Case 64 Answers

Basic Human Neuroanatomy

A Clinically Oriented Atlas

Case 64 Answers

1. Is the weakness on the left side of the face of the upper motor neuron or lower motor neuron type?

Upper motor neuron

2. Is the weakness on the left side of the body of the upper motor neuron or lower motor neuron type?

Upper motor neuron

3. What specific structure is involved by the pathologic process to produce the patient’s left facial weakness?

Right corticonuclear (corticobulbar) tract above the lower third of the pons

4. What specific structure is involved by the pathologic process to produce the patient’s left hemiparesis?

Right corticospinal tract above the lower third of the pons

5. Is it possible to specifically localize the lesion in this case? If so, where is the lesion localized, including the side. If not, indicate the possible sites of localization of the lesion, the side involved, and the specific structure(s) involved by the pathologic process.

Right pyramidal tract pathways (corticonuclear and corticospinal tracts), above the lower third of the pons. More precise localization is not possible in this case (see slide #1).

6. This patient’s clinical findings represent a classic neurological syndrome. What is the name of that syndrome, and what is its usual cause?

Pure motor hemiplegia.
Lacunar infarct, most often in the third quarter of the posterior limb of the internal capsule or the basilar part of the pons.

7. In general, what type of pathologic process is involved in this case?

Demyelinating disease: Multiple sclerosis (MS) vs acute disseminated encephalomyelitis (ADEM). In this patient, a small area of demyelination (i.e., a plaque) located in the middle of the right crus cerebri of the midbrain caused her “pure motor hemiplegia”.

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

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