Eye Disease and Visual Disturbances
A patient reports horizontal double vision. When a red glass is placed over her right eye and she is asked to look at a flashlight off to her left, she reports seeing a white light and a red light. The red light appears to her to be more to the left than the white light. Her right pupil is more dilated than her left pupil and responds less briskly to a bright light directed at it than does the left pupil. The injury likely to be responsible for all of these observations is one involving which of the following nerves?
a. The second cranial nerve
b. The third cranial nerve
c. The fourth cranial nerve
d. The sixth cranial nerve
The answer is b. The red glass test produces two images because the eyes are not moving in concert. That the red image appears to the left indicates that the eye covered by the red glass is not moving to the left as much as the other eye. A convenient way to remember this is simply to assume that the eye is not moving where the red image appears to be. This assumes that the red glass is over the impaired eye and that ocular motor function in the other eye is completely normal. Additionally, the outside image is always the false image. That the patient has pain behind the right eye and that the pupil of this eye reacts less vigorously to light than the pupil of the other eye suggests that the right eye is solely (or at least disproportionately) involved. Because the medial rectus and pupillary constrictor are involved, the lesioned nerve must be cranial nerve (CN) III.
A 15-year-old obese girl has frequent headaches and early papilledema. Brain magnetic resonance imaging (MRI) and lumbar puncture confirm the diagnosis of benign intracranial hypertension. Which of the following is the treatment of choice for pseudotumor cerebri in a young woman?
The answer is a. With pseudotumor cerebri, removal of some of the CSF produces a protracted lowering of the intracranial pressure. This pressure reduction is desirable because persistent pressure elevations will damage the optic nerve. Pseudotumor cerebri in the pregnant woman usually abates soon after the fetus leaves its mother, but this condition is ...