Continuous Peripheral Nerve Catheters — MCQs
In doing phrenic nerve block, it is best to infiltrate
Which of the following is NOT a symptom of carpal tunnel syndrome?
Which block is described as regional anesthesia of the arm:-
In spinal anesthesia, the needle is pierced up to which space?
What is the maximum concentration allowed for epidural block?
Intravenous regional anesthesia is suitable for :
Most commonly used nerve for monitoring during anesthesia
All are absolute contraindications for regional anesthesia EXCEPT:
Interscalene approach to brachial plexus block does not provide optimal surgical anaesthesia in the area of distribution of which of the following nerve?
Which of the following criteria should be satisfied to start MDT?
Continuous Peripheral Nerve Catheters Indian Medical PG Practice Questions and MCQs
Question 1: In doing phrenic nerve block, it is best to infiltrate
- A. Scalenus anterior
- B. Scalenus posterior
- C. Anterior border of sternomastoid
- D. Posterior border of sternomastoid (Correct Answer)
Explanation: Posterior border of sternomastoid - The phrenic nerve (C3-C5) descends on the anterior surface of the scalenus anterior muscle through the neck. - To block the phrenic nerve as it emerges from the brachial plexus roots, local anesthetic is ideally infiltrated at the posterior border of the sternomastoid muscle at the level of the cricoid cartilage (C6 vertebral level). Scalenus anterior - While the phrenic nerve rests on the anterior surface of the scalenus anterior, infiltrating this muscle directly might not be as effective for a complete block, as the nerve is relatively superficial at the posterior border of the sternomastoid. - Infiltration within the scalenus anterior could potentially lead to a less targeted block or hit other structures within the muscle. Scalenus posterior - The scalenus posterior muscle is located deeper and more laterally in the neck compared to the scalenus anterior. - The phrenic nerve does not have a direct anatomical relationship with the scalenus posterior that would make this an optimal site for a block. Anterior border of sternomastoid - The anterior border of the sternomastoid muscle provides an anatomical landmark for other neck structures, but the phrenic nerve is not readily accessible for blockade at this specific location. - Infiltrating here would be too anterior and medial to where the phrenic nerve emerges from the brachial plexus components.
Question 2: Which of the following is NOT a symptom of carpal tunnel syndrome?
- A. Phalen's sign
- B. Pain & paraesthesia of wrist
- C. Tinel sign
- D. Ulnar nerve dysfunction (Correct Answer)
Explanation: ***Ulnar nerve dysfunction*** - Carpal tunnel syndrome specifically involves compression of the **median nerve**, not the ulnar nerve. - Symptoms related to the median nerve include numbness and tingling in the **thumb, index, middle, and radial half of the ring finger**, along with **thenar muscle wasting**. *Tinel sign* - The **Tinel sign** is a common physical examination finding in carpal tunnel syndrome, elicited by tapping over the **median nerve** at the wrist. - A positive sign involves tingling or electric shock-like sensations in the **median nerve distribution**. *Phalen's sign* - **Phalen's sign** is another classic physical maneuver used to diagnose carpal tunnel syndrome, where exaggerated wrist flexion for 60 seconds reproduces symptoms. - This maneuver increases pressure within the **carpal tunnel**, exacerbating median nerve compression. *Pain & paraesthesia of wrist* - **Pain and paraesthesia (numbness and tingling)** in the wrist and hand are hallmark symptoms of carpal tunnel syndrome. - These symptoms are often worse at night or with repetitive hand movements, reflecting **median nerve irritation**.
Question 3: 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 4: 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 5: What is the maximum concentration allowed for epidural block?
