Regional Anesthesia — MCQs

Regional Anesthesia Indian Medical PG Practice Questions and MCQs

Question 201: Which of the following is NOT a contraindication for spinal anaesthesia?

A. Raised intracranial tension
B. Bleeding disorder
C. Hypertension (Correct Answer)
D. Infection at injection site

Explanation: ***Hypertension*** - While **severe uncontrolled hypertension** may necessitate blood pressure stabilization before surgery, **mild to moderate hypertension** is not an absolute contraindication for spinal anesthesia. - In fact, spinal anesthesia can sometimes be beneficial in hypertensive patients due to its **vasodilatory effects**, which may help lower blood pressure. *Bleeding disorder* - A **bleeding disorder** (e.g., thrombocytopenia, coagulopathy) is a **major contraindication** due to the high risk of **epidural or spinal hematoma** formation. - A hematoma can lead to **spinal cord compression** and irreversible neurological damage. *Raised intracranial tension* - **Raised intracranial tension (ICT)** is a **strict contraindication** because the drop in cerebrospinal fluid (CSF) pressure during spinal anesthesia can worsen the pressure gradient across the foramen magnum. - This can precipitate **herniation of the brainstem** and lead to catastrophic neurological injury or death. *Infection at injection site* - The presence of an **infection at the injection site** is an absolute contraindication as it poses a significant risk of introducing bacteria into the **subarachnoid space**. - This can lead to serious complications such as **meningitis** or a **spinal abscess**.

Question 202: What clinical sign is used to confirm the success of an epidural block?

A. Inability to dorsiflex the foot
B. Loss of sensation in the T10 dermatome (Correct Answer)
C. Loss of resistance (used during block placement)
D. Westphal's sign (diminished patellar reflex)

Explanation: ***Loss of sensation in the T10 dermatome*** - The **T10 dermatome** is a common and reliable landmark for assessing the spread and effectiveness of an epidural block, especially for surgical procedures or labor analgesia impacting the abdominal and pelvic regions. - A successful epidural block should produce a **bilateral, symmetric sensory deficit** to pinprick or cold sensation within the target dermatomes, indicating proper anesthetic distribution. *Inability to dorsiflex the foot* - This symptom suggests a motor block primarily affecting the **deep peroneal nerve** (L4-L5 nerve roots), which would be a sign of a dense spinal block rather than a typical epidural, or an overly extensive epidural block, especially if it's bilateral. - While some motor weakness is expected with an epidural block, a complete inability to dorsiflex the foot is not the primary or most sensitive indicator of its success for general pain relief. *Loss of resistance (used during block placement)* - **Loss of resistance** is a technique used *during the placement* of an epidural needle to identify the epidural space (passing through the ligamentum flavum). - It is a procedural step for correct needle positioning, not a clinical sign used *after* injection to confirm the block's effect. *Westphal's sign (diminished patellar reflex)* - **Westphal's sign** refers to the absence or diminution of the patellar reflex (an L2-L4 reflex), which can indicate a neurological issue involving the quadriceps muscles or the femoral nerve pathway. - While a dense epidural block can affect motor function and reflexes, Westphal's sign is not typically used as the primary or most accurate indicator of a successful epidural block's sensory coverage.

Question 203: Where is the local anesthetic introduced in spinal anesthesia?

A. Dura and pia
B. Between ligamentum flavum and dura
C. Directly into cord
D. Subarachnoid space (Correct Answer)

Explanation: ***Subarachnoid space*** - In **spinal anesthesia**, the local anesthetic is injected directly into the **subarachnoid space**, which contains **cerebrospinal fluid (CSF)** and surrounds the spinal cord. - This allows the anesthetic to directly block nerve roots, producing rapid and profound **sensory and motor blockade**. *Dura and pia* - The **dura mater** is the outermost membrane covering the spinal cord, and the **pia mater** is the innermost. The anesthetic is injected *between* the arachnoid and pia, not directly into these membranes. - Injecting into the dura itself would be an **intradural injection** but not the target for spinal anesthesia, and injecting into the pia is not feasible or desired. *Between ligamentum flavum and dura* - This describes the **epidural space**, which is where **epidural anesthesia** is administered. - While it's a common regional anesthetic technique, it is distinct from **spinal anesthesia** due to the different site of drug delivery and resulting pharmacological effects. *Directly into cord* - Injecting anesthetic directly into the **spinal cord** would cause severe and potentially irreversible neurological damage. - This is a highly dangerous and avoided procedure in all forms of regional anesthesia.

