Palinopsia

Palinopsia (Greek: palin for "again" and opsia for "seeing") is the persistent recurrence of a visual image after the stimulus has been removed. Palinopsia is not a diagnosis; it is a diverse group of pathological visual symptoms with a wide variety of causes. Visual perseveration is synonymous with palinopsia. In 2014, Gersztenkorn and Lee comprehensively reviewed all cases of palinopsia in the literature and subdivided it into two clinically relevant groups: illusory palinopsia and hallucinatory palinopsia. Hallucinatory palinopsia, usually due to seizures or posterior cortical lesions, describes afterimages that are formed, long-lasting, and high resolution. Illusory palinopsia, usually due to migraines, head trauma, prescription drugs, visual snow or hallucinogen persisting perception disorder (HPPD), describes afterimages that are affected by ambient light and motion and are unformed, indistinct, or low resolution. People with palinopsia frequently report other visual illusions and hallucinations such as photopsias, dysmetropsia i.e. Alice in Wonderland syndrome (micropsia, macropsia, teleopsia, and pelopsia), visual snow, oscillopsia, entoptic phenomena, and cerebral polyopia. Posterior visual pathway cortical lesions (tumor, abscess, hemorrhage, infarction, arteriovenous malformation, cortical dysplasia, aneurysm) and various seizure causes (hyperglycemia, ion channel mutations, Creutzfeldt–Jakob disease, idiopathic seizures, etc.) cause focal cortical hyperactivity or hyperexcitability, resulting in inappropriate, persistent activation of a visual memory circuit. Illusory palinopsia is a dysfunction of visual perception, resulting from diffuse, persistent alterations in neuronal excitability that affect physiological mechanisms of light or motion perception. Illusory palinopsia is caused by migraines, visual snow, HPPD, prescription drugs, head trauma, or may be idiopathic. Trazodone, nefazodone, mirtazapine, topiramate, clomiphene, oral contraceptives, and risperidone have been reported to cause illusory palinopsia.