Peripheral Neuropathies — MCQs
A 45-year-old woman presents with burning pain and numbness in the wrist and hand. Tinel's sign is positive. What is the most likely diagnosis?
Most useful test to differentiate upper from lower motor neuron lesion?
A patient at the orthopedics OPD complains of troubled sleep at night due to numbness and tingling sensation involving his lateral 3 digits. His symptoms are relieved as he lays his arms hanging from the bed. Which of the following options correctly describes his condition and the test used to assess it?
Bilateral facial nerve palsy is seen in
Pure motor paralysis is seen in :
In multiple sclerosis, slow conduction of motor and sensory pathways is due to?
Patient with ascending paralysis, areflexia and sphincter sparing is seen in?
In leprosy neuritis, which of the following statements is true? a) Intracutaneous thickening of the nerve, b) Facial palsy, c) It primarily occurs in warm and moist areas, d) Palpable peripheral nerves are present, e) More than 10 lesions may be found.
Vitamin B12 deficiency can lead to all EXCEPT:
In a patient with chronic alcoholism, which nutrient deficiency is most likely to cause neurological symptoms?
Peripheral Neuropathies Indian Medical PG Practice Questions and MCQs
Question 1: A 45-year-old woman presents with burning pain and numbness in the wrist and hand. Tinel's sign is positive. What is the most likely diagnosis?
- A. Radial nerve palsy
- B. Cubital tunnel syndrome
- C. Carpal tunnel syndrome (Correct Answer)
- D. Thoracic outlet syndrome
Explanation: ***Carpal tunnel syndrome*** - **Burning pain**, **numbness** in the hand, and a **positive Tinel's sign** at the wrist are classic symptoms of median nerve compression within the carpal tunnel [1]. - The median nerve supplies sensation to the thumb, index, middle, and radial half of the ring finger, which is where symptoms are typically experienced [1]. *Radial nerve palsy* - This condition affects the **radial nerve**, causing **wrist drop** and sensory loss over the posterior forearm and dorsum of the hand [1]. - It does not typically present with burning pain or numbness in the distribution described. *Cubital tunnel syndrome* - Involves compression of the **ulnar nerve** at the elbow, leading to numbness and tingling in the **little finger** and ulnar half of the ring finger [1]. - While it can cause burning pain, the anatomical distribution of symptoms is distinct from the patient's presentation. *Thoracic outlet syndrome* - Results from compression of neurovascular structures in the **thoracic outlet**, causing varied symptoms such as pain, numbness, and weakness in the arm and hand [2]. - A positive Tinel's sign at the wrist is not a characteristic finding, and the symptom distribution is often broader or less specific to a single nerve.
Question 2: Most useful test to differentiate upper from lower motor neuron lesion?
- A. Deep tendon reflexes (Correct Answer)
- B. Muscle tone
- C. Hoffman sign
- D. EMG changes
Explanation: ***Deep tendon reflexes*** - **Upper motor neuron (UMN)** lesions typically cause **hyperreflexia** due to loss of inhibitory input [1]. - **Lower motor neuron (LMN)** lesions typically result in **hyporeflexia or areflexia** due to damage to the reflex arc itself. *Muscle tone* - **UMN lesions** often lead to **spasticity** (velocity-dependent increase in tone) [2], [3]. - **LMN lesions** result in **flaccidity** or decreased tone due to loss of muscle innervation [1]. While helpful, reflex changes are more consistently discriminatory. *Hoffman sign* - The **Hoffman sign** is a pathological reflex used to detect **cervical myelopathy** or other **UMN dysfunction**, particularly in the upper limbs. - Its presence indicates UMN involvement, but its absence does not definitively rule out a UMN lesion elsewhere or confirm an LMN lesion. *EMG changes* - **Electromyography (EMG)** can help differentiate UMN from LMN lesions by evaluating nerve and muscle activity, showing features like **fibrillation potentials** and **fasciculations** in LMN lesions [1]. - However, it is an investigative test, and clinically, deep tendon reflexes provide a rapid and often sufficient distinction at the bedside.
Question 3: A patient at the orthopedics OPD complains of troubled sleep at night due to numbness and tingling sensation involving his lateral 3 digits. His symptoms are relieved as he lays his arms hanging from the bed. Which of the following options correctly describes his condition and the test used to assess it?
