What is Prosopometamorphopsia?

Prosopometamorphopsia refers to a visual perception disorder in which individuals view the faces of others to be distorted.¹ This is not the same as hallucination disorders, as hallucinations concern “imaginary objects or people” that don’t exist. Instead, patients with prosopometamorphopsia will perceive real faces to be stretched, melting, split, or otherwise contorted in a way that is often very disturbing to the patient. The disorder is extremely rare, and a recent study that attempted to collate reports of the disorder over the last century included less than 100 case studies, so our understanding of the disorder is limited.¹

What do facial distortions look like in Prosopometamorphopsia?

Image taken from “Visualising facial distortions in Prosopometamorphopsia”, Mello, Stehr, Bujarski, and Duchaine, 2024.² Researchers created this image based on descriptions of the facial distortions seen by their patients. This patient – a 58-year-old man - described a stretching of the facial features that appeared to him as ‘demonic’. In this case, the phenomenon only occurred for faces (not objects) and did not occur when looking at printed or digital photographs of faces.²

Some patients have described perceptual distortions to only one side of the perceived face, which remain constant across faces observed. For example, when observing the faces of others, some patients only see perceptual distortions such as stretching or ' melting’ of the facial features only on the left side of the face. This is referred to as vertical splitting and suggests that perhaps the two sides of the brain have somewhat separate networks in facial processing, although the two sides work together and are interdependent.

What causes Prosopometamorphopsia?

In prosopometamorphopsia, individuals perceive facial distortions such as stretching, melting or scrambling of features, either to the whole perceived face of others or half of the face (vertical splitting).^1,2 Hence, researchers believe that abnormalities in the face-selective network, which includes areas like occipital lobe, fusiform face area, corpus callosum and temporal lobes, may be the cause of facial distortions in the disorder.^1,3

Indeed, following World War II, several cases of prosopometamorphopsia were reported in soldiers who has suffered gunshot or shrapnel wounds to the occipital lobe (located at the back of the brain).¹ Furthermore, most reported cases have been attributed to lesions which affect the aforementioned brain areas. These lesions can be caused by stroke (infarction), multiple sclerosis, brain tumour, traumatic injury or epilepsy.^1,4 The disorder has, however, also been associated with conditions in which there is no physical damage to the brain, such as severe migraine, psychosis and ‘hallucinogen-persisting perception disorder’ (HPPD).^1,5 HPPD is a condition in which a patient has recurrent perceptual distortions, months or years after using a hallucinogen such as LSD or psilocybin. Many of the perceptual distortions in HPPD fit under the umbrella of Alice in Wonderland Syndrome (covered in more detail later), however, around 2% of patients with HPPD are thought to specifically experience prosopometamorphopsia.⁵

The limited number of cases of prosopometamorphopsia, and the wide variety of associated conditions thought to precede the disorder, make it very difficult to pin down a specific cause. However, a recent review of the literature published by Blom et al (2021)¹ considered 81 reported cases and proposed that it is an imbalance of neural activity across the face perception network within the brain. Their reasoning behind this explanation was that many cases of prosopometamorphopsia occur following some sort of traumatic injury or lesion to the brain and are most often temporary. Hence, it is likely that the immediate damage to the brain gives rise to an imbalance in its typical activity. When the brain has time to recover through plasticity, this imbalance is resolved and the disorder fades.

Treatments for Prosopometamorphopsia

As the disorder is so rare, there is no standard treatment plan for prosopometamorphopsia. Patients with the disorder most often have an associated condition, which (as discussed in the causes section) is thought to play a role in the development of the disorder. This could include a brain tumour, epilepsy, or severe migraines, for example. In these cases, patients may be treated using surgical intervention (i.e. removal of the brain tumour), anti-epileptic or migraine treatments.^1,6 Prosopometamorphopsia is often temporary, and resolves within days to weeks, most commonly. Because of the little research on the disorder, it is not known whether treatment of the associated condition (e.g. removal of a brain tumour) is what resolves the disorder, or whether it resolves on its own without medical intervention.

FAQs

The FAQs for this article focus on other visual perception disorders that can affect the perception of the face of oneself or others. Many of these perceptual disorders, like Prosopometamorphopsia, are very rare. This means that case studies most commonly inform our understanding of the disorders and their differences.

Prosopagnosia vs. Prosopometamorphopsia:

Both prosopagnosia and prosopometamorphopsia are likely to involve a similar neural network within the brain referred to as the ‘face-selective network’. However, prosopagnosia refers to the disorder in which an individual has a specific deficit in recognising familiar faces. Whereas prosopometamorphopsia refers to a different disorder in which faces are often recognisable but are perceived as distorted.

Is Prosopometamorphopsia the same as Alice in Wonderland Syndrome?

Alice in Wonderland Syndrome (AIWS) refers to a range of perceptual distortions in which the perception of the body or face is distorted.⁷ An individual with AIWS may also perceive time to pass extremely fast, or extremely slowly, and is most likely to experience distorted perception at night. This is inherently different from prosopometamorphopsia, in which perceptual distortions are described only for the faces of others, but not the body.

AIWS is also an extremely rare perceptual disorder and is most often associated with severe migraines, several epileptic syndromes (specifically temporal lobe epilepsy), infection with the Ebstein-Barr virus, brain tumors, and use (or abuse) of psychoactive drugs.^7,8

Is Prosopometamorphopsia the same as facial hallucinations?

Facial hallucinations describe the phenomenon where an individual sees faces where there are none.¹ In this case, the face is perceived but does not exist. On the other hand, prosopometamorphopsia is a different condition in which the perception of the face is distorted. In this case, the face being perceived does exist, however, it is the inaccurate perception of facial features that characterises the disorder that does not reflect reality. This includes the perception of features being stretched or morphed; often described as ‘demonic’ by patients with the condition. To sum up, in prosopometamorphopsia the face exists in reality, unlike facial hallucinations; however, the perception of the face is distorted.

Summary

Prosopometamorphopsia is a perceptual disorder in which an individual perceives the faces of others (or their own face, e.g., in the mirror) to be distorted. Prosopometamorphopsia is extremely rare, with less than 100 cases reported in the literature, making the disorder difficult to fully characterise, and presenting challenges to researchers who seek to determine its cause. Most commonly, the disorder resolves on its own or following treatment for an associated condition that affects the brain.