WBR0581

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Anatomy, MainCategory::Pathophysiology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A 68-year-old man with past history of coronary artery disease presents for acute onset severe vertigo and nausea. The patient explains that he was cooking dinner when all of a sudden he felt the room spin and he fell to the ground. His wife also noticed that his right eye was looking funny and that he sounded unusually hoarse. On exam, you notice drooping of the right eyelid and right miosis. You also detect loss of pain and temperature sensation from the left torso and arm and the right face. When asked to walk, the patient exhibits ataxic gait, frequently falling towards the right. An MRI shows an area of hyperintensity localized to the brainstem. Which of the following arteries is most likely occluded in this patient? ]]
Answer A	AnswerA::A
Answer A Explanation	[[AnswerAExp::This refers to the left posterior cerebral artery (PCA). Occlusion of the PCA leads to an infarct of the occipital cortex, specifically the visual cortex. Classically, this presents with homonymous hemianopia with macular sparing.]]
Answer B	AnswerB::B
Answer B Explanation	[[AnswerBExp::This refers to the left anterior inferior cerebellar artery (AICA). Occlusion of the AICA can present with features similar to our patient; however, nucleus ambiguus dysfunction (hoarsness, dysphagia, and absent gag reflex) is unusual. Instead AICA lesions present with an insult to the facial and cochlear nuclei.]]
Answer C	AnswerC::C
Answer C Explanation	[[AnswerCExp::This refers to the middle cerebral artery(MCA). Occlusion of the MCA in the dominant hemisphere leads to contralateral facial and upper extremity sensory-motor deficits. Crossed deficits are not seen in MCA strokes. MCA strokes can also lead to aphasia.]]
Answer D	AnswerD::D
Answer D Explanation	[[AnswerDExp::This refers to the right posterior inferior cerebellar artery (PICA) whose occlusion would explain the symptoms seen in our patient. PICA lesions present with crossed sensory deficits (ipsilateral face vs. contralateral body) and classically, nucleus ambiguus dysfunction.]]
Answer E	AnswerE::E
Answer E Explanation	AnswerEExp::This refers to the left PICA whose occlusion would lead to the same syndrome seen in our patient but the crossed deficit would be inverted (left face with right body).
Right Answer	RightAnswer::D
Explanation	[[Explanation:: This patient displays the classical features of the lateral medullary syndrome (Wallenberg’s Syndrome) due to the occlusion of the posterior inferior cerebellar artery. Typically, brainstem lesions present with crossed deficits with the facial involvement localizing the side of the lesion. Loss of pain and temperature sensation from the left torso and arm indicates right spinothalamic tract involvement, while the association of right facial sensation loss is consistent with injury to the right spinal trigeminal nucleus. His hoarseness is secondary to the involvement of the nucleus ambiguus which is usually specific to PICA lesions. Further investigation would probably show dysphagia and decreased gag reflex which are also indicative of nucleus ambiguus involvement. His initial vertigo and nausea would also suggest a lesion to the vestibular nucleus. In addition, the observed ataxia would indicated a lesion to the inferior cerebellar peduncle also localizing ipsilateral to the lesion. Educational Objective: PICA lesions present with lateral medullary syndrome characterized by crossed sensory deficits, vertigo, ataxia, ipsilateral Horner's syndrome, and nucleus ambiguus symptoms including dysphagia, hoarsness, and loss of gag reflex. References: Kim JS, Lee JH, Suh DC, Lee MC. Spectrum of lateral medullary syndrome. Correlation between clinical findings and magnetic resonance imaging in 33 subjects. Stroke. 1994;25(7):1405-10.]]
Approved	Approved::Yes
Keyword	WBRKeyword::PICA, WBRKeyword::AICA, WBRKeyword::Wallenberg syndrome, WBRKeyword::Wallenberg, WBRKeyword::Lateral medullary syndrome, WBRKeyword::Brainstem, WBRKeyword::Stroke
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