WBR0482

Author	[[PageAuthor::Ayokunle Olubaniyi, M.B,B.S [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Inpatient Facilities, MainCategory::Neurology
Sub Category	SubCategory::Neurology, SubCategory::Neurology
Prompt	[[Prompt::A 48-year-old woman is admitted to the hospital for breast augmentation surgery. She is in good health and has never been admitted to the hospital or had previous operations. Her only medication is an oral contraceptive pill. Shortly after the administration of general anesthesia she develops muscular rigidity, temperature increases to 41°C, pulse increases to 140/min and blood pressure decreases from 130/70 mm Hg to 80/50 mm Hg. Laboratory investigation revealed: Na+ 145 mmol/L K+ - 6.2 PO2 - 60 mm Hg PCO2 - 40 mm Hg pH - 7.13 Total CO2 - 17 mm Hg O2 saturation - 88% Which of the following medication is contraindicated in the acute management of this condition?]]
Answer A	AnswerA::Dantrolene
Answer A Explanation	AnswerAExp::This is the only antidote for the management of malignant hyperthermia, usually given intravenously.
Answer B	AnswerB::Nifedipine
Answer B Explanation	[[AnswerBExp::Generally, calcium channel blockers are contraindicated in the management of acute cases to prevent worsening of the hyperkalemia and hyperthermia.]]
Answer C	AnswerC::Sodium bicarbonate
Answer C Explanation	[[AnswerCExp::This is needed to correct the metabolic acidosis seen in MH.]]
Answer D	AnswerD::Cold saline infusion
Answer D Explanation	AnswerDExp::This constitutes one of the methods of reducing the high temperature associated with this condition.
Answer E	AnswerE::Diazepam
Answer E Explanation	AnswerEExp::This is sometimes used to alleviate the muscular rigidity observed in this condition.
Right Answer	RightAnswer::B
Explanation	[[Explanation::This is a case of malignant hyperthermia (MH). This is a genetic skeletal muscle abnormality characterized by an abnormal increase in intracellular calcium in the muscles when a genetically predisposed individual is exposed to some potent halogenated inhalational anesthetic agents (e.g., halothane, enflurane, isoflurane) and succinylcholine. Early signs include sinus tachycardia, muscle rigidity, while late signs may manifest as hyperthermia, EKG changes due to hyperkalemia, myoglobinuria, and excessive bleeding. This condition needs to be differentiated from neuroleptic malignant syndrome (NMS) which presents with similar symptoms. Management involves the discontinuation of the offending agent, supportive care correction of electrolyte imbalances, hyperthermia, and the administration of dantrolene, a skeletal muscle relaxant. Educational Objective: References: ]]
Approved	Approved::Yes
Keyword	WBRKeyword::Malignant hyperthermia, WBRKeyword::contraindication to acute management
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::