Neurology — MCQs

A 9-month-old child develops vomiting and drowsiness following routine immunization. On examination, there is a bulging anterior fontanelle and fundoscopy reveals papilledema. The child develops cranial nerve palsies within a few hours. Despite these findings, the child remains afebrile with a clear chest. What is the most probable diagnosis?

Q30Medium

Which feature differentiates hydranencephaly from hydrocephalus?

Neurology Indian Medical PG Practice Questions and MCQs

Question 21: Deep white matter lesions with bilateral deep bright thalamic appearance are suggestive of which disease?

A. Alexander disease
B. Canavan's disease
C. Krabbe's disease (Correct Answer)
D. Metachromatic leukodystrophy

Explanation: **Explanation:** **Krabbe’s Disease (Globoid Cell Leukodystrophy)** is a lysosomal storage disorder caused by a deficiency of the enzyme **galactocerebrosidase (GALC)**. This leads to the accumulation of psychosine, which is toxic to oligodendrocytes. * **Imaging Hallmark:** On CT/MRI, Krabbe’s disease characteristically presents with **hyperdensities/T2-hyperintensities** in the **thalami**, caudate nuclei, and posterior limb of the internal capsule. The "deep bright thalamic appearance" combined with white matter involvement is a classic radiologic sign for this condition. **Analysis of Incorrect Options:** * **Alexander Disease:** Characterized by **frontal lobe predominance** of white matter lesions and the presence of Rosenthal fibers. It often presents with macrocephaly. * **Canavan’s Disease:** Notable for diffuse white matter involvement and **macrocephaly**. The hallmark metabolic marker is elevated **N-acetylaspartic acid (NAA)** on MR spectroscopy. * **Metachromatic Leukodystrophy (MLD):** The most common leukodystrophy (Arylsulfatase A deficiency). It typically shows a **"tigroid" or "leopard skin" pattern** of demyelination, sparing the subcortical U-fibers, but does not typically show the bright thalamic sign. **High-Yield Pearls for NEET-PG:** * **Krabbe’s:** Look for "Globoid cells" on biopsy and optic atrophy clinically. * **Thalamic Hyperdensity (CT):** Krabbe’s disease is the classic pediatric association. * **Macrocephaly + Leukodystrophy:** Think Alexander disease or Canavan’s disease. * **Adrenoleukodystrophy:** Predominantly involves the **posterior (occipital)** white matter.

Question 22: Which of the following is NOT a sign of raised intracranial pressure in a 7-month-old infant?

A. Papilledema (Correct Answer)
B. Bulging fontanelle
C. Increase in head size
D. Increasing irritability

Explanation: In infants, the clinical presentation of raised intracranial pressure (ICP) differs significantly from that of older children and adults due to the presence of open cranial sutures and a patent anterior fontanelle. **Why Papilledema is the Correct Answer:** Papilledema (swelling of the optic disc) is rarely seen in infants under the age of 1 year, even with significantly raised ICP. This is because the **open sutures and fontanelles** act as a "safety valve," allowing the skull to expand and accommodate the increased pressure. This decompression prevents the pressure from being transmitted directly to the optic nerve sheath. Therefore, the absence of papilledema does **not** rule out raised ICP in an infant. **Explanation of Incorrect Options:** * **Bulging Fontanelle:** This is the most reliable clinical sign of raised ICP in an infant. When the intracranial volume increases, the non-ossified anterior fontanelle becomes tense and protrudes. * **Increase in Head Size:** Since the cranial sutures are not yet fused, increased pressure leads to "macrocephaly" or a rapid increase in head circumference (crossing percentiles on a growth chart) as the bones are pushed apart. * **Increasing Irritability:** This is a common non-specific behavioral sign of raised ICP. It may be accompanied by a high-pitched cry, poor feeding, or projectile vomiting. **NEET-PG High-Yield Pearls:** * **Macewen’s Sign (Cracked-pot sign):** Percussion of the skull in an infant with raised ICP/hydrocephalus yields a resonant sound due to separated sutures. * **Sunset Sign:** Downward deviation of the eyes (sclera visible above the iris) is a late sign of raised ICP in infants. * **Cushing’s Triad:** Hypertension, bradycardia, and irregular respirations (a late sign of impending herniation).

