Neuropathic Pain — MCQs
Slow, burning pain is primarily carried by which type of nerve fibers?
In a patient with a history of burning pain localized to the plantar aspect of the foot, the differential diagnosis must include -
Which of the following actions is NOT associated with tricyclic antidepressants?
The following classification is used to estimate nerve injury:
A 50-year-old male with diabetes presents with severe burning pain in his feet. Medications have been ineffective. What is the most appropriate next step in management?
A patient was treated for mantle cell Hodgkin lymphoma with radiation therapy. After 6 months he develops an electric shock-like pain along the spine on flexing his neck. What is the diagnosis?
Which of the following drugs is not effective in the treatment of trigeminal neuralgia?
An exaggerated pain response to a normally painful stimulus is called:
Most common drug used in Spasticity in patients with spinal cord injury is:
A female developed pain and a sensation like insects crawling on her legs at night which is relieved by shaking her legs. Which of the following is the drug of choice for this condition?
Neuropathic Pain Indian Medical PG Practice Questions and MCQs
Question 1: Slow, burning pain is primarily carried by which type of nerve fibers?
- A. Aα fibers
- B. Aβ fibers
- C. Aδ fibers
- D. C fibers (Correct Answer)
Explanation: ***C fibers*** - **C fibers** are small, unmyelinated nerve fibers responsible for transmitting **slow, dull, burning, and aching pain** sensations. - They conduct impulses slowly due to their lack of **myelin sheath**, leading to the characteristic long-lasting and diffuse nature of the pain. *Aα fibers* - **Aα fibers** are the largest and most heavily myelinated nerve fibers, primarily responsible for **proprioception** (sense of body position) and **motor control**. - They conduct impulses at the highest speeds and are not involved in pain transmission. *Aβ fibers* - **Aβ fibers** are moderately myelinated and transmit sensations of **touch and pressure**, as well as vibration. - While they are involved in tactile sensation, they do not primarily convey pain signals, especially not the slow, burning kind. *Aδ fibers* - **Aδ fibers** are thinly myelinated fibers responsible for transmitting **fast, sharp, and localized pain** (the "first pain"). - They convey rapid pain signals, distinct from the slow, burning pain transmitted by C fibers.
Question 2: In a patient with a history of burning pain localized to the plantar aspect of the foot, the differential diagnosis must include -
- A. Peripheral vascular disease
- B. Plantar fibromatosis
- C. Tarsal tunnel syndrome (Correct Answer)
- D. Tarsal coalition
Explanation: ***Tarsal tunnel syndrome*** - This condition involves **compression of the posterior tibial nerve** or its branches as they pass through the tarsal tunnel, leading to **burning pain, numbness, and tingling** on the plantar aspect of the foot [2]. - Symptoms are often exacerbated by activity or prolonged standing and can be reproduced by tapping on the nerve (Tinel's sign). *Peripheral vascular disease* - While it can cause foot pain, it typically presents as **intermittent claudication** (pain with exertion that resolves with rest) or **ischemic rest pain**, often in the toes or forefoot [1]. - The pain is usually described as cramping or aching rather than burning and is associated with signs of **poor circulation** like diminished pulses and cool skin [1]. *Plantar fibromatosis* - This condition, also known as **Ledderhose disease**, involves the formation of benign fibrous nodules within the **plantar fascia**. - It usually presents as **palpable lumps** on the sole of the foot, which may or may not be painful, but burning pain is not a primary or characteristic symptom. *Tarsal coalition* - This is a congenital condition where two or more bones in the midfoot or hindfoot are **abnormally fused**, most commonly the calcaneus and navicular or talus and calcaneus. - It typically causes **pain, stiffness, and flatfoot deformity** that worsens with activity, but burning neuropathic pain is not its primary symptom.
Question 3: Which of the following actions is NOT associated with tricyclic antidepressants?
- A. Block 5-HT or NE reuptake
- B. Anticholinergic action
- C. MAO inhibition (Correct Answer)
- D. Causes sedation
Explanation: ***MAO inhibition*** - Tricyclic antidepressants (TCAs) primarily exert their effects by inhibiting the reuptake of **norepinephrine** and **serotonin**, not by inhibiting monoamine oxidase (MAO). - **MAO inhibitors** are a distinct class of antidepressants with a different mechanism of action and side effect profile. *Anticholinergic action* - Many TCAs have significant **anticholinergic effects**, blocking muscarinic receptors and leading to side effects like dry mouth, constipation, and blurred vision. - These effects contribute to the **adverse event profile** of TCAs, especially in elderly patients. *Block 5-HT or NE reuptake* - The primary mechanism of action of TCAs involves the **inhibition of serotonin (5-HT)** and **norepinephrine (NE) reuptake** into presynaptic neurons. - This action increases the concentration of these neurotransmitters in the **synaptic cleft**, thereby potentiating their effects. *Causes sedation* - TCAs frequently cause **sedation**, particularly the more histaminergic ones (e.g., amitriptyline, doxepin), due to their **histamine H1 receptor antagonism**. - This side effect can be beneficial for patients with insomnia but can be problematic for daytime functioning.
