A case study of early-emerging prosopometamorphopsia

Prosopometamorphopsia (PMO) is a rare perceptual disorder characterized by facial distortions. This report presents the first thorough study of early-emerging PMO. Zed, who was 15 years old when first tested, has experienced lifelong, dynamic facial distortions in which features move, droop, disappear, expand, and rotate. He also experiences identity misrecognitions, perceiving familiar faces as strangers and vice versa. Behavioural assessments indicate Zed's distortions persist across different viewpoints, visual field positions, picture-plane orientations, and visual angles. Neuropsychological testing revealed deficits in face identity recognition, yet Zed performed normally on tests requiring fine-grained perception of facial age and sex. While structural MRI showed no lesions, MRI revealed reduced face-selectivity in right posterior face-selective areas, and diffusion tensor imaging indicated lower white matter integrity in the left inferior fronto-occipital fasciculus. This case offers novel insights into the manifestations of early-emerging PMO, its co-occurrence with other face-processing disorders, and its underlying neural correlates.