Pain Management — MCQs

Pain Management Indian Medical PG Practice Questions and MCQs

Question 41: Which of the following is NOT a complication of epidural opioid administration?

A. Pruritus
B. Respiratory depression
C. Less complete perineal relaxation
D. Hemodynamic alteration (Correct Answer)

Explanation: **Explanation:** The core concept to understand here is the difference between **neuraxial opioids** and **neuraxial local anesthetics**. **1. Why "Hemodynamic alteration" is the correct answer:** Unlike local anesthetics (e.g., Bupivacaine), which cause a sympathetic blockade leading to peripheral vasodilation and hypotension, **pure epidural opioids do not cause sympathetic block**. Therefore, they do not typically cause significant hemodynamic alterations like hypotension or bradycardia. This makes them an excellent choice for providing analgesia without compromising cardiovascular stability. **2. Analysis of Incorrect Options:** * **Pruritus (A):** This is the **most common** side effect of neuraxial opioids (occurring in up to 60-100% of cases). It is caused by the cephalad spread of the drug in the CSF and its interaction with opioid receptors in the trigeminal nucleus, rather than histamine release. * **Respiratory depression (B):** This is the most feared complication. It can be **early** (within 2 hours, due to systemic absorption) or **delayed** (6–24 hours, due to cephalad migration of hydrophilic opioids like Morphine to the medullary respiratory center). * **Less complete perineal relaxation (C):** Opioids provide visceral and somatic analgesia but do not cause motor blockade. In obstetric or pelvic surgeries, opioids alone provide inferior muscle relaxation compared to local anesthetics. **Clinical Pearls for NEET-PG:** * **Hydrophilic Opioid (Morphine):** Slow onset, long duration, high risk of **delayed** respiratory depression. * **Lipophilic Opioid (Fentanyl):** Rapid onset, short duration, risk of **early** respiratory depression. * **Treatment of Opioid-induced Pruritus:** Low-dose **Naloxone** or **Nalbuphine** (mixed agonist-antagonist) is highly effective. * **Urinary Retention:** Another common side effect due to the inhibition of the sacral parasympathetic outflow, leading to detrusor muscle relaxation.

Question 42: Which drug is NOT used for analgesia in a patient with head injury?

A. Morphine (Correct Answer)
B. NSAIDs
C. Rofecoxib
D. Acetaminophen

Explanation: **Explanation:** The primary reason **Morphine** (and other potent opioids) is contraindicated in head injury patients is its effect on respiratory drive and intracranial dynamics. 1. **Why Morphine is the Correct Answer:** * **Respiratory Depression:** Morphine causes hypoventilation, leading to an increase in arterial carbon dioxide ($PaCO_2$). $CO_2$ is a potent cerebral vasodilator; its accumulation causes increased cerebral blood flow, which significantly elevates **Intracranial Pressure (ICP)**. * **Pupillary Changes:** Morphine causes miosis (pinpoint pupils), which masks the pupillary signs (like dilation) necessary to monitor for brain herniation. * **Sedation:** It interferes with the Glasgow Coma Scale (GCS) assessment, making it difficult to distinguish between drug-induced sedation and neurological deterioration. 2. **Why other options are incorrect:** * **NSAIDs (e.g., Ibuprofen) & Rofecoxib (COX-2 Inhibitor):** These provide analgesia without affecting the respiratory center or pupillary size. While non-selective NSAIDs are sometimes avoided acutely due to anti-platelet effects (risk of expanding a bleed), they do not carry the specific contraindication related to ICP elevation that opioids do. * **Acetaminophen (Paracetamol):** This is the drug of choice for mild-to-moderate pain in head injuries as it has no effect on ICP, respiration, or neurological monitoring. **High-Yield Clinical Pearls for NEET-PG:** * **Ideal Analgesic in Head Injury:** Fentanyl is often preferred over Morphine if an opioid must be used, due to its shorter half-life and less effect on ICP, but non-opioids are first-line. * **The "Vicious Cycle":** Opioids $\rightarrow$ $\downarrow$ Ventilation $\rightarrow$ $\uparrow$ $PaCO_2$ $\rightarrow$ Cerebral Vasodilation $\rightarrow$ $\uparrow$ ICP. * **Ketamine:** Historically contraindicated in head injuries due to fears of increasing ICP, though recent evidence suggests it may be safe when the patient is ventilated. However, for exam purposes, Morphine remains the classic "wrong" choice for head trauma.

