A 16-year-old boy is brought to the office by his mother, who is worried that he has been acting "strange" for the past week. She says, "He stays up late at night and is unable to sleep. He eats very little and is really irritable. He seems nervous and hyper and argues with the family, which is not like him. I am a little worried because his father has bipolar disorder. I don't think he would use drugs, but I know that he has some friends who recently got in trouble for smoking marijuana." Medical history includes a football injury and arthroscopic surgery for an anterior cruciate repair 3 months ago. The patient has no other medical issues. He takes no medications other than diphenhydramine, which his mother has given him over the past week to help him sleep. Family history is significant for bipolar disorder and hypertension in his father and attention-deficit hyperactivity disorder in his younger brother, who is treated with medication. When interviewed alone, the patient states that he does not use alcohol, tobacco, or illicit drugs. He says, "I was nervous about final exams. After staying up late to study, it was hard to fall asleep." Temperature is 36.7 C (98 F), blood pressure is 130/90 mm Hg, pulse is 102/min, and respirations are 20/min. Examination shows a restless but otherwise healthy-looking boy. He is slightly diaphoretic and has trouble sitting still. The pupils are dilated and the mouth is dry. Examination of the ears and nose is normal. The lungs are clear on auscultation. The patient's heart is tachycardic with a loud S2 heard on auscultation. Abdominal examination shows no abnormalities. There are no neurologic deficits and no meningeal signs. The patient is talkative and his speech is mildly pressured. Which of the following is the most likely diagnosis?

Question

A 16-year-old boy is brought to the office by his mother, who is worried that he has been acting "strange" for the past week.  She says, "He stays up late at night and is unable to sleep.  He eats very little and is really irritable.  He seems nervous and hyper and argues with the family, which is not like him.  I am a little worried because his father has bipolar disorder.  I don't think he would use drugs, but I know that he has some friends who recently got in trouble for smoking marijuana."  Medical history includes a football injury and arthroscopic surgery for an anterior cruciate repair 3 months ago.  The patient has no other medical issues.  He takes no medications other than diphenhydramine, which his mother has given him over the past week to help him sleep.  Family history is significant for bipolar disorder and hypertension in his father and attention-deficit hyperactivity disorder in his younger brother, who is treated with medication.  When interviewed alone, the patient states that he does not use alcohol, tobacco, or illicit drugs.  He says, "I was nervous about final exams.  After staying up late to study, it was hard to fall asleep."  Temperature is 36.7 C (98 F), blood pressure is 130/90 mm Hg, pulse is 102/min, and respirations are 20/min.  Examination shows a restless but otherwise healthy-looking boy.  He is slightly diaphoretic and has trouble sitting still.  The pupils are dilated and the mouth is dry.  Examination of the ears and nose is normal.  The lungs are clear on auscultation.  The patient's heart is tachycardic with a loud S2 heard on auscultation.  Abdominal examination shows no abnormalities.  There are no neurologic deficits and no meningeal signs.  The patient is talkative and his speech is mildly pressured.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

Explanation: This patient's new-onset insomnia, decreased appetite, and irritability, together with physical examination findings of dilated pupils, tachycardia, hypertension, and diaphoresis, are most consistent with stimulant toxicity. Assessment of substance-induced causes of symptoms should include both illicit drugs as well as prescribed medications that the patient may have access to (eg, the brother's attention-deficit hyperactivity disorder medications, opioids prescribed for postoperative pain). Patients with stimulant intoxication may exhibit prominent psychiatric symptoms, including anxiety, agitation, irritability, and psychosis. Chest pain, arrhythmias, hyperthermia, and seizures can also occur. (Choice A) Diphenhydramine has anticholinergic properties, and some symptoms of anticholinergic toxicity (eg, mydriasis, tachycardia) overlap with those of stimulant intoxication. Anticholinergic toxicity is differentiated by the presence of dry skin (as opposed to diaphoresis) and other classic anticholinergic manifestations, such as ileus and urinary retention. (Choice B) This patient is at increased risk for bipolar disorder due to family history. However, his prominent physical findings (eg, mydriasis, diaphoresis, tachycardia, hypertension) are more consistent with substance intoxication. Substance-induced causes should be ruled out before concluding that a patient is having a bipolar hypomanic episode. (Choice C) Signs of cannabis intoxication include tachycardia, tachypnea, hypertension, dry mouth, conjunctival injection, and increased appetite. This patient has dilated pupils and decreased appetite. (Choice D) Although irritability and mydriasis are also seen in opioid withdrawal, this patient lacks other signs and symptoms of opioid withdrawal (eg, nausea, vomiting, abdominal cramping, lacrimation, myalgias, arthralgias). Educational objective: Stimulant toxicity is characterized by anxiety, agitation, insomnia, and loss of appetite. Physical findings include tachycardia, hypertension, diaphoresis, and mydriasis. Psychosis and seizures can also occur. References: Stimulant toxicity in children: a retrospective study on 147 patients. (http://www.ncbi.nlm.nih.gov/pubmed/26203623) Overdose of drugs for attention-deficit hyperactivity disorder: clinical presentation, mechanisms of toxicity, and management. (http://www.ncbi.nlm.nih.gov/pubmed/23757186) Methylphenidate intoxications in children and adults: exposure circumstances and evidence-based dose threshold for pre-hospital triage. (http://www.ncbi.nlm.nih.gov/pubmed/25650984)

A 16-Year-Old Boy Is Brought to the Office by His