Visual snow syndrome

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Visual snow syndrome
Other namesPersistent positive visual phenomenon, [1] visual static, aeropsia
Red-blue-noise.gif
Animated example of visual snow-like noise
Specialty Neurology, Neuro-ophthalmology
Symptoms Static and auras in vision, Palinopsia, Blue field entoptic phenomenon, Nyctalopia, Tinnitus
Complications Poor quality of vision, Photophobia, Heliophobia, Depersonalization and Derealization [2]
Usual onsetVisual Snow can appear at any time, but it commonly appears at birth, late teenage years, and early adulthood.
CausesUnknown, [3] hyperexcitability of neurons and processing problems in the visual cortex [4] [5]
Risk factors Migraine sufferer, [6] psychoactive substance use
Differential diagnosis Migraine aura, [7] Persistent aura without infarction, Hallucinogen persisting perception disorder [8] [9]
Medication Anticonvulsants [7] [3] (limited evidence and success)
FrequencyUncommon (understudied)

Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or colored dots across the whole visual field. [7] [4]

Contents

Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and tension headaches. [10] [11] The condition is typically always present and has no known cure, as viable treatments are still under research. [12] Astigmatism, although not presumed connected to these visual disturbances, is a common comorbidity. Migraines and tinnitus are common comorbidities that are both associated with a more severe presentation of the syndrome. [13]

The cause of the syndrome is unclear. [3] The underlying mechanism is believed to involve excessive excitability of neurons in the right lingual gyrus and left anterior lobe of the cerebellum. Another hypothesis proposes that visual snow syndrome could be a type of thalamocortical dysrhythmia and may involve the thalamic reticular nucleus (TRN). A failure of inhibitory action from the TRN to the thalamus may be the underlying cause for the inability to suppress excitatory sensory information. [4] [6] Research has been limited due to issues of case identification, diagnosis, and the limited size of any studied cohort, though the issue of diagnosis is now largely addressed. Initial functional brain imaging research suggests visual snow is a brain disorder. [14]

The difference between Visual Snow and Visual Snow Syndrome

Visual snow is a phenomenon where a person perceives visual disturbances, such as fine graininess or "static," in their field of vision. This can occur in low-light conditions, in the dark, or when the visual system amplifies light perception. In these cases, visual snow is a normal reaction of the body, related to the way photoreceptors (rods) and neurons respond to weak or insufficient stimuli.[ citation needed ]

However, if visual snow becomes persistent and continuous — especially if it is accompanied by other symptoms, such as headaches, difficulty focusing, or intense visual distortions — it may indicate visual snow syndrome. This syndrome is not just a phenomenon, but a neurological disorder, where a person experiences constant visual disturbances, regardless of lighting conditions. Visual snow syndrome is often linked to heightened neural sensitivity in the visual system and may require diagnosis and treatment, as it could be associated with underlying eye conditions or neurological disorders.[ citation needed ]

In summary:

Signs and symptoms

Normal vision vis-a-vis disturbed vision Vs with descriptions.jpg
Normal vision vis-à-vis disturbed vision

In addition to visual snow, many of those affected have other types of visual disturbances such as starbursts, increased afterimages, floaters, trails, and many others. [15]

Visual snow likely represents a clinical continuum, with different degrees of severity. The presence of comorbidities such as migraine and tinnitus is associated with a more severe presentation of visual symptoms. [13]

Non-visual symptoms may include difficulty concentrating, insomnia, frequent migraines, nausea, and vertigo. [16]

Diagnosis

Visual snow syndrome is usually diagnosed with the following proposed criteria: [17] [18] [13]

Additional and non-visual symptoms like tinnitus, ear pressure, brain fog, and more might be present. It can also be diagnosed by PET scan.

