A 12-year-old girl is brought to the office by her mother due to unusual nighttime behavior. The mother reports that once or twice a month over the past year she has found her daughter walking around the house between the hours of midnight and 2 AM. The mother says, “Although her eyes are open, she appears to be in a daze and doesn’t respond to me. I guide her back to bed and she goes back to sleep, but I worry that she could get hurt or fall down the stairs if I’m not there.” The girl has no recollection of the events. Which of the following EEG patterns is characteristic of the sleep stage associated with this behavior?

A 54-year-old man comes to the office due to difficulty maintaining an erection for the last several weeks. He says, “One night I was having sex with my wife and could not maintain an erection. Since then, it has continued to be a problem.” The patient still has morning erections. His medical history is significant for hypertension, coronary artery disease, and depression. He has been married for 20 years but reports that he and his wife have been arguing since he began spending more time at work following a promotion 2 months ago. His current medications include amlodipine, lisinopril, and bupropion. Physical examination is unremarkable. Which of the following is the most likely cause of this patient’s erectile dysfunction?

A 1-month-old, full-term boy is brought to the emergency department by his mother due to difficulty awakening him. The mother says that the infant was left alone for a few minutes this morning and rolled off a bed. Since then, he has been sleepy and less active than usual. Physical examination shows a lethargic boy with a large, full anterior fontanelle. Bilateral retinal hemorrhages are seen on funduscopic examination. Which of the following should be strongly suspected in this patient?

A 68-year-old man is brought to the emergency department by his daughter due to a change in mental status. Over the past 2 days, the patient has reported seeing strangers sneaking around the house when only he and his daughter were at home. He has also been intermittently confused, difficult to rouse, and distractible. The patient has had no headaches or focal weakness. He has no chronic medical or psychiatric problems other than seasonal allergies, which his daughter says have flared up since he moved in with her 2 weeks ago. Temperature is 36.7 C (98 F), blood pressure is 140/85 mm Hg, pulse is 88/min, and respirations are 12/min. On physical examination, the patient is somnolent but arousable to voice. He is not oriented to place or time. Pupils are bilaterally equal and reactive to light. Bilateral upper and lower extremity muscle strength, deep tendon reflexes, and pain sensation are normal. Blood cell counts and serum chemistry studies are within normal limits. Which of the following is the most likely cause of his current condition?

A 16-year-old boy with suicidal thoughts is brought to the office by his parents. He has been in constant conflict with his parents since refusing to stop drinking alcohol, which he does on a daily basis. The patient is the oldest of 6 children; his mother suffers from lower back pain and relies on him for child care, which he finds overwhelming. His father works 2 jobs and is often not around to help with the children. His mother keeps a firearm by her bedside for protection when she is alone with the children at night. The patient dropped out of high school last year after getting dumped by his girlfriend. He recently contracted Lyme disease with resultant symptoms of fatigue and myalgia. Which of the following interventions is the best next step to decrease this patient’s risk of completed suicide?

A 27-year-old man leaves the men’s room of a bar after smoking an unknown substance. He soon becomes disoriented and belligerent. The man displays uncoordinated, jerky movements of his extremities and assaults a bouncer who tries to calm him. When police and emergency medical services personnel arrive, he fights off 4 officers before being restrained and appears immune to pain. In the emergency department, the patient has visual hallucinations, cannot cooperate with the interview, and alternates between agitation and sedation. He is hypertensive and tachycardic, and examination shows vertical nystagmus. The patient does not cooperate with urine toxicology testing. Several hours later, during questioning by the emergency physician, he does not remember most of the preceding events. Which of the following is the primary mechanism of action of the drug most likely used by this patient?

A 2-year-old boy is brought to the clinic by his mother, who is concerned about his language development. She says, “I know that children speak at different ages and he is still young, but I am concerned that his speech isn’t progressing and that he needs to interact with other children more. His day care teacher says that he is shy and sits in a corner playing with his favorite truck. We have also been busy with a recent move and have not given him as much attention, which doesn’t help.” The patient’s birth history, medical history, and audiology screening are unremarkable. His mother is 6 months pregnant with her second child, and the family moved to a new home 3 months ago. In the examination room, the patient sits in a corner, avoiding eye contact with the doctor and repeatedly spinning the wheels of a toy truck. He does not respond to his name. He makes occasional grunting sounds but says no fully formed words. When his mother tries to take his truck away, he begins screaming and pulls it back. Which of the following is the most likely diagnosis in this patient?

