Peripheral Nerve Blocks: Lower Extremity — MCQs

10 questions

An RTA patient presented to the emergency department with severe pain in the ankle. An X-ray was performed, given below. What is the best next step in management?

What is the landmark for performing a pudendal nerve block?

Which nerve root is blocked in pudendal nerve block?

Which nerve block is given in forceps delivery?

Which nerve is targeted in the nasociliary nerve block?

What is the name of the nerve block technique shown in the image?

Which block is described as regional anesthesia of the arm:-

Most commonly used approach of brachial plexus block?

Q10

All of the following are complications of epidural anaesthesia, EXCEPT:

Peripheral Nerve Blocks: Lower Extremity Indian Medical PG Practice Questions and MCQs

Question 1: An RTA patient presented to the emergency department with severe pain in the ankle. An X-ray was performed, given below. What is the best next step in management?

A. Neurovascular Assessment and Closed reduction with slab application (Correct Answer)
B. Neurovascular Assessment and Closed reduction with cast application
C. Neurovascular Assessment and Immediate surgery
D. Neurovascular Assessment and Immediate open reduction

Explanation: ***Neurovascular Assessment and Closed reduction with slab application*** - The X-ray shows an **ankle dislocation without an obvious fracture**, making **closed reduction** the appropriate initial treatment. - A **slab (splint)** is preferred over a full cast initially for acute injuries to accommodate for swelling, reducing the risk of compartment syndrome, and allowing for serial neurovascular checks. *Neurovascular Assessment and Closed reduction with cast application* - While closed reduction is correct, applying a **full cast** immediately after an acute injury carries a risk of **compartment syndrome** due to potential swelling that cannot be accommodated by a rigid cast. - A cast would typically be applied after the initial swelling has subsided, usually a few days to a week after initial reduction and splinting. *Neurovascular Assessment and Immediate surgery* - **Immediate surgery** is generally reserved for **open fractures/dislocations**, dislocations that cannot be reduced closed (irreducible dislocations), or those with significant associated fractures that require surgical fixation to stabilize the joint. - In this case, the dislocation appears to be isolated and amenable to closed reduction, making surgery not the immediate next step. *Neurovascular Assessment and Immediate open reduction* - **Open reduction** is performed when closed reduction fails or is contraindicated, for example, due to soft tissue interposition or highly unstable fracture patterns. - Since closed reduction has not yet been attempted, immediate open reduction is premature and unnecessary for an apparently simple dislocation.

Question 2: 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 3: Match the following drugs in Column A with their contraindications in Column B. | Column A | Column B | | :-- | :-- | | 1. Morphine | 1. QT prolongation | | 2. Amiodarone | 2. Thromboembolism | | 3. Vigabatrin | 3. Pregnancy | | 4. Estrogen preparations | 4. Head injury |

A. A-1, B-3, C-2, D-4
B. A-4, B-1, C-3, D-2 (Correct Answer)
C. A-3, B-2, C-4, D-1
D. A-2, B-4, C-1, D-3

Explanation: ***A-4, B-1, C-3, D-2*** - **Morphine** is contraindicated in **head injury** as it can increase intracranial pressure and mask neurological symptoms. - **Amiodarone** is contraindicated in patients with **QT prolongation** due to its risk of inducing more severe arrhythmias like Torsades de Pointes. - **Vigabatrin** is contraindicated during **pregnancy** due to its potential for teratogenicity and adverse effects on fetal development. - **Estrogen preparations** are contraindicated in patients with a history of **thromboembolism** due to their increased risk of blood clot formation. *A-1, B-3, C-2, D-4* - This option incorrectly matches **Morphine** with QT prolongation and **Estrogen preparations** with head injury, which are not their primary contraindications. - It also incorrectly links **Vigabatrin** with thromboembolism and **Amiodarone** with pregnancy. *A-3, B-2, C-4, D-1* - This choice incorrectly associates **Morphine** with pregnancy and **Vigabatrin** with head injury, which are not the most critical or direct contraindications. - It also misaligns **Amiodarone** with thromboembolism and **Estrogen preparations** with QT prolongation. *A-2, B-4, C-1, D-3* - This option incorrectly matches **Morphine** with thromboembolism and **Amiodarone** with head injury, which are not their most significant contraindications. - It also incorrectly links **Vigabatrin** with QT prolongation and **Estrogen preparations** with pregnancy.

Question 4: Which nerve root is blocked in pudendal nerve block?

