Occipital Stroke

An occipital lobe stroke is a stroke that affects the back of the brain. The occipital lobe is the area of the brain that integrates our vision, allowing us to recognize and make sense of what our eyes see.

In general, occipital lobe stroke are not common. This is because the blood supply to the occipital lobe is made up of arteries that are arranged in a unique way. These arteries are called the vertebral arteries, the posterior cerebral arteries and the basilar arteries.

These arteries that provide blood to the back of the brain provide duplicate blood supply in some areas, often compensating for each other. Sometimes, this arrangement prevents serious consequences that could result from interruption of blood flow through one artery if another artery provides adequate blood. 

An occipital lobe stroke can cause a variety of visual changes which include partial vision loss, complete blindess and visual hallucinations, among other visual syndromes. These effects depend on where in the occipital lobe a stroke occurrs. Below you will find the most common symptoms brought on by occipital strokes.

Homonomous Hemianopia- Stroke Affecting the Entire Occipital Lobe on One Side

When the stroke affects most of the occipital lobe on one side of the brain, the visual problem that arises is called homonymous hemianopia.  This describes loss of half of the vision out of each eye.

A stroke survivor who has homonymous hemianopia is not able to see objects that are on the opposite side of the stroke. 

A stroke affecting the left occipital lobe of the brain would cause a stroke survivor to have difficulty seeing objects on the right side. This problem typically affects both eyes- meaning that a person cannot see the right side from the right eye and also cannot see the right side from the left eye.

Often, homonymous hemianopia is not perfectly symmetrical, as the eyes may not be affected equally.

Central Vision Defect-Stroke Affecting the Occipital Pole

The occipital pole is the area of the brain where central vision is processed. Central vision describes what you see at the center of your visual field when you are looking straight ahead. Therefore, a stroke affecting the occipital pole would cause you to have a large blind spot in the very middle of your visual field on the affected side.

A person with central vision deficit caused by a stroke of the occipital pole would have trouble seeing the face of a person standing directly across from him or her. For example, the stoke survivor may not be able to see the person's nose, upper lip, and the lower half of the eye on the affected side, but would still be able to see the person's shoulder and the top of their head.

These occipital pole strokes are quite rare.

Cortical Blindness- Stroke Affecting the Occipital Lobes on Both Sides

When the occipital lobes of the brain are completely affected by a stroke, the end result is a phenomenon called “cortical blindness.” In essence, this is the same as what we all understand by the term “blindness,” but this term is used when specific reason for blindness is damage to the brain cortex.

There are several symptoms of cortical blindness in addition to the loss of vision. Some stroke survivors are aware that they cannot see, while some stroke survivors are not aware of the blindness and experience visual hallucinations. The most well described syndromes characterized by cortical blindness and associated visual hallucinations are called Anton syndrome and Balint syndrome.

Some occiptal stroke survivors suffer from a condition called visual anosognosia, which is characterized by ignoring one side of vision.

Some Other Symptoms/Syndromes Associated with Occipital Stroke

A Word From Verywell

A stroke can cause serious changes in vision, including vision loss, changes in vision and strange patterns of vision. Not all stroke induced vision changes are caused by occipital lobe strokes, as strokes in other regions of the brain can also cause vision changes. Changes in vision after a stroke can have a major impact on lifestyle, particularly when it comes to driving after a stroke.

If you experience visual symptoms, you should get a medical evaluation. 

Source:

Strokes and vision: The management of ischemic arterial disease affecting the retina and occipital lobe, Lawlor M, Perry R, Hunt BJ, Plant GT, Surv Ophthalmol. 2015 Jul-Aug;60(4):296-309

Edited by Heidi Moawad MD

Continue Reading