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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{Rim}}, {{AJL}} {{Alison}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|MainCategory=Pharmacology
Line 20: Line 20:
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Neurology
|SubCategory=Neurology
|Prompt=A 32 year old male patient who is previously healthy is brought to the emergency department (ED) in a decreased level of consciousness.  His family reports he takes no medications and has no allergies.  Vital signs show a temperature of 36.3 degrees C (97.4 degrees F), a heart rate of 44 bpm, a respiratory rate of 6/min, and a blood pressure measuring 100/60 mmHg. On physical examination, the patient is difficult to arouse, he has pinpoint pupils, and track marks on his arm.  The physician in the ED suspects drug abuse. Which of the following corresponds to the mechanism of pupillary constriction in this patient?
|Prompt=A 32-year-old male is brought to the emergency room with a decreased level of consciousness.  Vital signs demonstrate a temperature of 36.3 °C, heart rate of 44 bpm, respiratory rate of 6 breaths/min, and blood pressure of 100/60 mmHg. Upon physical examination, the patient is difficult to arouse, has pinpoint pupils and track marks on his arm.  You suspect drug abuse. Which of the following mechanisms corresponds to the pupillary constriction in this patient?
|Explanation=Opioid analgesic overdose is a life-threatening condition that affects multiple organ systems.  Opioids increases the activity of G-protein-coupled transmembrane mu, delta, and kappa opioid receptors in various organs of the body.  As a result, heterodimer and homodimer receptors form to activate endogenous and exogenous compounds.  Patients with opioid overdose are usually in a comatose-like condition with signs of cardiopulmonary depression on physical examination (low heart rate, low respiratory rate, and low blood pressure).  On physical examination, patients with chronic abuse of opioids may have visible track marks on their arms.  Their ophthalmologic exam shows the characteristic finding of pinpoint pupils.
|Explanation= Opioid analgesic overdose is life-threatening and affects multiple organ systems.  Opioids increases the activity of G-protein-coupled transmembrane mu, delta, and kappa opioid receptors in various organs.  Heterodimer and homodimer receptors form to activate endogenous and exogenous compounds.  Patients with opioid overdose are frequently present with a comatose-like condition with signs of cardiopulmonary depression, such as low heart rate, low respiratory rate, and low blood pressure.  Upon physical examination, patients with chronic abuse of opioids may have visible track marks on their arms and characteristic pinpoint pupils.


Opioid receptors in the brain stem mediate the respiratory depression in patients with opioid toxicity.  Pinpoint pupils occur following the activation of the opioid receptor in the Edinger-Westphal nucleus of the oculomotor nerve.
Opioid receptors in the brain stem mediate the respiratory depression in patients with opioid toxicity.  Pinpoint pupils occur following the activation of the opioid receptor in the Edinger-Westphal nucleus of the oculomotor nerve.


Educational Objective:Opioid receptor in the Edinger-Westphal nucleus mediates the pupillary constriction in opioid toxicity.
|EducationalObjectives= The opioid receptor, in the Edinger-Westphal nucleus, mediates the pupillary constriction in opioid toxicity.
 
|References= Boyer EW. Management of opioid analgesic overdose. N Eng J Med. 2012;367:146-55.


