A 17-year-old boy is brought to the emergency department by his parents due to a recent change in behavior. The patient was previously polite and soft-spoken, but he has become intermittently irritable, impatient, and rude over the past few weeks. His parents initially dismissed his new behavior as a "phase"; however, they grew more concerned last night when they discovered that he had stolen money from their wallets and later found him pacing in his room at 4:00 AM. When questioned by his father about his strange behavior, the patient said, "I have to be careful because I'm being followed by CIA agents." He has no medical conditions. His father has chronic pain and insomnia, for which he takes oxycodone and diphenhydramine. Temperature is 36.6 C (97.9 F), blood pressure is 164/98 mm Hg, pulse is 124/min, and respirations are 18/min. On physical examination, the patient appears fearful. He is sweating profusely and his pupils are dilated. He is observed in the emergency department for several hours, his condition improves, and he is discharged to the care of his parents. Which of the following is the most likely diagnosis for this patient?

Question

A 17-year-old boy is brought to the emergency department by his parents due to a recent change in behavior.  The patient was previously polite and soft-spoken, but he has become intermittently irritable, impatient, and rude over the past few weeks.  His parents initially dismissed his new behavior as a "phase"; however, they grew more concerned last night when they discovered that he had stolen money from their wallets and later found him pacing in his room at 4:00 AM.  When questioned by his father about his strange behavior, the patient said, "I have to be careful because I'm being followed by CIA agents."  He has no medical conditions.  His father has chronic pain and insomnia, for which he takes oxycodone and diphenhydramine.  Temperature is 36.6 C (97.9 F), blood pressure is 164/98 mm Hg, pulse is 124/min, and respirations are 18/min.  On physical examination, the patient appears fearful.  He is sweating profusely and his pupils are dilated.  He is observed in the emergency department for several hours, his condition improves, and he is discharged to the care of his parents.  Which of the following is the most likely diagnosis for this patient?

Quizplus · Accepted Answer

This patient's episodic agitation, insomnia, psychosis (eg, delusions about the CIA), change in behavior (eg, stealing money), and signs of sympathetic hyperactivity (eg, mydriasis, tachycardia, hypertension, diaphoresis) with subsequent return to baseline functioning following an observed period of abstinence are consistent with amphetamine intoxication. Potential serious complications of amphetamine intoxication include cardiac arrhythmias, seizures, hyperthermia, and intracerebral hemorrhage. The diagnosis of amphetamine intoxication is clinical. A positive toxicology screen can be supportive. However, the decongestant pseudoephedrine and the antidepressants bupropion and selegiline can cause false positives for amphetamines on urine toxicology testing. Amphetamines include a range of substances, from those prescribed for the treatment of attention-deficit hyperactivity disorders to the newer synthetic cathinones (ie, bath salts), which are not detectable on routine toxicology screens. (Choice B) Some symptoms of anticholinergic poisoning (eg, mydriasis, hyperthermia, tachycardia) can occur due to amphetamine intoxication. Anticholinergic poisoning is differentiated by the presence of dry skin and mucous membranes, motor symptoms (eg, myoclonic jerks, tremors), and other classic anticholinergic manifestations such as ileus and urinary retention. Delirium is more likely than isolated psychotic symptoms. (Choice C) A manic episode of bipolar disorder is characterized by at least a week of elevated/irritable mood, increased energy, decreased need for sleep, and pressured speech; it may also include psychotic features. Stimulant intoxication can mimic mania and should be ruled out before concluding that a patient is having a manic episode. A manic episode would not subside quickly without any pharmacologic intervention. (Choice D) Diagnosis of primary psychotic disorders requires ruling out substance-induced causes. Brief psychotic disorder is characterized by acute onset of one or more psychotic symptoms lasting ≥1 day but <1 month, with eventual complete resolution. Although this patient has psychotic features, his pupillary dilation, tachycardia, diaphoresis, and elevated blood pressure combined with resolution of signs/symptoms during observation support a diagnosis of substance-induced psychosis. (Choice E) Delusional disorder can only be diagnosed if a delusion has been present for ≥1 month and does not result from intoxication, as in this patient. (Choice F) Opioid (eg, oxycodone) withdrawal symptoms include muscle spasms, joint pain, nausea and vomiting, diarrhea, abdominal cramps, rhinorrhea, lacrimation, and sweating. Irritability, hypertension, and mydriasis may occur. However, delusions are unlikely, and symptoms of opioid withdrawal often last 3-5 days. Educational objective: Amphetamine intoxication can present with psychiatric symptoms, including irritability, agitation, and psychosis. Common physical signs include tachycardia, hypertension, hyperthermia, diaphoresis, and mydriasis. References: Bath salts intoxication: a case series. (http://www.ncbi.nlm.nih.gov/pubmed/23827164) Overdose of drugs for attention-deficit hyperactivity disorder: clinical presentation, mechanisms of toxicity, and management. (http://www.ncbi.nlm.nih.gov/pubmed/23757186)

A 17-Year-Old Boy Is Brought to the Emergency Department by His