Regional Anesthesia Practice Questions

Q: Which of the following is a contraindication for spinal anesthesia?

Clotting disorders. **Explanation:** **Why Clotting Disorders is the Correct Answer:** Clotting disorders (coagulopathies) are a **relative to absolute contraindication** for spinal anesthesia. The primary concern is the risk of developing a **spinal or epidural hematoma**. Because the spinal canal is a non-distensible space, even a small amount of bleeding from a punctured vessel can compress the spinal cord or cauda equina, leading to permanent neurological damage or paralysis. Therefore, patients on anticoagulants or those with low platelet counts (typically <80,000–100,000/mm³) require careful evaluation. **Analysis of Incorrect Options:** * **Hypertension (A):** Controlled hypertension is not a contraindication. While spinal anesthesia causes sympathetic blockade leading to hypotension, this is managed with pre-loading/co-loading of fluids and vasopressors. * **Renal Disease (B):** Spinal anesthesia is often preferred over general anesthesia in renal patients as it avoids the need for muscle relaxants and opioids that may have prolonged clearance. * **Diabetes (C):** Diabetes is not a contraindication. In fact, regional anesthesia is beneficial as it allows for early postoperative oral intake and minimizes the metabolic stress response, aiding glucose control. **High-Yield Clinical Pearls for NEET-PG:** * **Absolute Contraindications:** Patient refusal (most important), raised intracranial pressure (risk of herniation), infection at the injection site, and severe hypovolemia. * **Aortic Stenosis:** Severe valvular heart disease (especially AS) is a classic contraindication because the sudden drop in systemic vascular resistance (SVR) can be fatal. * **ASRA Guidelines:** Always check the most recent guidelines regarding the timing of stopping antiplatelets (e.g., Clopidogrel for 5–7 days) before performing neuraxial blocks.

Q: Which of the following is NOT an advantage of using epidural opioids over local anesthetics?

Less expensive. **Explanation:** The core concept tested here is the pharmacological profile of **epidural opioids** compared to **local anesthetics (LA)**. **Why "Less expensive" is the correct answer:** Epidural opioids (such as Fentanyl, Morphine, or Sufentanil) are generally **more expensive** than traditional local anesthetics (like Bupivacaine or Lignocaine). While opioids offer several clinical advantages, cost-effectiveness is not one of them. **Analysis of Incorrect Options:** * **A. Less hypotension:** Local anesthetics cause a sympathetic blockade, leading to vasodilation and hypotension. Opioids act on specific receptors in the substantia gelatinosa of the spinal cord and do not cause sympathetic denervation, resulting in superior hemodynamic stability. * **B. No motor block:** LAs block sodium channels in motor nerves, leading to muscle weakness (motor block). Opioids provide "selective analgesia" without affecting motor neurons, allowing for early ambulation (e.g., "walking epidurals" in labor). * **C. Frequent injections not required:** Hydrophilic opioids like **Morphine** have a long duration of action (up to 12–24 hours) due to their slow clearance from the CSF, reducing the need for frequent redosing compared to boluses of short-acting local anesthetics. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Action:** Epidural opioids work primarily at the **Mu receptors** in the substantia gelatinosa (Rexed Lamina II). * **Side Effects:** While they avoid hypotension, opioids carry risks of **pruritus** (most common), urinary retention, nausea, and delayed **respiratory depression** (especially with Morphine). * **Synergy:** In clinical practice, a combination of low-dose LA and opioid is often used to maximize analgesia while minimizing the side effects of both.

Q: Infraorbital anesthesia involves which nerve?

Anterior superior alveolar nerve. **Explanation:** The **infraorbital nerve** is a direct continuation of the Maxillary division of the Trigeminal nerve (V2). As it travels through the infraorbital canal, it gives off the **Anterior Superior Alveolar (ASA) nerve** before exiting through the infraorbital foramen. An infraorbital nerve block anesthetizes the ASA nerve, providing anesthesia to the maxillary incisors, canines, and the associated labial periodontium. **Analysis of Options:** * **Anterior Superior Alveolar Nerve (Correct):** This nerve branches from the infraorbital nerve within the infraorbital canal. It supplies the anterior teeth and is consistently anesthetized during an infraorbital block. * **Posterior Superior Alveolar Nerve:** This nerve branches from the Maxillary nerve (V2) in the pterygopalatine fossa *before* it enters the infraorbital canal. It supplies the maxillary molars and requires a separate block (PSA block). * **Facial Nerve (CN VII):** This is primarily a motor nerve to the muscles of facial expression. While it may be inadvertently blocked during deep injections (causing temporary facial palsy), it does not provide sensory innervation to the teeth. * **Mandibular Nerve (V3):** This is a separate division of the Trigeminal nerve. It supplies the lower jaw and teeth via the Inferior Alveolar Nerve. **Clinical Pearls for NEET-PG:** * **Area Anesthetized:** An infraorbital block affects the lower eyelid, lateral aspect of the nose, upper lip, and the teeth from the midline to the premolars (if the Middle Superior Alveolar nerve is also reached). * **Landmark:** The infraorbital foramen is located approximately 1 cm inferior to the infraorbital notch, in line with the pupil (mid-pupillary line) and the second maxillary premolar. * **High-Yield Fact:** The ASA nerve also contributes to the innervation of the anterior part of the nasal cavity floor.

