What is the medical term for hallucinations where people's faces appear to change?

Medical Terminology for Face-Changing Hallucinations

The medical term for hallucinations where people's faces appear to change is prosopometamorphopsia (distortion of facial perception), though the broader clinical syndrome you're describing is most likely Charles Bonnet Syndrome (CBS) if occurring in the context of vision loss.

Understanding the Terminology

Charles Bonnet Syndrome is the primary diagnosis to consider when patients experience vivid visual hallucinations, including distorted or changing faces, particularly in elderly patients with vision impairment. 1 The syndrome is defined by four characteristic features:

• Recurrent, vivid visual hallucinations (which can include faces that appear distorted or changing) 1
• Preserved insight - patients recognize the hallucinations are not real 1, 2
• Absence of other neurological or medical explanations 1
• Some degree of vision loss (affecting 15-60% of visually impaired patients depending on the population) 1, 3

Specific Visual Phenomena Terms

The hallucinations in CBS can manifest as several distinct visual distortions:

• Metamorphopsia - distortion of visual images, including faces 4
• Micropsia - objects or faces appearing smaller than normal (sometimes called "Lilliputian hallucinations" in CBS) 3
• Macropsia - objects or faces appearing larger than normal 4
• Prosopometamorphopsia - specific distortion of facial features 4

The hallucinations are typically well-defined, organized, and clear images over which the patient has little control. 5 They represent release phenomena due to deafferentation of visual association areas of the cerebral cortex, creating a form of "phantom vision." 3, 5

Critical Diagnostic Distinctions

Red flags that suggest an alternative diagnosis rather than typical CBS include: 1, 2

• Lack of insight despite education about CBS - patient believes hallucinations are real 1, 6
• Hallucinations that interact with the patient (responding to or engaging with them) 1, 6
• Accompanying neurological signs (altered mental status, delirium, movement disorders) 2
• Other psychotic symptoms beyond isolated visual hallucinations 2

These features should prompt comprehensive neurological evaluation with brain MRI and consideration of:

• Dementia with Lewy bodies 1, 2
• Parkinson's disease 1, 2, 3
• Primary psychiatric disorders (schizophrenia, bipolar disorder with psychosis) 2
• Epilepsy or seizure phenomena 2, 4
• Medication-induced hallucinations (anticholinergics, steroids, dopaminergic agents) 1, 2

Clinical Context Matters

The presence or absence of vision loss is the key distinguishing feature. CBS specifically occurs in patients with significant visual impairment from conditions like age-related macular degeneration or glaucoma. 3, 5 The prevalence ranges from 10-40% in visually impaired populations, with one Australian study finding 17.5% prevalence. 3

If hallucinations of changing faces occur WITHOUT vision loss, consider alternative diagnoses including:

• Seizure activity (temporal or occipital lobe) 4
• Migraine-related phenomena 3, 4
• Primary psychiatric disorders 2
• Drug or alcohol effects 3
• Alice in Wonderland syndrome 3

Common Clinical Pitfall

Many patients do not spontaneously report these symptoms due to fear of being labeled mentally unstable. 3, 5 Sensitive and direct questioning is essential: "Some people with vision problems see things that aren't really there, like faces or patterns. Has this happened to you?" 5 This approach normalizes the experience and facilitates disclosure.