Question 43: A patient in the ICU has been on invasive monitoring with intra-arterial cannulation through the right radial artery for the last 3 days. The patient later developed swelling and discoloration of the right hand. What is the next line of management?

A. Stellate ganglion block (Correct Answer)
B. Paravertebral block
C. Radial nerve block
D. Celiac plexus block

Explanation: ### Explanation **Correct Option: A. Stellate ganglion block** The clinical presentation of swelling and discoloration following intra-arterial cannulation suggests **accidental intra-arterial injection** or **thromboembolism**, leading to acute limb ischemia and vasospasm. The **Stellate Ganglion Block (SGB)** is the treatment of choice because it provides a **sympathetic blockade** of the upper extremity. The stellate ganglion (formed by the fusion of the inferior cervical and first thoracic sympathetic ganglia) maintains sympathetic tone to the head, neck, and arms. Blocking it results in: 1. **Vasodilation:** By removing sympathetic vasoconstrictor tone, it improves collateral circulation and blood flow to the ischemic area. 2. **Pain Relief:** It interrupts the pain-spasm-pain cycle. **Why other options are incorrect:** * **B. Paravertebral block:** This is used for unilateral analgesia of the chest or abdomen (e.g., rib fractures or thoracic surgery) but does not provide targeted sympathetic blockade for the upper limb. * **C. Radial nerve block:** This is a somatic nerve block providing sensory and motor anesthesia. It does not cause the significant vasodilation required to treat ischemia. * **D. Celiac plexus block:** This is used for managing chronic abdominal pain, particularly from pancreatic malignancy; it has no role in upper limb pathology. **High-Yield Clinical Pearls for NEET-PG:** * **Horner’s Syndrome:** A successful Stellate Ganglion Block is confirmed by the presence of Horner’s syndrome (Miosis, Ptosis, Anhidrosis, Enophthalmos, and Conjunctival congestion). * **Anatomy:** The ganglion lies anterior to the neck of the first rib and the transverse process of **C7**. * **Chassaignac’s Tubercle:** The landmark for the block is the transverse process of **C6**, where the carotid artery is retracted laterally. * **Other Indications:** Complex Regional Pain Syndrome (CRPS) Type I and II of the upper limb, Raynaud’s disease, and refractory hyperhidrosis.

Question 44: A painful syndrome characterized by an increased reaction to a stimulus and an increased threshold, along with faulty identification and localization of the stimulus, is called as:

