Parietal Lobe Strokes

The parietal lobe is one of the richest areas in the brain

Elderly man with head in hands
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Parietal lobe strokes cause symptoms which can be separated into the four categories. The parietal lobe is one of the most important areas in the brain, providing connections and integration between several other regions of the brain. This is why a parietal lobe stroke has such a profound impact, even if the stroke is relatively small in size. In and around the parietal lobe, our brains create our perception of the world based on what we feel, hear and see.

What is Stroke?

A stroke is a medical event that affects the arteries leading to and within the brain. It is a leading cause of death and disability in the United States. A stroke occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts (or ruptures). When that happens, part of the brain cannot get the blood and oxygen that it needs, so the affected brain cells become damaged or die.

Visual Symptoms of a Parietal Stroke:

There are a number of different visual effects of a stroke, and many of them involve the parietal lobe to some degree.

  • Homonimous quadrantanopsia: There are nerve fibers that carry information from the lower parts of our visual field and travel through the parietal lobes on their way to the occipital lobe (where vision is processed). These nerve fibers can be damaged by parietal strokes, causing vision in the lower quarter of the side opposite the stroke to be lost.
  • Spatial Dysperception: Difficulty interpreting visual information in our surroundings, such as the length, depth, and size of objects may result from a parietal lobe stroke.
  • Hand-Eye Incoordination: Difficulty bringing one’s hand to a spot where one is looking. An example is a stroke survivor who looks at an object which lies on a table with the intention of picking it up, but his or her hand overshoots the target and he or she is unable to grab it.
  • Inability to visually scan one’s surroundings, in spite of having full eye movements. This prevents the stroke survivor from seeing objects, people, and other visual objects that are located in the periphery of vision (on the sides.)

Sensory Symptoms of a Parietal Stroke:

  • Sensory loss: The parietal lobe is where the sensory cortex is located. The sensory cortex integrates our sensations, such as touch, temperature and vibratory sense, allowing us to perceive these sensations. Strokes in the sensory cortex can cause numbness or inability to detect the location or type of sensation in the body.
  • Astereognosis

Abnormalities of Self-Perception of a Parietal Stroke:

  • Hemineglect: People with parietal strokes in the nondominant language side of their brain have a tendency to completely ignore the opposite side of their body. The deficit can be extremely striking. For example, stroke survivors who are left with hemiplegia (one sided weakness) after a stroke affecting both the motor and sensory regions of the brain may have hemineglect. Not only do stroke survivors with hemineglect ignore the fact that one side of their body is completely paralyzed, but they can't even recognize their own body parts on that side of their body. Consequently, this can cause stroke survivors who suffer from hemineglect to be unable to take care of one side of the body. Individuals who suffer from hemineglect might not shave or wear lipstick on the side affected by stroke.
  • Finger agnosia: Finger agnosis is the inability to name fingers, which is a characteristic of parietal lobe stroke. For instance, a stroke survivor might not be able to say that his thumb is a thumb.
  • Right-left confusion: Many people who have a parietal lobe stroke demonstrate a profound inability to differentiate right from left.
  • Difficulty with reading, writing, and math: These skills are centered in the parietal lobe and may be impaired when the dominant parietal lobe (the side opposite your dominant hand) is affected by a stroke.

Other Effects of a Parietal Stroke:

Some of the other effects of a parietal lobe stroke are typically associated with difficulties of spatial skills.

Spatial skills are skills that allow us to understand how objects fit into 3-dimensional space.

Reference:

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

Edited by Heidi Moawad MD

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