Common misconceptions

Comorbidities

Migraine and migraine with aura are common comorbidities. However, comorbid migraine worsens some of the additional visual symptoms and tinnitus seen in "visual snow" syndrome. This might bias research studies by patients with migraine being more likely to offer study participation than those without migraine due to having more severe symptoms. In contrast to migraine, comorbidity of typical migraine aura does not appear to worsen symptoms. [6]

Psychological side effects of visual snow can include depersonalization, derealization, depression, photophobia, and heliophobia in the individual affected. [2]

Patients with visual "snow" have normal equivalent input noise levels and contrast sensitivity. [21] In a 2010 study, Raghaven et al. hypothesize that what the patients see as "snow" is eigengrau. [21] This would also explain why many report more visual snow in low light conditions: "The intrinsic dark noise of primate cones is equivalent to ~4000 absorbed photons per second at mean light levels; below this the cone signals are dominated by intrinsic noise". [22] [23]

Causes

The causes of VSS are not clear. [3] The underlying mechanism is believed to involve excessive excitability of neurons within the cortex of the brain, [4] specifically the right lingual gyrus and left cerebellar anterior lobe of the brain. [6]

Persisting visual snow can feature as a leading addition to a migraine complication called persistent aura without infarction, [24] commonly referred to as persistent migraine aura (PMA). In other clinical sub-forms of migraine headache may be absent and the migraine aura may not take the typical form of the zigzagged fortification spectrum (scintillating scotoma), but manifests with a large variety of focal neurological symptoms. [25]

Visual snow does not depend on the effect of psychotropic substances on the brain. [13] Hallucinogen persisting perception disorder (HPPD), a condition caused by hallucinogenic drug use, is sometimes linked to visual snow, [26] but both the connection of visual snow to HPPD [8] and the cause and prevalence of HPPD are disputed. [9] Most of the evidence for both is generally anecdotal and subject to spotlight fallacy. [8] [9] Visual snow has also been correlated with head trauma and infection. [27]

Timeline

Treatments

It is difficult to resolve visual snow with treatment, but it is possible to reduce symptoms and improve quality of life through treatment, both of the syndrome and its comorbidities. [4] In some studies, lamotrigine as a treatment for visual snow syndrome only showed efficacy in 20% of patients, and in one study, patients using lamotrigine even reported worsening symptoms. [33] Medications that may be used include lamotrigine, acetazolamide, verapamil, [4] clonazepam, propranolol, and sertraline [34] but these do not always result in positive effects. [7] [3] As of 2021, two ongoing clinical trials were using transcranial magnetic stimulation and neurofeedback for visual snow. [35] [36]

A recent study in the British Journal of Ophthalmology has confirmed that common drug treatments are generally ineffective in visual snow syndrome (VSS). Vitamins and benzodiazepines, however, were shown to be beneficial in some patients and can be considered safe for this condition. [37]

Related Research Articles

<span class="mw-page-title-main">Migraine</span> Disorder resulting in recurrent moderate–severe headaches

Migraine is a genetically-influenced complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea and light and sound sensitivity. Other characterizing symptoms may include vomiting, cognitive dysfunction, allodynia, and dizziness. Exacerbation or worsening of headache symptoms during physical activity is another distinguishing feature.

<span class="mw-page-title-main">Headache</span> Pain in the head, neck, or face

A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches.

<span class="mw-page-title-main">Micropsia</span> Medical condition

Micropsia is a condition affecting human visual perception in which objects are perceived to be smaller than they actually are. Micropsia can be caused by optical factors, by distortion of images in the eye, by changes in the brain, and from psychological factors. Dissociative phenomena are linked with micropsia, which may be the result of brain-lateralization disturbance.

<span class="mw-page-title-main">Alice in Wonderland syndrome</span> Neurological disorder that distorts perception of objects size and distance

Alice in Wonderland Syndrome (AIWS), also known as Todd's Syndrome or Dysmetropsia, is a neurological disorder that distorts perception. People with this syndrome may experience distortions in their visual perception of objects, such as appearing smaller (micropsia) or larger (macropsia), or appearing to be closer (pelopsia) or farther (teleopsia) than they are. Distortion may also occur for senses other than vision.

