Behavioral Health & Nervous System/Special Senses, Physiology, USMLE Step 1 - Full Vignette with Ext скачать в хорошем качестве

Behavioral Health & Nervous System/Special Senses, Physiology, USMLE Step 1 - Full Vignette with Ext

A 43-year-old heavy smoker presents with a 24-hour history of mild left upper eyelid drooping, subtle pupil size difference more noticeable in darkness, and aching neck pain following lifting. She denies double vision, vision loss, or headache, yet exam reveals ptosis, anisocoria, and decreased facial sweating on the affected side. How should you approach her neurologic signs, and which clinical details are crucial for narrowing the differential diagnosis and guiding the next steps? VIDEO INFO Category: Behavioral Health & Nervous System/Special Senses, Physiology, USMLE Step 1 Difficulty: Moderate - Intermediate level - Requires solid foundational knowledge Question Type: Differential Comprehensive Case Type: Tricky Findings Explore more ways to learn on this and other topics by going to https://endlessmedical.academy/auth?h... QUESTION A 43-year-old woman who smokes three packs of cigarettes daily presents with 24 hours of mild drooping of the left upper eyelid and noticing in dim light that the left pupil looks smaller in photographs. She denies diplopia, painful eye movements, or vision loss. She reports aching in the left side of her neck after lifting boxes two days ago. Past history includes atrial fibrillation that is rate-controlled without anticoagulation and excision of a cutaneous squamous cell carcinoma last year.... OPTIONS A. Postganglionic Horner syndrome from internal carotid artery dissection causing ipsilateral ptosis and miosis with dilation lag; obtain urgent CTA or MRA of the head and neck to confirm and guide therapy. B. Oculomotor nerve palsy from a posterior communicating artery aneurysm because anisocoria greater in dim light implies parasympathetic injury; call neurosurgery before ordering vascular imaging. C. Mechanical ptosis from levator dehiscence, since preserved extraocular movements and normal vision exclude neurologic causes of anisocoria in a middle-aged smoker with recent neck aching. D. Cluster headache with autonomic features; treat acutely with high-flow oxygen and subcutaneous sumatriptan, and defer vascular imaging unless headaches become frequent and stereotyped. CORRECT ANSWER A. Postganglionic Horner syndrome from internal carotid artery dissection causing ipsilateral ptosis and miosis with dilation lag; obtain urgent CTA or MRA of the head and neck to confirm and guide therapy. EXPLANATION The correct answer is "Postganglionic Horner syndrome from internal carotid artery dissection causing ipsilateral ptosis and miosis with dilation lag; obtain urgent CTA or MRA of the head and neck to confirm and guide therapy." The patient has mild ptosis, anisocoria worse in the dark, facial anhidrosis, and recent neck aching-all consistent with sympathetic pathway injury, commonly from carotid dissection in painful or ache-associated new Horner syndrome. Full EOMs without diplopia and lack of ophthalmoplegia argue against a third-nerve palsy; increased anisocoria in the dark indicates impaired dilation (sympathetic deficit), not parasympathetic injury. The distractors misassign mechanism or urgency. "Oculomotor nerve palsy from a posterior communicating artery aneurysm because anisocoria greater in dim light implies parasympathetic injury; call neurosurgery before ordering vascular imaging." is incorrect: anisocoria greater in dim light points to sympathetic loss, not parasympathetic pupil involvement.... Further reading: Links to sources are provided for optional further reading only. The questions and explanations are independently authored and do not reproduce or adapt any specific third-party text or content. --------------------------------------------------- Our cases and questions come from the https://EndlessMedical.Academy quiz engine - multi-model platform. Each question and explanation is forged by consensus between multiple top AI models (i.e. Open AI GPT, Claude, Grok, etc.), with automated web searches for the latest research and verified references. Calculations (e.g. eGFR, dosages) are checked via code execution to eliminate errors, and all references are reviewed by several AIs to minimize hallucinations. Important note: This material is entirely AI-generated and has not been verified by human experts; despite stringent consensus checks, perfect accuracy cannot be guaranteed. Exercise caution - always corroborate the content with trusted references or qualified professionals, and never apply information from this content to patient care or clinical decisions without independent verification. Clinicians already rely on AI and online tools - myself included - so treat this content as an additional focused aid, not a replacement for proper medical education. Visit https://endlessmedical.academy for more AI-supported resources and cases. This material can not be treated as medical advice. May contain errors. ---------------------------------------------------