A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 37-year-old man comes to the emergency department with his wife because of a 3-day history of severe pain in his right arm. He also reports that he cannot move his right arm. The symptoms began after the patient woke up one morning, having slept on his side. He is otherwise healthy. He works as a waiter and says that he feels exhausted from working several night shifts per week. He adds that he “can barely keep his eyes open” when looking after their daughter the next day. Since the onset of the pain, he has been unable to work and is fully dependent on his wife, who took an extra shift to make enough money to pay their monthly bills. The patient appears relaxed but only allows himself to be examined after his wife convinces him. His vital signs are within normal limits. Examination shows 1/5 muscle strength in the right arm. Reflexes are normal. He has no sensation to light touch over the entire right arm and forearm. When a pin prick test is conducted, the patient rapidly withdraws the right arm. Which of the following is the most likely diagnosis?
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A
Brachial neuritisIncorrect. Brachial neuritis (Parsonage-Turner) causes severe shoulder pain followed by weakness in a defined nerve distribution and would not produce a glove-like sensory loss with intact withdrawal.
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B
Factitious disorderIncorrect. Factitious disorder involves intentional symptom production for the internal psychological reward of being a patient—not the clear external secondary gain (avoiding work, wife taking extra shift) seen here.
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C
MalingeringCorrect. Anatomically impossible exam findings combined with a clear external incentive (avoiding exhausting night shifts, wife supporting him) define malingering.
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D
Radial nerve palsyIncorrect. Radial nerve palsy ("Saturday night palsy") would cause wrist drop and sensory loss over the dorsal first web space—not 1/5 strength of the entire arm with circumferential sensory loss and preserved reflexes.
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E
Conversion disorderIncorrect. Conversion disorder produces unintentional neurologic symptoms incompatible with anatomy after a psychological stressor, with patients typically distressed and lacking external incentive; this patient's clear secondary gain (avoiding work) and relaxed demeanor point to malingering.
↑ Tap an answer to reveal the reasoning
Answer: C. A patient with severe arm weakness and complete sensory loss but normal reflexes, whose pain conveniently makes him fully dependent on his working wife, exhibits the cardinal features of malingering. The diagnostic clue is the external incentive: his wife is now taking an extra shift to support him, while he is freed from his exhausting night-shift job. Malingering is the intentional production of false or exaggerated symptoms motivated by external secondary gain (financial benefit, avoiding work, avoiding legal consequences, obtaining drugs).
The neurologic exam is anatomically inconsistent—rapid withdrawal from pinprick despite "no sensation to light touch" over the entire arm and forearm, plus preserved reflexes despite 1/5 strength, can't be explained by any single peripheral or central lesion. True brachial neuritis or radial nerve palsy would respect a nerve-root or peripheral-nerve distribution and wouldn't cause withdrawal to a stimulus the patient claims he can't feel.
Key distinction from factitious disorder: factitious disorder is the intentional production of symptoms for the internal psychological reward of assuming the sick role (no external gain). Conversion disorder is involuntary and lacks any inconsistency on examination beyond what disease pathophysiology dictates.
**Why each option:**
**A.** Brachial neuritis (Parsonage-Turner) causes severe shoulder pain followed by weakness in a defined nerve distribution and would not produce a glove-like sensory loss with intact withdrawal.
**B.** Factitious disorder involves intentional symptom production for the internal psychological reward of being a patient—not the clear external secondary gain (avoiding work, wife taking extra shift) seen here.
**C.** Correct. Anatomically impossible exam findings combined with a clear external incentive (avoiding exhausting night shifts, wife supporting him) define malingering.
**D.** Radial nerve palsy ("Saturday night palsy") would cause wrist drop and sensory loss over the dorsal first web space—not 1/5 strength of the entire arm with circumferential sensory loss and preserved reflexes.