Question 204: In spinal anesthesia, the drug is deposited between

A. Dura and arachnoid
B. Pia and arachnoid (Correct Answer)
C. Dura and vertebra
D. Into the cord substance

Explanation: ***Pia and arachnoid*** - Spinal anesthesia involves injecting anesthetic into the **subarachnoid space**, which is the anatomical region located between the pia mater and the arachnoid mater. - This space contains **cerebrospinal fluid (CSF)**, allowing the anesthetic to mix and spread, blocking nerve impulses at the spinal cord roots. *Dura and arachnoid* - The space between the dura mater and arachnoid mater is the **subdural space**, and it is typically a potential space rather than an actual one for anesthetic injection. - Injecting here would lead to a **subdural block**, which is distinct from spinal anesthesia and has different characteristics and risks. *Dura and vertebra* - The space between the dura mater and the vertebral canal is the **epidural space**. - **Epidural anesthesia** involves injecting anesthetic into this space, but it is distinct from spinal anesthesia as the drug does not mix directly with CSF and requires a larger dose. *Into the cord substance* - Injecting anesthetic directly into the **spinal cord substance** (intrathecal injection into the cord) would be highly dangerous and cause severe neurological damage. - Anesthetic drugs exert their effect by blocking nerve roots as they exit the spinal cord, not by acting directly on the cord parenchyma.

Question 205: Which of the following is not used in the management of post-dural headache?

A. Hydration
B. Epidural blood patch
C. Propped up position (Correct Answer)
D. Sumatriptan

Explanation: ***Propped up position*** - Maintaining a **propped-up position** can worsen a post-dural puncture headache (PDPH) because it increases the hydrostatic pressure gradient on the brain, exacerbating the intracranial hypotension. - PDPH is typically relieved by lying **supine** and worsened by sitting or standing, indicating that an upright position is contraindicated for symptom relief. *Sumatriptan* - **Sumatriptan**, a selective serotonin receptor agonist, can be used to treat post-dural puncture headache (PDPH) in some patients, particularly if the headache has migrainous features. - It works by causing **vasoconstriction** of intracranial blood vessels, which may help reduce cerebral blood flow and alleviate headache pain. *Hydration* - **Hydration**, specifically increasing fluid intake, is a common and often effective conservative measure for managing post-dural puncture headache (PDPH). - Adequate hydration can help increase **cerebrospinal fluid (CSF) volume** and pressure, thereby reducing the severity of the headache caused by CSF leakage. *Epidural blood patch* - An **epidural blood patch (EBP)** is considered the definitive treatment for severe or persistent post-dural puncture headache (PDPH) that does not respond to conservative measures. - It involves injecting a small amount of the patient's own blood into the epidural space, forming a clot that seals the dural puncture site and **stops CSF leakage**.

Question 206: In spinal anesthesia, the needle is pierced up to which space?

A. Subarachnoid space (Correct Answer)
B. Intrathecal space
C. Epidural space
D. Subdural space

Explanation: ***Subarachnoid space*** - In **spinal anesthesia**, the anesthetic agent is injected directly into the **cerebrospinal fluid (CSF)**, which is located in the subarachnoid space. - This space is targeted to achieve rapid and widespread blockade of spinal nerves, leading to anesthesia and paralysis below the level of injection. *Epidural space* - The **epidural space** is located outside the **dura mater** and contains fat and blood vessels; it is targeted in **epidural anesthesia**, not spinal anesthesia. - Anesthetic agents in the epidural space provide a slower onset and a more segmental block compared to spinal anesthesia. *Intrathecal space* - The term **intrathecal space** broadly refers to the space containing CSF, which includes the subarachnoid space, but is a less precise anatomical term for the site of injection in spinal anesthesia. - While technically correct in referring to an injection into the CSF, "subarachnoid space" is the specific anatomical term for where the needle tip rests. *Subdural space* - The **subdural space** is a potential space between the **dura mater** and the **arachnoid mater**; it is not the intended target for either spinal or epidural anesthesia. - Accidental injection into the subdural space during spinal or epidural procedures can lead to an unpredictable block with delayed onset and variable spread.

Question 207: What is the landmark for performing a pudendal nerve block?

A. Ischial tuberosity
B. Sacroiliac joint
C. Ischial spine (Correct Answer)
D. None of the options

Explanation: ***Ischial spine*** - The **ischial spine** serves as a crucial anatomical landmark for a pudendal nerve block as it is where the **pudendal nerve crosses dorsally** just before it enters Alcock's canal. - Palpating the ischial spine allows for precise needle placement to anesthetize the pudendal nerve, providing pain relief to the **perineum, vulva**, and **distal vagina**. *Ischial tuberosity* - The **ischial tuberosity** is a bony prominence that is inferior to the ischial spine and is a superficial landmark. - While it helps in general orientation of the perineum, it is **not the direct landmark** for the pudendal nerve itself, which is located more superiorly and medially in relation to the main nerve trunk. *Sacroiliac joint* - The **sacroiliac joint** connects the sacrum and the ilium and is involved in transmitting weight from the upper body to the lower limbs. - It is **anatomically distant** from the pudendal nerve's path and is not used as a landmark for a pudendal nerve block. *None of the options* - This option is incorrect because the **ischial spine** is a recognized and essential landmark for performing a pudendal nerve block.