An 18-year-old boy is brought to the emergency department by his mother due to his strange behavior. The mother says that he laughs inappropriately and seems sluggish. The boy has recently been hanging out with a new group of friends that he describes as “really cool.” He has also stopped attending family events and appears apathetic about his schoolwork. When asked in private, the boy admits smoking marijuana. Which of the following physiologic effects is most likely to be observed in this patient?

A 21-year-old woman comes to the office due to constipation and vague abdominal pain.  She says, “For the last few months I have felt bloated and my stomach doesn’t feel right.”  Review of systems is notable for irregular menses and occasional fatigue.  Medical history is significant for a broken femur at age 6 but is otherwise noncontributory.  Family history is significant for Graves disease in her father and primary myelofibrosis in her paternal grandmother.  The patient smokes a pack of cigarettes daily and drinks wine when relaxing with friends.  She does not use illicit drugs.  Temperature is 37.2 C (99 F), blood pressure is 90/60 mm Hg, pulse is 118/min, and respirations are 16/min.  BMI is 25.6 kg/m2.  Physical examination shows eroded enamel of the teeth.

Laboratory results are as follows:

Which of the following is the most likely cause of this patient’s condition?

A 24-year-old man is brought to the emergency department by police and emergency medical services personnel due to aggressive behavior toward his girlfriend. She reports that he has no history of medical or psychiatric illness and that this behavior is new. During transport, the patient was combative and difficult to restrain. He currently appears agitated, disoriented, and confused and seems to be responding to internal stimuli. Temperature is 37.2 C (99 F), blood pressure is 170/96 mm Hg, pulse is 118/min, and respirations are 20/min. Nystagmus and ataxia are present on initial neurologic examination. The patient does not cooperate with urine toxicology testing. His symptoms begin to resolve after 8 hours in the emergency department. He has very poor recollection of the previous night’s events. Which of the following substances is most likely causing the constellation of symptoms seen in this patient?

A 28-year-old medical student comes to the office due to anxiety and trouble concentrating. He has worked part-time as a volunteer firefighter and reports that he has been struggling to concentrate in class ever since witnessing a child who had been badly burnt pulled out of a house fire 3 weeks ago. On two occasions the patient began to sweat, shake, and have trouble breathing: “I felt like my head was spinning and had to run out of the classroom to catch my breath.” He also reports having trouble sleeping, being irritable with friends and family, and occasionally feeling like he is in a dream. The patient says, “Sometimes I’ll be sitting in class, and I suddenly feel like I am back in the burning house. I can smell the fire and see the child.” He has missed almost half of his classes to avoid being in crowded classrooms and has recently quit his volunteer job. Which of the following is the most likely diagnosis?

A 24-year-old man comes to the physician due to excessive daytime sleepiness. The patient is a college student whose symptoms started around age 12, when he began needing more sleep than his peers to feel refreshed. Two years later, he started having daily episodes of sudden weakness, consistently triggered by laughter or crying, in which his head would nod or his knees would buckle for about 30 seconds. The patient also describes times when he was unable to move for several minutes after awakening from sleep. He mentions nightly dreams that seem very real, often featuring activities that he had been engaged in during the preceding day. If measured, which of the following compounds is most likely to be abnormal in this patient’s cerebrospinal fluid?

A 52-year-old woman comes to the office for a checkup. Her medical problems include hypertension and hypercholesterolemia. The patient has a long-standing relationship with her primary care physician, who has treated her children as well. During the examination, she confides that she has been “down” since her youngest child left for college 2 months ago. The patient is worried about her daughter being away from home for the first time and whether she will be successful at school. At work, the patient occasionally has lapses of concentration when worrying about whether her daughter is okay, but it has not affected her productivity. She says, “I still enjoy going out with my husband but all we do is talk about our kids.” The patient has occasional insomnia and tension headaches but notes that these are nothing new. Physical examination is normal. Which of the following is the most likely explanation for this patient’s condition?

A 14-year-old boy is brought to the office by his mother for a 6-month checkup for asthma. Although the patient’s asthma is generally well controlled with long-acting agents, he has episodes of exercise-induced bronchoconstriction for which he was prescribed a short-acting beta agonist. His mother became concerned after the physical education teacher called from school saying that her son was refusing to participate in class. When asked about this, the patient said that it was easier to avoid exercising than to use an inhaler at school. Family history is significant for chronic obstructive pulmonary disease (COPD) in his maternal grandfather, heart disease in his father, and generalized anxiety disorder in his mother. Vital signs and physical examination are within normal limits. Which of the following factors would most likely increase this patient’s adherence with bronchodilator administration?

