Illusory palinopsia is caused by migraines,[3] hallucinogen persisting perception disorder (HPPD),[4] prescription drugs, and head trauma,[5] but is also sometimes idiopathic.
Illusory palinopsia is often worse with high stimulus intensity and contrast ratio in a dark adapted state.
For example, after seeing a bright light such as a car headlight or a camera flash, a persistent afterimage remains in the visual field for several minutes.
The prolonged image or light is typically isochromatic (positive afterimage) to the original stimulus, but can fade to different colors over time.
Patients commonly report of difficulty with night driving since the headlights of oncoming cars cause multiple streaks which obscure vision.
[12] These variants usually lack the realistic clarity of hallucinatory palinopsia, and the generation of the palinoptic images is affected by fixation time, motion, stimulus intensity, or contrast.
[2] Trazodone,[9] nefazodone,[13] mirtazapine,[14] topiramate,[15] clomiphene,[16] oral contraceptives, and risperidone[17] have been reported to cause illusory palinopsia.
[19] Because of the drugs that cause illusory palinopsia, 5-HT2a receptor excitotoxicity or a disruption of GABAergic transmission have been proposed as possible mechanisms.
Light and motion perception are dynamic operations involving processing and feedback from structures throughout the central nervous system.
A patient frequently has multiple types of diffuse, persistent illusory symptoms which represent dysfunctions in both light and motion perception.
These momentary afterimages appear at a different location in the visual field than the original stimulus, occur a few times per month, and are affected by external light and motion.
Studying these momentary formed afterimages, in relation to alterations in cortical excitability, could advance our understanding of migraine pathogenesis and mechanisms associated with encoding visual memory.
There are no clear guidelines on the work-up for illusory palinopsia, but it is not unreasonable to order automated visual field testing and neuroimaging since migraine aura can sometimes mimic seizures or cortical lesions.
Due to the subjective nature of the symptoms and the lack of organic findings, clinicians may be dismissive of illusory palinopsia, sometimes causing the patient distress.
There are cases which report successful treatment with clonidine, clonazepam, lamotrigine, nimodipine, topiramate, verapamil, divalproex sodium, gabapentin, furosemide, and acetazolamide, as these drugs have mechanisms that decrease neuronal excitability.