Fever and Hyperthermia — MCQs
Febrile response in CNS is mediated by all except:
Drug causing malignant hyperthermia:(Asked twice in the exam)
Lesion of preoptic nucleus of hypothalamus is associated with which of the following conditions?
Nonshivering thermogenesis in adults is due to:
A 6-year-old with recurrent febrile seizures presents lethargic with a high fever. What is the most appropriate next step in management?
Which of the following represents the PRIMARY mechanism by which cytokines induce fever?
Which of the following statements is false regarding hyperthermia?
30 year old lady was on the OT and during the mastoidectomy, after having inhalational anaesthesia, suddenly developed fever, increased heart rate, raised BP, acidosis and arrythmia. What is the next best intervention?
A 17-year-old boy is admitted to the hospital with a traumatic brain injury, sustained when he fell off his motorcycle. He develops a fever of 39°C, which is unrelated to an infection or inflammation. The fever is most likely due to a lesion of which of the following?
A 12-year-old boy with a femur fracture after a motor vehicle collision undergoes operative repair. After induction of anesthesia, he develops a fever of 40degC (104degF), shaking rigors, and blood-tinged urine. Which of the following is the best treatment option?
Fever and Hyperthermia Indian Medical PG Practice Questions and MCQs
Question 1: Febrile response in CNS is mediated by all except:
- A. Interferon
- B. IL-10 (Correct Answer)
- C. Bacterial toxin
- D. IL-1
Explanation: ***IL-10*** - **IL-10 (Interleukin-10)** is a potent **anti-inflammatory cytokine** that primarily functions to suppress immune responses. It is not involved in mediating fever; rather, it would counteract pro-inflammatory mechanisms that lead to fever. - Its main roles include inhibiting the production of **pro-inflammatory cytokines** (like IL-1, TNF-α, and IL-6) and downregulating antigen presentation, thereby promoting immune tolerance. *Interferon* - **Interferons (IFNs)**, particularly **IFN-α and IFN-β**, are **pro-inflammatory cytokines** primarily known for their antiviral effects, but they also contribute to the febrile response. - They induce the production of pyrogenic cytokines and prostaglandin E2 within the hypothalamus, leading to an elevation in body temperature. *Bacterial toxin* - **Bacterial toxins**, such as **lipopolysaccharide (LPS)** from gram-negative bacteria, are potent **exogenous pyrogens**. - LPS directly stimulates immune cells (e.g., macrophages) to release **endogenous pyrogens** like IL-1, TNF-α, and IL-6, which then act on the hypothalamus to raise the body's set point temperature, causing fever. *IL-1* - **IL-1 (Interleukin-1)**, specifically **IL-1β**, is a key **endogenous pyrogen** and a central mediator of the febrile response. - It acts directly on the **hypothalamus** to induce the production of **prostaglandin E2 (PGE2)**, which then raises the body's thermostatic set point, resulting in fever.
Question 2: Drug causing malignant hyperthermia:(Asked twice in the exam)
- A. Thiopentone
- B. Propofol
- C. Cisatracurium
- D. Suxamethonium (Correct Answer)
Explanation: ***Suxamethonium*** - **Suxamethonium** (succinylcholine) is a potent trigger for **malignant hyperthermia** (MH) in susceptible individuals due to its depolarizing action on skeletal muscle. - MH is a pharmacogenetic disorder characterized by a rapid and uncontrolled increase in **skeletal muscle metabolism**, leading to severe hyperthermia, muscle rigidity, and acidosis. *Thiopentone* - **Thiopentone** is an intravenous anesthetic that acts as a GABA-A receptor agonist, primarily causing central nervous system depression. - It is **not associated** with triggering malignant hyperthermia. *Propofol* - **Propofol** is a widely used intravenous anesthetic known for its rapid onset and recovery. - It is **not a known trigger** for malignant hyperthermia and is often considered a safe alternative for susceptible patients. *Cisatracurium* - **Cisatracurium** is a nondepolarizing neuromuscular blocker that competitively antagonizes acetylcholine at the neuromuscular junction. - It does **not trigger malignant hyperthermia** and is frequently used in patients with a history of MH.
Question 3: Lesion of preoptic nucleus of hypothalamus is associated with which of the following conditions?
