Bonnie is a 70-year-old woman who lives alone. One evening, she felt light-headed and dizzy. When her head began to ache, she decided to take an analgesic and go to bed early

Question

The following morning, upon awakening, she was unable to move the bed sheets with her right arm. At this point she was experiencing tingling sensations in her limbs, and she had difficulty keeping her balance. She dialed 911 for help, and by the time the ambulance arrived, she was confused and unable to articulate her words although she knew what information he was asking of her. In the hospital, she was examined and treated for ischemic stroke.

Stroke, or brain attack, involves brain tissue injury. Describe ischemic penumbra and what factors contribute to the survival of the neurons involved. What happens if the cells of the penumbra are unable to be preserved?

Compare and contrast hypoxia and ischemia. What condition is more dangerous to the brain? Explain your answer.

Knowing what you do about the effects of ischemia on the brain, why would someone with ischemic stroke develop cerebral edema?

What type of aphasia was Bonnie exhibiting when talking to her care givers? Explain your answer.

Answer 1

The ischemic penumbra is a band of neurons surrounding a core of dead or dying cells created by the vascular accident. The cells of the penumbra are physically intact but functionally impaired from a marginalized blood flow. The penumbra may avoid further insult depending on the speed of circulatory restoration, alterations in local blood flow, the amount of toxins released by damaged neighboring cells, and the extent of cerebral edema. If noxious conditions persist, the cells of the penumbra die and the core of dead tissue enlarges.

Both hypoxia and ischemia are conditions that involve alterations in oxygen availability at the tissue level. Hypoxia is a term used to describe a lack of oxygen at a given site although blood circulation to the area is intact. Ischemia, on the other hand, describes a lack of blood circulation to an area. In ischemia, tissues are vulnerable not only to oxygen deficiency but also to glucose deficiency and the accumulation of metabolic wastes.

The brain is able to maintain limited cellular activity by anaerobic metabolism and is therefore able to survive for some time in a state of hypoxia. With ischemia, nutrient stores are rapidly depleted and not replenished. The lack of blood supply also means that metabolic waste accumulates at the cellular level, creating a state of acidosis. Ischemia is therefore more detrimental to brain tissue than hypoxia. Normal metabolism in the brain is needed, in part, to produce ATP for the normal function of ion pumps in the cellular membranes. When perfusion is inadequate, ATP production declines and active transport pumps, like the Na+/K+ pump, fail. Sodium flows down the concentration gradient into the cell as a result, creating an osmotic gradient that causes the development of interstitial and intracellular edema.

Bonnie was expressing expressive or nonfluent aphasia. This type of speech is characterized by verbalizations that are meaningless and performed in a halting, limited manner. Communication in someone with expressive aphasia requires effort and is not spontaneous. Comprehension, however, is unaffected, and the individual knows what is being said by others. Bonnie was aware of what was being asked, but was answering in ways that were incomprehensible.