A. Causalgia
B. Hyperpathia (Correct Answer)
C. Hyperesthesia
D. Phantom pain

Explanation: ### Explanation **Correct Answer: B. Hyperpathia** **Hyperpathia** is a clinical symptom of neuropathic pain characterized by an abnormally exaggerated response to a stimulus, especially a repetitive one. It is defined by three key features mentioned in the question: 1. **Increased Threshold:** The patient requires a stronger-than-normal stimulus to perceive any sensation. 2. **Increased Reaction:** Once the threshold is reached, the pain is perceived as explosive, agonizing, and out of proportion to the stimulus. 3. **Faulty Localization/Identification:** The patient often has difficulty pinpointing exactly where the stimulus is applied and may experience "summation" (pain increasing with repeated stimuli) or "after-sensations." --- ### Why the other options are incorrect: * **A. Causalgia:** Now termed **CRPS Type II**, this is a syndrome of sustained burning pain, allodynia, and hyperpathia following a **traumatic nerve injury**. While hyperpathia is a feature of causalgia, the question describes the definition of hyperpathia itself. * **C. Hyperesthesia:** This is a broad, "umbrella" term for increased sensitivity to stimulation, excluding the special senses. It includes both allodynia and hyperalgesia but does not specifically require an increased threshold or faulty localization. * **D. Phantom Pain:** This refers to painful sensations perceived in a limb or organ that has been **amputated** or is no longer physically present. --- ### NEET-PG High-Yield Pearls: * **Allodynia:** Pain due to a stimulus that does **not** normally provoke pain (e.g., light touch/clothing). * **Hyperalgesia:** An **increased response** to a stimulus that is normally painful. * **Dysesthesia:** An unpleasant, abnormal sensation, whether spontaneous or evoked. * **CRPS Type I (Reflex Sympathetic Dystrophy):** Occurs **without** a definable nerve injury. * **CRPS Type II (Causalgia):** Occurs **with** a specific nerve injury.

Question 45: What is the most common side effect of neuraxial opioids?

A. Nausea and vomiting
B. Pruritus (Correct Answer)
C. Urinary retention
D. Sedation

Explanation: **Explanation:** Neuraxial opioids (administered via spinal or epidural routes) are highly effective for perioperative analgesia but are associated with specific side effects due to their interaction with opioid receptors in the spinal cord and cephalad spread in the cerebrospinal fluid. **1. Why Pruritus is Correct:** **Pruritus (itching)** is the **most common** side effect of neuraxial opioids, occurring in approximately 30% to 100% of patients (highest in obstetric cases). Unlike systemic opioids where itching is often histamine-mediated, neuraxial opioid-induced pruritus is primarily caused by the interaction of the drug with **mu-opioid receptors in the trigeminal nucleus** and the dorsal horn of the spinal cord. It is typically localized to the face, neck, or upper thorax. **2. Analysis of Incorrect Options:** * **Nausea and Vomiting (Option A):** Occurs in about 30% of patients due to the cephalad migration of the drug to the *area postrema* in the medulla. While frequent, its incidence is lower than pruritus. * **Urinary Retention (Option B):** Common (especially in young males), caused by the inhibition of sacral parasympathetic outflow leading to detrusor muscle relaxation. However, it is less frequent than pruritus. * **Sedation (Option D):** Usually a precursor to respiratory depression. While serious, it is relatively uncommon compared to the minor side effects. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Side Effect:** Pruritus. * **Most Serious/Dreaded Side Effect:** Delayed Respiratory Depression (especially with Morphine due to its low lipid solubility/hydrophilic nature). * **Treatment of Pruritus:** Low-dose **Naloxone** or **Nalbuphine** (mixed agonist-antagonist) are effective. Antihistamines are generally ineffective as the mechanism is non-histaminergic. * **Lipid Solubility:** Fentanyl (lipophilic) has a rapid onset and short duration; Morphine (hydrophilic) has a slow onset but carries a higher risk of delayed respiratory depression (up to 24 hours).

Question 46: The usefulness of the technique of transcutaneous electrical nerve stimulation is explained by which of the following?