Question 23: A 7-year-old boy has progressive difficulty in climbing stairs, walks with a waddling gait, and also has calf muscle hypertrophy. What is the most likely diagnosis?

A. Duchenne Muscular Dystrophy (DMD)
B. Myositis
C. Dermatomyositis
D. Becker's Muscular Dystrophy (Correct Answer)

Explanation: **Explanation** The clinical presentation of progressive proximal muscle weakness (difficulty climbing stairs), waddling gait, and **pseudohypertrophy of the calves** is characteristic of X-linked dystrophinopathies. **1. Why Becker’s Muscular Dystrophy (BMD) is correct:** The key differentiator here is the **age of the patient**. In Duchenne Muscular Dystrophy (DMD), symptoms typically manifest between 3–5 years of age, and most children are wheelchair-bound by age 12. In this case, the boy is 7 years old and still ambulatory with a waddling gait. BMD is a milder form of dystrophinopathy with a later onset (usually >7 years) and a slower rate of progression. While both DMD and BMD present with Gowers' sign and calf hypertrophy, the "later" presentation points toward BMD. **2. Why other options are incorrect:** * **Duchenne Muscular Dystrophy (DMD):** Though clinically similar, DMD is more severe and typically presents earlier (toddler age). By age 7, a DMD patient would usually show much more significant functional decline. * **Myositis/Dermatomyositis:** These are inflammatory myopathies. While they cause proximal weakness, they are usually associated with muscle pain, tenderness, and systemic features (fever, malaise). Dermatomyositis specifically presents with characteristic skin findings like **Gottron papules** and **Heliotrope rash**, which are absent here. Calf hypertrophy is not a feature of inflammatory myositis. **Clinical Pearls for NEET-PG:** * **Genetics:** Both DMD and BMD are X-linked recessive. DMD involves a **frameshift mutation** (total absence of dystrophin), while BMD involves a **non-frameshift mutation** (reduced or truncated dystrophin). * **Gowers' Sign:** The use of hands to "climb up" one's own body to stand up, indicating pelvic girdle weakness. * **Diagnosis:** Elevated Serum Creatine Kinase (CK) is the initial screening test (often >10x normal). Genetic testing for the *DMD* gene is the gold standard. * **Cardiac Involvement:** Dilated cardiomyopathy is a common complication in both, but often more prominent in BMD relative to the degree of muscle weakness.

Question 24: A 6-year-old child, weighing 20 kg, with a known seizure disorder and already on Valproate 200 mg twice daily, presents with breakthrough seizures to the pediatric casualty. The seizures were aborted with Inj. Lorazepam. What should be the next medication administered to this child?

A. Phenobarbitone
B. Phenytoin
C. Sodium Valproate (Correct Answer)
D. Levetiracetam

Explanation: **Explanation:** The core principle in managing breakthrough seizures in a child already on an Anti-Epileptic Drug (AED) is to **optimize the dose of the current medication** before switching or adding a new class, provided the current drug is appropriate for the seizure type. **Why Sodium Valproate is correct:** The child is currently receiving 400 mg/day (20 mg/kg/day) of Valproate. The standard therapeutic range for Valproate in pediatrics is **20–40 mg/kg/day**. Since the child is at the lower end of the therapeutic window and experiencing breakthrough seizures, the immediate next step is to administer an intravenous loading dose of Sodium Valproate (usually 15–20 mg/kg) to rapidly achieve therapeutic levels and prevent recurrence. **Why other options are incorrect:** * **Phenytoin:** It is a potent hepatic enzyme inducer. Adding it to Valproate complicates metabolism and increases the risk of drug-drug interactions and toxicity. It is generally avoided if Valproate can be optimized. * **Phenobarbitone:** While effective, it causes significant sedation and respiratory depression, especially when used after benzodiazepines (Lorazepam). It is typically reserved for refractory cases or neonatal seizures. * **Levetiracetam:** Although a safe add-on, the priority is to maximize the primary drug (Valproate) that has already been chosen for this patient's specific epilepsy syndrome. **Clinical Pearls for NEET-PG:** * **Valproate Loading Dose:** 20–40 mg/kg IV over 5–10 minutes. * **Drug of Choice:** Valproate is the drug of choice for generalized tonic-clonic seizures (GTCS) and myoclonic seizures in children. * **Status Epilepticus Protocol:** If seizures persist after two doses of benzodiazepines, the next step is a long-acting AED (Fosphenytoin, Valproate, or Levetiracetam). In a patient already on Valproate, Valproate is the preferred choice.

