Neuroanesthesia — MCQs
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Which one of the following increases intracranial tension
Air embolism in neural surgery maximum in which position:
Intracranial pressure is increased by
Which inhalational agent increases intracranial pressure most significantly?
A 70-year-old male with a history of Parkinson's disease is scheduled for a hip replacement. Which anesthetic agent should be avoided due to its potential adverse effects on Parkinsonian symptoms?
In a patient undergoing spine surgery, which monitoring modality is essential for the early detection of spinal cord ischemia?
Which of the following agents is preferred for rapid sequence induction in a patient with suspected increased intracranial pressure?
Which anesthetic agent is safe to use in patients with elevated intracranial pressure (ICP)?
Inhalational agent of choice for neurosurgery?
Which anesthetic agent is known to increase intracranial pressure in patients with head injuries?
Neuroanesthesia Indian Medical PG Practice Questions and MCQs
Question 31: Which one of the following increases intracranial tension
- A. Thiopentone
- B. Ketamine (Correct Answer)
- C. Propofol
- D. Halothane
Explanation: ***Ketamine*** - Ketamine causes a dose-dependent increase in **cerebral blood flow (CBF)** and **intracranial pressure (ICP)**, which is why it is generally avoided in patients with increased intracranial tension. - This effect is mediated by its mechanism of action as an **NMDA receptor antagonist**, which can indirectly lead to cerebral vasodilation. *Thiopentone* - Thiopentone, a **barbiturate**, decreases **cerebral metabolic rate of oxygen (CMRO2)**, leading to a reduction in **cerebral blood flow (CBF)** and consequently, a decrease in **intracranial pressure (ICP)**. - It is often used to treat elevated ICP, providing **neuroprotection** by reducing brain activity. *Propofol* - Propofol significantly reduces **cerebral blood flow (CBF)** and **cerebral metabolic rate of oxygen (CMRO2)**, leading to a decrease in **intracranial pressure (ICP)**. - Its rapid onset and offset, coupled with its ability to lower ICP, make it a favorable agent for sedation in neurosurgical patients. *Halothane* - While halothane can cause **cerebral vasodilation** and an increase in **cerebral blood flow (CBF)**, leading to increased ICP, its use has largely been replaced by newer inhalational agents like isoflurane and sevoflurane, which have less pronounced effects on ICP or even decrease it. - Its propensity for inducing dose-dependent **cerebral vasodilation** when used at higher concentrations makes it less ideal in situations where ICP is a concern.
Question 32: Air embolism in neural surgery maximum in which position:
- A. Left lateral
- B. Sitting (Correct Answer)
- C. Supine
- D. Trendelenburg
Explanation: ***Sitting*** - In the **sitting position** for neural surgery, the surgical field, particularly the head, is often elevated above the heart. This creates a **negative pressure gradient** in the venous system, increasing the risk of air entrainment if a vein is opened and air is allowed to enter. - The **higher elevation of the operative site** relative to the right atrium significantly increases the likelihood of air being sucked into open veins. *Left lateral* - While air embolism can occur in any position, the **left lateral position** does not inherently create the same significant negative pressure gradient as the sitting position in the surgical field relative to the heart. - The patient's body is positioned on its side, which can help in certain surgical approaches but typically does not elevate the head as dramatically as the sitting position. *Supine* - In the **supine position**, the patient is lying on their back, and the operative field (head or spine) is generally at or below the level of the heart, reducing the pressure gradient that favors air entrainment. - This position typically offers a **lower risk of air embolism** compared to the sitting position due to less negative pressure in exposed veins. *Trendelenburg* - The **Trendelenburg position** involves placing the patient head-down and feet-up, which increases venous pressure in the upper body and head. - This position actively works against the negative pressure gradient, thereby **reducing the risk of air entrainment** into open veins through increased venous pressure.
Question 33: Intracranial pressure is increased by
- A. Ketamine (Correct Answer)
- B. Thiopentone
- C. Ether
- D. Halothane
Explanation: ***Ketamine*** - **Ketamine** is known to increase **cerebral blood flow** and thus intracranial pressure, making it generally avoided in patients with elevated ICP. - This effect is mediated by its influence on **cerebral metabolism** and **vasodilation**. *Thiopentone* - **Thiopentone** is a barbiturate that typically **reduces cerebral blood flow** and **metabolic rate**, thereby decreasing intracranial pressure. - It is often used for **neuroprotection** and to control elevated ICP due to its vasoconstrictive properties. *Ether* - **Ether** is an older inhalational anesthetic that generally causes **cerebral vasodilation**, which can lead to an increase in intracranial pressure. - While it does increase ICP, it is **no longer commonly used** in modern anesthesia practice due to its side effects and flammability. *Halothane* - **Halothane** is an inhalational anesthetic that causes dose-dependent **cerebral vasodilation**, leading to an increase in intracranial pressure. - Its use has largely been replaced by newer agents (**isoflurane, sevoflurane**) which have a more favorable ICP profile or are less likely to cause hepatic toxicity.
