Tuesday, April 16, 2024


Mello A, Stehr D, Bujarski K, Duchaine B. Visualising facial distortions in prosopometamorphopsia. Lancet. 2024 Mar 23;403(10432):1176. doi: 10.1016/S0140-6736(24)00136-3. PMID: 38521562 (no abstract)

It sounds like the stuff of horror films — but for people who are afflicted with a rare disorder, it’s a terrifying reality.

A condition called prosopometamorphopsia (PMO) causes facial features to appear distorted, according to researchers from Dartmouth College in Hanover, New Hampshire.

A study published in The Lancet revealed that a 58-year-old man reported seeing faces as distorted or "demonic" for 2½ years.

"The patient stated that the distortions — severely stretched features of the face, with deep grooves on the forehead, cheeks and chin — were present on every person's face he encountered, but he reported no distortions when looking at objects, such as houses or cars," the researchers wrote in the findings.

The patient did not see those same distortions when looking at two-dimensional faces on printed paper or digital screens.

Still, despite the distortions, the patient reported that he was able to recognize people.

After the researchers showed the man some images on a screen of a person, they then had him compare the images with that same person’s actual face.

The patient provided feedback on the differences he perceived between the two — and the researchers used computer software to edit the photograph to capture what he was seeing.

"Through the process, we were able to visualize the patient’s real-time perception of the face distortions," said Antonio Mello, a PhD student in psychological and brain sciences at Dartmouth who worked on the study, in a press release.

Dr. Jonathan Tiu, a neurologist and assistant professor of neurology at Hackensack Meridian School of medicine in New Jersey, was not involved in the study but reviewed the findings.

"Fascinatingly, the patient highlighted in the recent Lancet case report was still able to recognize everyone he was looking at," Tiu told Fox News Digital.

"This suggests that the brain's way of visually ‘displaying’ faces, and the brain's ability to recognize a person's face, might be occurring in two different parts of the brain."

What to know about PMO

The name of the disorder, prosopometamorphopsia, comes from "prosopo" (the Greek word for face, prosopon) and "metamorphopsia," which refers to perceptual distortions.

Tiu described PMO as a "very rare visual disorder" that causes a person to see visual distortions of facial features.

Experts don't fully understand how PMO occurs and who is more likely to experience it.

"This can include a twisting or stretching of someone's eyes or a visual ballooning of that person's chin, or they might even see features where they shouldn't be, like seeing that person's teeth hover over their lips," he said.

Experts don't fully understand how PMO occurs and who is more likely to experience it.

"It is thought that an injury to specific parts of facial processing networks in the brain, whether it be from a stroke or tumor, can produce the symptoms of PMO," Tiu said.

The condition has also been known to occur as an effect of migraines or seizures, but sometimes it comes on without any identifiable cause.

PMO is very rare, with fewer than 100 documented cases, according to the neurologist.

There are different types of PMO, as noted in a separate article published by senior author Brad Duchaine, a professor of psychological and brain sciences at Dartmouth.

"It’s a problem that people often don’t understand."

The two most common types are full-face prosopometamorphopsia (full-face PMO) and hemi-prosopometamorphopsia (hemi-PMO), he noted.

Most cases last only a few days or weeks.

Some patients, however, continue seeing the distortions for years.

Among the people who have had PMO, it is common for them to have been misdiagnosed at some point, the researchers stated in the study findings.

"We’ve heard from multiple people with PMO that they have been diagnosed by psychiatrists as having schizophrenia and put on anti-psychotics, when their condition is a problem with the visual system," Duchaine said in the release.

"And it’s not uncommon for people who have PMO to not tell others about their problem with face perception because they fear others will think the distortions are a sign of a psychiatric disorder," he added.

For those who have the condition, the optimal treatment should be tailored to the underlying cause of the symptom, Tiu noted.

In one study from 2021 that reviewed 81 individuals with PMO, the authors found that there was full or virtually full recovery in more than half of the reported cases, he pointed out.