Question 25: A six-year-old girl presents with brief, irregular contractions in her feet. These symptoms are suspected to be a result of an untreated streptococcal infection. What is the most likely diagnosis?

A. Chorea gravidarum
B. Chorea major
C. Ballism
D. Sydenham chorea (Correct Answer)

Explanation: **Explanation:** The correct answer is **Sydenham chorea (D)**. This condition is a major clinical manifestation of **Acute Rheumatic Fever (ARF)**, occurring due to molecular mimicry where antibodies against Group A Beta-hemolytic Streptococcus (GABHS) cross-react with the basal ganglia (specifically the caudate and putamen). **Why Sydenham Chorea is correct:** It typically presents in children (ages 5–15) weeks to months after a streptococcal pharyngeal infection. The clinical hallmark is "chorea"—brief, purposeless, irregular, involuntary movements—often accompanied by muscular hypotonia and emotional lability. **Analysis of Incorrect Options:** * **A. Chorea gravidarum:** This refers to chorea occurring during pregnancy. While it is often a recurrence of Sydenham chorea triggered by hormonal changes, it is not the primary diagnosis for a six-year-old child. * **B. Chorea major:** This is an archaic term sometimes used for Huntington’s disease or severe chorea, but it is not a standard clinical diagnosis in the context of post-streptococcal sequelae. * **C. Ballism:** This involves large-amplitude, violent, flinging movements of the proximal limbs, usually unilateral (hemiballismus) and typically caused by a lesion in the subthalamic nucleus, not streptococcal infection. **Clinical Pearls for NEET-PG:** * **Jones Criteria:** Sydenham chorea is a **Major Criterion** for the diagnosis of ARF. * **Latent Period:** It has the longest latent period of all ARF features (up to 6 months). * **Clinical Signs:** Look for the **"Milkmaid’s grip"** (irregular contractions of hand muscles), **"Jack-in-the-box tongue"** (inability to protrude the tongue steadily), and **"Pronator sign."** * **Treatment:** Usually self-limiting; however, bed rest and penicillin prophylaxis are essential to prevent rheumatic heart disease. Severe cases may require valproate or carbamazepine.

Question 26: All of the following are causes of hypotonia in a 2-year-old child, except:

A. Trisomy 21
B. Spinal muscular atrophy
C. Congenital muscular dystrophy
D. Cerebral palsy (Correct Answer)

Explanation: **Explanation:** The core concept in pediatric hypotonia is distinguishing between **Lower Motor Neuron (LMN)** and **Upper Motor Neuron (UMN)** lesions. **Why Cerebral Palsy (CP) is the correct answer:** Cerebral Palsy is a non-progressive UMN disorder caused by an insult to the developing brain. While children with CP may present with transient "floppiness" in early infancy (the hypotonic phase), by age 2, the condition typically evolves into **spasticity** (hypertonia) and hyperreflexia. Therefore, in a 2-year-old, CP is characterized by increased muscle tone rather than persistent hypotonia. **Analysis of Incorrect Options:** * **Trisomy 21 (Down Syndrome):** This is a classic cause of **central (syndromic) hypotonia**. The hypotonia is persistent and associated with joint hyperlaxity and developmental delay. * **Spinal Muscular Atrophy (SMA):** This is an **LMN disorder** involving the anterior horn cells. It presents with profound, progressive hypotonia, "frog-leg" positioning, and absent deep tendon reflexes. * **Congenital Muscular Dystrophy (CMD):** This is a **myopathic cause** of hypotonia. It presents at birth or early childhood with muscle weakness, hypotonia, and often contractures. **Clinical Pearls for NEET-PG:** * **The "Floppy Infant" Rule:** Most cases of neonatal hypotonia are **Central** (80%), but if the infant is alert with severe weakness, suspect **Peripheral** causes (like SMA). * **Evolution of Tone:** CP is the most common cause of "changing tone"—starting as hypotonia and evolving into spasticity. * **Gower’s Sign:** While associated with Duchenne, it can be seen in various muscular dystrophies. * **SMA Type 1 (Werdnig-Hoffmann):** Most common genetic cause of death in infants; look for tongue fasciculations.

