Neuroleptic Malignant Syndrome — MCQs
A patient on clozapine develops fever, confusion, and muscle rigidity. CK is elevated. Most appropriate next step?
What is the primary cause of death in Neuroleptic Malignant Syndrome?
Which of the following conditions does not cause a rise in end-tidal CO2 during thyroid surgery?
A patient on clozapine develops fever, confusion, and muscle rigidity. Creatine kinase (CK) is elevated. Most appropriate next step?
A patient on clozapine develops fever, confusion, and muscle rigidity. CK is elevated. Most appropriate next step?
Which of the following is LEAST likely to cause hyperthermia?
A child during anesthesia with halothane and succinylcholine develops severe stiffness of masseters. What is the most probable diagnosis?
Which of the following is not true about polymyositis
Which of the following has the least malignant potential?
A 39-year-old male patient presents with waxy flexibility, negativism and rigidity. Most probable diagnosis is?
Neuroleptic Malignant Syndrome Indian Medical PG Practice Questions and MCQs
Question 1: A patient on clozapine develops fever, confusion, and muscle rigidity. CK is elevated. Most appropriate next step?
- A. Add antipyretic
- B. Continue clozapine
- C. Reduce dose
- D. Stop clozapine (Correct Answer)
Explanation: ***Stop clozapine*** - The presentation of **fever, confusion, muscle rigidity**, and elevated **creatine kinase (CK)** in a patient on clozapine is highly suggestive of **Neuroleptic Malignant Syndrome (NMS)**, a potentially fatal adverse reaction. - **Immediate discontinuation** of the causative antipsychotic, in this case **clozapine**, is the cornerstone of NMS management to prevent further clinical deterioration and complications. *Add antipyretic* - While a **fever** is present, simply adding an **antipyretic** would only address a symptom and not the underlying severe adverse drug reaction, potentially delaying critical intervention. - The fever in NMS is often due to **hypothalamic dysfunction** and **muscle rigidity**, not just a simple infection responsive to antipyretics alone. *Continue clozapine* - Continuing clozapine in the presence of NMS symptoms would **exacerbate the condition**, leading to increased morbidity and mortality, as it is the likely causative agent. - Further exposure to the drug would worsen the **hyperthermia, muscle rigidity**, and potential **organ damage**. *Reduce dose* - **Reducing the dose** of clozapine is insufficient if NMS is suspected, as even lower doses can maintain the toxic effect and progression of the syndrome. - The priority is to remove the offending agent completely, rather than merely decreasing its concentration.
Question 2: What is the primary cause of death in Neuroleptic Malignant Syndrome?
- A. Respiratory failure
- B. Liver failure
- C. None of the options (Correct Answer)
- D. Drug toxicity
Explanation: ***None of the options*** - The **primary cause of death** in Neuroleptic Malignant Syndrome is **renal failure secondary to rhabdomyolysis**, which is not listed among the options. - **Severe muscle rigidity** in NMS leads to massive muscle breakdown (rhabdomyolysis) → release of myoglobin → myoglobinuria → acute tubular necrosis → acute renal failure. - Mortality in NMS ranges from **10-20%**, with renal complications being the leading cause of death. - Other significant causes include **cardiovascular collapse, arrhythmias, DIC**, and **respiratory complications**, but renal failure remains the most common fatal outcome. *Respiratory failure* - While respiratory complications occur in NMS (aspiration pneumonia, respiratory muscle rigidity), this is **not the primary cause of death**. - Respiratory failure can contribute to mortality but is typically **secondary** to other complications or occurs less frequently than renal failure as the direct cause. - It is a serious complication but not the most common fatal outcome. *Liver failure* - **Hepatotoxicity** is not a characteristic feature or primary cause of death in NMS. - Though elevated liver enzymes may occur, liver failure is **not a typical cause of mortality** in NMS. - The pathophysiology centers on **dopamine blockade**, autonomic instability, and muscle breakdown, not hepatic dysfunction. *Drug toxicity* - NMS is an **idiosyncratic reaction** to dopamine antagonists (typical and atypical antipsychotics), not a dose-dependent toxic effect. - Death results from the **physiological complications of the syndrome** (renal failure, cardiovascular collapse, hyperthermia), not from direct drug toxicity or overdose. - The mechanism is related to dopamine receptor blockade and subsequent dysregulation, not toxic poisoning.