- A. Guyon's canal syndrome, Froment's test
- B. Carpal tunnel syndrome, Froment's test
- C. Guyon's canal syndrome, Durkan's test
- D. Carpal tunnel syndrome, Durkan's test (Correct Answer)
Explanation: ***Carpal tunnel syndrome, Durkan's test*** - The symptoms of **numbness and tingling** in the **lateral 3 digits** (thumb, index, middle, and radial half of the ring finger) are classic for **carpal tunnel syndrome (CTS)**, caused by compression of the **median nerve**. Relief with hanging the arm is due to gravity reducing swelling and pressure. - **Durkan's test** (or **median nerve compression test**) is highly specific for CTS. It involves direct pressure over the carpal tunnel, reproducing symptoms within 30 seconds. *Guyon's canal syndrome, Froment's test* - **Guyon's canal syndrome** involves compression of the **ulnar nerve** at the wrist, primarily affecting the **little finger** and the **ulnar half of the ring finger**, not the lateral 3 digits. - **Froment's test** assesses **ulnar nerve palsy** by observing the strength of adductor pollicis during a pinch grip, which is unrelated to median nerve compression. *Carpal tunnel syndrome, Froment's test* - While **carpal tunnel syndrome** is correctly identified based on the symptoms, **Froment's test** is not used to assess it. - As mentioned, Froment's test evaluates **ulnar nerve function**, particularly the adductor pollicis muscle. *Guyon's canal syndrome, Durkan's test* - The symptoms described (lateral 3 digits) are inconsistent with **Guyon's canal syndrome**, which affects the ulnar nerve distribution. - Although **Durkan's test** is appropriate for carpal tunnel syndrome, the diagnosis for Guyon's canal syndrome is incorrect.
Question 4: Bilateral facial nerve palsy is seen in
- A. Melkersen Rosenthal syndrome
- B. Ramsay Hunt syndrome
- C. Guillain Barre syndrome (Correct Answer)
- D. Herpes zoster
Explanation: Guillain Barre syndrome - Guillain-Barré syndrome (GBS) is an acute, rapidly progressive, acquired demyelinating polyneuropathy that can classically present with bilateral facial nerve palsy [1]. - This is due to the widespread nature of the demyelination affecting peripheral nerves, including the facial nerves. Melkersen Rosenthal syndrome - This syndrome is characterized by a triad of recurrent facial paralysis, persistent orofacial swelling (e.g., cheilitis granulomatosa), and a fissured tongue. - While it causes facial nerve palsy, it is typically unilateral and recurrent, though it can occasionally be bilateral. Ramsay Hunt syndrome - This syndrome is caused by the reactivation of the varicella-zoster virus in the geniculate ganglion, leading to herpes zoster oticus. - It presents with unilateral facial paralysis, often accompanied by painful vesicular rash in the external auditory canal or on the auricle, hearing loss, and vertigo [2]. Herpes zoster - Herpes zoster (shingles) is a viral infection caused by the reactivation of the varicella-zoster virus, primarily affecting dermatomes. - While it can cause facial palsy (if it affects the geniculate ganglion, leading to Ramsay Hunt Syndrome), it is generally unilateral and not typically associated with bilateral facial nerve palsy [2].
Question 5: Pure motor paralysis is seen in :
- A. Sub-Acute Combined Degeneration
- B. Diabetes mellitus
- C. Guillain-Barré syndrome
- D. Polio (Correct Answer)
Explanation: **Polio** - Polio primarily infects motor neurons in the **anterior horn of the spinal cord** [3], leading to **flaccid paralysis** without sensory involvement [4]. - The destruction of these motor neurons results in **muscle weakness and atrophy**, consistent with pure motor paralysis [3]. *Sub-Acute Combined Degeneration* - This condition is caused by **vitamin B12 deficiency** and affects both the **posterior and lateral columns** of the spinal cord. - It typically presents with a combination of **motor deficits** (weakness, spasticity) and **sensory deficits** (paresthesias, proprioception loss), making it not purely motor [2]. *Diabetes mellitus* - Diabetic neuropathy can cause various types of nerve damage, including **motor, sensory, and autonomic neuropathies** [2]. - While motor weakness can occur, it is rarely a **pure motor paralysis** and is often accompanied by significant sensory symptoms (e.g., numbness, tingling) [1]. *Guillain-Barré syndrome* - GBS is an acute demyelinating polyneuropathy that causes **progressive symmetrical weakness**, often starting in the lower limbs. - Although primarily motor, it can also involve **sensory disturbances** (paresthesias, pain) and autonomic dysfunction, so it is not strictly pure motor.
