People with Anton's syndrome have a strong belief that they can see things that they cannot and behave and speak as though they can see them.
What is Anton-Babinski syndrome?
Anton’s syndrome, also called Anton-Babinski syndrome, is an extremely rare neurological condition characterized by cortical blindness and denial of vision loss. Their denial of vision loss is accompanied by confabulation, the act of making up memories and experiences that they never had. They honestly believe what they say, not knowing they are making things up.
Loss of vision results from damage to the occipital (lower back) cortex of the brain and a defect or injury to the brain rather than to the eyes.
Hemorrhage or stroke involving the posterior cerebral arteries and occipital lobes in the brain is the most common cause. Additionally, complications from the following can be contributing factors:
How many people have Anton’s syndrome?
Anton-Babinski syndrome is a relatively uncommon condition; only 28 cases have been recorded between 1965 and 2016.
- Because cerebrovascular accidents are the most frequent cause of Anton’s syndrome, older adults with many vascular risk factors are most frequently affected.
- Anton’s syndrome has been reported in younger age groups. A 24-year-old lady was diagnosed with Anton’s syndrome because of exacerbated multiple sclerosis. In addition, cases have been reported secondary to obstetric hemorrhage following an incomplete abortion in a 19-year-old woman and after trauma in a 36-year-old woman.
- Additionally, bilateral optic nerve radiations in Trousseau’s syndrome cause Anton’s syndrome.
What are the symptoms of Anton’s syndrome?
Signs and symptoms of Anton’s syndrome include the following:
- Vision loss
- Visual anosognosia, which means the person is unaware of their blindness
- Creating false memories of seeing something that was not there
Despite the evidence, people with Anton’s syndrome often reject that they are blind.
- For instance, if you held out an item and asked what it was, they would confidently make a guess. Even if they were erroneous, they would act as if it were the appropriate response. They will create a visual story for you when you ask them to describe what they see. Even though their actions may seem strange, they are not lying to you. Their brain is unable to comprehend this.
- In one case report, an older individual with Anton’s syndrome brought on by an occipitoparietal stroke gave rapid but inaccurate answers when asked about the doctor's tie or appearance. They found the utensils on a food tray and feed themselves when left alone. However, they were spilling their food. They acknowledged the assistance but remained in denial about their vision loss.
- In another case report, the doctor extended their hand for a handshake, but the person extended their hand out in the opposite direction.
What causes Anton’s syndrome?
Anton’s syndrome is caused by damage to the occipital lobe, which is found at the back of the brain. The occipital lobe is responsible for vision and comprehension of what you see.
Stroke is one of the leading causes of Anton’s syndrome. If an artery is clogged or a blood clot obstructs blood flow to the brain, it is a medical emergency. Any part of the brain that is oxygen-deprived begins to lose brain cells. When the occipital lobes of the brain sustain complete damage from a stroke, it results in cortical blindness.
Studies yet have not understood the way Anton’s syndrome manifests. According to one theory, individuals who have sustained damage to their primary visual cortex may have damaged their visual association cortex as well. The primary visual cortex processes visual data, and the visual association cortex connects those signals to other parts of the brain to interpret them. Dysfunctions in both could be the reason that people are unaware of their blindness.
Even though a stroke is the most frequent cause of Anton’s syndrome, it can happen in conjunction with other illnesses that harm the occipital lobe, such as:
- Multiple sclerosis exacerbation
- Pregnancy-induced hypertensive encephalopathy
- Post-cardiac surgery
- Obstetric hemorrhage
- Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes
- Cerebral angiography
- Central nervous system angiitis
- HIV-related progressive multifocal leukoencephalopathy
How to diagnose Anton’s syndrome
A head CT and MRI can identify any clear signs of occipital lobe injury, most likely signs of ischemia or hemorrhage. However, if the condition is linked to the onset or aggravation of another disease process, such as multiple sclerosis, scans may show demyelinating lesions.
Total blindness can be proven by the lack of response to simulated visual cues.
Total blindness can be diagnosed with a physical exam in people with Anton’s syndrome. The fundoscopy will not be noteworthy. When they are verbally instructed to look in certain directions, their eye movements will remain intact, but they would not be able to track a finger or light.
People who are cortically blind could perceive hand motions, also called the Riddoch phenomenon. They can see moving things but not stationary ones. However, people with Anton’s syndrome do not blink in response to ominous hand motions during an eye test.
Occipital lesions are posterior to the lateral geniculate nucleus, which ensures that pupillary reflexes are unaffected and there is no damage to the pupillary pathway. The corneal blink reflex does not rely on cortical input.
Can Anton’s syndrome be cured?
Anton’s syndrome is treated by treating the assumed underlying contributor to the occipital lobe damage.
Even though Anton’s syndrome is a rare disorder with vascular origins, one study has shown that a person had developed it because of a multiple sclerosis exacerbation. They underwent treatment with intravenous methylprednisolone and plasmapheresis, and over two years, they gradually recovered. Recovery started with a delayed realization of their impairment and ended with the restoration of acuity.
If a stroke caused Anton’s syndrome, treatment would focus on reducing further stroke-related damages. This would require monitoring risk factors, including blood pressure, glucose (blood sugar) levels, and medications, such as aspirin or statins.
Sometimes, vision can improve with treatment. This frequently depends on the age and condition of the person. Significant improvement is more likely in a person younger than 40 years old and who never had a stroke, diabetes, or high blood pressure.
Anton’s syndrome is less likely to improve after a stroke, but the main goal of treatment will probably be to stop subsequent cardiovascular issues.
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Visual Anosognosia (Anton-Babinski Syndrome): Report of Two Cases Associated with Ischemic Cerebrovascular Disease. https://www.scirp.org/html/14-3900115_22110.htm
Anton's Syndrome Due to Cerebrovascular Disease: A Case Report. https://cyberleninka.org/article/n/186826/viewer
Anton syndrome as a result of MS exacerbation. https://cp.neurology.org/content/7/2/e19 Anton Syndrome. https://eyewiki.aao.org/Anton_Syndrome
Anton syndrome after subarachnoid hemorrhage and delayed cerebral ischemia: A case report. https://doi.org/10.1016/j.cccb.2021.100023
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