Question 3: Which of the following conditions does not cause a rise in end-tidal CO2 during thyroid surgery?
- A. Anaphylaxis (Correct Answer)
- B. Thyroid storm
- C. Neuroleptic malignant syndrome
- D. Malignant hyperthermia
Explanation: **Anaphylaxis** - During anaphylaxis, there is often **bronchospasm** and **hypoventilation**, leading to a *decrease* or no change in end-tidal CO2 due to reduced gas exchange. - While it can cause cardiovascular collapse, the primary respiratory effect that impacts ETCO2 measurement is typically decreased CO2 excretion rather than increased production. *Malignant hyperthermia* - This condition is characterized by a rapid, uncontrolled increase in **metabolism** and **muscle rigidity**, resulting in massive **CO2 production**. - The increased CO2 production overwhelms the ventilatory capacity, leading to a marked and rapid rise in **end-tidal CO2** despite increased minute ventilation. *Thyroid storm* - Thyroid storm causes a hypermetabolic state with increased **cellular oxygen consumption** and **CO2 production**. - The body's significantly elevated metabolic rate leads to higher CO2 levels that can be reflected in an elevated **end-tidal CO2**. *Neuroleptic malignant syndrome* - This syndrome involves severe **muscle rigidity** and a hypermetabolic state similar to malignant hyperthermia, although with a different etiology. - The uncontrolled muscle activity and enhanced cellular metabolism result in increased **CO2 production** and, consequently, a rise in **end-tidal CO2**.
Question 4: A patient on clozapine develops fever, confusion, and muscle rigidity. Creatine kinase (CK) is elevated. Most appropriate next step?
- A. Stop clozapine (Correct Answer)
- B. Continue clozapine
- C. Add antipyretic
- D. Reduce dose
Explanation: **Stop clozapine** - The described symptoms (**fever, confusion, muscle rigidity, elevated CK**) are highly suggestive of **Neuroleptic Malignant Syndrome (NMS)**, a potentially life-threatening idiosyncratic reaction to antipsychotics like clozapine. - **Immediate discontinuation** of the causative agent (clozapine) is the cornerstone of NMS management to prevent further clinical deterioration and complications. *Continue clozapine* - Continuing clozapine in the presence of NMS symptoms would worsen the condition, potentially leading to **rhabdomyolysis**, **renal failure**, and death. - NMS is a serious adverse effect requiring urgent intervention, not continued exposure to the trigger. *Add antipyretic* - While fever is a symptom of NMS, simply adding an antipyretic only addresses a symptom and does not treat the underlying pathological process. - Treating the fever alone will not reverse the progression of NMS or resolve the neurological and muscular symptoms. *Reduce dose* - NMS is an **idiosyncratic reaction** and not dose-dependent in the classic sense; it can occur at any dose. - Dose reduction is insufficient to mitigate the severe risks associated with NMS, and full discontinuation is necessary.
Question 5: A patient on clozapine develops fever, confusion, and muscle rigidity. CK is elevated. Most appropriate next step?
- A. Stop clozapine (Correct Answer)
- B. Add antipyretic
- C. Reduce dose
- D. Continue clozapine
Explanation: ***Stop clozapine*** - The constellation of **fever, confusion, muscle rigidity**, and **elevated CK** in a patient on clozapine is highly suggestive of **Neuroleptic Malignant Syndrome (NMS)**, a life-threatening adverse effect. - The immediate and most crucial intervention for suspected NMS is the **discontinuation of the offending antipsychotic medication**, as continuation can lead to worsening symptoms and increased mortality. *Add antipyretic* - While fever is a symptom, merely adding an **antipyretic** addresses only one aspect of NMS and does not treat the underlying pathological process or prevent disease progression. - This approach would delay definitive treatment and could be dangerous given the severity of NMS. *Reduce dose* - **Reducing the clozapine dose** is insufficient for NMS, as the syndrome is an idiosyncratic reaction, not dose-dependent in the usual sense. - Even a reduced dose could continue to trigger or sustain the NMS, making immediate discontinuation the safer option. *Continue clozapine* - **Continuing clozapine** is contraindicated in suspected NMS, as it would exacerbate the condition, potentially leading to complications such as **renal failure from rhabdomyolysis**, arrhythmias, or respiratory failure. - This option would drastically increase patient morbidity and mortality by allowing the syndrome to progress unchecked.