Question 4: The following classification is used to estimate nerve injury:
- A. Seddons classification (Correct Answer)
- B. Seddon's and Sunderland classification
- C. Sunderland classification
- D. None of the options
Explanation: ***Seddons classification*** - The **Seddons classification** is a well-established system for classifying the severity of nerve injuries. - It categorizes nerve injuries into three main types: **neurapraxia**, **axonotmesis**, and **neurotmesis**. *Seddon's and Sunderland classification* - While both **Seddon's** and **Sunderland's classifications** are used for nerve injury, the question asks for "the following classification" implying a single, primary classification. - **Sunderland's classification** is a more detailed, five-grade system, often considered an extension of Seddon's. *Sunderland classification* - The **Sunderland classification** is a valid and widely used system, but it is not the *only* classification and the question implies a single, specific classification in its phrasing. - Sunderland's system provides more granular detail on the extent of nerve damage compared to Seddon's, with five degrees of injury. *None of the options* - This option is incorrect because the **Seddons classification** is indeed a valid and frequently used method for estimating nerve injury. - There are established classification systems for nerve injuries.
Question 5: A 50-year-old male with diabetes presents with severe burning pain in his feet. Medications have been ineffective. What is the most appropriate next step in management?
- A. Prescribe opioid analgesics
- B. Prescribe corticosteroids
- C. Trial of pregabalin (Correct Answer)
- D. Refer for physical therapy
Explanation: ***Trial of pregabalin*** - **Pregabalin**, a gamma-aminobutyric acid (GABA) analog, is a first-line treatment for **diabetic neuropathic pain** due to its efficacy in modulating neurotransmitter release [2]. - Given that previous medications have been ineffective for **severe burning pain** [1] in diabetic neuropathy, exploring other pharmacological options like pregabalin is the most appropriate next step [2]. *Prescribe opioid analgesics* - **Opioid analgesics** are generally reserved for neuropathic pain that is refractory to other treatments due to concerns about tolerance, dependence, and significant side effects [1]. - They are not considered a first-line or early second-line treatment for **diabetic neuropathy**, especially when other agents like pregabalin have not yet been trialed [2]. *Prescribe corticosteroids* - **Corticosteroids** are potent anti-inflammatory agents but are not indicated for the chronic management of **diabetic neuropathic pain**, which is primarily a nerve damage issue rather than an inflammatory one. - Long-term steroid use carries significant risks and would likely worsen diabetes control, making it an inappropriate choice. *Refer for physical therapy* - **Physical therapy** can be beneficial for managing some aspects of diabetic neuropathy, such as improving balance or muscle strength, but it is unlikely to directly alleviate severe burning neuropathic pain as a primary monotherapy. - While a valuable adjunctive treatment, it is not the most appropriate initial next step for directly addressing severe pain symptoms when pharmacological options are still available [2].
Question 6: A patient was treated for mantle cell Hodgkin lymphoma with radiation therapy. After 6 months he develops an electric shock-like pain along the spine on flexing his neck. What is the diagnosis?
- A. Multiple sclerosis
- B. Cervical arthritis
- C. Spinal cord compression
- D. Radiation-induced myelopathy (Correct Answer)
Explanation: ***Radiation-induced myelopathy*** - This diagnosis is signaled by the **electric shock-like pain** along the spine upon neck flexion (Lhermitte's sign) developing 6 months after receiving **radiation therapy** for lymphoma. - This condition represents a delayed complication of radiation, affecting the **spinal cord's white matter**. *Multiple sclerosis* - While it can present with **Lhermitte's sign**, the patient's history of **radiation therapy** and its timing strongly favor myelopathy. [1] - MS is a demyelinating disease usually presenting with a **variety of neurological symptoms** over time, rather than isolated Lhermitte's sign post-radiation. *Cervical arthritis* - This condition would typically present with **neck pain and stiffness**, possibly radiating pain, and limited range of motion, but not specifically an electric shock sensation on neck flexion (Lhermitte's sign). [2] - While an osteophyte might cause compression, the specific **Lhermitte's sign** points away from simple degenerative changes. *Spinal cord compression* - While Lhermitte's sign can indicate spinal cord involvement, **spinal cord compression** usually implies an acute or subacute onset with more severe and progressive neurological deficits, such as motor weakness or sensory loss, and bladder/bowel dysfunction. [3] - Given the 6-month delay and the isolated Lhermitte's sign after radiation, **radiation-induced myelopathy** is a more specific and likely cause.
Question 7: Which of the following drugs is not effective in the treatment of trigeminal neuralgia?