Q: Lignocaine can be used in all of the following conditions except?

Convulsions. **Explanation:** The correct answer is **Convulsions**. Lignocaine (Lidocaine) is a Class Ib anti-arrhythmic and a versatile local anesthetic; however, it is contraindicated in the treatment of convulsions because it is itself a potent **pro-convulsant** at high plasma concentrations. **1. Why Convulsions is the correct answer:** Lignocaine toxicity follows a predictable pattern of Central Nervous System (CNS) effects. While it initially causes circumoral numbness and tinnitus, higher doses lead to excitatory effects, including **generalized tonic-clonic seizures**. This occurs because lignocaine selectively inhibits inhibitory cortical pathways, leading to unopposed excitatory activity. Therefore, it is never used to treat seizures; instead, benzodiazepines (like Midazolam) or Intralipid emulsion are used to treat lignocaine-induced convulsions. **2. Analysis of Incorrect Options:** * **Ventricular Fibrillation:** Lignocaine is a Class Ib anti-arrhythmic that blocks activated and inactivated sodium channels. It is indicated in the ACLS protocol for pulseless VT/VF (though Amiodarone is often preferred). * **Spinal Anesthesia:** Lignocaine (5% heavy) was historically used for spinal anesthesia due to its rapid onset. However, its use has decreased due to the risk of **Transient Neurological Symptoms (TNS)**. * **Epidural Anesthesia:** Lignocaine (1.5%–2%) is frequently used for epidural anesthesia when a rapid onset of sensory and motor block is required (e.g., emergency Cesarean section). **Clinical Pearls for NEET-PG:** * **Maximum Dose:** 4 mg/kg (plain) and 7 mg/kg (with Adrenaline). * **Metabolism:** Primarily in the liver by CYP450 enzymes. * **Drug of Choice:** Lignocaine is the drug of choice for **ventricular arrhythmias** occurring post-Myocardial Infarction. * **Toxicity Sign:** The earliest sign of systemic toxicity (LAST) is often **perioral numbness** or a metallic taste.

Q: Tuohy's needle is used for which of the following procedures?

Epidural block. **Explanation:** The **Tuohy needle** is the standard instrument used for **Epidural block (Option B)**. Its defining feature is a **curved tip (Huber tip)**, which serves two critical functions: 1. It allows the clinician to feel the "loss of resistance" more distinctly as the needle passes through the *ligamentum flavum*. 2. The directional curve helps steer the epidural catheter upward or downward into the epidural space and prevents the catheter from being sheared or passing straight through the dura (reducing the risk of accidental dural puncture). **Analysis of Incorrect Options:** * **A & C (Spinal/Saddle Block):** These procedures involve puncturing the dura to enter the subarachnoid space. They typically use smaller-gauge, straight-tipped needles to minimize post-dural puncture headaches (PDPH). Common examples include **Quincke** (cutting tip) or **Whitacre/Sprotte** (pencil-point) needles. * **D (Brachial Plexus Block):** These peripheral nerve blocks usually utilize short-bevel, insulated needles (for nerve stimulation) or high-visibility needles (for ultrasound guidance), rather than the bulky, curved Tuohy needle. **High-Yield Clinical Pearls for NEET-PG:** * **Needle Gauge:** Tuohy needles are typically **16–18 G** and have **1 cm markings** to monitor the depth of insertion. * **Loss of Resistance (LOR):** This is the most common technique to identify the epidural space. * **Combined Spinal-Epidural (CSE):** A "needle-through-needle" technique where a long spinal needle is passed through the lumen of a Tuohy needle. * **Episcleral/Eye Blocks:** Atkinson or Honan needles are used (not Tuohy).

Q: All of the following drugs can be given intrathecally, except?