<span class="mw-page-title-main">Cluster headache</span> Neurological disorder

Cluster headache is a neurological disorder characterized by recurrent severe headaches on one side of the head, typically around the eye(s). There is often accompanying eye watering, nasal congestion, or swelling around the eye on the affected side. These symptoms typically last 15 minutes to 3 hours. Attacks often occur in clusters which typically last for weeks or months and occasionally more than a year.

A medication overuse headache (MOH), also known as a rebound headache, usually occurs when painkillers are taken frequently to relieve headaches. These cases are often referred to as painkiller headaches. Rebound headaches frequently occur daily, can be very painful and are a common cause of chronic daily headache. They typically occur in patients with an underlying headache disorder such as migraine or tension-type headache that "transforms" over time from an episodic condition to chronic daily headache due to excessive intake of acute headache relief medications. MOH is a serious, disabling and well-characterized disorder, which represents a worldwide problem and is now considered the third-most prevalent type of headache. The proportion of patients in the population with Chronic Daily Headache (CDH) who overuse acute medications ranges from 18% to 33%. The prevalence of medication overuse headache (MOH) varies depending on the population studied and diagnostic criteria used. However, it is estimated that MOH affects approximately 1-2% of the general population, but its relative frequency is much higher in secondary and tertiary care.

Mal de debarquement syndrome is a neurological condition usually occurring after a cruise, aircraft flight, or other sustained motion event. The phrase mal de débarquement is French and translates to "illness of disembarkment".

Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light, such as heliophobia. The term photophobia comes from Greek φῶς (phōs) 'light' and φόβος (phóbos) 'fear'.

<span class="mw-page-title-main">Diplopia</span> Double vision

Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary. However, when occurring involuntarily, it results from impaired function of the extraocular muscles, where both eyes are still functional, but they cannot turn to target the desired object. Problems with these muscles may be due to mechanical problems, disorders of the neuromuscular junction, disorders of the cranial nerves that innervate the muscles, and occasionally disorders involving the supranuclear oculomotor pathways or ingestion of toxins.

<span class="mw-page-title-main">Hallucinogen persisting perception disorder</span> Medical condition

Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after using drugs, including but not limited to psychedelics, dissociatives, entactogens, tetrahydrocannabinol (THC), and SSRIs. Despite being designated as a hallucinogen-specific disorder, the specific contributory role of psychedelic drugs is unknown.

Palinopsia 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.

<span class="mw-page-title-main">Aura (symptom)</span> Symptom of epilepsy and migraine

An aura is a perceptual disturbance experienced by some with epilepsy or migraine. An epileptic aura is actually a minor seizure.

Acephalgic migraine is a neurological syndrome. It is a relatively uncommon variant of migraine in which the patient may experience some migraine symptoms such as aura, nausea, photophobia, and hemiparesis, but does not experience headache. It is generally classified as an event fulfilling the conditions of migraine with aura with no headache. It is sometimes distinguished from visual-only migraine aura without headache, also called ocular migraine.

Persistent aura without infarction (PAWOI) is a rare and seemingly benign condition, first described in case reports in 1982 as "prolonged/persistent migraine aura status", and in 2000 as "migraine aura status", that is not yet fully understood. PAWOI is said to possibly be a factor involved in a variety of neurological symptoms, including visual snow, loss of vision, increased afterimages, tinnitus, and others. The pathogenesis of PAWOI is unknown. It is not clear which medical examinations are useful in diagnosing PAWOI. At present, PAWOI is usually diagnosed solely based on the patient's current and past symptoms. It is possible that an "overactive brain" or a chemical imbalance underlies the disorder. Various medications have been tried as treatment, notably acetazolamide, valproate, lamotrigine, topiramate, and furosemide.

New daily persistent headache (NDPH) is a primary headache syndrome which can mimic chronic migraine and chronic tension-type headache. The headache is daily and unremitting from very soon after onset, usually in a person who does not have a history of a primary headache disorder. The pain can be intermittent, but lasts more than 3 months. Headache onset is abrupt and people often remember the date, circumstance and, occasionally, the time of headache onset. One retrospective study stated that over 80% of patients could state the exact date their headache began.

Vestibular migraine (VM) is vertigo with migraine, either as a symptom of migraine or as a related neurological disorder.