Question 6: In multiple sclerosis, slow conduction of motor and sensory pathways is due to?
- A. Loss of myelin sheath (Correct Answer)
- B. Dysfunction of sodium channels
- C. Dysfunction of calcium channels
- D. Defect in the nodes of Ranvier
Explanation: ***Loss of myelin sheath*** - Multiple sclerosis (MS) is characterized by **demyelination**, which is the destruction of the **myelin sheath** surrounding nerve fibers in the central nervous system. - Myelin acts as an electrical insulator, facilitating rapid, **saltatory conduction** of nerve impulses; its loss directly leads to **slowed or blocked signal transmission**. *Dysfunction of sodium channels* - While sodium channel dysfunction can occur secondary to demyelination, it is not the primary cause of slow conduction in MS but rather a downstream effect or an adaptive change. - The initial and fundamental problem leading to slowed conduction in MS is the **loss of the myelin sheath**, which renders the exposed axon less efficient at propagating action potentials. *Dysfunction of calcium channels* - Dysfunction of calcium channels is not the primary pathological mechanism responsible for the slowed conduction in MS. - While calcium dysregulation can play a role in **axonal damage** and neurodegeneration in MS, it is not the direct cause of the characteristic **slowed nerve impulse propagation**. *Defect in the nodes of Ranvier* - The **nodes of Ranvier** are uncovered gaps in the myelin sheath that are crucial for **saltatory conduction**. While their integrity is important, a primary "defect" in the nodes themselves is not the initial cause of slowed conduction in MS. - Slowed conduction occurs because the **myelin surrounding the axons** is lost, leading to longer distances for the action potential to travel and exposing segments of the axon unprepared for continuous conduction.
Question 7: Patient with ascending paralysis, areflexia and sphincter sparing is seen in?
- A. G.B.S (Correct Answer)
- B. Botulinism
- C. Snake bite
- D. Polio
Explanation: **G.B.S** - **Guillain-Barré Syndrome (GBS)** is characterized by **ascending paralysis** and **areflexia**, meaning loss of deep tendon reflexes [1]. - **Sphincter sparing** is also typical in GBS, differentiating it from other causes of paralysis where autonomic involvement can lead to bladder and bowel dysfunction [1]. *Botulism* - Botulism typically presents with **descending paralysis**, weakness starting in the cranial nerves and progressing downwards. - While it causes significant muscle weakness and can lead to **areflexia**, the pattern of paralysis (descending vs. ascending) and the presence of prominent cranial nerve involvement help distinguish it. *Snake bite* - Neurotoxic snake bites can cause **flaccid paralysis** and **areflexia**, but the paralysis often starts at the site of the bite or affects cranial nerves preferentially before generalized ascending paralysis. - The history of a **snake bite** and presence of **local envenomation signs** (swelling, pain) would also be prominent. *Polio* - Polio primarily causes **asymmetric flaccid paralysis** and **areflexia**, due to the destruction of anterior horn cells in the spinal cord. - Unlike GBS, polio does not typically present with an ascending pattern affecting both sides symmetrically and often involves sensory sparing.
Question 8: In leprosy neuritis, which of the following statements is true? a) Intracutaneous thickening of the nerve, b) Facial palsy, c) It primarily occurs in warm and moist areas, d) Palpable peripheral nerves are present, e) More than 10 lesions may be found.
- A. Facial palsy, Palpable peripheral nerves are present.
- B. Intracutaneous thickening of the nerve, Facial palsy.
- C. Palpable peripheral nerves are present, More than 10 lesions may be found.