A 20-year-old college student is brought to the emergency department by his roommate. The patient is frightened and claims that campus police are following him and plotting to kill him. His roommate says that the patient seemed “totally normal” until a few days ago, when he began to stay up all night to prepare for final exams. The patient has no known medical or psychiatric history, but his father has schizophrenia. Blood pressure is 150/95 mm Hg and pulse is 110/min. Examination shows clear lungs and tachycardia with normal S1 and S2. The abdomen is soft and nontender. Extraocular movements are intact, and the pupils are dilated. The patient is diaphoretic. He appears hypervigilant, paces during the examination, and has mildly pressured speech. Which of the following is the most likely diagnosis in this patient?

A 55-year-old man comes to the office for a checkup. His medical history is significant for major depression treated with sertraline for the past 4 months, hypertension controlled with lisinopril, and diabetes mellitus controlled with diet. He does not use tobacco and drinks a glass of wine with dinner a few times a week. Vital signs are all within normal limits, and no abnormalities are noted on physical examination. Hemoglobin A1c is within normal limits. Which of the following is the most likely side effect of the treatment prescribed for this patient’s depression?

A 26-year-old woman comes to the emergency department to report that her life is in danger. The patient believes that transmitters inserted in her bedroom walls are broadcasting her thoughts to a central government agency that is now plotting to kill her. On mental status examination, she is fearful and paces the examining room. The patient makes poor eye contact with the examiner, and her responses are interrupted by frequent pauses during which she appears to talk back to a person who is not present. She has no medical history. The patient smokes a pack of cigarettes daily and does not use illicit drugs. Physical examination shows a thin, disheveled young woman but no abnormalities. She is hospitalized, improves with medication over the course of 2 weeks, and is discharged on olanzapine. At this patient’s 3-month checkup, which of the following studies should be obtained?

A 27-year-old man is brought to a family therapist by his wife following a violent outburst in which he nearly injured her. They were having what seemed like a minor argument over a miscommunication about her being late when he suddenly flew into a rage, started shouting, and threw several plates against the wall. His wife is now threatening to leave him because similar episodes keep happening despite his promise to control his anger. The patient is remorseful and says, “I have been getting into trouble because of my temper since high school. Once I get angry, I feel out of control and it’s impossible to stop.” The patient has no medical history. He drinks beer and uses cannabis to relax approximately 2-3 times a month. Which of the following is the most likely diagnosis in this patient?

A 54-year-old man arrives for an appointment with a new physician. At the front desk, the receptionist tells him that the physician is running behind schedule and gives him several forms to complete regarding his personal and family medical history. The patient politely agrees to fill them out and has a seat in the waiting area. However, when his paperwork is reviewed by the physician, it contains only the patient’s signature. The patient says, “I’m sure a doctor with your education can take a good history.” When asked if anything is wrong he says, “Oh, nothing, I’m fine.” Which of the following best describes this patient’s behavior?

A 32-year-old man is diagnosed with major depressive disorder and started on the selective serotonin reuptake inhibitor sertraline. At his 2-week follow-up, the patient reports that his mood is “about the same.” He continues to feel sad and unmotivated most days and is short-tempered with his wife and kids. He has little interest in food, sleeps poorly, and struggles to stay focused at work. In the first 2-3 days of taking the medication, the patient experienced some mild nausea and anxiety that has since resolved. He is now tolerating the medication without difficulty but is considering stopping it because he is discouraged by the lack of clear improvement. Which of the following is the most likely explanation for this patient’s lack of response?

A 14-year-old boy is brought to the emergency department by a teacher after being found staggering and falling on the ground in the school parking lot between classes. When she found him, the patient seemed lethargic and disoriented and his speech was slurred. His condition slowly improved over the next 30 minutes; when the patient is evaluated in the emergency department an hour after the teacher found him, he is alert, oriented, and able to speak clearly. Temperature is 36.7 C (98.1 F), blood pressure is 102/65 mm Hg, and pulse is 62/min. On physical examination, there are abrasions on the right forearm and shin and a rash around the nostrils and mouth. The patient has no known medical history. Which of the following substances is the most likely cause of this patient’s symptoms?