The classification of all headaches, including migraines, is organized by the International Headache Society, and published in the International Classification of Headache Disorders (ICHD). The current version, the ICHD-3 beta, was published in 2013.

Migralepsy is a rare condition in which a migraine is followed, within an hour period, by an epileptic seizure. Because of the similarities in signs, symptoms, and treatments of both conditions, such as the neurological basis, the psychological issues, and the autonomic distress that is created from them, they individually increase the likelihood of causing the other. However, also because of the sameness, they are often misdiagnosed for each other, as migralepsy rarely occurs.

<span class="mw-page-title-main">Illusory palinopsia</span> Subtype of palinopsia

Illusory palinopsia is a subtype of palinopsia, a visual disturbance defined as the persistence or recurrence of a visual image after the stimulus has been removed. Palinopsia is a broad term describing a heterogeneous group of symptoms, which is divided into hallucinatory palinopsia and illusory palinopsia. Illusory palinopsia is likely due to sustained awareness of a stimulus and is similar to a visual illusion: the distorted perception of a real external stimulus.

A migrainous infarction is a rare type of ischaemic stroke which occurs in correspondence with migraine aura symptoms. Symptoms include headaches, visual disturbances, strange sensations and dysphasia, all of which gradually worsen causing neurological changes which ultimately increase the risk of an ischaemic stroke. Typically, women under the age of 45 who experience migraine with aura (MA) are at the greatest risk for developing migrainous infarction, especially when combined with smoking and use of oral contraceptives.

