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Palinopsia necessitates a full ophthalmologic and neurologic history and physical exam. Hallucinatory palinopsia warrants automated visual field testing and neuroimaging since the majority of hallucinatory palinopsia is caused by posterior cortical lesions and seizures. It is generally easy to diagnose the underlying cause of hallucinatory palinopsia. The medical history typically includes concerning symptoms, and neuroimaging usually reveals cortical lesions. In patients with hallucinatory palinopsia and unremarkable neuroimaging, blood tests or clinical history often hints at the cause. The practitioner should be considering visual seizures in these cases.
Research needs to be performed on the efficacy of the various pharmaceuticals for treating illusory palinopsia. It is unclear if the symptoms' natural history and treatment are influenced by the cause. It is also not clear if there is treatment efficacy overlap for illusory palinopsia and the other co-existing diffuse persistent illusory phenomenon such as visual snow, oscillopsia, dysmetropsia, and halos.
Future advancements in fMRI could potentially further our understanding of hallucinatory palinopsia and visual memory. Increased accuracy in fMRI might also allow for the observation of subtle metabolic or perfusional changes in illusory palinopsia, without the use of ionizing radiation present in CT scans and radioactive isotopes. Studying the psychophysics of light and motion perception could advance our understanding of illusory palinopsia, and vice versa. For example, incorporating patients with visual trailing into motion perception studies could advance our understanding of the mechanisms of visual stability and motion suppression during eye movements (e.g. saccadic suppression).
Palinopsia necessitates a full ophthalmologic and neurologic history and physical exam. 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. However, in a young patient without risk factors or other worrisome symptoms or signs (vasculopathy, history of cancer, etc.), neuroimaging for illusory palinopsia is low-yield but may grant the patient peace of mind.
The physical exam and work-up are usually non-contributory in illusory palinopsia. Diagnosing the etiology of illusory palinopsia is often based on the clinical history. Palinopsia is attributed to a prescription drug if symptoms begin after drug initiation or dose increase. Palinopsia is attributed to head trauma if symptoms begin shortly after the incident. Continuous illusory palinopsia in a migraineur is usually from persistent visual aura. HPPD can occur any time after hallucinogen ingestion and is a diagnosis of exclusion in patients with previous hallucinogen use. Migraines and HPPD are probably the most common causes of palinopsia. Idiopathic palinopsia may be analogous to the cerebral state in persistent visual aura with non-migraine headache or persistent visual aura without headache.
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 is considerable evidence in the literature confirming the symptom legitimacy, so validating the patient’s symptoms can help ease anxiety. Unidirectional visual trails or illusory symptoms confined to part of a visual field suggest cortical pathology and necessitate further work-up.
Palinopsia from cerebrovascular accidents generally resolves spontaneously, and treatment should be focused on the vasculopathic risk factors. Palinopsia from neoplasms, AVMs, or abscesses require treatment of the underlying condition, which usually also resolves the palinopsia. Palinopsia due to seizures generally resolves after correcting the primary disturbance and/or treating the seizures. In persistent hallucinatory palinopsia, a trial of an anti-epileptic drug can be attempted. Anti-epileptics reduce cortical excitability and could potentially treat palinopsia caused by cortical deafferentation or cortical irritation. Patients with idiopathic hallucinatory palinopsia should have close follow-up.
There is limited data on treating the visual disturbances associated with HPPD, persistent visual aura, or post-head trauma visual disturbances, and pharmaceutical treatment is empirically-based. It is not clear if the etiology or type of illusory symptom influences treatment efficacy. Since the symptoms are usually benign, treatment is based on the patient’s zeal and willingness to try many different drugs. 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. However, other patients report treatment failure from the same drugs. Based on the available evidence and side-effect profile, clonidine might be an attractive treatment option. Many patients report improvement from sunglasses. FL-41 tinted lenses may provide additional relief, as they have shown some efficacy in providing relief to visually-sensitive migraineurs.
