Case 2: Limp Arm
This patient noticed that her left arm went "limp." It lasted about 20 minutes, then things were fine. She drove herself to the emergency room where they thought she might be having a heart attack. When cardiac testing showed no problems, she was sent home. The next day she noticed "numbness" in two fingers that lasted a bit longer but resolved completely. The third day she again complained of numbness in the same two fingers, and was admitted to the hospital. She got worse, with problems involving her face, her enunciation of words ("I lisped"), and her left arm. Auscultation of her neck revealed a carotid bruit. Right carotid stenosis, greater than 70%, was confirmed by ultrasound and cerebral arteriography. It was also found that she had developed significant external to internal carotid blood flow through anastomoses of these vessels around her right eye. She was treated surgically (a carotid endarterectomy) and given antihypertensive medications, a statin agent, and a daily aspirin. She has had no further problems.
Diagrams
Note
Expert Note Case 4.
Unsafe Driver
Like a patient who has this lesion in the left language-dominant hemisphere (see Case 3), the patient described here also has a contralateral hemiplegia and mild sensory loss involving primarily face, hand, and arm. However instead of severe impairment of language, she has a different specific cognitive disorder which involves visuospatial perceptions of her own body and of the outside world. In her case, which is quite mild, the problem causes her to ignore stimuli delivered to the left side when the stimulus is given bilaterally.
We really don't understand the details, but clinical evidence suggests that the right hemisphere plays an important role in attending to the entire visuospatial world while the left hemisphere has a more limited role and only attends to the right. Thus damage to the right hemisphere would be expected to particularly affect attention to and conceptualization of left personal and general space. The anatomic basis is unclear, but there is evidence that spatial conceptualization involves systems distributed in the frontal as well as parietal and temporal lobes. Parts of these systems are therefore nourished by the superior cortical branches of MCA, although other critical components lie in inferior MCA territory.
| Clinical Note: Immediately after their strokes, patients with superior cortical branch lesions in either the left or right hemispheres may have their eyes (or their eyes and head) turned toward the side of the lesion. Impairment of eye movements contralateral to the cortical lesion usually lasts for only a few days, even when other motor deficits remain. |
| Question: |
| Do you know of some part of the gaze mechanism involving the frontal lobes? |
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