"Of those who recovered, the PMO resolved quickly within days to weeks," Tiu said.

The facial processing networks that involve PMO may be in a part of the brain that has generally good potential for recovery.

"However, some patients took years to recover, and in a group of patients, the symptoms did not demonstrate any improvement."

The study authors concluded that the facial processing networks that involve PMO may be in a part of the brain that has generally good potential for recovery, Tiu added.

The Dartmouth researchers expressed hope that this latest study will help raise awareness of the rare but impactful condition.

As Duchaine added, "It’s a problem that people often don’t understand."


Winton-Brown TT, Smith L, Laing J, O'Brien TJ, Neal A. Ictal face perception disturbance, tattoos, and reclaiming the self. Epilepsy Behav Rep. 2023 Mar 15;22:100595. doi: 10.1016/j.ebr.2023.100595. PMID: 37025370; PMCID: PMC10070365.


We present a case of a young man with frightening ictal disturbance of face perception, or prosopometamorphopsia, arising from the left temporo-occipital region, leading to significant psychosocial impairment. A vivid forearm tattoo of the ictal experience conveyed its nature to the treating team and facilitated a psychotherapeutic process leading to significant psychosocial recovery. This case highlights the marked psychosocial and developmental impacts of epilepsy and the benefit of incorporating these into assessment and treatment.

Herald SB, Almeida J, Duchaine B. Face distortions in prosopometamorphopsia provide new insights into the organization of face perception. Neuropsychologia. 2023 Apr 15;182:108517. doi: 10.1016/j.neuropsychologia.2023.108517. Epub 2023 Feb 20. PMID: 36813107.


Prosopometamorphopsia (PMO) is a striking condition of visual perception in which facial features appear distorted, for example drooping, swelling, or twisting. Although numerous cases have been reported, few of those investigations have carried out formal testing motivated by theories of face perception. However, because PMO involves conscious visual distortions to faces which participants can report, it can be used to probe fundamental questions about face representations. Here we review cases of PMO that address theoretical questions in visual neuroscience including face specificity, inverted face processing, the importance of the vertical midline, dissociable representations for each half of the face, hemispheric specialization, the relationship between face recognition and conscious face perception, and the reference frames that face representations are embedded within. Finally, we list and touch upon eighteen open questions that make clear how much is left to learn about PMO and the potential it has to provide important advances in face perception.

Blom JD, Ter Meulen BC, Dool J, Ffytche DH. A century of prosopometamorphopsia studies. Cortex. 2021 Jun;139:298-308. doi: 10.1016/j.cortex.2021.03.001. Epub 2021 Mar 12. PMID: 33865569.


Prosopometamorphopsia is an extremely rare disorder of visual perception characterised by facial distortions. We here review 81 cases (eight new ones and 73 cases published over the past century) to shed light on the perception of face gestalts. Our analysis indicates that the brain systems underlying the perception of face gestalts have genuine network properties, in the sense that they are widely disseminated and built such that spatially normal perception of faces can be maintained even when large parts of the network are compromised. We found that bilateral facial distortions were primarily associated with right-sided and bilateral occipital lesions, and unilateral facial distortions with lesions ipsilateral to the distorted hemifield and with the splenium of the corpus callosum. We also found tentative evidence for the involvement of the left frontal regions in the fusing of vertical hemi-images of faces, and of right parietal regions in the fusing of horizontal hemi-images. Evidence supporting the remarkable adaptability of the network comes from the relatively high recovery rates that we found, from the ipsilateral hemifield predominance of hemi-prosopometamorphopsia, and from a phenomenon called cerebral asthenopia (heightened visual fatigability) which points to the dynamic nature of compensatory mechanisms maintaining normal face perception, even in chronic cases of prosopometamorphopsia. Finally, our analysis suggests that specialised networks for the representation of face gestalts in familiar-versus-unfamiliar faces and for own-versus-other face may be present, although this is in need of further study.

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