After suffering a stroke, a 62-year-old man is unable to abduct his right eye. In addition, he has muscle weakness in his upper and lower left limb as well as the right side of his face. The combined deficits in this patient can most accurately be attributed to damage in which of the following vessels?

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Quizplus · Accepted Answer

The patient's symptoms indicate a combination of cranial nerve and long tract signs, which are characteristic of a brainstem stroke. The inability to abduct the right eye suggests damage to the abducens nerve (CN VI), which controls the lateral rectus muscle. The muscle weakness in the upper and lower left limbs indicates a contralateral hemiparesis, which is a sign of damage to the corticospinal tract. The right-sided facial weakness can be attributed to involvement of the facial nerve (CN VII) or corticobulbar tract affecting the lower motor neurons or their pathways that innervate the facial muscles. These combined deficits are most consistent with a lesion in the paramedian branches of the basilar artery, which supply the medial part of the brainstem, where these pathways are located.

After Suffering a Stroke, a 62-Year-Old Man Is Unable to Abduct