Etomidate. **Explanation:** The correct answer is **D. Etomidate**. **1. Why Etomidate is the correct answer:** Etomidate is a carboxylated imidazole derivative used exclusively for the **induction of general anesthesia** via the intravenous route. It is not formulated for neuraxial (intrathecal or epidural) administration. Its primary mechanism involves GABA-A receptor modulation in the brain. Furthermore, etomidate is dissolved in propylene glycol, which is **neurotoxic** if injected into the subarachnoid space. **2. Analysis of incorrect options:** * **Morphine (A):** Opioids are frequently used intrathecally as adjuvants to local anesthetics to provide prolonged postoperative analgesia. Morphine is highly water-soluble (hydrophilic), leading to a slow onset but a long duration of action. * **Ketamine (B):** Preservative-free ketamine can be administered intrathecally. It acts on NMDA receptors in the spinal cord to provide analgesia. However, it is rarely used in routine clinical practice due to concerns regarding potential neurotoxicity if preservatives (like benzethonium chloride) are present. * **Bupivacaine (C):** This is the **gold standard** and most commonly used local anesthetic for spinal anesthesia (intrathecal) due to its long duration and potent sensory/motor blockade. **3. High-Yield Clinical Pearls for NEET-PG:** * **Etomidate's unique feature:** It is the induction agent of choice for patients with **cardiovascular instability** (minimal effect on BP/HR). * **Side effect of Etomidate:** It causes transient **adrenocortical suppression** by inhibiting the enzyme 11-beta-hydroxylase. * **Intrathecal Morphine:** Watch for **delayed respiratory depression** (up to 24 hours) due to its hydrophilic nature and cephalad spread in the CSF. * **Chloroprocaine:** Recently regained popularity as a short-acting drug for spinal anesthesia in day-care surgeries.

Question 1

Which of the following options represents the anatomical landmark for achieving the objective signs of an inferior alveolar nerve block?

Accepted Answer

Unilateral landmark between the mandibular first premolar and the central incisor.

Answer

Bilateral landmark between the mandibular first premolars and the central incisors.

Answer

Unilateral landmark between the mandibular second molar and the central incisor.

Answer

Bilateral landmark between the mandibular second molars and the central incisors.

Question 2

Which of the following is a contraindication for spinal anesthesia?

Accepted Answer

Clotting disorders

Answer

Hypertension

Answer

Renal disease

Answer

Diabetes

Question 3

Which of the following is NOT an advantage of using epidural opioids over local anesthetics?

Accepted Answer

Less expensive

Answer

Less hypotension

Answer

No motor block

Answer

Frequent injections not required

Question 4

Infraorbital anesthesia involves which nerve?

Accepted Answer

Anterior superior alveolar nerve

Answer

Posterior superior alveolar nerve

Answer

Facial nerve

Answer

Mandibular nerve

Question 5

Lignocaine can be used in all of the following conditions except?

Accepted Answer

Convulsions

Answer

Ventricular fibrillation

Answer

Spinal anesthesia

Answer

Epidural anesthesia

Question 6

Tuohy's needle is used for which of the following procedures?

Accepted Answer

Epidural block

Answer

Spinal block

Answer

Saddle block

Answer

Brachial plexus block

Question 7

Following a nerve block, what is the typical sequence of recovery of sensation?

Accepted Answer

Skeletal Muscle Tone (SMT) > Proprioception > Touch > Temperature > Pain

Answer

Pain > Temperature > Touch > Proprioception > Skeletal Muscle Tone (SMT)

Answer

Skeletal Muscle Tone (SMT) > Proprioception > Temperature > Touch > Pain

Answer

Recovery sequence is random.

Question 8

All of the following drugs can be given intrathecally, except?

Accepted Answer

Etomidate

Answer

Morphine

Answer

Ketamine

Answer

Bupivacaine

Question 9

For a 78-year-old man undergoing transurethral resection of the prostate, what is the ideal anesthetic method and why?

Accepted Answer

Signs of hyponatremia can easily be detected under spinal anesthesia.

Answer

General anesthesia causes more bleeding than spinal anesthesia.

Answer

Spinal anesthesia abolishes obturator nerve stimulation by electrocautery.

Answer

Obstructive uropathy and renal failure may be associated with prostatic enlargement.

Question 10

Which of the following topical anesthetics is primarily used to anesthetize mucosa?

Accepted Answer

Bupivacaine

Answer

Benzocaine

Answer

Lidocaine

Answer

Tetracaine

Regional Anesthesia — MCQs

Regional Anesthesia — MCQs

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