Early thalamic and cortical hypometabolism in adult-onset dementia due to metachromatic leukodystrophy

A case of early-onset adult dementia with family history of dementia is rep orted characterised by neuropsychological deficits, suggesting frontal invo lvement, with mild iron specific white matter abnormalities on CT scan. Fam ilial Alzheimer's disease was suspected but the neuropathological diagnosis on brain biopsy was metachromatic leukodystrophy. 18FDG-PET revealed a ver y peculiar pattern of metabolic impairment in thalamic areas, in medial and frontopolar regions, and in occipital lobes. Neuropsychological follow-up showed relatively, stable difficulties of long-term memory and signs of fro ntal lobe dysfunction, similar to those observed in subcortical dementias. MRI subsequently showed periventricular leukoencephalopathy. The brain meta bolic pattern observed in that case of metachromatic leukodystrophy was qui te different from that reported in other types of dementia.