- D. Intracutaneous thickening of the nerve, Facial palsy, Palpable peripheral nerves are present. (Correct Answer)
Explanation: ***Intracutaneous thickening of the nerve, Facial palsy, Palpable peripheral nerves are present.*** - Leprosy neuritis is characterized by the **infiltration of nerves** by *Mycobacterium leprae*, leading to inflammation and thickening, which can be **palpable** in superficial nerves [1]. - Facial nerves, along with other peripheral nerves, can be affected, causing **facial palsy** due to nerve damage [1]. *Facial palsy, Palpable peripheral nerves are present.* - While **facial palsy** and **palpable peripheral nerves** are indeed features of leprosy neuritis, this option is incomplete as it omits other key features described in the question [1]. - It does not mention **intracutaneous thickening of the nerve**, which is a direct consequence of the inflammatory process. *Intracutaneous thickening of the nerve, Facial palsy.* - This option correctly identifies **intracutaneous thickening of the nerve** and **facial palsy** as manifestations of leprosy neuritis [1]. - However, it fails to include the important clinical sign of **palpable peripheral nerves**, which is a common finding in the disease [1]. *Palpable peripheral nerves are present, More than 10 lesions may be found.* - **Palpable peripheral nerves** are a hallmark of leprosy neuritis, indicating nerve involvement [1]. - While more than 10 lesions can be found in multibacillary leprosy, the question specifically asks about **leprosy neuritis** features rather than the generalized skin lesion count [1].
Question 9: Vitamin B12 deficiency can lead to all EXCEPT:
- A. Optic atrophy
- B. Peripheral neuropathy
- C. Myopathy (Correct Answer)
- D. Myelopathy
Explanation: ***Myopathy*** - **Myopathy**, or muscle disease, is generally characterized by **muscle weakness** and pain, but it is **not a classic manifestation** of vitamin B12 deficiency [2]. - The neurological effects of B12 deficiency primarily impact the **nervous system**, not directly the muscle fibers themselves. *Optic atrophy* - **Optic atrophy**, characterized by progressive vision loss due to damage to the **optic nerve**, can be a rare but known complication of chronic vitamin B12 deficiency. - The deficiency impairs the **myelination** and function of the optic nerve. *Peripheral neuropathy* - **Peripheral neuropathy**, manifesting as **numbness**, **tingling**, and **weakness** in the extremities, is a very common neurological symptom of vitamin B12 deficiency [1]. - It results from **demyelination** and axonal degeneration of peripheral nerves [1]. *Myelopathy* - **Myelopathy**, specifically **subacute combined degeneration** of the spinal cord (SCD), is a hallmark neurological complication of vitamin B12 deficiency. - It involves demyelination and degeneration of the **posterior** and **lateral columns** of the spinal cord, leading to gait disturbances, spasticity, and sensory deficits.
Question 10: In a patient with chronic alcoholism, which nutrient deficiency is most likely to cause neurological symptoms?
- A. Vitamin B6
- B. Thiamine (Correct Answer)
- C. Folate
- D. Vitamin B12
Explanation: ***Thiamine*** - **Thiamine (Vitamin B1)** deficiency is extremely common in chronic alcoholism due to poor nutrition and impaired absorption, leading to neurological disorders like **Wernicke-Korsakoff syndrome** [1]. - **Wernicke-Korsakoff syndrome** manifests with symptoms such as **ataxia**, **ophthalmoplegia**, **confusion**, and **memory impairment** [2]. *Vitamin B6* - While **Vitamin B6 (pyridoxine)** deficiency can occur in alcoholism, it is more commonly associated with peripheral neuropathy rather than the extensive neurological picture seen with thiamine deficiency. - Severe B6 deficiency can cause **seizures** and **encephalopathy**, but these are less common as primary neurological manifestations in typical chronic alcoholics compared to Wernicke-Korsakoff syndrome. *Folate* - **Folate deficiency** is very common in chronic alcoholism and primarily leads to **macrocytic anemia**. - While it can indirectly contribute to neurological issues due to anemia, it does not directly cause the classic acute neurological syndromes seen with thiamine deficiency. *Vitamin B12* - **Vitamin B12 deficiency** can cause neurological symptoms, including **peripheral neuropathy**, **ataxia**, and **cognitive impairment**, but it is less directly associated with alcoholism compared to thiamine deficiency. - B12 deficiency is more commonly seen in strict vegetarians, pernicious anemia, or malabsorption conditions involving the ileum.
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