Substance Use And Addiction - USMLE Step 2

1. A 31-year-old man has fever, diaphoresis, tremor, hyperreflexia, and clonus after taking linezolid with sertraline. Which diagnosis is most likely?
   Answer: Serotonin syndrome This question tests medical students' understanding of substance use and addiction management in a clinical context, focusing on psychiatric principles. Substance use disorders require a nuanced understanding of withdrawal symptoms, intoxication effects, and management strategies, emphasizing evidence-based practice. In this vignette, the patient's presentation and history provide critical clues for diagnosis and management, such as fever, diaphoresis, tremor, hyperreflexia, and clonus after linezolid with sertraline. The correct answer, choice A, is the best clinical decision because serotonin syndrome arises from MAOI-SSRI interaction per pharmacology guidelines. A common distractor, choice B, is incorrect because neuroleptic malignant syndrome involves rigidity and antipsychotic use, not this combination. Effective strategies include familiarizing oneself with withdrawal protocols and staying updated on guidelines. Practicing case scenarios and understanding the nuances of dual diagnosis can improve decision-making skills.
2. Initiation of which of the following medications for alcohol use disorder is contraindicated in this patient?
   Answer: Naltrexone Naltrexone is an opioid receptor antagonist. Administering it to a patient who is physically dependent on opioids, such as the prescribed morphine in this case, would block the effects of the morphine and precipitate an acute, severe opioid withdrawal syndrome. Therefore, current use of opioids is an absolute contraindication to naltrexone. Acamprosate, disulfiram, and topiramate do not act on opioid receptors and would not cause this reaction.
3. Which of the following is the most appropriate initial medication for this patient's agitation and hypertension?
   Answer: Intravenous lorazepam The management of sympathomimetic toxicity from cocaine focuses on controlling agitation, hypertension, and tachycardia. Benzodiazepines, like lorazepam, are the first-line treatment. They reduce central sympathetic outflow, thereby controlling agitation and lowering heart rate and blood pressure. Beta-blockers (even non-selective ones like labetalol) should be avoided due to the risk of unopposed alpha-adrenergic stimulation, which can worsen hypertension and coronary vasospasm. Haloperidol can be used for psychosis but does not address the underlying sympathomimetic storm as well as benzodiazepines. Phentolamine is a pure alpha-blocker used for refractory hypertension.
4. The patient's clinical presentation is most likely due to which of the following mechanisms?
   Answer: Direct myocyte toxicity and catecholamine-induced damage This patient has a non-ischemic, dilated cardiomyopathy. Chronic cocaine use is a well-established cause of this condition. The pathophysiology is multifactorial and includes direct toxic effects on cardiac myocytes, as well as chronic damage from catecholamine excess, leading to fibrosis, myocyte apoptosis, and ventricular remodeling. While cocaine can cause vasospasm and ischemia (A), the normal coronary arteries and global dysfunction point away from an ischemic etiology. Concentric hypertrophy (D) is seen with chronic hypertension, not a dilated cardiomyopathy.
5. Which of the following is the most likely diagnosis?
   Answer: Substance/medication-induced psychotic disorder The development of psychotic symptoms (delusions) in the context of recent, heavy substance use (amphetamines) makes a substance-induced psychotic disorder the most likely diagnosis. The temporal relationship between substance use and the onset of symptoms is key. Schizophrenia and schizophreniform disorder are less likely given the clear substance use trigger and lack of prior psychiatric history. A brief psychotic disorder is a diagnosis of exclusion and is less likely when a substance is the probable cause.
6. In addition to airway support and supplemental oxygen, which of the following is the most appropriate immediate intervention?
   Answer: Intravenous naloxone The clinical presentation of respiratory depression, pinpoint pupils (miosis), and unresponsiveness in a patient with evidence of intravenous drug use is classic for an opioid overdose. Naloxone is a competitive opioid antagonist and is the specific antidote that can rapidly reverse the life-threatening respiratory depression. Flumazenil is a benzodiazepine antagonist. A head CT would be considered if there was suspicion of trauma, but overdose is far more likely. Gastric lavage is not indicated for intravenous drug use and is generally not recommended for toxic ingestions.