- A. Phenytoin sodium
- B. Carbamazepine
- C. Baclofen
- D. Acetaminophen (Correct Answer)
Explanation: ***Acetaminophen*** - **Acetaminophen** is a common **analgesic** and antipyretic but lacks the direct effect on neuronal hyperexcitability required for treating **neuropathic pain** conditions like trigeminal neuralgia. - Its mechanism of action primarily involves inhibiting prostaglandin synthesis peripherally and centrally, which is insufficient for managing the sharp, stabbing pain of **trigeminal neuralgia**. *Carbamazepine* - **Carbamazepine** is considered the **first-line treatment** for trigeminal neuralgia due to its efficacy in stabilizing hyperexcitable nerve membranes. - It works by blocking **voltage-gated sodium channels**, thereby reducing the firing of trigeminal nerve fibers. *Phenytoin sodium* - **Phenytoin** is an **antiepileptic drug** that can be used as a second-line or adjunctive treatment for trigeminal neuralgia. - Similar to carbamazepine, it acts by **inhibiting voltage-gated sodium channels**, thereby preventing repetitive firing of action potentials. *Baclofen* - **Baclofen** is a **GABA-B receptor agonist** that can be used in combination with carbamazepine or as an alternative for patients who do not respond to or tolerate carbamazepine. - It helps reduce the intensity and frequency of pain by **inhibiting excitatory neurotransmitter release** in the brainstem trigeminal nucleus.
Question 8: An exaggerated pain response to a normally painful stimulus is called:
- A. Causalgia
- B. Allodynia
- C. Hypersensitivity
- D. Hyperalgesia (Correct Answer)
Explanation: ***Hyperalgesia*** - This term describes an **increased sensitivity to pain** where a stimulus that is normally painful is perceived as even more painful than usual. - It often results from **damage to nociceptive afferent pathways** or central sensitization. *Causalgia* - This is an older term now largely replaced by complex regional pain syndrome type II (**CRPS II**), characterized by severe, burning pain following a **nerve injury**. - Unlike hyperalgesia, it specifically refers to a **syndrome of severe pain** after nerve trauma, not just an increased response to noxious stimuli. *Allodynia* - This refers to pain caused by a stimulus that **does not normally provoke pain**, such as light touch or brushing of the skin. - It differs from hyperalgesia, which is an exaggerated response to a **normally painful stimulus**. *Hypersensitivity* - This is a **general term** meaning an increased physical or allergic sensitivity to a substance or condition. - It is a **broader concept** and not as specific to pain perception as hyperalgesia or allodynia.
Question 9: Most common drug used in Spasticity in patients with spinal cord injury is:
- A. Salicylates
- B. Tizanidine
- C. Baclofen (Correct Answer)
- D. Diazepam
Explanation: ***Baclofen*** - **Baclofen** is the most commonly prescribed muscle relaxant for spasticity, especially in cases related to **spinal cord injury** and multiple sclerosis. - It acts as a **GABA-B receptor agonist**, reducing excitatory neurotransmitter release and thus decreasing muscle tone. *Salicylates* - **Salicylates** (e.g., aspirin) primarily act as **analgesics** and **anti-inflammatory** agents. - They are not used for treating spasticity. *Tizanidine* - **Tizanidine** is an **alpha-2 adrenergic agonist** used for spasticity, but it is generally considered a second-line agent compared to baclofen. - It works by reducing the release of excitatory amino acids, thereby enhancing presynaptic inhibition. *Diazepam* - **Diazepam** is a **benzodiazepine** that acts as a **GABA-A receptor agonist**, enhancing inhibitory neurotransmission. - While it can reduce spasticity, its sedative effects and potential for dependence make it less preferred than baclofen for chronic management in spinal cord injury.
Question 10: A female developed pain and a sensation like insects crawling on her legs at night which is relieved by shaking her legs. Which of the following is the drug of choice for this condition?
- A. Iron supplementation (if deficient)
- B. Pramipexole (Correct Answer)
- C. Gabapentin
- D. Vitamin B12 supplementation
Explanation: ***Pramipexole*** - **Pramipexole** is a **dopamine agonist** and is considered a first-line treatment for Restless Legs Syndrome (RLS) due to its efficacy in reducing symptoms. - It works by stimulating **dopamine receptors**, which are thought to play a role in the pathophysiology of RLS. *Iron supplementation (if deficient)* - While **iron deficiency is a common reversible cause of RLS**, iron supplementation is primarily indicated when serum ferritin levels are low. In the absence of confirmed deficiency, it is not the initial drug of choice. - Correcting iron deficiency can improve RLS symptoms, but it's a treatment for the underlying cause rather than a symptomatic drug of choice when iron status is unknown. *Gabapentin* - **Gabapentin** is an alpha-2-delta ligand and is an effective second-line or alternative treatment for RLS, especially when patients do not respond to dopamine agonists or have comorbid pain or anxiety. - Although effective, it is generally not considered the primary drug of choice over dopamine agonists for most RLS patients. *Vitamin B12 supplementation* - **Vitamin B12 deficiency** can cause neurological symptoms, but it is not typically associated with Restless Legs Syndrome (RLS) or an "insect crawling" sensation specifically relieved by movement. - Supplementation is only indicated if a **diagnosed deficiency is present**, and it would not be the drug of choice for RLS symptoms as described.
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