X-Linked Adrenoleukodystrophy Occipital EEG

A 7-year-old previously healthy boy presents with a 4-month history of declining school performance, difficulty reading, behavioral changes, and left-sided visual neglect. Examination reveals left homonymous hemianopia, mild left hemiparesis, and adrenal insufficiency (low morning cortisol, elevated ACTH). MRI brain shows symmetric bilateral parieto-occipital white matter T2 hyperintensity with a contrast-enhancing leading edge of demyelination (Loehs stage 3-4). Very long chain fatty acid analysis confirms X-linked adrenoleukodystrophy (ALD). The EEG finding marked **A** in the diagram—focal posterior parieto-occipital polymorphic delta with sharp waves and absent posterior dominant rhythm—correlates with which pathophysiological process?