A. Allodynia
B. Central pain
C. Gate theory of pain (Correct Answer)
D. Referred pain

Explanation: **Explanation:** The correct answer is **C. Gate theory of pain.** **Mechanism of Action:** The Gate Control Theory, proposed by Melzack and Wall in 1965, is the physiological basis for Transcutaneous Electrical Nerve Stimulation (TENS). According to this theory, the transmission of pain signals can be modulated in the **dorsal horn of the spinal cord** (specifically the Substantia Gelatinosa). * **Large-diameter A-beta fibers** (which carry non-painful stimuli like touch and vibration) have a lower threshold than small-diameter **C-fibers** (which carry slow pain). * TENS stimulates these A-beta fibers, which in turn activate inhibitory interneurons. These interneurons "close the gate," preventing the transmission of pain signals from C-fibers to the higher brain centers. **Analysis of Incorrect Options:** * **A. Allodynia:** This refers to pain resulting from a stimulus that does not normally provoke pain (e.g., a light touch on sunburned skin). It is a feature of neuropathic pain, not a mechanism for its relief. * **B. Central pain:** This is pain initiated or caused by a primary lesion or dysfunction in the Central Nervous System (e.g., Thalamic pain syndrome). TENS is primarily used for peripheral and musculoskeletal pain. * **D. Referred pain:** This is pain perceived at a location other than the site of the painful stimulus (e.g., left arm pain during a myocardial infarction). It is a diagnostic phenomenon, not a therapeutic mechanism. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Site:** The "Gate" is located in the **Rexed Lamina II** (Substantia Gelatinosa) of the spinal cord. * **Neurotransmitters:** TENS also stimulates the release of endogenous opioids (endorphins and enkephalins). * **Contraindications:** TENS should be avoided in patients with **cardiac pacemakers**, over the carotid sinus, or over a pregnant uterus. * **Frequency:** High-frequency TENS (50-100 Hz) is most commonly used for acute pain relief via the gate mechanism.

Question 47: Which of the following is the best indicator for pain assessment in a patient?

A. Asking the patient directly about their pain
B. Tachycardia (Correct Answer)
C. Tachypnea
D. Bradypnea

Explanation: **Explanation:** In the context of clinical anesthesiology and acute pain management, physiological responses are often more objective indicators of pain than subjective reports, especially in the perioperative or critical care setting. **Why Tachycardia is the Correct Answer:** Pain triggers a **sympathetic nervous system (SNS) surge**. This "fight or flight" response leads to the release of catecholamines (epinephrine and norepinephrine), which act on the beta-1 receptors of the heart to increase the heart rate (**Tachycardia**). In an anesthetized or non-communicative patient, tachycardia is considered one of the most reliable and earliest physiological markers of inadequate analgesia or a painful stimulus. **Analysis of Incorrect Options:** * **A. Asking the patient directly:** While the "Self-Report" (Visual Analog Scale) is the gold standard for *chronic* or *conscious* pain assessment, it is often unreliable in the acute perioperative period due to sedation, intubation, or cognitive impairment. In the context of this specific question (likely focusing on objective monitoring), physiological signs take precedence. * **C. Tachypnea:** While pain can increase the respiratory rate, it is less specific than tachycardia. Tachypnea can be caused by hypercapnia, hypoxia, or anxiety without significant pain. * **D. Bradypnea:** This is typically a sign of opioid overdose or deep anesthesia, rather than a response to pain. **High-Yield Clinical Pearls for NEET-PG:** * **The "Autonomic Triad" of Pain:** Tachycardia, Hypertension, and Diaphoresis (sweating). * **Gold Standard:** Patient self-report is the gold standard for *conscious* patients, but **Tachycardia** is the most sensitive *objective* sign. * **FLACC Scale:** Used for pediatric pain assessment (Face, Legs, Activity, Cry, Consolability). * **CPOT (Critical-Care Pain Observation Tool):** Used for assessing pain in intubated patients in the ICU.

Question 48: A two month old infant has undergone a major surgical procedure. Regarding postoperative pain relief which one of the following is recommended:

A. Spinal narcotics intrathecal route
B. Intravenous narcotic infusion in lower dosage (Correct Answer)
C. Only paracetamol suppository is adequate
D. No medication is needed as infant does not feel pain after surgery due to immaturity of nervous system

