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?
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°C (98.6°F), 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.
Which of the following factors would increase this patient’s risk for developing the most likely underlying condition?
A. A family member with similar symptoms that began at age 60
B. Prior substance misuse
C. Military service
D. Prior blood transfusion with a surgical procedure
E. Family history of tremor that improves with alcohol use
Scroll down for the correct answer!
The correct answer to today’s USMLE® Step 2 Question is…
A. A family member with similar symptoms that began at age 60
Correct: See Main Explanation.
Incorrect Answer Explanations
B. Prior substance misuse
Incorrect: 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.
C. Military service
Incorrect: Prior military service can increase an individual’s risk for mental health conditions, including depression, anxiety, and post-traumatic stress disorder. However, this patient’s accompanying choreiform movements and signs of acute psychosis are more suggestive of Huntington disease.
D. Prior blood transfusion with a surgical procedure
Incorrect: Patients with iatrogenic Creutzfeldt-Jacob disease from blood transfusions can present with involuntary movements that typically include myoclonus, ataxia, and akinetic mutism. This patient’s choreiform movements, together with acute psychosis and a history of depression, are more suggestive of Huntington disease.
E. Family history of tremor that improves with alcohol use
Incorrect: Patients with 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.
Main Explanation
This patient presents with involuntary irregular movements (i.e., choreiform movements) without tremor, findings consistent with acute psychosis, and a history of depression suggestive of Huntington disease. Patients with Huntington disease may have a family history of similar symptoms that present earlier in subsequent generations. This is secondary to the phenomenon of anticipation 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.
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 tremor is not part of the involuntary movements, the differential diagnosis includes tics, Creutzfeld-Jacob disease, Huntington disease, 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.
Major Takeaway
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.
Want to learn more about this topic?
Watch the Osmosis video: Approach to involuntary movements: Clinical sciences
References
- Ross, C.A. et al. (24 June 2019). Movement Disorder Society Task Force Viewpoint: Huntington’s Disease Diagnostic Categories. Movement Disorders Clinical Practice 6(7): 541-546.
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