Reference: Boyer EW. Management of opioid analgesic overdose. N Eng J Med. 2012;367:146-55.
|AnswerA=Activation of gamma-aminobutyric acid (GABA) receptors in the geniculocalcarine radiations
|AnswerA=Activation of gamma-aminobutyric acid (GABA) receptors in the geniculocalcarine radiations
|AnswerAExp=Opioid receptors are activated in opioid toxicity.  GABA has no role in pupillary constriction. The geniculocalcarine radiations are not responsible for pupillary constriction.
|AnswerAExp= GABA and the geniculocalcarine radiations have no role in pupillary constriction.
|AnswerB=Activation of opioid receptors in the Edinger-Westphal nucleus
|AnswerB=Activation of opioid receptors in the Edinger-Westphal nucleus
|AnswerBExp=The activation of opioid receptors in the Edinger-Westphal nucleus is the mechanism behind pupillary constriction in opioid toxicity.
|AnswerBExp=See overall explanation.
|AnswerC=Activation of glutamate receptors in the lateral geniculate nucleus
|AnswerC=Activation of glutamate receptors in the lateral geniculate nucleus
|AnswerCExp=Opioid receptors are activated in opioid toxicity.  GABA has no role in pupillary constriction. The lateral geniculate nucleus is not responsible for pupillary constriction.
|AnswerCExp= GABA and the The lateral geniculate nucleus have no role in pupillary constriction.
|AnswerD=Activation of opioid receptors in the superior colliculus
|AnswerD=Activation of opioid receptors in the superior colliculus
|AnswerDExp=The superior colliculus is not responsible for pupillary constriction.
|AnswerDExp=The superior colliculus is not responsible for pupillary constriction.
|AnswerE=Activation of GABA receptors in the oculomotor nerve
|AnswerE=Activation of GABA receptors in the oculomotor nerve
|AnswerEExp=Opioid receptors are activated in opioid toxicity.  GABA has no role in pupillary constriction.  Although the oculomotor nerve is involved due to the activation of receptors in the Edinger-Westphal nucleus, the activated receptors are of opioid type not GABA.
|AnswerEExp=GABA has no role in pupillary constriction.  Although the oculomotor nerve is involved, due to the activation of receptors in the Edinger-Westphal nucleus, the activated receptors are of opioid type, not GABA.
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=opioid, toxicity, Edinger, Westphal, Edinger-westphal, edinger westphal, pupillary, constriction, pupillary constriction, morphine, drug, overdose
|WBRKeyword=opioid toxicity, Edinger-westphal, pupillary, pupillary constriction, morphine, drug overdose, addiction, optical, drug abuse,
|Approved=No
|Approved=Yes
}}
}}

Revision as of 18:42, 31 July 2014
Author [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pharmacology
Sub Category SubCategory::Neurology
Prompt [[Prompt::A 32-year-old male is brought to the emergency room with a decreased level of consciousness. Vital signs demonstrate a temperature of 36.3 °C, heart rate of 44 bpm, respiratory rate of 6 breaths/min, and blood pressure of 100/60 mmHg. Upon physical examination, the patient is difficult to arouse, has pinpoint pupils and track marks on his arm. You suspect drug abuse. Which of the following mechanisms corresponds to the pupillary constriction in this patient?]]
Answer A AnswerA::Activation of gamma-aminobutyric acid (GABA) receptors in the geniculocalcarine radiations
Answer A Explanation AnswerAExp::GABA and the geniculocalcarine radiations have no role in pupillary constriction.
Answer B AnswerB::Activation of opioid receptors in the Edinger-Westphal nucleus
Answer B Explanation AnswerBExp::See overall explanation.
Answer C AnswerC::Activation of glutamate receptors in the lateral geniculate nucleus
Answer C Explanation AnswerCExp::GABA and the The lateral geniculate nucleus have no role in pupillary constriction.
Answer D AnswerD::Activation of opioid receptors in the superior colliculus
Answer D Explanation AnswerDExp::The superior colliculus is not responsible for pupillary constriction.
Answer E AnswerE::Activation of GABA receptors in the oculomotor nerve
Answer E Explanation AnswerEExp::GABA has no role in pupillary constriction. Although the oculomotor nerve is involved, due to the activation of receptors in the Edinger-Westphal nucleus, the activated receptors are of opioid type, not GABA.
Right Answer RightAnswer::B
Explanation [[Explanation::Opioid analgesic overdose is life-threatening and affects multiple organ systems. Opioids increases the activity of G-protein-coupled transmembrane mu, delta, and kappa opioid receptors in various organs. Heterodimer and homodimer receptors form to activate endogenous and exogenous compounds. Patients with opioid overdose are frequently present with a comatose-like condition with signs of cardiopulmonary depression, such as low heart rate, low respiratory rate, and low blood pressure. Upon physical examination, patients with chronic abuse of opioids may have visible track marks on their arms and characteristic pinpoint pupils.

Opioid receptors in the brain stem mediate the respiratory depression in patients with opioid toxicity. Pinpoint pupils occur following the activation of the opioid receptor in the Edinger-Westphal nucleus of the oculomotor nerve.
Educational Objective: The opioid receptor, in the Edinger-Westphal nucleus, mediates the pupillary constriction in opioid toxicity.
References: Boyer EW. Management of opioid analgesic overdose. N Eng J Med. 2012;367:146-55.]]

Approved Approved::Yes
Keyword WBRKeyword::opioid toxicity, WBRKeyword::Edinger-westphal, WBRKeyword::pupillary, WBRKeyword::pupillary constriction, WBRKeyword::morphine, WBRKeyword::drug overdose, WBRKeyword::addiction, WBRKeyword::optical, WBRKeyword::drug abuse
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