References

  1. ↑ Licht, Joseph; Ireland, Kathryn; Kay, Matthew (2016). "Visual Snow: Clinical Correlations and Workup A Case Series". researchgate.net. Larkin Community Hospital. doi:10.13140/RG.2.1.2393.9443 . Retrieved 3 September 2017.
  2. 1 2 "Diagnostic Criteria | Visual Snow Initiative". 23 March 2023.
  3. 1 2 3 4 5 Brodsky, Michael C. (2016). Pediatric Neuro-Ophthalmology. Springer. p. 285. ISBN   9781493933846.
  4. 1 2 3 4 5 6 Bou Ghannam, A; Pelak, VS (March 2017). "Visual snow: a potential cortical hyperexcitability syndrome". Current Treatment Options in Neurology. 19 (3): 9. doi:10.1007/s11940-017-0448-3. PMID   28349350. S2CID   4829787.
  5. ↑ Bou Ghannam, A.; Pelak, V. S. (2017). "Visual Snow: A Potential Cortical Hyperexcitability Syndrome". Current Treatment Options in Neurology. 19 (3): 9. doi:10.1007/s11940-017-0448-3. PMID   28349350. S2CID   4829787.
  6. 1 2 3 4 Schankin, CJ, Maniyar, FH, Sprenger, T, Chou, DE, Eller, M, Goadsby, PJ, 2014, The Relation Between Migraine, Typical Migraine Aura and "Visual Snow", Headache, doi : 10.1111/head.12378
  7. 1 2 3 4 Dodick, David; Silberstein, Stephen D. (2016). Migraine. Oxford University Press. p. 53. ISBN   9780199793617.
  8. 1 2 3 Schankin, C.; Maniyar, F.; Hoffmann, J.; Chou, D.; Goadsby, P. (22 April 2012). "Visual Snow: A New Disease Entity Distinct from Migraine Aura (S36.006)". Neurology. 78 (Meeting Abstracts 1): S36.006. doi:10.1212/WNL.78.1_MeetingAbstracts.S36.006.
  9. 1 2 3 Halpern, J (1 March 2003). "Hallucinogen persisting perception disorder: what do we know after 50 years?". Drug and Alcohol Dependence. 69 (2): 109–119. doi:10.1016/S0376-8716(02)00306-X. PMID   12609692.
  10. ↑ "Visual snow syndrome - About the Disease - Genetic and Rare Diseases Information Center". rarediseases.info.nih.gov. Retrieved 2022-10-30.
  11. ↑ Puledda, Francesca; Schankin, Christoph; Goadsby, Peter J. (2020-02-11). "Visual snow syndrome: A clinical and phenotypical description of 1,100 cases". Neurology. 94 (6): e564 –e574. doi:10.1212/WNL.0000000000008909. ISSN   0028-3878. PMC   7136068 . PMID   31941797.
  12. ↑ Schankin, CJ; Goadsby, PJ (June 2015). "Visual snow--persistent positive visual phenomenon distinct from migraine aura". Current Pain and Headache Reports. 19 (6): 23. doi:10.1007/s11916-015-0497-9. PMID   26021756. S2CID   6770765.
  13. 1 2 3 4 Puledda, Francesca; Schankin, Christoph; Goadsby, Peter (2020). "Visual snow syndrome. A clinical and phenotypical description of 1,100 cases" (PDF). Neurology. 94 (6): e564 –e574. doi:10.1212/WNL.0000000000008909. PMC   7136068 . PMID   31941797.
  14. ↑ Traber, Ghislaine L.; Piccirelli, Marco; Michels, Lars (February 2, 2020). "Visual snow syndrome: a review on diagnosis, pathophysiology, and treatment". Current Opinion in Neurology. 33 (1): 74–78. doi:10.1097/WCO.0000000000000768. ISSN   1350-7540. PMID   31714263 – via NHI.
  15. ↑ Podoll K, Dahlem M, Greene S. Persistent migraine aura symptoms aka visual snow. (archived Feb 8, 2012)
  16. ↑ Cleveland Clinic. (2024). Visual Snow Syndrome. https://my.clevelandclinic.org/health/diseases/24444-visual-snow-syndrome.
  17. ↑ Schankin, Christoph J.; Maniyar, Farooq H.; Digre, Kathleen B.; Goadsby, Peter J. (2014-03-18). "'Visual snow' – a disorder distinct from persistent migraine aura". Brain. 137 (5): 1419–1428. doi: 10.1093/brain/awu050 . ISSN   1460-2156. PMID   24645145.
  18. ↑ "Headache Classification Committee of the International Headache Society (IHS) The International Classification of Headache Disorders, 3rd edition". Cephalalgia. 38 (1): 1–211. 2018-01-25. doi: 10.1177/0333102417738202 . ISSN   0333-1024. PMID   29368949.
  19. ↑ Angueyra, J. M.; Rieke, F. (October 6, 2013). "Origin and effect of phototransduction noise in primate cone photoreceptors". Nature Neuroscience. 16 (11): 1692–1700. doi:10.1038/nn.3534. PMC   3815624 . PMID   24097042.
  20. ↑ Mewes, R. (November 4, 2022). "Recent developments on psychological factors in medically unexplained symptoms and somatoform disorders". Frontiers in Public Health. 10. doi: 10.3389/fpubh.2022.1033203 . PMC   9672811 . PMID   36408051.