Question 34: Which inhalational agent increases intracranial pressure most significantly?
- A. Halothane (Correct Answer)
- B. Sevoflurane
- C. Isoflurane
- D. Desflurane
Explanation: ***Halothane*** - **Halothane** causes a greater increase in **cerebral blood flow** and thus **intracranial pressure (ICP)** compared to newer volatile anesthetics due to its more potent cerebral vasodilation. - Its use has largely declined due to concerns about its effects on ICP and potential for **hepatotoxicity**. *Sevoflurane* - While sevoflurane can cause **cerebral vasodilation** and increase ICP, its effect is generally less pronounced than halothane, especially when normocapnia is maintained. - It is often favored in neuroanesthesia due to its rapid onset and offset, allowing for quicker adjustments in anesthetic depth. *Isoflurane* - Isoflurane causes less cerebral vasodilation and a smaller increase in ICP compared to halothane, particularly at lower concentrations. - It maintains **cerebral vascular autoregulation** better than halothane, helping to preserve a more stable ICP. *Desflurane* - Desflurane also causes cerebral vasodilation and can increase ICP, but its effect is typically less significant than halothane. - Rapid increases in desflurane concentration can lead to sympathetic stimulation and transient increases in blood pressure, which can indirectly affect ICP.
Question 35: A 70-year-old male with a history of Parkinson's disease is scheduled for a hip replacement. Which anesthetic agent should be avoided due to its potential adverse effects on Parkinsonian symptoms?
- A. Ketamine
- B. Propofol
- C. Midazolam
- D. Droperidol (Correct Answer)
Explanation: ***Droperidol*** - **Droperidol** is a **dopamine receptor antagonist** and can worsen parkinsonian symptoms by further depleting existing dopamine levels or blocking its effects. - Patients with Parkinson's disease already have a deficiency in **dopamine**, and medications that block dopamine receptors should be avoided. *Ketamine* - **Ketamine** is a dissociative anesthetic that acts primarily as an **NMDA receptor antagonist**. - It does not directly interfere with dopamine pathways in a way that would exacerbate Parkinson's disease. *Propofol* - **Propofol** is a short-acting intravenous anesthetic that primarily acts on **GABA-A receptors**. - It has no known adverse effects on **dopaminergic pathways** or Parkinson's disease symptoms. *Midazolam* - **Midazolam** is a benzodiazepine that enhances the effects of **GABA** at the **GABA-A receptor**. - It is used for sedation and anxiety relief and does not typically affect Parkinson's disease symptoms.
Question 36: In a patient undergoing spine surgery, which monitoring modality is essential for the early detection of spinal cord ischemia?
- A. Electroencephalography
- B. Somatosensory evoked potentials (Correct Answer)
- C. Pulse oximetry
- D. Capnography
Explanation: ***Somatosensory evoked potentials*** - **Somatosensory Evoked Potentials (SSEPs)** monitor the integrity of the **dorsal column-medial lemniscus pathway**, which is sensitive to spinal cord ischemia. - A significant decrease in amplitude or increase in latency of SSEPs can indicate **ischemia** or **mechanical injury** to the spinal cord during surgery, allowing for timely intervention. *Electroencephalography* - **Electroencephalography (EEG)** primarily monitors **cortical activity** and is essential for detecting cerebral ischemia or seizure activity, but it does not directly monitor spinal cord function. - While global ischemia can affect both brain and spinal cord, EEG is not specific for early detection of **spinal cord-specific ischemia**. *Pulse oximetry* - **Pulse oximetry** measures **peripheral oxygen saturation** and pulse rate, reflecting systemic oxygenation. - It does not provide direct information about the **spinal cord's perfusion** or neural integrity. *Capnography* - **Capnography** measures the **partial pressure of carbon dioxide in exhaled breath**, primarily used for monitoring ventilation and confirming endotracheal tube placement. - It offers no direct insight into the **spinal cord's neurological status** or blood supply.
Question 37: Which of the following agents is preferred for rapid sequence induction in a patient with suspected increased intracranial pressure?
- A. Etomidate (Correct Answer)
- B. Propofol
- C. Thiopental
- D. Ketamine
Explanation: ***Etomidate*** - **Etomidate** is preferred for rapid sequence induction in patients with suspected increased ICP because it provides rapid onset of **sedation and hypnosis** while maintaining **cardiovascular stability**. - It causes minimal changes in **heart rate** or **blood pressure**, which is crucial in patients who may be hemodynamically unstable from their injury or who are sensitive to changes in **cerebral perfusion pressure**. *Propofol* - While **propofol** reduces ICP, it can cause significant **hypotension** due to systemic vasodilation and myocardial depression. - This **hypotension** can compromise **cerebral perfusion pressure** in patients with already elevated ICP, potentially worsening outcomes. *Thiopental* - **Thiopental**, a barbiturate, effectively reduces ICP by decreasing cerebral metabolic rate and blood flow but can also lead to significant **hypotension**. - Its longer half-life compared to etomidate makes it less ideal for rapid sequence induction where quick recovery or titrated effects might be desired. *Ketamine* - Traditionally, **ketamine** was avoided in patients with increased ICP because it was thought to directly increase cerebral blood flow and ICP. - Although more recent data suggest it might be safe or even beneficial in some trauma settings, its potential to increase ICP makes it a less preferred first-line agent when increased ICP is suspected compared to etomidate.
