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

Area of Science:

• Neuroscience
• Neuropathology
• Developmental Neurology

Background:

• Focal cortical dysplasia (FCD) type II and hemimegalencephaly (HME) are recognized as a pathological continuum, primarily differentiated by lesion size.
• Partial HME, particularly in the posterior cortex, is well-documented.

Observation:

• A 17-year-old male presented with focal seizures since age nine, exhibiting diminished right-hand dexterity but otherwise unremarkable neurological and cognitive status.
• The patient experienced a relapsing-remitting epilepsy course with extended remission periods.
• MRI revealed a dysplastic left frontal lobe lesion, including the paracentral lobule, characterized by cortical thickening, polymicrogyria-like abnormal gyration, intraparenchymal calcifications, and white matter hypodensities.

Findings:

• The presented case exhibits features intermediate to FCD type II and HME.
• Frontal lobe lesion localization and clinical presentation (childhood onset, relapsing-remitting epilepsy, absence of hemiparesis or significant cognitive impairment) align more closely with FCD type II.
• Shared MRI characteristics between HME and FCD type II are observed in this case.

Implications:

• This case expands the understanding of the FCD type II/HME spectrum, particularly concerning extensive frontal lobe involvement.
• It underscores the importance of considering the full spectrum of these conditions in epilepsy diagnosis and management.
• Further research into the specific MRI signatures and clinical correlations across the FCD/HME continuum is warranted.