- A. Chlorprocaine (Correct Answer)
- B. Lidocaine
- C. Ropivacaine
- D. Bupivacaine
Explanation: ***Chlorprocaine*** - **Chlorprocaine** is an ester-type local anesthetic that can be safely used in higher concentrations for epidural blocks up to **3%**, due to its rapid hydrolysis by plasma pseudocholinesterase, leading to a very short half-life and reduced systemic toxicity. - Its rapid metabolism minimizes the risk of accumulation and systemic toxicity, making it a suitable choice when a dense block is needed and a short duration of action is acceptable. *Lidocaine* - **Lidocaine** is an amide-type local anesthetic commonly used in epidural blocks, but its maximum concentration for this application is typically limited to **2%** to avoid systemic toxicity. - Higher concentrations of lidocaine are associated with an increased risk of neurological and cardiovascular adverse effects. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic that is less cardiotoxic than bupivacaine, with common concentrations for epidural use ranging from **0.2% to 1%**. - Its maximum concentration is significantly lower than chlorprocaine due to its longer duration of action and potential for systemic toxicity at higher doses. *Bupivacaine* - **Bupivacaine** is a potent amide-type local anesthetic with a high risk of cardiotoxicity, and its maximum concentration for epidural use is generally restricted to **0.5%** or even less for continuous infusions. - Using concentrations above this limit significantly increases the risk of severe cardiovascular complications, including arrhythmias and cardiac arrest.
Question 6: Intravenous regional anesthesia is suitable for :
- A. Caesarian section
- B. Head and neck surgery
- C. Orthopedic manipulation on the upper limb (Correct Answer)
- D. Vascular surgery on the lower limb
Explanation: ***Orthopedic manipulation on the upper limb*** - **Intravenous regional anesthesia (IVRA)**, also known as a Bier block, is ideal for **short-duration procedures on the extremities**, especially the upper limb. - The technique involves isolating the limb with a **tourniquet** and injecting a local anesthetic intravenously, making it suitable for procedures like **orthopedic manipulations** that are typically less than an hour. *Caesarian section* - A Caesarian section requires **widespread anesthesia** to the lower abdomen and uterus, which cannot be achieved with IVRA. - It is typically performed under **spinal or epidural anesthesia**, or general anesthesia. *Head and neck surgery* - **IVRA** is a regional technique limited to the extremities below the tourniquet; it cannot provide anesthesia for the **head and neck region**. - Procedures in this area usually require **general anesthesia** or sometimes regional blocks like cervical plexus blocks. *Vascular surgery on the lower limb* - While IVRA can be used on the lower limb, **vascular surgery** often involves **longer durations** and may require more profound muscle relaxation and sensory blockade than IVRA can reliably provide. - Additionally, the use of a **tourniquet for extended periods** in vascular surgery patients can be contraindicated due to potential ischemic complications.
Question 7: Most commonly used nerve for monitoring during anesthesia
- A. Facial nerve
- B. Ulnar nerve (Correct Answer)
- C. Radial nerve
- D. Median nerve
Explanation: ***Ulnar nerve*** - The **ulnar nerve** is most commonly used for **neuromuscular monitoring** during anesthesia due to its accessibility at the wrist and predictable response to stimulation. - Stimulation typically elicits an adductor pollicis contraction, which is easily observed and quantified with various monitoring devices. *Facial nerve* - The **facial nerve** is primarily monitored during **neurosurgical procedures** where facial nerve integrity is at risk, such as parotidectomy or acoustic neuroma resection. - While it can be monitored, it is not the standard choice for general neuromuscular blockade assessment due to its complex innervation patterns and the need for specific electrode placement. *Radial nerve* - The **radial nerve** is less frequently used for standard neuromuscular monitoring compared to the ulnar nerve. - Its stimulation can lead to more variable and less quantifiable thumb or finger extension, making it less ideal for precise assessment of blockade depth. *Median nerve* - The **median nerve** can be used for neuromuscular monitoring, often stimulating the thenar muscles to produce thumb flexion. - However, it is generally considered a secondary site compared to the ulnar nerve due to greater anatomical variability in electrode placement and response.
