A 27-year-old man is brought to the emergency department by his roommates because of an inability to walk. He began to notice some problems with his balance 2 days ago, and his walking has become progressively worse since then. He had an episode of optic neuritis in the right eye 3 years ago. He is 157 cm (5 ft 2 in) tall and weighs 55 kg (121 lb); BMI is 22 kg/m². His temperature is 37°C (98.6°F), pulse is 55/min, respirations are 10/min, and blood pressure is 110/70 mm Hg. Examination shows spastic lower extremities and moderate weakness of the left lower extremity, more prominently in the flexor than in the extensor muscles. Deep tendon reflexes are normal in the upper extremities but hyperactive in the lower extremities, especially on the left. There is clonus at the left ankle. Proprioception and sensation to vibration are absent over the left lower extremity and decreased over the right lower extremity to the level of the hip. Sensation to pain and temperature is decreased at the lower costal margin and below, most pronounced on the right. Which of the following cell types is most affected by this patient's condition?

(A) Astrocytes

(B) Ependymal cells

(C) Neurons

(D) Oligodendrocytes

(E) Schwann cells

(Answer: D)

A 2-year-old girl with sickle cell disease is brought to the emergency department by her parents because of painful swelling of her feet for the past 3 hours. Her temperature is 37.0°C (98.6°F). Physical examination shows swelling and tenderness of her feet; no other abnormal findings are noted. Results of laboratory studies are shown: 

Which of the following is the most likely diagnosis?

(A) Bone infarction

(B) Escherichia coli sepsis

(C) Osteomyelitis

(D) Pneumococcal sepsis

(E) Staphylococcal sepsis

(Answer: A)

A 54-year-old woman with severe rheumatoid arthritis comes to the office for a routine follow-up examination. Rheumatoid arthritis was diagnosed at age 35 years, and the patient has been unable to work for the past 10 years. She has difficulty bathing and dressing, but she is able to stand and walk independently. Medical history is otherwise unremarkable. Medications include etanercept, methotrexate, prednisone, and tramadol. She tells you that her husband of 30 years left her 6 months ago. She appears depressed. Vital signs are normal. Physical examination discloses marked joint deformities in the hands, wrists, shoulders, and feet; the findings are unchanged from previous visits. The patient says, "I cannot continue to live as I am. I've had it." Which of the following is the most appropriate response?

(A) "Do you think you're depressed? I can help with that."

(B) "Have you considered moving to an assisted living facility where your quality of life could be much better?"

(C) "I know just how you feel."

(D) "I'd like to refer you to a counselor."

(E) "Would you like to tell me more about why you feel this way?"

(Answer: E)

A 17-year-old boy is brought to the emergency department by a caregiver after sustaining a large knife wound to his left arm. The caregiver reports that the patient cut himself with a knife, but it is unknown whether this was a suicide attempt. The patient lives in a group home with three other individuals and the caregiver; it is apparent from talking to the patient that he has limited intellectual capacity. He has an appointed legal guardian who has been contacted and is due to arrive at the hospital in approximately 45 to 60 minutes. The patient's vital signs are temperature 36.5°C (97.7°F), pulse 134/min, respirations 22/min, and blood pressure 70/40 mm Hg. He appears pale and he has a large, blood-soaked towel wrapped around his left forearm. Removal of the towel discloses a 9-cm laceration with obvious arterial hemorrhage and tendon exposure. Examinations of the chest and abdomen are unremarkable. A pressure bandage is immediately applied and consultation is obtained with a surgeon, who wants to take the patient immediately to the operating room. Which of the following statements is most accurate regarding consent for this patient?

(A) The caregiver can legally provide consent

(B) The need for consent can be waived

(C) The patient is emancipated and can legally give consent

(D) Psychiatric clearance should be obtained for patient consent

(E) Surgery must be delayed until the guardian arrives

(Answer: B)

A 24-year-old man and a 22-year-old woman come to the office for the first time for premarital evaluation and counseling. Neither of them has ever been sexually active, because they "want to wait" until after marriage to have sexual intercourse. Other discussion reveals that they have never had blood transfusions, used illicit drugs, or drunk excessive amounts of alcohol. They have heard about the test for HIV antibody and wonder whether they should obtain this test before marriage. Compared with persons who have multiple risk factors for HIV, which of the following statements best applies to this couple?

(A) The negative predictive value of the test would be lower

(B) The positive predictive value of the test would be lower

(C) The sensitivity of the test would be higher

(D) The sensitivity of the test would be lower

(E) The specificity of the test would be lower

(Answer: B)

A previously healthy 54-year-old man comes to the emergency department at his wife's insistence 6 days after a stray dog bit his right leg while he and his wife were walking near the dog during a trip to South America. The bite punctured the skin. He immediately cleaned the wound thoroughly with soap and peroxide and has done so daily since the incident occurred. The area of the bite is not painful, and the patient has not had fever or chills. He takes no medications. He had a tetanus booster vaccination 3 years ago. Vital signs today are normal. Examination of the right lower extremity shows healing bite puncture wounds. There is minimal erythema and the area is not fluctuant. Lymph nodes in the groin are not palpable. Which of the following is the most appropriate next step?

(A) Administer rabies vaccination

(B) Administer tetanus immune globulin

(C) Order cerebrospinal fluid analysis

(D) Order an MRI of the brain and spine

(E) No action is necessary at this time

(Answer: A)