Question 208: Which nerve roots are blocked in a pudendal nerve block?

A. L1, L2, L3 (lumbar nerves)
B. L2, L3 (lumbar nerves)
C. S4 (sacral nerve)
D. S2, S3, S4 (sacral nerves) (Correct Answer)

Explanation: ***S2, S3, S4 (sacral nerves)*** - The **pudendal nerve** is primarily formed from the ventral rami of spinal nerves **S2, S3, and S4**. - A pudendal nerve block aims to anesthetize these specific sacral nerve roots, providing sensation to the perineum, external genitalia, and anal region. *L1, L2, L3 (lumbar nerves)* - These nerve roots contribute to the **lumbar plexus**, supplying sensory and motor innervation to the anterior and medial thigh, and parts of the abdomen. - They are not involved in the formation or innervation distribution of the pudendal nerve. *L2, L3 (lumbar nerves)* - These specific lumbar nerve roots contribute to the **femoral nerve** and **obturator nerve**, innervating parts of the lower limb. - They are distinct from the sacral nerve roots responsible for the pudendal nerve. *S4 (sacral nerve)* - While **S4** does contribute to the pudendal nerve, it is not the sole nerve root. The pudendal nerve is a composite nerve. - A complete pudendal nerve block requires targeting the contributions from **S2, S3, and S4** for effective anesthesia.

Question 209: Which of the following techniques is appropriate for the reduction of the shoulder?

A. Spinal anesthesia
B. Interscalene block (Correct Answer)
C. Axillary brachial block
D. Bier block

Explanation: ***Interscalene block*** - An **interscalene block** targets the brachial plexus at the level of the neck, providing excellent anesthesia for shoulder procedures. - This technique effectively blocks the nerves innervating the shoulder joint, allowing for **muscle relaxation** and pain control necessary for reduction. *Spinal anesthesia* - **Spinal anesthesia** provides anesthesia to the lower body and is primarily used for procedures below the waist. - It does not provide adequate **analgesia or muscle relaxation** for a shoulder reduction. *Axillary brachial block* - An **axillary brachial block** anesthetizes the distal arm and hand, but it often spares the more proximal shoulder innervation. - While useful for forearm and hand surgery, it typically does not provide sufficient **anesthesia for the shoulder** joint itself. *Bier block* - A **Bier block**, or intravenous regional anesthesia, is suitable for procedures on the distal extremities, such as the hand or foot. - It involves tourniquet inflation and intravenous injection of local anesthetic, making it **unsuitable for shoulder reduction** due to the large muscle mass and proximal location.

Question 210: Vasopressor of choice in hypotension produced during subarachnoid block is

A. Ephedrine (Correct Answer)
B. Mephentermine
C. Epinephrine
D. Dobutamine

Explanation: ***Ephedrine*** - **Ephedrine** is a sympathomimetic with both direct (on adrenergic receptors) and indirect (releasing norepinephrine) effects, causing vasoconstriction and increased heart rate, making it suitable for treating **hypotension** during **subarachnoid block**. - Its slower onset and longer duration of action compared to direct-acting vasopressors can be beneficial for sustained pressure support in this context. *Mephentermine* - While mephentermine is also an indirect-acting sympathomimetic used for hypotension, it has a **slower onset** and a more prolonged effect compared to ephedrine. - Ephedrine is generally preferred due to its faster action in acute settings like **subarachnoid block-induced hypotension**, where rapid correction is often required. *Epinephrine* - **Epinephrine** is a potent vasopressor with significant alpha and beta-adrenergic effects, leading to strong vasoconstriction and cardiac stimulation. - Its use might lead to **tachycardia** and arrhythmias, which are generally undesirable when milder agents like ephedrine can achieve the desired effect. *Dobutamine* - **Dobutamine** is primarily a beta-1 adrenergic agonist, meaning it mainly increases cardiac contractility and heart rate with minimal effect on systemic vascular resistance. - It is not the agent of choice for hypotension due to **vasodilation** from subarachnoid block, as it does not sufficiently address the primary problem of decreased vascular tone.

Practice by Chapter

Neuraxial Anatomy

Practice Questions

Spinal Anesthesia

Practice Questions

Epidural Anesthesia

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Combined Spinal-Epidural Anesthesia

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Peripheral Nerve Blocks: Upper Extremity

Practice Questions

Peripheral Nerve Blocks: Lower Extremity

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Truncal Blocks

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Ultrasound-Guided Regional Anesthesia

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Complications of Regional Anesthesia

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Regional Anesthesia in Pediatric Patients

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Regional Anesthesia in Obstetrics

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Continuous Peripheral Nerve Catheters

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