Since this condition is usually coupled with other neurological disorders or deficits, there is no known cure for cerebral polyopia. However, measures can be taken to reduce the effects of associated disorders, which have proven to reduce the effects of polyopia. In a case of occipital lobe epilepsy, the patient experienced polyopia. Following administration of valproate sodium to reduce headaches, the patient’s polyopia was reduced to palinopsia. Further, after administering the anticonvulsant drug Gabapentin in addition to valproate sodium, the effects of palinopsia were decreased, as visual perseveration is suppressed by this anticonvulsant drug. Thus, in cases of epilepsy, anticonvulsant drugs may prove to reduce the effects of polyopia and palinopsia, a topic of which should be further studied.
In other cases of polyopia, it is necessary to determine all other present visual disturbances before attempting treatment. Neurological imaging can be performed to determine if there are present occipital or temporal lobe infarctions that may be causing the polyopia. CT scans are relatively insensitive to the presence of cerebral lesions, so other neurological imaging such as PET and MRI may be performed. The presence of seizures and epilepsy may also be assessed through EEG. In addition, motor visual function should be assessed through examination of pupillary reactions, ocular motility, optokinetic nystagmus, slit-lamp examination, visual field examination, visual acuity, stereo vision, bimicroscopic examination, and funduscopic examination. Once the performance of such functions have been assessed, a plan for treatment can follow accordingly. Further research should be conducted to determine if the treatment of associated neurological disturbances can reduce the effects of polyopia.
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, or hallucinogen persisting perception disorder (HPPD), describes afterimages that are affected by ambient light and motion and are unformed, indistinct, or low resolution.
There is no established treatment for visual snow. It is difficult to resolve visual snow with treatment, but it is possible to reduce symptoms and improve quality of life through treatment.
Medications that may be used include lamotrigine, acetazolamide, or verapamil. But these do not always result in benefits.
Proposed diagnostic criteria for the "visual snow" syndrome:
- Dynamic, continuous, tiny dots in the entire visual field.
- At least one additional symptom:
- Palinopsia (visual trailing and afterimages)
- Enhanced entoptic phenomena (floaters, photopsia, blue field entoptic phenomenon, self-light of the eye)
- Photophobia
- Tinnitus
- Impaired night vision
- Symptoms are not consistent with typical migraine aura.
- Symptoms are not attributed to another disorder (ophthalmological, drug abuse).
Cerebral diplopia or polyopia describes seeing two or more images arranged in ordered rows, columns, or diagonals after fixation on a stimulus. The polyopic images occur monocular bilaterally (one eye open on both sides) and binocularly (both eyes open), differentiating it from ocular diplopia or polyopia. The number of duplicated images can range from one to hundreds. Some patients report difficulty in distinguishing the replicated images from the real images, while others report that the false images differ in size, intensity, or color. Cerebral polyopia is sometimes confused with palinopsia (visual trailing), in which multiple images appear while watching an object. However, in cerebral polyopia, the duplicated images are of a stationary object which are perceived even after the object is removed from the visual field. Movement of the original object causes all of the duplicated images to move, or the polyopic images disappear during motion. In palinoptic polyopia, movement causes each polyopic image to leave an image in its wake, creating hundreds of persistent images (entomopia).
Infarctions, tumors, multiple sclerosis, trauma, encephalitis, migraines, and seizures have been reported to cause cerebral polyopia. Cerebral polyopia has been reported in extrastriate visual cortex lesions, which is important for detecting motion, orientation, and direction. Cerebral polyopia often occurs in homonymous field deficits, suggesting deafferentation hyperexcitability could be a possible mechanism, similar to visual release hallucinations (Charles Bonnet syndrome).
Akinetopsia can be separated into two categories based on symptom severity and the amount the akinetopsia affects the patient's quality of life.
Akinetopsia (Greek: a for "without", kine for "to move" and opsia for "seeing"), also known as cerebral akinetopsia or motion blindness, is a neuropsychological disorder in which a patient cannot perceive motion in their visual field, despite being able to see stationary objects without issue. There are varying degrees of akinetopsia: from seeing motion as a cinema reel to an inability to discriminate any motion. There is currently no effective treatment or cure for akinetopsia.