Alice in Wonderland syndrome (AIWS) is a rare neurological disorder that distorts perception, causing alterations in visual perception of objects, such as appearing smaller or larger than they actually are. The syndrome is also known as Todds syndrome or dysmetropsia. AIWS is often associated with migraines, head trauma, or viral encephalitis caused by Epstein–Barr virus infection. It is also theorized that it can be caused by abnormal amounts of electrical activity, resulting in abnormal blood flow in those parts of the brain that process visual perception and texture.

AIWS is characterized by the individual being able to recognize the distortion in the perception of their own body and is episodic. Episodes typically last from a few minutes to an hour, and each episode may vary in experience. Symptoms of AIWS include visual distortions such as metamorphopsia, macropsia, and micropsia. Metamorphopsia is a visual distortion where objects appear distorted, macropsia is seeing images larger than normal, and micropsia is seeing images smaller than normal.

Although there are cases of AIWS in both adolescents and adults, it is most commonly seen in children. The cause of AIWS is currently unknown, and diagnosis and recognition of the syndrome has barely improved over the past few decades. Brain imaging studies suggest that AIWS may be caused by a dysfunction of a region of the brain called the temporo-parietal-occipital junction, where visual perception is processed.

Treatment for AIWS depends on the underlying cause of the syndrome. In some cases, AIWS may resolve on its own, while in other cases, treatment may involve medications to manage migraines or other underlying conditions. Future studies are encouraged to include global collaborative efforts that may help improve understanding of AIWS and its epidemiology.