The Effects of an Occipital Lobe Stroke

An occipital stroke happens in the back of the brain. This lobe, or part of the brain, helps people to recognize what they see. That means strokes in the occipital lobe can cause vision changes, which occur in 8% to 25% of all people who have a stroke.

Strokes in the frontal, parietal, or temporal lobes happen more often than occipital lobe strokes do. They also almost always affect only one side of the brain, but occipital lobe strokes can happen in one or both occipital lobes.

This article will go over why occipital lobe strokes happen. You will also learn the symptoms of occipital lobe strokes and how strokes in this part of your brain can affect your vision.

What Causes an Occipital Lobe Stroke?

The occipital lobes allow for visuospatial abilities and processing (understanding of immediate surroundings) including:

• Depth perception
• Distance
• Interpretation of colors
• Facial recognition
• Object recognition
• Formation of memories

The occipital lobes' role in these functions means that a stroke to this area can cause partial vision loss, visual hallucinations, or even total blindness. Occipital lobe strokes do not happen often because of the anatomy of the Circle of Willis, a group of arteries that supply blood to the brain.

You have three arteries along the back of your neck. They are called the vertebral arteries, the posterior cerebral arteries, and the basilar arteries.

The three arteries connect and create a "backup'" system called a redundant blood supply. This allows the parts to take over for each other if needed. For example, if one small artery is blocked, another can step up to keep the blood flowing. This can help prevent a stroke.

Even with a backup system, strokes still happen. Occipital lobe strokes can also occur at the same time as a stroke affecting other areas of the brain, such as a cerebellar stroke or a brainstem stroke. They can be either an ischemic stroke, a type caused by a blockage that leads to tissue damage, or a hemorrhagic stroke, caused by a bleed in the lobe.

Occipital Lobe Stroke Risk Factors

Occipital strokes are linked to a number of risk factors, some of which can be reduced through lifestyle changes, medication, and other factors. Others, such as age, cannot.

Most strokes happen in people over the age of 65, with about 25% occurring in younger people. There's some evidence to suggest that occipital strokes may develop at younger ages, including rare cases in children. This may be due to iron deficiency anemia, or mutations in the POLG1 gene, leading to occipital strokes in children.

For most people, though, the most common cause of strokes are hypertension (high blood pressure) and atherosclerosis (causing blocked arteries). Other common causes include:

• Underlying medical conditions such as a history of high cholesterol, diabetes or sickle cell disease
• Previous ministroke, called transient ischemic attack
• Obesity and a sedentary lifestyle (lack of exercise)
• Oral contraceptive use, which can raise the risk of stroke in females

Other factors contributing to your risk of stroke include smoking and/or alcohol and the use of drugs such as cocaine and methamphetamine.

Occipital Stroke Symptoms

Occipital strokes typically affect vision, although symptoms affecting the eyes are common with other types of TIAs and strokes, too. These can range from blurred vision to total blindness in one or both eyes or a specific change like an inability to recognize faces.

An occipital stroke may also cause common symptoms of stroke, including:

• A sudden severe headache or dizziness 
• Seizure
• Changes in mental status or responsiveness, like confusion
• Difficulty speaking or understanding speech, called aphasia
• Loss of motor function (movement) on one side of the body
• Loss of feeling on one side of the body

How Occipital Stroke Affects Vision

An occipital lobe stroke can cause visual changes. If you have a stroke in this part of your brain you may experience partial vision loss, complete blindness, and seeing things that are not really there (visual hallucinations). Some people develop other vision syndromes.

The occipital lobe is not the same shape and size all around. Each part of the lobe plays a different role in helping you see. The visual problems caused by a stroke in this lobe depend on which region of it is affected. Strokes in other parts of the brain can also cause vision changes.

Homonomous Hemianopia

When the stroke affects most of the occipital lobe on one side of the brain, you may lose half of the vision in each eye. This condition is called homonymous hemianopia.

A stroke survivor with homonymous hemianopia cannot see objects on one side. It will be the side that is opposite from the side where the stroke happened. For example, if the stroke was in the left occipital lobe of the brain, the person would have a hard time seeing objects to the right.