7. Which of the following is the recommended treatment for this patient's opioid use disorder during pregnancy?
   Answer: Initiation of methadone maintenance therapy The standard of care for opioid use disorder in pregnancy is opioid agonist maintenance therapy, with methadone being the most extensively studied and traditional gold standard. Buprenorphine is also a first-line option. These treatments stabilize the patient, reduce illicit drug use, improve prenatal care engagement, and prevent cycles of withdrawal and intoxication that are harmful to the fetus. Medically supervised withdrawal is associated with high relapse rates and risk of fetal demise, and is generally not recommended.
8. What is the most important step to distinguish between a primary depressive disorder and a substance-induced depressive disorder?
   Answer: Achieve a sustained period of abstinence from alcohol Heavy alcohol use can cause depressive symptoms that are indistinguishable from major depressive disorder. The most crucial diagnostic step is to determine if the mood symptoms persist during a period of sobriety. If the depressive symptoms resolve within about 4 weeks of abstinence, a diagnosis of substance-induced depressive disorder is made. If they persist, a primary depressive disorder is more likely. Starting an SSRI or obtaining more history is premature until the effect of the substance is removed.
9. Which of the following is the most appropriate medication-assisted treatment to offer this patient?
   Answer: Buprenorphine-naloxone Buprenorphine is a partial opioid agonist that can be prescribed from a certified physician's office, making it ideal for stable patients who do not require the structure of a daily methadone clinic. It effectively reduces cravings and prevents withdrawal. It is typically combined with naloxone to deter intravenous misuse. Methadone requires daily visits to a licensed opioid treatment program. Naltrexone requires a period of complete opioid abstinence before initiation, or it will precipitate withdrawal. Clonidine only treats the autonomic symptoms of withdrawal and is not a maintenance therapy.
10. In addition to addressing his medical complications, which of the following interventions is most important for preventing further progression of his liver disease?
    Answer: Initiate treatment with acamprosate for alcohol use disorder This patient has decompensated cirrhosis from chronic alcohol use and continues to drink heavily. Complete abstinence from alcohol is essential to prevent further liver damage and potentially allow some recovery of liver function. Medication-assisted treatment for alcohol use disorder, such as acamprosate (which is safe in liver disease), significantly improves abstinence rates compared to counseling alone. Vitamin supplementation is important but doesn't address the root cause. Any continued alcohol consumption will worsen liver disease.
11. Which of the following should be administered before any glucose-containing fluids?
    Answer: Thiamine The patient's presentation with the classic triad of encephalopathy (confusion), oculomotor dysfunction (nystagmus), and gait ataxia is highly suggestive of Wernicke encephalopathy, a condition caused by thiamine (vitamin B1) deficiency. In malnourished patients, particularly those with chronic alcoholism, administering glucose can precipitate or worsen Wernicke encephalopathy by rapidly depleting the body's limited thiamine reserves, as thiamine is a crucial cofactor in glucose metabolism. Therefore, thiamine must always be given before glucose.
12. Which of the following medications is most appropriate to initiate to help this patient maintain abstinence?
    Answer: Naltrexone Naltrexone is an opioid antagonist that is a first-line, FDA-approved treatment for alcohol use disorder. It helps reduce cravings and the rewarding effects of alcohol, thereby decreasing the risk of relapse. Disulfiram is a second-line agent that works by causing an aversive reaction to alcohol and is less effective due to adherence issues. Chlordiazepoxide is a benzodiazepine used for managing acute alcohol withdrawal, not for long-term maintenance. Clonidine is used to manage autonomic symptoms of withdrawal.
13. Which of the following is the most likely diagnosis?
    Answer: Opioid use disorder, severe This patient meets multiple DSM-5 criteria for a severe opioid use disorder, including tolerance (needing higher doses), loss of control (taking more than intended, unsuccessful attempts to cut down), spending a great deal of time on the substance, and functional impairment (missing work). The presence of 6 or more criteria indicates a severe disorder. While he may have underlying pain, his behaviors clearly constitute a substance use disorder. Somatic symptom disorder involves distressing physical symptoms with excessive thoughts/feelings about them, which is not the primary issue. Malingering involves faking symptoms for external gain, which is not described here.