Question 8: All are absolute contraindications for regional anesthesia EXCEPT:
- A. Lack of resuscitation facilities
- B. INR > 2 in ophthalmic procedures (Correct Answer)
- C. Infection at injection site
- D. Patient refusal
Explanation: ***INR > 2 in ophthalmic procedures*** - While a high INR (international normalized ratio) indicates increased bleeding risk, an INR > 2 is generally considered a **relative contraindication** for most regional anesthesia procedures, especially in ophthalmic cases where the risk of significant hemorrhage might be lower compared to deeper blocks. - The decision to proceed often depends on the specific procedure, patient's overall condition, and a careful risk-benefit analysis, rather than being an absolute bar. *Lack of resuscitation facilities* - The absence of proper **resuscitation equipment and trained personnel** is an absolute contraindication for regional anesthesia, as serious complications (e.g., local anesthetic systemic toxicity, respiratory depression) can occur, requiring immediate intervention. - Performing regional anesthesia in such a setting puts the patient at extreme risk of irreversible harm or death in the event of an adverse reaction. *Infection at injection site* - Performing regional anesthesia through an infected area carries a high risk of introducing bacteria into deeper tissues, including the **neuraxial space** or surrounding nerves, leading to serious complications like **abscess formation, meningitis, or osteomyelitis**. - This is an **absolute contraindication** to prevent the spread of infection. *Patient refusal* - **Informed consent** is a fundamental ethical and legal principle in medicine; a competent patient's refusal to undergo a procedure, including regional anesthesia, must always be respected. - Proceeding against a patient's wishes constitutes **assault and battery** and is an absolute contraindication for any medical intervention.
Question 9: Interscalene approach to brachial plexus block does not provide optimal surgical anaesthesia in the area of distribution of which of the following nerve?
- A. Median
- B. Musculocutaneous
- C. Radial
- D. Ulnar (Correct Answer)
Explanation: ***Ulnar*** - The **ulnar nerve** (C8-T1) emerges from the lower trunk of the brachial plexus. During an **interscalene block**, the local anesthetic is typically deposited at the level of the roots and trunks (C5-C7), which is superior to the origin of the lower trunk that gives rise to the ulnar nerve. - Due to the **cephalad spread** of the local anesthetic from an interscalene block, the **C8 and T1** nerve roots (and thus the ulnar nerve) are often not adequately blocked, leading to suboptimal anesthesia in its distribution. *Median* - The **median nerve** (C5-T1) originates from the lateral and medial cords, which are typically well-covered by the spread of local anesthetic in an interscalene block due to its formation from the middle and upper trunks. - Optimal anesthesia in the distribution of the median nerve is generally achieved with an interscalene block, as its nerve roots are within the targeted antegrade spread. *Musculocutaneous* - The **musculocutaneous nerve** (C5-C7) arises from the lateral cord, which is formed by the upper and middle trunks. These structures are reliably blocked during an interscalene approach. - Sensory and motor functions of the musculocutaneous nerve, such as **biceps contraction** and lateral forearm sensation, are usually well anesthetized. *Radial* - The **radial nerve** (C5-T1) is a branch of the posterior cord, which receives fibers from all three trunks. Its upper and middle trunk components are generally well-blocked by an interscalene approach. - While complete anesthesia of the entire brachial plexus can be variable, the radial nerve is more consistently affected by an interscalene block than the ulnar nerve due to its more extensive proximal root contributions which are within the typical spread.
Question 10: Which of the following criteria should be satisfied to start MDT?
- A. Peripheral nerve thickening
- B. Hypopigmented patch with sensory loss (Correct Answer)
Explanation: Hypopigmented patch with sensory loss - The presence of a **hypopigmented patch with definite sensory loss** is a cardinal sign of leprosy, indicating nerve involvement and active disease requiring multidrug therapy (MDT) [1]. - This finding, even as a single lesion, fulfills the World Health Organization (WHO) criteria for diagnosis and initiation of **MDT for paucibacillary leprosy** [1]. *Peripheral nerve thickening* - While **peripheral nerve thickening** is a significant sign of leprosy, it is often accompanied by other features such as sensory loss in the affected area. - It's a key diagnostic feature, but in isolation, it is usually assessed in conjunction with sensory alterations or skin lesions for treatment initiation.
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