Question 27: What is the most common cause of fatal ventriculomegaly?

A. Arnold Chiari Malformation - I
B. Arnold Chiari Malformation - II
C. Aqueductal Stenosis (Correct Answer)
D. Dandy Walker Malformation

Explanation: **Explanation:** **Aqueductal Stenosis** is the most common cause of congenital obstructive (non-communicating) hydrocephalus, accounting for approximately 33% of cases. It involves a narrowing of the Aqueduct of Sylvius, which connects the third and fourth ventricles. This obstruction leads to significant **ventriculomegaly** (enlargement of the lateral and third ventricles) and is the leading cause of fetal/neonatal macrocephaly requiring surgical intervention. **Analysis of Options:** * **Arnold Chiari Malformation - II (Option B):** While this is the most common cause of hydrocephalus associated with **myelomeningocele**, it is less frequent as an isolated cause of fetal ventriculomegaly compared to aqueductal stenosis. * **Arnold Chiari Malformation - I (Option A):** This typically presents in adolescence or adulthood with cerebellar symptoms (downbeat nystagmus, ataxia) and is rarely a cause of significant fetal ventriculomegaly. * **Dandy Walker Malformation (Option D):** This involves cystic dilation of the fourth ventricle and cerebellar hypoplasia. While it causes hydrocephalus, its incidence is lower than that of aqueductal stenosis. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** "Setting sun" sign (downward gaze), bulging fontanelle, and rapidly increasing head circumference. * **X-ray finding:** "Copper beaten skull" (Luckenschadel skull) due to chronic increased intracranial pressure. * **Associated Infections:** Congenital **Toxoplasmosis** is a classic infectious cause of aqueductal stenosis due to periaqueductal inflammation/scarring. * **Genetic Link:** X-linked hydrocephalus (L1CAM mutation) is the most common inherited form, specifically causing aqueductal stenosis.

Question 28: What is the most common cause of extradural/subdural hemorrhage in children?

A. Arteriovenous malformation
B. Skull fracture (Correct Answer)
C. Aneurysm
D. Atherosclerosis

Explanation: **Explanation:** In the pediatric population, **trauma** is the leading cause of intracranial hemorrhage. Specifically, **skull fractures** are the most common cause of both extradural (epidural) and subdural hemorrhages. * **Extradural Hemorrhage (EDH):** This usually occurs due to an arterial bleed (most commonly the **middle meningeal artery**) following a skull fracture that lacerates the vessel. In children, the dura is less firmly attached to the skull than in adults, but a forceful impact causing a fracture remains the primary trigger. * **Subdural Hemorrhage (SDH):** While SDH is caused by the tearing of **bridging veins**, these injuries are frequently associated with high-impact trauma and concomitant skull fractures, or in infants, via non-accidental trauma (Shaken Baby Syndrome). **Analysis of Incorrect Options:** * **A. Arteriovenous Malformation (AVM):** While AVMs are a common cause of *intraparenchymal* or *subarachnoid* hemorrhage in children, they are rarely the primary cause of extradural or subdural bleeds. * **C. Aneurysm:** Cerebral aneurysms are rare in children compared to adults and typically present as *subarachnoid* hemorrhage (SAH). * **D. Atherosclerosis:** This is a disease of the elderly and is virtually non-existent as a cause of hemorrhage in the pediatric age group. **Clinical Pearls for NEET-PG:** * **EDH Shape:** Biconvex/Lens-shaped (does not cross sutures). * **SDH Shape:** Crescent-shaped (can cross sutures). * **Lucid Interval:** Classically associated with EDH. * **Non-Accidental Trauma (NAT):** If a child presents with SDH and retinal hemorrhages without a clear history of major trauma, suspect child abuse.

Question 29: A 9-month-old child develops vomiting and drowsiness following routine immunization. On examination, there is a bulging anterior fontanelle and fundoscopy reveals papilledema. The child develops cranial nerve palsies within a few hours. Despite these findings, the child remains afebrile with a clear chest. What is the most probable diagnosis?

