Question

On one particular day, two patients were brought in to a local emergency room, each with different signs and different prognoses, but each with the same underlying disease, stroke.

The first patient, a 70-year-old male, arrived by ambulance and was accompanied by his elderly wife. The patient was awake and alert, but was unable to move independently due to paralysis on his right side. He looked responsive and seemed to understand what was said to him, but he could not speak. His condition was first discovered by his wife when she woke him that morning. She called 911 when she realized that her husband could not get out of bed, he was unable to move his right arm and leg, and he could not talk to her.

The second patient arrived a few hours later, also by ambulance. Unlike the first patient, this woman was unconscious. She was breathing on her own and she showed no signs of paralysis. Her daughter had discovered her sitting in her chair, slumped over the table. She had been unable to arouse her and called 911.

CAT-scans were done on both patients and confirmed the tentative diagnosis of stroke. They were immediately treated with clot-dissolving drugs, in hopes of stopping more progressive damage. In Patient #1's case, the CAT-scan revealed a blockage in the left middle cerebral artery which supplies the posterior portion of the frontal lobe called the pre-central gyrus. In the case of Patient #2, the blockage was seen in the basilar artery which supplies the brainstem

1. What is the function of the two different areas of the brain affected in these two different cases of stroke? How does that account for the differences seen in Patient #1 and Patient #2?
2. What would account for Patient #1 seeming to understand what he heard, but not be able to speak? If the stroke had affected the first patient's right cerebral artery instead, would the outcome have been different?
3. Why was patient #2 unconscious? What are the underlying causes that lead to unconsciousness.
4. Are there any differences in prognoses for these two patients?

Answer 1

Solution:

Q. What is the function of the 2 different areas affected ….

Ans. In case of Patient 1, the affected area is the posterior portion of frontal lobe called pre-central gyrus.

Pre-central gyrus is found on the lateral surface of the frontal lobe and functions as the primary motor area of the brain, which is responsible for controlling voluntary movement on the contralateral side of the body. In addition the precentral gyrus also contains a region of the supplementary motor cortex involved in the planning of voluntary limb movement. Lesions in the pre-central gyrus result in paralysis, facial palsy, arm/leg monoparesis, hemiparesis. These account for the symptoms in patient 1.

In the case of patient 2, the affected area is the brainstem.

The brainstem plays a role in relaying information from the body to the cerebrum and cerebellum and vice versa. This function is called conduction. Also the cranial nerves that emerge from the brainstem supply the head, face and viscera. The brainstem has important functions in cardiovascular, respiratory control, pain, alertness, and consciousness. These account for the symptoms in patient 2.

Q. What would account for Patient #1 seeming to understand what he heard....

Ans. The MCA stroke affects the dominant left cerebral hemisphere which results in aphasia.

Q. If the stroke had affected the first patient's right cerebral artery instead…..

Ans. There would be Visual perceptual deficits and left neglect

Q. Why was patient 2 unconscious…

Ans. Pateint 2 was unconscious and CAT scans revealed blockage/ occlusion in the basilar artery, which is caused by embolism. This causes the pontine damage and carries the risk of Locked Down syndrome, decreased levels of consciousness, occulomotor defects and arm positioning.

Q. Are there any differences in prognoses for these two patients?

Ans. Brainstem damage has grave prognosis, with mortality rates of up to 90%. The middle cerebral artery stroke is also fatal with 80% fatality.