{"id":8911,"date":"2025-12-14T00:01:00","date_gmt":"2025-12-14T08:01:00","guid":{"rendered":"https:\/\/www.osmosis.org\/blog\/?p=8911"},"modified":"2026-06-19T13:00:25","modified_gmt":"2026-06-19T21:00:25","slug":"usmle-step-2-ck-question-of-the-day-erratic-movements","status":"publish","type":"post","link":"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements","title":{"rendered":"USMLE\u00ae Step 2 CK Question of the Day:\u00a0Erratic movements"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_80 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">In This Article<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\/#The_correct_answer_to_todays_USMLE%C2%AE_Step_2_Question_is%E2%80%A6\" >The correct answer to today\u2019s USMLE\u00ae Step 2 Question is\u2026<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\/#Incorrect_Answer_Explanations\" >Incorrect Answer Explanations<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\/#Main_Explanation\" >Main Explanation<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\/#Major_Takeaway\" >Major Takeaway<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\/#Want_to_learn_more_about_this_topic\" >Want to learn more about this topic?<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\/#References\" >References<\/a><\/li><\/ul><\/nav><\/div>\n\n<p class=\"wp-block-paragraph\"><em><strong>A 41-year-old man presents with psychosis, paranoia, and involuntary writhing and tongue movements despite normal vitals and a negative drug screen. Which factor would increase his risk for developing this condition?<\/strong><\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A 41-year-old man is brought to the emergency department by emergency medical services for evaluation of aggressive behavior, delusions, paranoia and involuntary movements. Bystanders called 911 when the patient was seen in a public park exhibiting erratic movements and yelling about aliens chasing him. Past medical history includes depression for which he takes fluoxetine. Temperature is 37.0\u00b0C (98.6\u00b0F), pulse is 84\/min, respirations are 16\/min, and blood pressure is 134\/86 mmHg. Examination shows a disheveled man with asynchronous writhing movements of the bilateral upper extremities and neck as well as repetitive tongue thrusting. There is no tremor. He repeats that he is being chased by aliens. Urine drug screen and serum ethanol level are negative. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Which of the following factors would increase this patient\u2019s risk for developing the most likely underlying condition?<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>A. A family member with similar symptoms that began at age 60<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>B. Prior substance misuse<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>C. Military service<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>D. Prior blood transfusion with a surgical procedure<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>E. Family history of tremor that improves with alcohol use<\/strong><\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><em>Scroll down for the correct answer!<\/em><\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Osmosis.org at the University College London, UK\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/DIp3u0oTLo4?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"The_correct_answer_to_todays_USMLE%C2%AE_Step_2_Question_is%E2%80%A6\"><\/span>The correct answer to today\u2019s USMLE\u00ae Step 2 Question is\u2026<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>A. A family member with similar symptoms that began at age 60&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Correct:<\/strong> See Main Explanation.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Incorrect_Answer_Explanations\"><\/span>Incorrect Answer Explanations<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>B. Prior substance misuse&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong> While substance use can acutely and chronically cause mental health symptoms and involuntary movements, this patient does not have evidence of substance use. His depression, acute psychosis, and choreiform movements with normal vital signs are more suggestive of Huntington disease.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>C. Military service&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong> Prior military service can increase an individual\u2019s risk for mental health conditions, including depression, anxiety, and post-traumatic stress disorder. However, this patient\u2019s accompanying choreiform movements and signs of acute psychosis are more suggestive of Huntington disease.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>D. Prior blood transfusion with a surgical procedure&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect: <\/strong>Patients with<strong> <\/strong>iatrogenic Creutzfeldt-Jacob disease from blood transfusions can present with involuntary movements that typically include myoclonus, ataxia, and akinetic mutism. This patient\u2019s choreiform movements, together with acute psychosis and a history of depression, are more suggestive of Huntington disease.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>E. Family history of tremor that improves with alcohol use&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect: <\/strong>Patients with<strong> <\/strong>essential tremor commonly have a family history of tremor that improves with alcohol use. Tremor is not the predominant manifestation in this patient with involuntary movements that are choreiform in nature, along with acute psychosis and depression; this presentation is more suggestive of Huntington disease.