Question 38: Which anesthetic agent is safe to use in patients with elevated intracranial pressure (ICP)?
- A. Thiopentone (Correct Answer)
- B. Halothane
- C. Ketamine
- D. Ether
Explanation: ***Thiopentone*** - **Thiopentone** is a barbiturate that **decreases cerebral blood flow** and **metabolic rate**, leading to a reduction in intracranial pressure (ICP). - Its rapid onset and short duration of action make it suitable for inducing anesthesia in patients with elevated ICP. *Halothane* - **Halothane** is a potent **vasodilator** that can increase cerebral blood flow and consequently **elevate intracranial pressure**, making it unsuitable. - It also has a **slow onset and offset**, which can be problematic in emergent situations involving ICP. *Ketamine* - **Ketamine** is known to significantly **increase cerebral blood flow** and **intracranial pressure**, making it generally contraindicated in patients with elevated ICP. - It can also cause **dissociative states** and **emergence delirium**, which can further complicate neurological assessment. *Ether* - **Ether** is an older anesthetic agent known to cause **significant cerebral vasodilation** and an **increase in intracranial pressure**. - It is **highly flammable** and rarely used in modern clinical practice due to its side effects and safety profile.
Question 39: Inhalational agent of choice for neurosurgery?
- A. Halothane
- B. Enflurane
- C. Isoflurane (Correct Answer)
- D. N2O
Explanation: ***Isoflurane*** - **Isoflurane** is preferred in neurosurgery due to its minimal impact on **cerebral blood flow** and **intracranial pressure (ICP)**, allowing cerebral autoregulation to be largely preserved. - It maintains **cerebral perfusion pressure** well and has a relatively fast onset and offset, facilitating neurological assessment post-operatively. *Halothane* - **Halothane** significantly increases **cerebral blood flow** and **intracranial pressure (ICP)**, which is undesirable in neurosurgical patients. - Its slow elimination can prolong recovery and neurological assessment, making it unsuitable for neurosurgery. *Enflurane* - **Enflurane** can cause central nervous system excitation and has been associated with **seizure activity** at higher concentrations, making it contraindicated in neurosurgical procedures. - Like halothane, it can also increase **cerebral blood flow** and **intracranial pressure**. *N2O* - **Nitrous oxide (N2O)** should be avoided in neurosurgery, especially if there's a risk of **intracranial air** or **pneumocephalus**, as it can expand air-filled spaces and increase ICP. - It also has a weak anesthetic effect and is often combined with other agents, but its cerebral vasodilatory properties can still be problematic.
Question 40: Which anesthetic agent is known to increase intracranial pressure in patients with head injuries?
- A. Ketamine (Correct Answer)
- B. Propofol
- C. Etomidate
- D. Ether
Explanation: ***Ketamine*** - **Ketamine** can cause a direct cerebral vasodilator effect, leading to increased cerebral blood flow and **intracranial pressure (ICP)**. - This effect makes it generally contraindicated in patients with acute head injuries or elevated ICP. *Propofol* - **Propofol** is known to decrease cerebral metabolic rate and cerebral blood flow, leading to a **reduction in ICP**. - It is often favored in neurosurgical settings for its ability to lower ICP and improve cerebral perfusion pressure. *Etomidate* - **Etomidate** is a short-acting hypnotic agent that can also cause a significant **reduction in ICP** due to decreased cerebral blood flow and metabolic rate. - It is commonly used for induction of anesthesia in patients with head injuries due to its hemodynamic stability. *Ether* - **Ether** (diethyl ether) is an older anesthetic agent that has largely been replaced due to its many side effects, including a tendency to **increase ICP**. - While it can increase ICP, its use in modern anesthetic practice is minimal, and ketamine is a more contemporary concern for this effect.
Practice by Chapter
Cerebral Physiology and Pathophysiology
Practice Questions
Anesthetics and Cerebral Blood Flow
Practice Questions
Intracranial Pressure Management
Practice Questions
Anesthesia for Supratentorial Craniotomy
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Anesthesia for Infratentorial Craniotomy
Practice Questions
Anesthesia for Traumatic Brain Injury
Practice Questions
Neuromonitoring Techniques
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Anesthesia for Spine Surgery
Practice Questions
Anesthesia for Neurovascular Procedures
Practice Questions
Awake Craniotomy
Practice Questions
Neuromuscular Disorders
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Postoperative Care in Neurosurgical Patients
Practice Questions
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