A. Meningitis
B. Sagittal sinus thrombosis
C. Vitamin A toxicity (Correct Answer)
D. Astrocytoma

Explanation: ### Explanation The clinical presentation describes **Pseudotumor Cerebri** (Idiopathic Intracranial Hypertension), characterized by signs of increased intracranial pressure (ICP) such as vomiting, drowsiness, bulging fontanelle, papilledema, and cranial nerve palsies (typically CN VI), in an **afebrile** child. **Why Vitamin A Toxicity is Correct:** Acute Vitamin A toxicity is a well-known cause of bulging fontanelle and increased ICP in infants. In many developing countries, high-dose Vitamin A supplementation is administered alongside routine immunizations (e.g., Measles vaccine at 9 months). This explains the temporal relationship mentioned in the question. Excess Vitamin A interferes with the resorption of cerebrospinal fluid (CSF) at the arachnoid villi, leading to rapid onset of intracranial hypertension without fever or meningeal signs. **Why Other Options are Incorrect:** * **Meningitis:** Ruled out by the absence of fever and the rapid progression of focal signs without systemic inflammatory markers. * **Sagittal Sinus Thrombosis:** While it causes increased ICP, it is usually associated with predisposing factors like severe dehydration, prothrombotic states, or infection (mastoiditis), and often presents with seizures. * **Astrocytoma:** Brain tumors cause a more subacute or chronic progression of symptoms rather than an acute onset following a specific event like immunization. **NEET-PG High-Yield Pearls:** * **Classic Triad of Pseudotumor Cerebri:** Headache (or bulging fontanelle in infants), papilledema, and normal CSF composition with increased opening pressure. * **Common Triggers:** Vitamin A (excess or deficiency), Tetracyclines, Steroid withdrawal, and Growth Hormone therapy. * **Cranial Nerve Involvement:** The 6th cranial nerve is most commonly affected due to its long intracranial course (false localizing sign). * **Management:** Withdrawal of the offending agent; acetazolamide may be used to decrease CSF production.

Question 30: Which feature differentiates hydranencephaly from hydrocephalus?

A. Hydranencephaly is static while hydrocephalus continues to increase in size.
B. Hydranencephaly does not cause an increase in head size.
C. Cerebral cortex is deficient or hypoplastic in hydranencephaly. (Correct Answer)
D. All of the above.

Explanation: **Explanation:** The fundamental difference between these two conditions lies in the **presence or absence of the cerebral mantle**. 1. **Why Option C is Correct:** **Hydranencephaly** is a rare condition where the cerebral hemispheres are absent and replaced by sacs filled with cerebrospinal fluid (CSF). It is typically caused by a vascular insult (bilateral internal carotid artery occlusion) in utero. Because the brain tissue itself is destroyed or never developed, the **cerebral cortex is deficient or hypoplastic**. In contrast, **Hydrocephalus** is a disorder of CSF dynamics (production, flow, or absorption) where the cerebral cortex is present but may be thinned or compressed due to increased intracranial pressure. 2. **Why Other Options are Incorrect:** * **Option A:** While hydrocephalus is often progressive, hydranencephaly is not always "static." The head size in hydranencephaly can actually increase over time due to continued CSF production by the preserved choroid plexus, making this a poor differentiating feature. * **Option B:** Hydranencephaly **can** cause macrocephaly (increased head size). In fact, it often presents with an enlarging head circumference, mimicking hydrocephalus clinically. **NEET-PG High-Yield Pearls:** * **Transillumination Test:** This is the classic clinical test. In hydranencephaly, the entire skull transilluminates brilliantly because there is no cortex to block the light. In hydrocephalus, transillumination is usually limited or absent (unless the cortical mantle is <1 cm). * **Preserved Structures:** In hydranencephaly, the posterior fossa structures (cerebellum, brainstem) and parts of the basal ganglia are usually **preserved** because they are supplied by the vertebral-basilar system, not the carotid system. * **Clinical Presentation:** Infants with hydranencephaly may initially appear normal (due to intact brainstem reflexes) but fail to meet developmental milestones.

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