Explanation: ***Intravenous narcotic infusion in lower dosage*** - **Intravenous narcotic infusion** provides continuous pain relief and allows for careful titration of the dose, which is crucial in infants due to their developing metabolism and increased sensitivity to opioids. - Lower dosages are recommended because infants have a **reduced capacity for drug metabolism** and excretion, making them more susceptible to side effects like respiratory depression. *Spinal narcotics intrathecal route* - While effective, the **intrathecal route** carries risks such as neurotoxicity and spinal cord injury, which are particularly concerning in infants due to their small size and developing neural structures. - The **pharmacokinetics** of intrathecal narcotics can also be unpredictable in infants, leading to potential for delayed respiratory depression. *Only paracetamol suppository is adequate* - For **major surgical procedures**, a single agent like **paracetamol** is typically insufficient to manage severe postoperative pain effectively. - While paracetamol is a useful adjunct, it lacks the potent analgesic effects of opioids needed for comprehensive pain control after significant surgery. *No medication is needed as infant does not feel pain after surgery due to immaturity of nervous system* - This statement is **incorrect** and a dangerous misconception; infants, even neonates, have a **fully developed pain pathway**, perceive pain, and require appropriate analgesia. - The **pain response** in infants can be more exaggerated due to an immature inhibitory pain system, necessitating careful and effective pain management.

Question 49: Stellate ganglion block is useful in :

A. osteoarthritis of first CMC joint
B. tenosynovitis
C. sudeck osteodystrophy (Correct Answer)
D. compound palmar ganglion

Explanation: ***sudeck osteodystrophy*** - Stellate ganglion block is a common treatment for **Sudeck's atrophy**, also known as **Complex Regional Pain Syndrome (CRPS) Type I**. - It helps by interrupting the efferent sympathetic innervation to the upper extremity, thereby decreasing **vasoconstriction** and related pain. *osteoarthritis of first CMC joint* - This condition is primarily a **degenerative joint disease** and is typically managed with conservative measures, injections, or surgery. - A stellate ganglion block does not address the underlying **arthritic process** or provide long-term relief for this condition. *tenosynovitis* - Tenosynovitis is an inflammation of the **tendon sheath**, often caused by overuse or repetitive strain. - Treatment usually involves **rest**, **nsaids**, corticosteroid injections, or in severe cases, surgical release, not sympathetic blockade. *compound palmar ganglion* - A compound palmar ganglion is a **synovial cyst** formation, often associated with chronic tenosynovitis of the flexor tendons in the palm. - Management typically involves **aspiration** with steroid injection or **surgical excision**, as it is a mechanical issue, not a sympathetically mediated pain syndrome.

Question 50: Following are the features of persistent postoperative pain EXCEPT:

A. Pain from pre-surgical problem is excluded
B. Pain present for at least 3 months (Correct Answer)
C. Pain where other causes are excluded
D. Pain that develops after surgical procedure

Explanation: *Pain present for at least 3 months* - This statement is an **incorrect** feature of persistent postoperative pain. The diagnostic criteria for persistent postoperative pain typically define it as pain lasting for at least **2 months** after surgery. - The definition requires a minimum duration of 2 months, not 3 months, for the pain to be considered chronic or persistent. **Pain from pre-surgical problem is excluded** - Persistent postoperative pain refers to new or increased pain directly attributable to the surgical procedure itself, excluding the original pain condition. - This criterion ensures that the **chronic pain** being evaluated is a consequence of the surgery and not a continuation or recurrence of the initial problem. *Pain where other causes are excluded* - This is a key diagnostic criterion, as it ensures that the pain is not due to other independent medical conditions, infections, or surgical complications. - Excluding other causes helps to confirm that the persistent pain syndrome is directly related to the **surgical intervention**. *Pain that develops after surgical procedure* - The pain must have developed or significantly increased in intensity after the surgical procedure for it to be considered persistent postoperative pain. - This distinguishes it from pre-existing pain conditions that may be ongoing but are not directly linked to the **surgical trauma**.

Practice by Chapter

Pain Physiology and Pathways

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Acute Pain Management

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Chronic Pain Syndromes

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Neuropathic Pain

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Multimodal Analgesia

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Opioid Pharmacology

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Non-opioid Analgesics

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Adjuvant Analgesics

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Patient-Controlled Analgesia

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Interventional Pain Procedures

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Cancer Pain Management

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Perioperative Pain Management

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