Question 6: Which of the following is LEAST likely to cause hyperthermia?
- A. Neuroleptic malignant syndrome
- B. Phencyclidine use (Correct Answer)
- C. Aspirin toxicity
- D. None of the options
Explanation: ***Phencyclidine use*** - While PCP can lead to a *delirious state* and *agitation*, **hyperthermia** is not a primary or common direct toxic effect. - Its primary central nervous system effects are dissociative and hallucinogenic, and while **rhabdomyolysis** can occur (which can indirectly elevate temperature), direct **hyperthermia** is less characteristic than with the other listed conditions. *Neuroleptic malignant syndrome* - This is a severe, life-threatening reaction to **antipsychotic drugs** [1] characterized by **fever**, muscle rigidity, autonomic instability, and altered mental status [2]. - **Hyperthermia** is a hallmark symptom due to severe muscle rigidity and impaired thermoregulation [1], [3]. *Aspirin toxicity* - **Salicylate poisoning** directly causes **hyperthermia** by uncoupling oxidative phosphorylation, leading to increased metabolic rate and heat production. - It also stimulates the respiratory center, leading to **respiratory alkalosis**, and can cause metabolic acidosis. *None of the options* - This option is incorrect because **phencyclidine use** is indeed the least likely to cause hyperthermia among the choices provided. - The other conditions listed are well-known causes of significant **hyperthermia** [1], [3].
Question 7: A child during anesthesia with halothane and succinylcholine develops severe stiffness of masseters. What is the most probable diagnosis?
- A. Malignant hyperthermia (Correct Answer)
- B. Halothane hepatitis
- C. Neuroleptic malignant syndrome
- D. Anaphylaxis
Explanation: ***Malignant hyperthermia*** - **Masseter muscle rigidity** following exposure to **succinylcholine** and a **halogenated inhalational anesthetic** (like halothane) is a hallmark sign of malignant hyperthermia. - This inherited disorder results in uncontrolled **calcium release** from the sarcoplasmic reticulum in skeletal muscle, leading to hypermetabolism, severe muscle contraction, and a rapid rise in body temperature. *Halothane hepatitis* - This is an idiosyncratic liver injury that can occur hours to days after exposure to halothane, not an acute intraoperative event causing muscle stiffness. - Symptoms include elevated liver enzymes, jaundice, and often fever, but without the immediate muscle rigidity seen here. *Neuroleptic malignant syndrome* - This condition is associated with the use of **antipsychotic medications** and presents with muscle rigidity, fever, altered mental status, and autonomic instability. - It does not involve exposure to succinylcholine or inhalational anesthetics and has a slower onset, typically over days. *Anaphylaxis* - Anaphylaxis is a severe, acute allergic reaction characterized by **bronchospasm**, **hypotension**, **urticaria**, and angioedema. - While it can manifest rapidly during anesthesia, it does not typically cause severe, generalized muscle stiffness as the primary symptom.
Question 8: Which of the following is not true about polymyositis
- A. Limb girdle weakness
- B. Para-neoplastic syndrome
- C. Ophthalmoplegia (Correct Answer)
- D. Spontaneous discharge in EMG
Explanation: ***Ophthalmoplegia*** - **Polymyositis** primarily affects **proximal limb and trunk muscles**, sparing the extraocular muscles [1]. - **Ophthalmoplegia**, or paralysis of the extraocular muscles, is not a typical feature of polymyositis and would suggest a different neuromuscular disorder. *Limb girdle weakness* - **Polymyositis** characteristically causes **symmetric proximal muscle weakness**, affecting the muscles of the shoulder (pectoral) and hip (pelvic) girdles [1]. - Patients typically present with difficulty rising from a chair, climbing stairs, or lifting objects overhead [1]. *Para-neoplastic syndrome* - Polymyositis, like other inflammatory myopathies, can be a **paraneoplastic syndrome**, particularly in older adults [2]. - It is important to screen for underlying malignancies in patients diagnosed with polymyositis, especially if they have atypical features or are above a certain age [2]. *Spontaneous discharge in EMG* - **Electromyography (EMG)** in polymyositis typically shows findings of muscle irritation and degeneration, including **spontaneous activity** (e.g., fibrillations, positive sharp waves) at rest. - These findings reflect active muscle inflammation and necrosis, which are hallmarks of the disease.
