveal pathogenic variants in ion transporters such as ATP1A2 , CACNA1A , or SCN1A genes, usually with autosomal dominant inheritance.

Vascular malformations can present with focal motor or sensory symptoms including cranial nerve palsies, monoparesis, or hemiparesis–hemiplegia. Headaches may also occur, particularly in the setting of hemorrhagic transformation.