The authors write a very comprehensive review of palinopsia, which is the persistence or recurrence of a visual image after the stimulus has been removed. They comment on visual snow, epileptic discharges, release phenomena, medications and illicit drugs, in addition to visual trailing, migraine and light streaking. This is a must-read for anyone interested in palinopsia.
Palinopsia is not a diagnosis but a broad term that describes a heterogeneous group of visual symptoms with a wide variety of etiologies. It may be the presenting symptom of a potentially life-threatening posterior cortical lesion or a benign medication side effect.
The authors comprehensively review all published cases and divide palinopsia into two clinically relevant categories: illusory palinopsia and hallucinatory palinopsia. They discuss its symptomology, etiology, pathophysiology, diagnostic evaluation, prognosis and treatment.
They describe hallucinatory palinopsia as afterimages that are long-lasting, isochromatic, of high resolution and not usually affected by environmental conditions of light or motion. This can include formed image perseveration, scene perseveration, categorical incorporation and patterned visual spread.
Hallucinatory palinopsia represents a dysfunction in visual memory and is caused by posterior cortical lesions or seizures, typically resolving after treating the underlying pathology. If no etiology is found, these alarming symptoms warrant further testing or prompt follow-up.
Illusory palinopsia describes afterimages that are unformed, indistinct or of low resolution and are affected by ambient light and motion. They consist of momentary formed image perseveration, prolonged indistinct afterimages, light streaking and visual trailing.
Illusory palinopsia represents a dysfunction in visual perception and is a result of migraines, prescription drugs, illicit drugs or head trauma but can also be idiopathic. The perseverated images occur in the same location in the visual field as the original stimulus.
The authors say that while more evidence is needed on the efficacy of pharmaceuticals for palinopsia, clonidine, gabapentin, acetazolamide, magnesium or calcium channel blockers could be treatment options.