Question 9: Which of the following has the least malignant potential?
- A. Hamartomatous polyps associated with Peutz-Jeghers syndrome
- B. Adenomatous polyps associated with Familial adenomatous polyposis
- C. Juvenile polyps associated with juvenile polyposis syndrome (Correct Answer)
- D. Adenomatous polyps associated with Lynch syndrome (HNPCC)
Explanation: ***Juvenile polyps associated with juvenile polyposis syndrome*** - **Isolated juvenile polyps** are benign hamartomas with **minimal intrinsic malignant potential**. - While **juvenile polyposis syndrome (JPS)** as a condition carries an increased lifetime colorectal cancer risk (15-38%), this is primarily due to the development of **co-existing adenomatous polyps** or dysplastic changes, not from the typical juvenile polyp histology itself [1]. - Among the listed options, juvenile polyps have the **least malignant potential**. *Hamartomatous polyps associated with Peutz-Jeghers syndrome* - **Peutz-Jeghers syndrome (PJS)** is characterized by distinctive **hamartomatous polyps** and carries a significantly increased lifetime risk of various cancers, including colorectal, gastric, small intestine, and pancreatic cancers (cumulative risk ~93% by age 70) [1]. - Although hamartomas are benign lesions, these polyps can undergo **malignant transformation** or harbor areas of **adenomatous change and dysplasia**, contributing to the cancer risk [4]. *Adenomatous polyps associated with Familial adenomatous polyposis* - **Familial adenomatous polyposis (FAP)** is caused by a germline mutation in the **APC gene** and is characterized by hundreds to thousands of **adenomatous polyps** in the colon [2]. - Without colectomy, there is a nearly **100% lifetime risk of developing colorectal cancer** due to the malignant transformation of these adenomas [3]. - This represents the **highest malignant potential** among the options. *Adenomatous polyps associated with Lynch syndrome (HNPCC)* - **Lynch syndrome (hereditary nonpolyposis colorectal cancer, HNPCC)** is caused by mutations in DNA mismatch repair genes, leading to an increased risk of various cancers, most notably **colorectal cancer** (lifetime risk 50-80%) [2]. - The polyps associated with Lynch syndrome are typically **adenomatous polyps**, which develop at an earlier age and progress more rapidly to cancer (2-3 years vs 10-15 years for sporadic adenomas) compared to sporadic adenomas [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 813. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, p. 817. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 821-822. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 813-814.
Question 10: A 39-year-old male patient presents with waxy flexibility, negativism and rigidity. Most probable diagnosis is?
- A. None of the options
- B. Stuporous catatonia (Correct Answer)
- C. Paranoid schizophrenia
- D. Excitatory catatonia
Explanation: ***Stuporous catatonia*** - **Waxy flexibility**, **negativism**, and **rigidity** are classic symptoms of catatonia, specifically indicating the stuporous presentation where there is a marked decrease in reactivity to the environment. - In this subtype, the patient often exhibits features such as **immobility**, mutism, and fixed postures, alongside the mentioned symptoms. *Excitatory catatonia* - Characterized by **psychomotor agitation**, restlessness, and sometimes violent behavior, which is contrary to the reduced reactivity seen in the patient. - Patients with excitatory catatonia may present with **purposeless motor activity** and impulsivity, along with other catatonic features. *Paranoid schizophrenia* - Primarily defined by prominent **delusions of persecution** or grandeur and **auditory hallucinations**. - While catatonic features can sometimes occur in schizophrenia, they are not the hallmark symptoms; the described features are more directly indicative of catatonia itself. *None of the options* - This is incorrect because the constellation of symptoms (waxy flexibility, negativism, rigidity) clearly points to a specific and well-recognized clinical syndrome, which is stuporous catatonia. - The symptoms provided are classic for a recognized psychiatric condition, making an "all of the above" or "none of the above" option unlikely if a specific diagnosis fits perfectly.
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