Parietal Stroke

A parietal lobe stroke can have a variety of effects because the parietal lobe is a key region of the brain that controls a number of important functions, primarily related to sensation and integrating sensory and visual information. If you or a loved one has had a parietal stroke, you may notice some confusing symptoms.

What does the parietal lobe do?

The parietal lobe is a substantial part of the cerebral cortex.

It is located at the top and near the back of the brain. We have a right parietal lobe and a left parietal lobe. The parietal lobes are primarily involved with sensation, awareness of body position, vision, reading and speech. The parietal lobes are heavily involved in interacting with other regions of the brain, connecting sensory input from the environment with awareness and interpretation of that information.

The right parietal lobe allows us to make sense of how the left side of the body feels and the left parietal lobe allows us to make sense of how the right side of the body feels. The parietal lobe helps us understand speech, helps us make sense of our vision and even gives us awareness of our body position to help us coordinate our movements.

What is a parietal lobe stroke?

Blood vessels

A parietal lobe stroke occurs when one or more of the blood vessels that supply blood to the parietal lobe is blocked or bleeding.

The parietal lobe receives its blood supply from the middle cerebral artery, the anterior cerebral artery and the posterior cerebral arteries.

Sensory changes

A parietal lobe stroke may result in impaired sensation. Sensations such as pain, touch and temperature perception are usually not substantially affected by a parietal lobe stroke.

However, after a parietal lobe stroke, stroke survivors are generally unable to detect exactly where on the body (for example, which part of the arm, hand or leg) a sensation is specifically located.

A parietal stroke can interfere with sensation of the entire opposite side of your body, or just a small area, such as your hand or foot. Some people experience unusual sensations, called paresthesias, after a parietal lobe stroke, even when nothing is touching the affected part of the body.

Vision changes

Often, a portion of vision is lost, making it difficult to see or to recognize and reach for objects. Vision changes caused by a parietal stroke are often described as homonymous hemianopia, which is symmetric or almost symmetric loss of vision of both eyes. A parietal lobe stroke is most likely to result in inferior quandrantanopia, which means loss of vision affecting the right or left lower fields of vision of both eyes.

Lack of awareness

The parietal lobe controls your perception of yourself and your ability to know where the parts of your body are.

Some people with a parietal stroke do not get weaker, but still have trouble figuring out 'how' to move the body in a normal, purposeful way.

Often, after a parietal stroke, stroke survivors are not aware of the stroke. This is called asomatognosia. Stroke survivors who have asomatognosia are unaware of sensations or objects on one side of the body,  and may be so unaware of the issue that they adamantly deny that there is a problem.

Many parietal lobe stroke survivors experience hemiagnosia, which is the lack of awareness of one side of the body and one side of the environment. Sometimes, a parietal lobe stroke causes a similar, but milder effect called extinction. People with extinction will notice the impaired side, but not if there is simultaneous stimulation on the 'normal' side at the same time. 

Alexia

Another problem called alexia can occur after a parietal lobe stroke. This is characterized by the inability to read, despite seeing the letters. Strangely, some parietal lobe stroke survivors experience a condition called alexia without agraphia. This means that a person can write, but cannot read.

Motor Apraxia

Motor apraxia can affect stroke survivors who have a stroke of the left parietal lobe. People with motor apraxia are not able to carry out simple motor skills such as brushing hair, despite the fact that they are not weak.

Gertsmann Syndrome

Gertsmann syndrome is a trademark consequence of a parietal lobe stroke. People who have Gertsmann syndrome are confused between left and right, cannot name the fingers on the two hands, cannot do simple math calculations and cannot write.

Will I recover?

When a parietal stroke is large, it can cause short term swelling of the brain. This can be serious, but with careful medical treatment the swelling usually resolves and most people experience a degree of improvement.

Recovery after a parietal stroke takes time and hard work, including intense rehabilitation.

Caring for a stroke survivor after a parietal stroke

It is a challenge taking care of a stroke survivor who has had a parietal lobe stroke.

Sensory loss can cause injury, as your loved one might not notice sensations such as hot temperatures or even sharp objects.

Hemiagnosia is a particularly challenging disability because stroke survivors with hemiagnosia are often less aware of their surroundings.

The burden of caring for a stroke survivor who has had a parietal lobe stroke is heavy, and it is important to try to get as much support and information as possible from the health care team, from your family, and from support groups.

Sources

Specific Brain Lesions Impair Explicit Motor Imagery Ability: A Systematic Review of the Evidence, McInnes K, Friesen C, Boe S, Arch Phys Med Rehabil. 2016 Mar;97(3):478-489

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