  21. 1 2 Raghavan, Manoj; Remler, Bernd F.; Rozman1, Stephanie; Pelli, Denis G. (2010). "Patients with visual 'snow' have normal equivalent input noise levels" (PDF). Investigative Ophthalmology & Visual Science (51). Archived from the original (PDF) on 2016-04-11. Retrieved 2017-04-12.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  22. ↑ Dunn, FA; Rieke, F (August 2006). "The impact of photoreceptor noise on retinal gain controls". Current Opinion in Neurobiology. 16 (4): 363–70. doi:10.1016/j.conb.2006.06.013. PMID   16837189. S2CID   15543432.
  23. ↑ Hass, C. A.; Angueyra, J. M.; Lindbloom-Brown, Z.; Rieke, F.; Horwitz, G. D. (November 2, 2015). "Chromatic detection from cone photoreceptors to V1 neurons to behavior in rhesus monkeys". Journal of Vision. 15 (15): 1. doi:10.1167/15.15.1. PMC   4633035 . PMID   26523737.
  24. ↑ International Headache Society. The International Classification of Headache Disorders, 2nd edition" Cephalalgia 2004; 24 (suppl. 1): 1-160.
  25. ↑ "Headache". casemed.case.edu. Archived from the original on 2020-02-26. Retrieved 2019-11-04.
  26. ↑ Abraham HD (1983). "Visual phenomenology of the LSD flashback". Arch Gen Psychiatry. 40 (8): 884–889. doi:10.1001/archpsyc.1983.01790070074009. PMID   6135405.
  27. ↑ Hang, Chenyue; Leishangthem, Lakshmi; Yan, Yan (November 10, 2021). "Not All Cases of Visual Snows are Benign: Mimics of Visual Snow Syndrome". Neuropsychiatric Disease and Treatment. 17: 3293–3300. doi: 10.2147/NDT.S338111 . ISSN   1178-2021. PMC   8591117 . PMID   34785899.
  28. ↑ Schankin, Christoph; Goadsby, Peter (2015). "Visual Snow—Persistent Positive Visual Phenomenon Distinct from Migraine Aura" (PDF). Current Pain and Headache Reports. Uncommon and/or Unusual Headaches and Syndromes (6): 23. doi:10.1007/s11916-015-0497-9. PMID   26021756. S2CID   6770765.
  29. ↑ Puledda, Francesca; Goadsby, Peter (2021). "Localised increase in regional cerebral perfusion in patients with visual snow syndrome: a pseudo-continuous arterial spin labelling study" (PDF). Migraine. 92 (9): 918–926. doi:10.1136/jnnp-2020-325881. PMC   8372400 . PMID   34261750.
  30. ↑ MIchels, Lars; Traber, Ghislaine (21 September 2021). "Widespread White Matter Alterations in Patients With Visual Snow Syndrome". Frontiers in Neurology. 12: 723805. doi: 10.3389/fneur.2021.723805 . PMC   8490630 . PMID   34621237.
  31. ↑ Puledda, F., Dipasquale, O., Gooddy, B. J., Karsan, N., Bose, R., Mehta, M. A., Williams, S., & Goadsby, P. (2023). Abnormal Glutamatergic and Serotonergic Connectivity in Visual Snow Syndrome and Migraine with Aura. Annals of Neurology, 94(5), 873–884. https://doi.org/10.1002/ana.26745
  32. ↑ Ala-Laurila, Petri; Rieke, Fred (December 2, 2014). "Coincidence Detection of Single-Photon Responses in the Inner Retina at the Sensitivity Limit of Vision". Current Biology. 24 (24): 2888–2898. Bibcode:2014CBio...24.2888A. doi:10.1016/j.cub.2014.10.028. PMC   4269560 . PMID   25454583.
  33. ↑ Silva, Elisa Martins; Puledda, Francesca (August 8, 2023). "Visual snow syndrome and migraine: a review". Eye. 37 (12): 2374–2378. doi:10.1038/s41433-023-02435-w. ISSN   1476-5454. PMC   10397188 . PMID   36788360.
  34. ↑ Gomides, Dr. Mariuche; Starling-Alves, Isabela; H. Santos, Dr Flavia (2023-12-06). "Chapter 11 - Insights into pathophysiology and treatment of visual snow syndrome: A systematic review". Update on Emerging Treatments for Migraine. Progress on Brain Research. Vol. 255. Elsevier. pp. 311–326. doi:10.1016/bs.pbr.2020.05.020. ISBN   978-0443223105. PMID   33008511. S2CID   222146213.
  35. ↑ "Neurofeedback in Visual Snow". ClinicalTrials.gov. U.S. National Library of Medicine. August 2021.
  36. ↑ "Transcranial Magnetic Stimulation For Visual Snow Syndrome (TMSVS)". ClinicalTrials.gov. U.S. National Library of Medicine. 7 June 2021.
  37. ↑ Puledda, Francesca; Vandenbussche, Nicolas; et al. (16 October 2021). "Evaluation of treatment response and symptom progression in 400 patients with visual snow syndrome". British Journal of Ophthalmology. 106 (9): 1318–1324. doi:10.1136/bjophthalmol-2020-318653. PMC   9411880 . PMID   34656983. S2CID   239006203.
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