A. L5, S1
B. L2-4
C. S2-4 (Correct Answer)
D. L2-3

Explanation: ***S2-4*** - The **pudendal nerve** is primarily formed by nerve fibers originating from the **sacral spinal nerve roots S2, S3, and S4**. - A pudendal nerve block targets these specific nerve roots to achieve **anesthesia** or **pain relief** in the perineum and external genitalia. *L5, S1* - These nerve roots primarily contribute to the **sciatic nerve** and innervate the posterior thigh and leg; they do not form the pudendal nerve. - Blocking L5 and S1 would affect lower limb motor and sensory function, unrelated to the **perineal region**. *L2-4* - These nerve roots primarily contribute to the **femoral nerve** (L2-L4) and **obturator nerve** (L2-L4). - They are responsible for innervating the anterior and medial thigh, not the **pudendal region**. *L2-3* - These nerve roots contribute to the **femoral nerve** and **obturator nerve**, primarily innervating the thigh. - They do not directly contribute to the formation or innervation of the **pudendal nerve**.

Question 5: Which nerve block is given in forceps delivery?

A. Posterior femoral
B. Genitofemoral
C. Ilioinguinal
D. Pudendal (Correct Answer)

Explanation: ***Pudendal*** - A **pudendal block** anesthetizes the **perineum, vulva, and lower vagina**, providing pain relief for instrumental deliveries like **forceps delivery** and for episiotomy. - It involves injecting a local anesthetic near the **pudendal nerve** as it passes posterior to the **ischial spine**. *Posterior femoral* - The **posterior femoral cutaneous nerve** primarily innervates the skin of the posterior thigh and part of the perineum but does not provide sufficient deep analgesia for a forceps delivery. - Blocking this nerve alone would not adequately cover the extensive area affected during instrumental delivery. *Genitofemoral* - The **genitofemoral nerve** primarily innervates the skin of the upper medial thigh and parts of the genitalia but is not the primary nerve for pain relief during vaginal delivery procedures. - Its blockade would not provide the comprehensive analgesia needed for a forceps delivery. *Ilio inguinal* - The **ilioinguinal nerve** innervates the skin of the groin, mons pubis, and labia majora but does not provide sufficient anesthesia for the deeper structures involved in a forceps delivery. - An ilioinguinal nerve block is more commonly used for pain control in procedures involving the groin or hernia repair, not for instrumental vaginal delivery.

Question 6: Which nerve is targeted in the nasociliary nerve block?

A. Greater palatine nerve
B. Sphenopalatine nerve
C. Anterior ethmoidal nerve
D. Nasociliary nerve (Correct Answer)

Explanation: ***Nasociliary nerve*** - A nasociliary nerve block specifically targets the **nasociliary nerve** itself. - This block is used to anesthetize the sensory innervation of structures supplied by the nasociliary nerve, such as parts of the **nasal cavity**, **eyeball**, and **skin of the nose**. *Greater palatine nerve* - The **greater palatine nerve** supplies sensation to the posterior hard palate and is targeted in a **greater palatine nerve block**. - This nerve is a branch of the **maxillary nerve** and is primarily involved in dental and palatal anesthesia. *Sphenopalatine nerve* - The **sphenopalatine nerve**, or pterygopalatine ganglion, contains sensory fibers for the nasal cavity, palate, and pharynx, and its block is distinct from a nasociliary block. - A **sphenopalatine ganglion block** is mainly used for conditions like cluster headaches and facial pain, not for direct eyeball sensation. *Anterior ethmoidal nerve* - The **anterior ethmoidal nerve** is a branch of the nasociliary nerve, but a nasociliary nerve block targets the main trunk, which includes all its branches. - While the anterior ethmoidal nerve supplies the anterior part of the nasal septum and lateral wall, it is a **component** of the nasociliary innervation rather than the sole target.

Question 7: What is the name of the nerve block technique shown in the image?

A. Intra-arterial anesthesia (Correct Answer)
B. Bier's block
C. Regional anesthesia
D. Axillary block

Explanation: ***Intra-arterial anesthesia*** - The image shows a **cannula inserted directly into an artery**, indicated by the blood reflux and the context of anesthesia, suggesting direct drug delivery into the arterial system. - This method is used for specific types of regional pain management or diagnostic procedures where direct arterial access is required for **localized drug distribution**. *Bier's block* - A Bier's block, or **intravenous regional anesthesia**, involves injecting local anesthetic into a **vein** in an extremity after it has been exsanguinated and isolated by a tourniquet. - The image clearly shows a **bright red blood flash**, characteristic of arterial cannulation, not venous. *Regional anesthesia* - This is a broad term referring to the **anesthesia of a specific region** of the body and encompasses various techniques. - While intra-arterial anesthesia is a type of regional anesthesia, "regional anesthesia" itself is too general to specifically describe the technique shown. *Axillary block* - An **axillary block** is a type of peripheral nerve block targeting the brachial plexus in the axilla to anesthetize the arm. - The image does not depict the axillary region or the characteristic needle placement for an axillary block; instead, it shows direct vascular access.