A 72-year-old man is hospitalized due to a leg injury following a high-speed motor vehicle collision. Medical history is significant for hypertension, hypercholesterolemia, and hearing loss. The patient drinks a glass of wine every day. Examination shows localized swelling and severe tenderness under the right knee; the presence of a tibial fracture is confirmed by imaging. The patient undergoes open reduction and internal fixation without any perioperative complications. On the first postoperative night, he describes visual hallucinations of his deceased brother in the hospital room with him and perseverates about people invading his home. Vital signs are normal. The patient is disoriented and unable to cooperate with the mental status examination. He appears to respond to internal stimuli. Which of the following interventions is most likely indicated to prevent further worsening of his condition?

A 34-year-old man comes to the office with a 5-day history of nasal congestion and cough. He says that he occasionally coughs up thick, yellow sputum and is worried about the lack of improvement. The patient mentions that he has received antibiotics for similar symptoms in the past and says, “Antibiotics always seem to help me feel better fast.” Temperature is 37.2 C (99 F), blood pressure is 120/70 mm Hg, pulse is 76/min, and respirations are 18/min. Physical examination shows pharyngeal erythema; the remainder of the examination, including cardiopulmonary evaluation, is normal. Which of the following responses by the physician is most appropriate?

A 46-year-old man is admitted to the hospital for atypical chest pain. His medical history is significant for hypertension controlled with amlodipine and hypercholesterolemia treated with atorvastatin; he has a family history of depression and heart disease. During review of his substance use history, the patient says that he has been a “regular drinker” for the last 5 years. He drinks a 6-pack of beer every night and has 2 more beers in the morning to help him “get through the day.” He also admits to smoking marijuana occasionally but does not use tobacco or other illicit drugs. Which of the following symptoms or signs is most likely to appear earliest during this patient’s hospitalization?

A 72-year-old man comes to the office due to poor sleep. He is concerned that he is sleeping less since he retired a year ago. He says, “I used to sleep a solid 8 hours, but now I wake up several times a night. And I’m up for the day between 5:00 and 6:00 AM, which is a full hour before I want to get up. I’m probably only getting about 6 or 7 hours of sleep total.” The patient typically falls asleep while watching television at 10:00 PM. He sometimes awakens to use the bathroom in the middle of the night but typically falls back asleep within 15 minutes. The patient likes to do crosswords and play golf in the mornings but occasionally takes 30-minute naps in the afternoon. The patient’s wife says that he snores softly, but she has not witnessed any breathing pauses. Medical problems include hypertension and a history of depression. The patient does not use alcohol or illicit drugs. Which of the following is the most likely cause of this patient’s symptoms?

A 10-year-old boy is brought to the pediatric clinic due to unusual classroom behavior for the past year, which has worsened over the last few weeks. Although the patient is generally quiet, he intermittently disrupts the class with sniffling, repetitive throat clearing, and grunting sounds. His teacher states that the boy distracts other students and that his focus in class is poor. The behaviors worsen when he is tired, stressed, or excited. The patient’s parents are also concerned because he has only a few friends and his classmates make fun of him. Medical history is significant for recurrent otitis media as a toddler, atopic dermatitis, and an influenza infection 9 months ago. Family history is significant for rheumatoid arthritis and anxiety in his mother. Temperature is 36.7 C (98 F), pulse is 78/min, blood pressure is 110/72 mm Hg, and respirations are 14/min. Physical examination shows frequent eye blinking and shoulder shrugging but is otherwise normal. Which of the following is the most likely diagnosis?

A 2-year-old girl is brought to the office due to concerns about her development. The girl says approximately 40 words and does not string words together. She can jump, walk upstairs slowly, build a 6-block tower, and follow short commands. She feeds and helps to dress herself. The girl’s mother says, “My daughter is such a happy child. She loves playing with the other kids at day care. She is affectionate and caring toward us and her dog. I don’t know why she won’t speak. Her sister was using sentences by age 2. Is there something wrong with her?” Which of the following is the most appropriate response by the physician?

A 22-year-old woman is hospitalized due to suicidal ideation. The patient describes feelings of intense sadness, emptiness, and despair for the past week following the breakup of her month-long romantic relationship. For the past week, she has had difficulty falling and staying asleep but has had no change in appetite, energy level, or concentration. She feels betrayed by her boyfriend and is furious at her parents for turning against her. Since the breakup, the patient has been going to bars, engaging in unsafe sex, and drinking excessively. She describes having intense mood swings since adolescence and has a history of 2 suicide attempts involving an overdose of sleeping pills. Which of the following is the most likely diagnosis?