- A. Impaired thermoregulation
- B. Increased body temperature
- C. Hyperthermia (Correct Answer)
- D. Normal thermoregulation
Explanation: ***Hyperthermia*** - The **preoptic nucleus** of the anterior hypothalamus is the primary **heat-loss center** containing warm-sensitive neurons. - Lesion of this area impairs **heat dissipation mechanisms** (sweating, cutaneous vasodilation), preventing the body from lowering its temperature. - Results in **hyperthermia** - a pathological elevation of core body temperature due to failure of heat dissipation, not a change in set point. - This is the **most specific and clinically accurate** term for this condition. *Impaired thermoregulation* - While technically true, this is too **broad and non-specific**. - Impaired thermoregulation could refer to inability to either increase or decrease temperature. - In medical terminology, we use more specific terms like "hyperthermia" to describe the actual clinical condition. *Increased body temperature* - This is a **general descriptive term** rather than a specific clinical diagnosis. - While the body temperature is indeed increased, **hyperthermia** is the precise medical term that indicates the mechanism (impaired heat dissipation). - Less specific than "hyperthermia" for exam purposes. *Normal thermoregulation* - Clearly incorrect - a lesion in the primary thermoregulatory center would **abolish normal temperature control**. - The preoptic nucleus is essential for detecting and responding to temperature changes.
Question 4: Nonshivering thermogenesis in adults is due to:
- A. Muscle metabolism
- B. Thyroid hormone
- C. Noradrenaline
- D. Brown fat between the shoulders (Correct Answer)
Explanation: ***Brown fat between the shoulders*** - In adults, the primary **effector tissue** for **non-shivering thermogenesis** is **brown adipose tissue (BAT)**, with major depots located between the shoulders, around the neck, and along the spine. - **BAT** contains specialized mitochondria with **uncoupling protein 1 (UCP1)** that uncouples oxidative phosphorylation, generating heat instead of ATP. - This is the tissue where non-shivering thermogenesis actually occurs, making it the direct answer to what non-shivering thermogenesis is "due to." *Noradrenaline* - **Noradrenaline** is the key neurotransmitter that **activates brown fat** via **β3-adrenergic receptors** to initiate non-shivering thermogenesis. - While noradrenaline is the **trigger/stimulus**, the actual heat production occurs in brown adipose tissue. - Noradrenaline itself does not produce heat directly; it acts as the signal that activates the thermogenic machinery in BAT. *Thyroid hormone* - **Thyroid hormone** increases **basal metabolic rate** and can potentiate the thermogenic response by upregulating UCP1 expression in brown fat. - Its role is **permissive and long-term** rather than being the immediate effector of acute non-shivering thermogenesis. - It modulates overall cellular metabolism but is not the primary mechanism for rapid heat generation in cold exposure. *Muscle metabolism* - **Muscle contraction** during shivering generates heat through increased ATP hydrolysis, which is **shivering thermogenesis**. - **Non-shivering thermogenesis** specifically refers to heat production **without muscle contraction**, making muscle metabolism the mechanism for shivering, not non-shivering, thermogenesis.
Question 5: A 6-year-old with recurrent febrile seizures presents lethargic with a high fever. What is the most appropriate next step in management?
- A. Perform lumbar puncture (Correct Answer)
- B. Consider using antipyretics for comfort
- C. Start anticonvulsants
- D. Order urgent EEG
Explanation: ***Perform lumbar puncture*** - The combination of **lethargy**, high fever, and a history of recurrent febrile seizures in a 6-year-old child raises suspicion for **meningitis or encephalitis**, necessitating a prompt **lumbar puncture** to analyze **cerebrospinal fluid (CSF)**. - While febrile seizures alone are benign, **altered mental status (lethargy)** in conjunction with fever is a red flag for **central nervous system infection**. *Consider using antipyretics for comfort* - **Antipyretics** can help reduce fever and improve comfort but do not address the underlying cause of lethargy and potential CNS infection. - Delaying definitive diagnostic steps like a **lumbar puncture** while waiting for antipyretics to work could worsen the patient's prognosis if a serious infection is present. *Start anticonvulsants* - **Anticonvulsants** are primarily used for managing ongoing seizures or preventing recurrent non-febrile seizures but are **not indicated as a first-line diagnostic or emergency treatment** for a child presenting with **fever and lethargy without active seizures**. - There is no clinical indication of current seizure activity, and the immediate concern is detecting a potential **CNS infection**. *Order urgent EEG* - An **EEG (electroencephalogram)** is useful for evaluating seizure disorders or encephalopathy but is **not the most appropriate initial diagnostic step** when a **serious CNS infection like meningitis** is suspected. - A **lumbar puncture** is crucial for diagnosing or ruling out meningitis, which requires immediate treatment.