&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Main_Explanation\"><\/span>Main Explanation<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"975\" height=\"541\" src=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2025\/11\/Huntington-Disease.jpg\" alt=\"**HUNTINGTON DISEASE**\n\n**Hx**\n\n* FIDGETY MOVEMENTS\n  \u2003\u21b3 FACE\n  \u2003\u21b3 ARM\n  \u2003\u21b3 LEG\n* TROUBLE WALKING\n* WORSENING COGNITION\n* FAMILY MEMBERS who had SIMILAR SYMPTOMS PRESENT at OLDER AGE\n* AUTOSOMAL DOMINANT DISORDER\n* +\/- DEPRESSION, AGGRESSIVE BEHAVIOR, or PSYCHOSIS\n\n*phenomenon of anticipation*\n\" class=\"wp-image-8915\" srcset=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2025\/11\/Huntington-Disease.jpg 975w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2025\/11\/Huntington-Disease.jpg?resize=300,166 300w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2025\/11\/Huntington-Disease.jpg?resize=768,426 768w\" sizes=\"auto, (max-width: 975px) 100vw, 975px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">This patient presents with<em> <\/em><strong>involuntary irregular movements<\/strong> (i.e., <strong>choreiform <\/strong>movements) without tremor, findings consistent with<strong> acute psychosis<\/strong>, and a history of <strong>depression<\/strong> suggestive of <strong><a href=\"https:\/\/www.osmosis.org\/learn\/Huntington_disease\">Huntington disease<\/a><\/strong>. Patients with Huntington disease may have a<strong> family history of similar symptoms<\/strong> that present <strong>earlier in subsequent generations<\/strong>. This is secondary to the phenomenon of <strong>anticipation<\/strong> as Huntington disease is an autosomal dominant trinucleotide repeat disorder. The diagnosis can be made with genetic testing of the Huntington gene showing CAG trinucleotide repeat expansion.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Evaluation of involuntary movements relies on a detailed history, physical exam, and laboratory studies. For patients who present with involuntary movements and metabolic derangements (such as hypocalcemia, hypomagnesemia, hypokalemia), renal or hepatic failure should be ruled out with a comprehensive metabolic profile. A careful medication history should be taken to rule out medication-induced parkinsonism, tardive dyskinesia, and dystonia. Drug screening should also be performed. In patients like this one where<strong> tremor is not part of the involuntary movements<\/strong>, the differential diagnosis includes tics, Creutzfeld-Jacob disease, <strong>Huntington disease<\/strong>, or (in the case of pediatric patients) Sydenham chorea. If the predominant manifestation in a patient with non-medication-induced movement disorder is tremor, the differential diagnosis includes essential tremor and Parkinson disease.&nbsp;&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Major_Takeaway\"><\/span>Major Takeaway<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Huntington disease is an autosomal dominant trinucleotide repeat disorder. A careful history may reveal similar symptoms of involuntary movements in family members of previous generations.&nbsp;<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Want_to_learn_more_about_this_topic\"><\/span>Want to learn more about this topic?<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Watch the Osmosis video: <a href=\"https:\/\/www.osmosis.org\/learn\/Approach_to_involuntary_movements:_Clinical_sciences\">Approach to involuntary movements: Clinical sciences<\/a><\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"References\"><\/span>References<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Ross, C.A. et al. (24 June 2019). Movement Disorder Society Task Force Viewpoint: Huntington\u2019s Disease Diagnostic Categories. Movement Disorders Clinical Practice 6(7): 541-546.&nbsp;<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full\"><a href=\"https:\/\/www.osmosis.org\/plans\"><img loading=\"lazy\" decoding=\"async\" width=\"700\" height=\"250\" src=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2020\/10\/Blog_Display_Ads_MD3_2023.png\" alt=\"\" class=\"wp-image-5300\" srcset=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2020\/10\/Blog_Display_Ads_MD3_2023.png 700w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2020\/10\/Blog_Display_Ads_MD3_2023.png?resize=300,107 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>Want more USMLE\u00ae Step 2 CK practice questions? Try Osmosis from Elsevier today! Access your&nbsp;<em><a href=\"https:\/\/www.osmosis.org\/plans\" target=\"_blank\" rel=\"noreferrer noopener\">free trial<\/a><\/em>&nbsp;and discover why millions of current and future clinicians and caregivers love learning with us.<\/strong><\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A patient presents with psychosis and unusual movements. Discover how family history and other factors may increase risk for certain hereditary neurological disorders.<\/p>\n","protected":false},"author":204,"featured_media":8913,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[27,20,16,1366,1370,45],"tags":[2319,2309,1025,2316,2320,2310,2313,2315,2308,2317,2312,2311,2318,2307,2314],"class_list":["post-8911","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicine","category-exam-prep","category-do","category-questions","category-step-2-questions","category-step-2","tag-autosomal-dominant-disorders","tag-chorea","tag-differential-diagnosis","tag-family-history","tag-genetic-testing","tag-huntington-disease","tag-involuntary-movements","tag-movement-disorder-causes","tag-movement-disorders","tag-neurogenetics","tag-neurological-genetics","tag-neuropsychiatric-symptoms","tag-psychiatric-neurology","tag-psychosis","tag-trinucleotide-repeat"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.6 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>USMLE\u00ae Step 2 CK Question of the Day:\u00a0Erratic movements - Osmosis Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-2-ck-question-of-the-day-erratic-movements\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"USMLE\u00ae Step 2 CK Question of the Day:\u00a0Erratic movements - Osmosis Blog\" \/>\n<meta property=\"og:description\" content=\"A patient presents with psychosis and unusual movements. 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