Case 178 Answers

Basic Human Neuroanatomy

A Clinically Oriented Atlas

Case 178 Answers

1. Where in the visual pathway would you localize the lesion in this case (optic nerve, optic chiasma, optic tract, optic radiations, or occipital cortex)?

Right optic nerve (II), near the optic disc

2. What is an afferent pupillary defect (APD, Marcus Gunn pupil), what is its anatomical basis, and what localizing significance does it have?

Paradoxical dilation of a pupil ipsilateral to an optic nerve lesion, when the light is shined back onto that pupil during the “swinging flashlight test”. An APD is due to an impaired direct light reflex with an intact consensual light reflex. It localizes the lesion to the ipsilateral optic nerve (or widespread retinal disease).

3. What specific structure(s) is involved by the pathologic process in this case?

Right optic nerve (II), near the optic disc

4. How would you describe or characterize this patient’s visual problems in the right eye?

Optic neuritis, OD

5. How would you characterize or classify this patient’s headache problem? Do you think that the patient’s headache problem and visual problem are related?

Headache due to ipsilateral acute optic neuritis (inflammation).
Yes

6. In general, what type of pathologic process was involved in this case?

Demyelinating disease/inflammation

7. What is your tentative diagnosis or diagnoses in this case? What other considerations would be in this patient’s differential diagnosis?

Multiple sclerosis.
Other considerations : Neuromyelitis optica (NMO). Acute disseminated encephalomyelitis (ADEM), autoimmune disease, sarcoid, other inflammatory conditions.

8. What diagnostic procedure(s) would you undertake at this point?

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