Question 6: Which of the following represents the PRIMARY mechanism by which cytokines induce fever?
- A. Prostaglandins inhibit fever by reducing hypothalamic set point
- B. IL-1 and TNF-alpha induce fever via hypothalamus (Correct Answer)
- C. Endotoxins directly act on hypothalamic neurons to induce fever
- D. The vagus nerve is the primary pathway for fever induction
Explanation: ***IL-1 and TNF-alpha induce fever via hypothalamus*** - **Interleukin-1 (IL-1)** and **tumor necrosis factor-alpha (TNF-alpha)** are key pyrogenic cytokines that act on the **hypothalamus** to raise the thermoregulatory set point. - They stimulate the production of **prostaglandin E2 (PGE2)** within the hypothalamus, which directly mediates the fever response. *Prostaglandins inhibit fever by reducing hypothalamic set point* - **Prostaglandins**, specifically **PGE2**, are actual mediators of fever, not inhibitors; they increase the hypothalamic set point. - Blocking prostaglandin synthesis (e.g., with NSAIDs) helps **reduce fever**. *Endotoxins directly act on hypothalamic neurons to induce fever* - While **endotoxins** (lipopolysaccharides from Gram-negative bacteria) are potent pyrogens, they primarily induce fever indirectly by stimulating immune cells to release **cytokines** (like IL-1 and TNF-alpha). - These cytokines then act on the hypothalamus, rather than endotoxins acting directly on neurons. *The vagus nerve is the primary pathway for fever induction* - The **vagus nerve** can transmit signals from peripheral immune activation to the brain and contribute to the sickness response, but it is not the primary pathway for the direct induction of fever. - The primary pathway involves **circulating cytokines** affecting the **hypothalamus**.
Question 7: Which of the following statements is false regarding hyperthermia?
- A. It does not involve resetting of the hypothalamic set point.
- B. Heat stroke is a form of hyperthermia
- C. Antipyretics are highly effective in treating it. (Correct Answer)
- D. It is not always due to infection.
Explanation: **Antipyretics are highly effective in treating it.** - This statement is **false** because **antipyretics** (like NSAIDs or acetaminophen) work by **resetting the hypothalamic set point** to a lower temperature, which is elevated during fever. - In **hyperthermia**, the **hypothalamic set point is not elevated**, so antipyretics are generally **ineffective** in lowering the body temperature. *It does not involve resetting of the hypothalamic set point.* - This statement is **true**. In **hyperthermia**, the body's thermoregulatory mechanisms are **overwhelmed**, and the core body temperature rises **above the normal range** without a change in the hypothalamic set point. - This differentiates it from a **fever**, where the hypothalamic set point is **actively raised** in response to pyrogens. *Heat stroke is a form of hyperthermia* - This statement is **true**. **Heat stroke** is a severe and life-threatening condition caused by a failure of the body's **thermoregulation** in response to extreme heat, leading to uncontrolled rise in body temperature. - It is a classic example of **hyperthermia**, where the body's heat dissipation mechanisms are **overwhelmed**. *It is not always due to infection.* - This statement is **true**. While fever is commonly caused by infections, **hyperthermia** can result from various non-infectious causes such as **heat exposure** (e.g., heat stroke), **certain drugs** (e.g., ecstasy, neuroleptic malignant syndrome), or **endocrine disorders** (e.g., thyroid storm). - The underlying mechanism is an **excessive heat load** or impaired heat dissipation, rather than an immune response to pathogens.
Question 8: 30 year old lady was on the OT and during the mastoidectomy, after having inhalational anaesthesia, suddenly developed fever, increased heart rate, raised BP, acidosis and arrythmia. What is the next best intervention?