14. The patient's symptoms are most consistent with which of the following?
    Answer: Cannabis withdrawal syndrome This patient is experiencing a classic cannabis withdrawal syndrome. Symptoms typically begin within a week of cessation after prolonged, heavy use and include irritability, anger, anxiety, insomnia, disturbing dreams, decreased appetite, and physical symptoms like headaches or sweating. The clear temporal relationship to quitting cannabis makes this the most likely diagnosis. While he has symptoms of anxiety and depression, they are better explained by the withdrawal syndrome.
15. Which of the following is the most serious potential complication of her current condition?
    Answer: Generalized seizures This patient is experiencing acute benzodiazepine withdrawal. Abrupt cessation of long-term benzodiazepine use leads to a state of CNS hyperexcitability. While autonomic instability and perceptual disturbances are common, the most dangerous and life-threatening complication is the development of generalized tonic-clonic seizures. Management involves reinstating a long-acting benzodiazepine and initiating a slow taper.
16. These findings are most suggestive of which of the following complications of his substance use?
    Answer: Tricuspid valve endocarditis The classic triad of fever, a new heart murmur, and a history of intravenous drug use is highly suggestive of infective endocarditis. In IV drug users, the tricuspid valve is most commonly affected due to the introduction of bacteria into the venous system. The murmur of tricuspid regurgitation is typically a holosystolic murmur at the left lower sternal border that increases with inspiration (Carvallo's sign). The tender nodules (Osler nodes) are an immunologic phenomenon associated with endocarditis.
17. Which of the following is the most appropriate medication to treat this patient's condition?
    Answer: Lorazepam This patient is exhibiting signs and symptoms of delirium tremens (DTs), a severe and life-threatening manifestation of alcohol withdrawal. The treatment of choice is a benzodiazepine, such as lorazepam, diazepam, or chlordiazepoxide. Benzodiazepines work by potentiating the effect of GABA, counteracting the CNS hyperexcitability of withdrawal. Haloperidol can be used for severe agitation but can lower the seizure threshold and does not address the underlying pathophysiology. Clonidine and propranolol can help control autonomic hyperactivity but do not prevent seizures or delirium.
18. Which of the following is the most appropriate management for this patient's condition?
    Answer: Provide supportive counseling and psychoeducation This patient is experiencing stimulant withdrawal syndrome, often called 'the crash'. It is characterized by dysphoria, anhedonia, fatigue, and intense cravings. The withdrawal is not medically dangerous, and there is no FDA-approved pharmacotherapy. The mainstay of treatment is supportive care, including counseling, psychoeducation, and monitoring of mood. While medications like bupropion and modafinil have been studied, they have not shown consistent efficacy and are not standard of care. Benzodiazepines are not indicated.
19. Which of the following medications is the safest option for relapse prevention in this patient?
    Answer: Acamprosate Acamprosate is primarily excreted by the kidneys and does not undergo hepatic metabolism, making it the safest first-line medication for alcohol use disorder in patients with severe liver disease or cirrhosis. Both naltrexone and disulfiram are metabolized by the liver and can be hepatotoxic, making them relatively or absolutely contraindicated in patients with decompensated cirrhosis. Topiramate is used off-label and also has hepatic metabolism.
20. A 52-year-old man with alcohol use disorder has confusion, ataxia, and nystagmus in the ED. Glucose is 52 mg/dL. Which next step is best?
    Answer: Administer IV thiamine before giving IV dextrose This question tests medical students' understanding of substance use and addiction management in a clinical context, focusing on psychiatric principles. Substance use disorders require a nuanced understanding of withdrawal symptoms, intoxication effects, and management strategies, emphasizing evidence-based practice. In this vignette, the patient's presentation and history provide critical clues for diagnosis and management, such as confusion, ataxia, nystagmus, and hypoglycemia in alcohol use disorder. The correct answer, choice A, is the best clinical decision because IV thiamine before dextrose prevents Wernicke encephalopathy exacerbation per neurology guidelines. A common distractor, choice B, is incorrect because giving dextrose first without thiamine can precipitate acute Wernicke syndrome in thiamine-deficient patients. Effective strategies include familiarizing oneself with withdrawal protocols and staying updated on guidelines. Practicing case scenarios and understanding the nuances of dual diagnosis can improve decision-making skills.

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