Question 8: Which block is described as regional anesthesia of the arm:-

A. Interscalene block
B. Infraclavicular block
C. Axillary block
D. Supraclavicular brachial plexus block (Correct Answer)

Explanation: ***Supraclavicular brachial plexus block*** - The **supraclavicular block** targets the **trunks of the brachial plexus** as they exit the scalene muscles, providing comprehensive anesthesia to the entire upper limb, including the shoulder, arm, forearm, and hand. - This block is particularly effective for procedures involving the arm due to its proximal location within the brachial plexus, covering multiple nerve distributions. *Interscalene block* - An **interscalene block** primarily targets the **roots or trunks of the brachial plexus** and is typically used for shoulder and upper arm surgery, but may spare the ulnar nerve. - While it anesthetizes the arm, it is primarily chosen for more proximal procedures and may not provide complete distal arm anesthesia compared to the supraclavicular approach. *Infraclavicular block* - An **infraclavicular block** targets the **cords of the brachial plexus** and is suitable for procedures involving the elbow, forearm, and hand, providing good coverage for these areas. - While it does anesthetize the distal arm, it is more distal than the supraclavicular block and may not provide full coverage for the entire upper arm and shoulder. *Axillary block* - An **axillary block** targets the **terminal branches of the brachial plexus** in the axilla, mainly anesthetizing the forearm and hand. - This block is often used for procedures distal to the elbow and provides less comprehensive coverage for the entire upper arm and shoulder compared to more proximal blocks.

Question 9: Most commonly used approach of brachial plexus block?

A. Interscalene
B. Infraclavicular
C. Supraclavicular
D. Axillary (Correct Answer)

Explanation: ***Axillary*** - The **axillary approach** is the most frequently utilized technique for **brachial plexus block** due to its relatively superficial location, making it safer and easier to perform. - This approach is particularly effective for procedures involving the **forearm and hand**, as it reliably blocks the terminal branches of the brachial plexus. *Interscalene* - The **interscalene block** is primarily used for **shoulder surgery** as it provides excellent anesthesia to the shoulder, clavicle, and upper arm. - It carries a higher risk of complications like **phrenic nerve palsy** and **hoarseness** due to its proximity to vital structures. *Supraclavicular* - The **supraclavicular block** targets the **trunks** of the brachial plexus, making it suitable for procedures involving the **upper arm, forearm, and hand**. - This approach has a higher risk of **pneumothorax** due to its close proximity to the pleura. *Infraclavicular* - The **infraclavicular block** targets the **cords** of the brachial plexus, offering good anesthesia for surgeries of the **distal upper arm, forearm, and hand**. - It involves a deeper approach compared to axillary and is often guided by ultrasound to minimize risks, but is not as commonly used as the axillary for general procedures.

Question 10: All of the following are complications of epidural anaesthesia, EXCEPT:

A. Urinary retention
B. Total spinal analgesia
C. Hypopnoea
D. Hypertension (Correct Answer)

Explanation: ***Hypertension*** - Epidural anesthesia commonly causes **vasodilation** and a subsequent drop in **blood pressure** (hypotension), not hypertension, due to sympathetic blockade. - While hypertension can occur due to pain or anxiety during the procedure, it is not a direct physiological complication of the epidural anesthetic itself. *Urinary retention* - Epidural anesthesia can affect the nerves controlling the **bladder**, leading to temporary **urinary retention**. - This is a common complication, often requiring catheterization until the epidural wears off. *Total spinal analgesia* - This occurs if the epidural needle inadvertently punctures the **dura** and a large dose of local anesthetic is injected into the **subarachnoid space**. - It results in widespread **sensory and motor blockade**, potentially leading to respiratory arrest and hemodynamic collapse. *Hypopnoea* - High epidural blocks or accidental **intrathecal administration** can cause paralysis of **intercostal muscles** and the diaphragm. - This can lead to **respiratory depression** (hypopnoea) or even apnea, necessitating ventilatory support.

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