Occipital Lobe Stroke

The occipital lobe is a region in the the back of the brain that plays a major role in integrating our vision, allowing us to recognize what our eyes see.

An occipital lobe stroke can affect one or both occipital lobes. In general, occipital lobe strokes are not common.

Effects of Occipital Lobe Stroke

An occipital lobe stroke can cause a variety of visual changes, which include partial vision loss, complete blindness and visual hallucinations, as well as some unique visual syndromes.

The occipital lobe is not completely uniform, and the regions within the occipital lobe have different functions in integrating vision. Therefore the specific visual problems that result from an occipital lobe stroke depend on the specific location of a stroke within the occipital lobe.

Visual Changes After Occipital Lobe Stroke

  • 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 visual integration from the eyes may not be affected equally.

  • Central Vision Defect-Stroke Affecting the Occipital Pole

Occipital pole strokes are quite rare.

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.

  • 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.” This is similar to what we all understand by the term “blindness," but this term is used when damage to the cortex of the brain is the cause of blindness.

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

What Causes Occipital Lobe Stroke?

Arteries that run along the back of the neck, called the vertebral arteries, the posterior cerebral arteries and the basilar arteries, supply oxygenated blood to the occipital lobes. If one or both the occipital lobes suffers from interrupted blood supply, then a stroke results.

Occipital lobe strokes are uncommon because the blood supply to the occipital lobe is arranged in a unique way. The vertebral arteries, the posterior cerebral arteries and the basilar arteries that provide blood to the back of the brain, connect with each other in some areas, which allows them to provide duplicate blood supply, often compensating for each other. This arrangement often works to prevent strokes to the regions in the back of the brain when the flow through one small artery is obstructed, if another artery provides adequate blood flow.

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 seek medical attention right away, as vision changes may be the first sign of a serious medical problem, such as a stroke.

Source:

Visual hallucinations in patients with acute stroke: a prospective exploratory study, Morenas-Rodríguez E, Camps-Renom P, Pérez-Cordón A, Horta-Barba A, Simón-Talero M, Cortés-Vicente E, Guisado-Alonso D, Vilaplana E, García-Sánchez C, Gironell A, Roig C, Delgado-Mederos R, Martí-Fàbregas J, Eur J Neurol. 2017 May;24(5):734-740.

 

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