This vision problem usually affects both of your eyes. You won't be able to see your right side from your right eye or your left eye.

However, your eyes work together to see. This is called visual integration. If you have homonymous hemianopia, your eyes might not be affected to the same degree.

Central Vision Defect

Central vision is what you see in the middle of your field of vision when you're looking straight ahead. Your central vision is handled by a part of your brain called the occipital pole. While strokes in this part of your brain are rare, they do happen.

An occipital pole stroke can cause a big blind spot in the middle of your vision. The blind spot will be on the same side as the stroke.

This blind spot would make you have trouble seeing the face of a person standing directly across from you.

You might not be able to see the person's nose, upper lip, and the lower half of their eye on the side where you have the blind spot. However, you would still be able to see the person's shoulder and the top of their head.

Cortical Blindness

When the occipital lobes of the brain are completely affected by a stroke, it causes total vision loss. This is called “cortical blindness.” It means the vision loss was caused by damage to the cortex of the brain.

Some stroke survivors know that they cannot see, but others do not. Some people are not aware of their blindness and experience visual hallucinations. The is called Anton syndrome or Balint syndrome.

Some occipital stroke survivors have a condition called visual anosognosia. The condition means that the brain ignores one side of the person's vision.

Visual Illusions

An occipital stroke can lead to visual illusions. People may have double vision when there's only one object in view, or their vision can be monochromatic (all colors are the same).

People who have strokes also may have difficulty in identifying the correct size, shape, and weight of objects, even though they can see them. This feature can become important during post-stroke therapy and in avoiding harms, such as falls, during recovery.

Face Blindness

Face blindness, also known as prosopagnosia, occurs naturally in up to 2% of the population, but it can also be acquired. People who once had no difficulty may find they can't identify faces after a stroke or head injury.

In some cases, therapy can help them to recover their ability to recognize faces but the gains may be limited.

Inability to Read

Some people who experience an occipital stroke may develop alexia, an inability to read. The deficit doesn't seem to extend to writing ability, though. In this case, it's called alexia without agraphia.

People with this type of "word blindness" may even be able to spell words and recognize individual letters, but they can't read them. In some cases, they can't read the words they just wrote since their ability to see and write wasn't affected but their alexia remains.

Remedial therapy, including computer-based techniques, may help to restore some reading ability but there is no cure at this time.

Treatment for Occipital Lobe Stroke

Occipital stroke treatment will vary depending on a number of factors, including:

• Age and overall health
• Specific type of stroke (a blockage or bleed) and its location, as with tissue plasminogen activator tPA used to break up a clot
• Response to initial stroke treatments when contemplating therapy, rehabilitation and long-term medication use
• Complications, if any, from the occipital stroke

Healthcare providers caring for people who have visual impairment after an occipital stroke will choose specific methods designed to help restore function or, where necessary, help them to adapt to new limitations.

Recovering from an Occipital Stroke

Each person's recovery from an occipital stroke will be different, depending on the extent of the stroke damage and other factors. That said, vision changes are common, with some 70% of people diagnosed with a stroke having some type of eye movement disorder.

Recovery may involve a wide range of options, from balance and gait exercises for preventing falls, to specific eye therapies like vision restoration therapy or head posture exercises. Healthcare providers also will monitor underlying conditions that may have contributed to the stroke, like high blood pressure or diabetes.

How long recovery takes, and how complete a recovery is achieved, also depends on individual circumstances. Research suggests that focused rehabilitation care within three to six months of a stroke can lead to maximum recovery and improved outcomes.

Summary

The occipital lobes of the brain help you see. If a stroke happens in this part of the brain, it can change your vision.

For example, you might not be able to see a person's face well if they're standing right in front of you. You might not be able to see things on one side of your body. Some people see things that are not there. Other people lose their sight completely after a stroke.

Occipital lobe strokes are not common. However, other strokes can also cause vision changes. It's important to know that sudden, intense vision changes can be a sign that you're having a stroke. If you suddenly cannot see or are seeing unusual things, seek medical care right away.