- A. Antipyretics
- B. Sodium bicarbonate
- C. Procainamide
- D. Dantrolene (Correct Answer)
Explanation: ***Dantrolene*** - The patient's presentation with **fever**, **tachycardia**, **hypertension**, **acidosis**, and **arrhythmia** during inhalational anesthesia is highly indicative of **malignant hyperthermia**. - **Dantrolene** is the specific and most effective treatment for malignant hyperthermia as it acts by interfering with muscle contraction by blocking calcium release from the sarcoplasmic reticulum. *Antipyretics* - While the patient has a fever, **antipyretics** like paracetamol or NSAIDs are not sufficient to manage the rapidly rising core body temperature in malignant hyperthermia. - The fever is a symptom of severe metabolic dysregulation, and simple antipyresis does not address the underlying pathology. *Sodium bicarbonate* - The patient has acidosis, but **sodium bicarbonate** is used to correct metabolic acidosis by buffering excess acid only after the primary cause is addressed. - While it may be used as supportive care, it does not treat the underlying mechanism of malignant hyperthermia. *Procainamide* - **Procainamide** is an antiarrhythmic drug used to treat various arrhythmias but does not address the fundamental cause of the arrhythmias in malignant hyperthermia. - The arrhythmias in malignant hyperthermia are a consequence of severe metabolic derangements and hyperkalemia, which require dantrolene and supportive care to resolve.
Question 9: A 17-year-old boy is admitted to the hospital with a traumatic brain injury, sustained when he fell off his motorcycle. He develops a fever of 39°C, which is unrelated to an infection or inflammation. The fever is most likely due to a lesion of which of the following?
- A. The posterior nucleus
- B. The anterior hypothalamus (Correct Answer)
- C. The arcuate nucleus
- D. The lateral hypothalamus
Explanation: ***The anterior hypothalamus*** - The **anterior hypothalamus** is responsible for **heat dissipation**, including sweating and vasodilation. A lesion here impairs the body's ability to cool down, leading to **hyperthermia** (fever) even without infection or inflammation. - This type of fever, often seen after traumatic brain injury, is referred to as **central fever** or **hypothalamic fever**. *The posterior nucleus* - The **posterior hypothalamus** is primarily involved in **heat conservation** and production, such as shivering and vasoconstriction. - A lesion here would more likely lead to **hypothermia** due to impaired heat generation, rather than hyperthermia. *The arcuate nucleus* - The **arcuate nucleus** plays a crucial role in regulating **appetite** and **satiety** through the production of neuropeptides like NPY and POMC. - It is not directly involved in the central control of body temperature, so a lesion here would not cause fever. *The lateral hypothalamus* - The **lateral hypothalamus** contains the **feeding center** and is primarily involved in stimulating appetite. - Damage to this area typically leads to **anorexia** and weight loss, not an uncontrolled increase in body temperature.
Question 10: A 12-year-old boy with a femur fracture after a motor vehicle collision undergoes operative repair. After induction of anesthesia, he develops a fever of 40degC (104degF), shaking rigors, and blood-tinged urine. Which of the following is the best treatment option?
- A. Administration of intravenous steroids and an antihistamine agent with continuation of the procedure
- B. Administration of dantrolene sodium and continuation with the procedure
- C. Alkalinization of the urine, administration of mannitol, and continuation with the procedure
- D. Administration of dantrolene sodium and termination of the procedure (Correct Answer)
Explanation: ***Administration of dantrolene sodium and termination of the procedure*** - The sudden onset of **high fever, rigors, and blood-tinged urine** during anesthesia strongly suggests **malignant hyperthermia**, a life-threatening pharmacogenetic disorder. The immediate and definitive treatment involves **dantrolene sodium** to block calcium release from the sarcoplasmic reticulum, and the procedure must be **terminated** to prevent further exposure to triggering agents and manage the crisis. - Continuation of the surgery under these conditions would be extremely dangerous and could lead to **multi-organ failure** and death. *Administration of intravenous steroids and an antihistamine agent with continuation of the procedure* - This treatment would be appropriate for an **anaphylactic reaction**, which typically presents with **hypotension, bronchospasm, and rash**, not the specific constellation of fever, rigors, and blood-tinged urine seen here. - While anaphylaxis can occur, the **elevated temperature and muscle rigidity** (implied by rigors in this context) are not characteristic, and continuing the procedure would be harmful if it were malignant hyperthermia. *Administration of dantrolene sodium and continuation with the procedure* - While **dantrolene sodium** is the correct pharmacological treatment for malignant hyperthermia, **continuing the procedure** poses a significant risk as it prolongs exposure to anesthetic agents that may be triggering the reaction. - The goal is to stabilize the patient, not to proceed with surgery while under active malignant hyperthermia crisis. *Alkalinization of the urine, administration of mannitol, and continuation with the procedure* - **Alkalinization of urine and mannitol** are interventions for preventing **renal damage** due to myoglobinuria, which can occur as a complication of malignant hyperthermia. - However, these are **supportive measures** and not the primary treatment for the underlying malignant hyperthermia itself, nor should they lead to continuation of the procedure.
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