Objective:

To construct a “perceptual homunculus” of prosopometamorphopsia (PMO) by aligning lesion locations with distinct perceptual distortions and to create a “visual directory” depicting the different distortion patterns.

Background:

PMO is a rare disorder involving facial distortion, which is often misattributed as psychiatric hallucination. Decades of reports reveal clusters of lesions and a variety of distortion “phenotypes.” Identifying potential links between lesion locations and these different “phenotypes” may help identify relationships between anatomical areas and distinct distortion patterns.

Design/Methods:

A review of PMO cases from 1947-2025 was performed via PubMed and Google Scholar. Inclusion required individual-level clinical and lesion location data. Lesion locations were translated into Montreal Neurological Institute (MNI) coordinates using the Harvard-Oxford atlas then mapped onto the Scalable Brain Atlas, resulting in a “heat map” of affected brain regions. Commonly affected regions were paired with patient-described visual distortions to identify “location-phenotype” associations. Representative illustrations were generated from verbatim patient descriptions of their visual distortions to form a visual reference for each distortion subtype.

Results:

Location-phenotype associations were consistent. Splenial and forceps major lesions produced hemi-face or eye-specific distortions, sometimes described as “demonic.” Fusiform and occipitotemporal lesions yielded “Picasso-like” or prosopagnosic distortions, whereas occipital and vertical occipital fasciculus lesions caused “motion-like,” patchy, or wavy distortions. Parietal involvement resulted in “displacement” of facial features. Rare presentations included self-face distortions and animal- or cartoon-like transformations. Overlays confirmed a right-hemisphere predominance with convergence in the fusiform gyrus, splenium, and occipital pole.

Conclusions:

This work defines the first “perceptual homunculus” of facial distortion, demonstrating how discrete lesion locations map to specific perceptual disturbances. These associations can help establish an educational “atlas” for teaching face-perception disorders. The accompanying AI-generated image set also constitutes the first “visual directory” of PMO, offering an intuitive framework for recognizing PMO and transforming descriptive data into a powerful educational tool for clinicians and trainees.