A 10 year old previously healthy girl presents with insidious changes in her behavior. She starts performing worse in school and has emotional changes with easy crying, irritability, and inappropriate laughter. This is followed by distal movements of the hands: rapid, irregular, nonstereotypical jerks that are continuous while the patient is awake but improve with sleep. The involuntary movements are generalized. You also note facial grimacing and fasciculations of the tongue. There is loss of fine motor control in addition to weakness and hypotonia. When you shake the patient's hand, you note that the pressure of the patient's grip increases and decreases continuously and capriciously. When she talks, her speech is "jerky" with sudden changes in pitch and loudness. An LP is performed and all studies are normal.
Challenge: This disease has decreased in incidence in Western countries, but you recognize it and listen closely to the heart because your presumed diagnosis is...what?
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