WBR0586: Difference between revisions
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{{WBRQuestion | {{WBRQuestion | ||
|QuestionAuthor={{ | |QuestionAuthor= {{SSK}} (Reviewed by Serge Korjian) | ||
|ExamType=USMLE Step 1 | |ExamType=USMLE Step 1 | ||
|MainCategory=Pathophysiology | |MainCategory=Pathophysiology | ||
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|MainCategory=Pathophysiology | |MainCategory=Pathophysiology | ||
|SubCategory=Head and Neck, Neurology | |SubCategory=Head and Neck, Neurology | ||
|MainCategory=Pathophysiology | |||
|MainCategory=Pathophysiology | |MainCategory=Pathophysiology | ||
|MainCategory=Pathophysiology | |MainCategory=Pathophysiology | ||
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|MainCategory=Pathophysiology | |MainCategory=Pathophysiology | ||
|SubCategory=Head and Neck, Neurology | |SubCategory=Head and Neck, Neurology | ||
|Prompt=A 45 year old woman with past medical history significant for resected breast cancer presents to the emergency department after suffering a tonic-clonic seizure lasting 3 minutes. She explains that she was walking her dog and then found herself on the ground with several people surrounding her, not knowing what had happened. The patient | |Prompt=A 45-year-old woman with past medical history significant for resected breast cancer presents to the emergency department after suffering a tonic-clonic seizure lasting 3 minutes. She explains that she was walking her dog and then found herself on the ground with several people surrounding her, not knowing what had happened. The patient reports that she had been recovering well since her last chemotherapy cycle, and has had no complaints except some minor visual disturbances. On physical exam, you notice the pattern of visual loss shown below. You order a brain MRI that shows an intracranial lesion with high suspicion for metastasis. Where is the most likely location of the lesion given the patient's findgins? | ||
[[Image:Visual2.gif]] | [[Image:Visual2.gif]] | ||
|Explanation=[[Image:Optic_tract_with_explanation.jpg| | |Explanation=[[Image:Optic_tract_with_explanation.jpg|1000px]] | ||
Superior homonymous [[quadrantanopia]] is characterized by loss of vision in the upper quadrant of the visual field. It usually occurs with contralateral temporal lesions due to the interruption of the left [[Meyer's loop]]. Although classically associated with the [[temporal lobe]], it can also occur with certain lesions to the contralateral [[lateral geniculate nucleus]] (LGN) and certain localized lesions to the contralateral [[visual cortex]]. Superior quadrantanopia is commonly seen in patients with direct temporal lobe trauma, temporal lobe tumors commonly metastatic, or [[MCA]] infarcts. | |||
|AnswerA=Parietal lobe | |||
|AnswerAExp=Parietal lobe lesions are usually associated with inferior homonymous quadrananopia due to the interruption of the dorsal optic radiations (Baum's loop). Parietal lobe lesions do not usually cause superior quadrantanopia except if large enough to cause a mass effect. | |||
|AnswerB=Frontal lobe | |||
|AnswerBExp=Frontal lobe lesions usually cause visual field defects by compression the optic tracts or the optic nerve causing unilateral anopia. Frontal lesions can also affect the frontal eye fields involved in eye movements, such as voluntary saccades and pursuit. Frontal lobe lesions do not usually cause quadrantanopia. | |||
| | |AnswerC=Temporal lobe | ||
| | |AnswerCExp=Temporal lobe lesions usually present with visual field disturbances similar to our patient. Superior quadrantanopia is seen in temporal lesions due to the interruption of the Meyer's loop | ||
|AnswerD= | |AnswerD=Occipital lobe | ||
|AnswerDExp= | |AnswerDExp=Occipital lobe lesions usually cause homonymous hemianopia, although cases of quadrantanopia are also encountered. However, superior quadrantanopia is classically seen in temporal lobe lesions. | ||
|AnswerE= | |AnswerE=Cerebellum | ||
|AnswerEExp= | |AnswerEExp=The cerebellar lesions are usually not associated with visual field defects. | ||
|EducationalObjectives=Superior quadrantanopia is characteristic of temporal lesions due to the interruption of the Meyer's loop. | |||
|References=Jacobson DM. The localizing value of a quadrantanopia. Arch Neurol. 1997;54(4):401-4. | |||
|RightAnswer=C | |RightAnswer=C | ||
|WBRKeyword=Upper quadrantopia, Temporal lesions, Visual field defects, | |WBRKeyword=Upper quadrantopia, Temporal lesions, Visual field defects, Quadrantanopia, Scotoma, | ||
|Approved= | |Approved=Yes | ||
}} | }} |
Latest revision as of 01:03, 28 October 2020
Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
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Exam Type | ExamType::USMLE Step 1 |
Main Category | MainCategory::Pathophysiology |
Sub Category | SubCategory::Head and Neck, SubCategory::Neurology |
Prompt | [[Prompt::A 45-year-old woman with past medical history significant for resected breast cancer presents to the emergency department after suffering a tonic-clonic seizure lasting 3 minutes. She explains that she was walking her dog and then found herself on the ground with several people surrounding her, not knowing what had happened. The patient reports that she had been recovering well since her last chemotherapy cycle, and has had no complaints except some minor visual disturbances. On physical exam, you notice the pattern of visual loss shown below. You order a brain MRI that shows an intracranial lesion with high suspicion for metastasis. Where is the most likely location of the lesion given the patient's findgins? |
Answer A | AnswerA::Parietal lobe |
Answer A Explanation | [[AnswerAExp::Parietal lobe lesions are usually associated with inferior homonymous quadrananopia due to the interruption of the dorsal optic radiations (Baum's loop). Parietal lobe lesions do not usually cause superior quadrantanopia except if large enough to cause a mass effect.]] |
Answer B | AnswerB::Frontal lobe |
Answer B Explanation | [[AnswerBExp::Frontal lobe lesions usually cause visual field defects by compression the optic tracts or the optic nerve causing unilateral anopia. Frontal lesions can also affect the frontal eye fields involved in eye movements, such as voluntary saccades and pursuit. Frontal lobe lesions do not usually cause quadrantanopia.]] |
Answer C | AnswerC::Temporal lobe |
Answer C Explanation | AnswerCExp::Temporal lobe lesions usually present with visual field disturbances similar to our patient. Superior quadrantanopia is seen in temporal lesions due to the interruption of the Meyer's loop |
Answer D | AnswerD::Occipital lobe |
Answer D Explanation | AnswerDExp::Occipital lobe lesions usually cause homonymous hemianopia, although cases of quadrantanopia are also encountered. However, superior quadrantanopia is classically seen in temporal lobe lesions. |
Answer E | AnswerE::Cerebellum |
Answer E Explanation | AnswerEExp::The cerebellar lesions are usually not associated with visual field defects. |
Right Answer | RightAnswer::C |
Explanation | [[Explanation::
|
Approved | Approved::Yes |
Keyword | WBRKeyword::Upper quadrantopia, WBRKeyword::Temporal lesions, WBRKeyword::Visual field defects, WBRKeyword::Quadrantanopia, WBRKeyword::Scotoma |
Linked Question | Linked:: |
Order in Linked Questions | LinkedOrder:: |