Neurology Practice Questions

Q: Sudden onset of tics and obsessive-compulsive symptoms in a child after Scarlet fever is most likely due to which of the following mechanisms?

Autoimmune response. ### Explanation The clinical presentation described is characteristic of **PANDAS** (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections). **1. Why the Correct Answer is Right:** The underlying mechanism is an **autoimmune response** triggered by Group A Beta-hemolytic Streptococcus (GABHS), the causative agent of Scarlet fever. Similar to Sydenham’s chorea in Rheumatic Fever, PANDAS involves **molecular mimicry**. Antibodies produced against streptococcal antigens cross-react with host tissues—specifically the **basal ganglia**. This neuroinflammation leads to the sudden, "overnight" onset of motor/vocal tics and Obsessive-Compulsive Disorder (OCD) symptoms. **2. Why the Other Options are Wrong:** * **Meningitis (A):** Presents with fever, headache, neck stiffness, and altered sensorium. It does not typically cause isolated, sudden-onset tics or OCD. * **Misdiagnosis (C):** Scarlet fever has a distinct clinical triad (strawberry tongue, sandpaper rash, circumoral pallor); a misdiagnosis would not explain the specific neuropsychiatric sequelae. * **Bacterial emboli (D):** This is a feature of Infective Endocarditis, leading to focal neurological deficits (strokes) or abscesses, rather than behavioral and tic disorders. **3. NEET-PG High-Yield Pearls:** * **Diagnostic Criteria:** Sudden onset, pediatric age group (3 years to puberty), association with GABHS (positive throat culture or elevated ASO/Anti-DNase B titers), and episodic (waxing/waning) course. * **Anatomical Site:** The **Basal Ganglia** (specifically the caudate nucleus) is the primary site of pathology. * **Differential:** Always differentiate from **Sydenham’s Chorea**, which involves purposeless, involuntary movements but is a major Jones criterion for Rheumatic Fever. PANDAS is specifically characterized by tics and OCD.

Q: A 12-year-old girl presents with headache, unsteadiness, and hearing loss that has worsened over the past 5 years. Her father has a history of brain surgery and has been deaf since age 35. What is the most likely diagnosis in the child?

Neurofibromatosis 2. ### Explanation The clinical presentation of progressive hearing loss, unsteadiness (vestibular dysfunction), and headache in a child with a strong paternal history of similar symptoms is classic for **Neurofibromatosis Type 2 (NF2)**. **Why NF2 is the correct answer:** NF2 is an autosomal dominant condition caused by a mutation in the *merlin* gene on **chromosome 22**. The hallmark of NF2 is **bilateral vestibular schwannomas** (acoustic neuromas). These tumors compress the VIII cranial nerve, leading to sensorineural hearing loss, tinnitus, and dysequilibrium. The patient’s headache and unsteadiness suggest increased intracranial pressure or cerebellar compression. The father’s history of brain surgery and deafness further confirms an inherited tumor syndrome. **Analysis of Incorrect Options:** * **A. Optic glioma:** This is a characteristic feature of **NF1** (chromosome 17), not NF2. NF1 typically presents with Lisch nodules, café-au-lait spots, and neurofibromas, rather than early-onset bilateral deafness. * **B. Tuberous sclerosis:** This neurocutaneous syndrome presents with the triad of seizures, intellectual disability, and adenoma sebaceum. It is associated with subependymal giant cell astrocytomas (SEGA), not vestibular schwannomas. * **D. Late onset congenital deafness:** This would not explain the unsteadiness, headaches, or the father’s history of brain surgery, which point toward a neoplastic process. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for NF2:** **22** (Chromosome **22**, **2** ears/bilateral schwannomas, **2** eyes/cataracts). * **Ocular finding in NF2:** Juvenile posterior subcapsular lenticular opacity (cataract) is a common early sign. * **MISME Syndrome:** NF2 is often associated with **M**ultiple **I**ntracranial **S**chwannomas, **M**eningiomas, and **E**pendymomas. * **Diagnostic Gold Standard:** Gadolinium-enhanced MRI of the brain and internal auditory canal.

Q: A 12-year-old boy presents with progressive muscular weakness and is unable to get up from a squatting position. He is diagnosed with a hereditary muscular disorder. What is the mode of inheritance in this disorder?

X-linked recessive. **Explanation:** The clinical presentation of a 12-year-old boy with progressive proximal muscle weakness and difficulty rising from a squatting position (indicative of a positive **Gowers’ sign**) is classic for **Duchenne Muscular Dystrophy (DMD)** or the milder **Becker Muscular Dystrophy (BMD)**. Both conditions are caused by mutations in the *DMD* gene located on the X chromosome, which encodes the protein **dystrophin**. **1. Why X-linked Recessive is correct:** DMD and BMD follow an **X-linked recessive (XLR)** inheritance pattern. This means the disorder primarily affects males, while females are typically asymptomatic carriers. The gene is located on the short arm of the X chromosome (Xp21). **2. Why other options are incorrect:** * **Autosomal Dominant:** While some muscular dystrophies like Facioscapulohumeral (FSHD) or Myotonic Dystrophy follow this pattern, they present with different clinical features (e.g., facial involvement or myotonia) and usually at a later age. * **Mitochondrial:** These disorders (e.g., MELAS) involve multi-system organs (brain, heart) and are inherited exclusively from the mother to all offspring. * **X-linked Dominant:** In this pattern, both males and females are affected, and an affected father would pass the trait to all his daughters but no sons. **Clinical Pearls for NEET-PG:** * **Gowers’ Sign:** Using hands to "climb up" one's own body to stand due to pelvic girdle weakness. * **Pseudohypertrophy:** The calves appear large but are actually composed of fat and connective tissue (fibrosis). * **Lab Marker:** Significantly elevated **Serum Creatine Kinase (CPK)** levels (often >10-50 times normal). * **Diagnosis:** Genetic testing (MLPA) is the gold standard; Muscle biopsy shows absent (DMD) or reduced (BMD) dystrophin. * **Cause of Death:** Usually respiratory failure or dilated cardiomyopathy in the late teens or early twenties.

Q: An infant presents with hypotonia and hyporeflexia. During the intrauterine period, there was polyhydramnios and decreased fetal movements. What is the most probable diagnosis?

Spinal muscular atrophy. ### Explanation The clinical presentation of **hypotonia** (floppy infant) and **hyporeflexia** (absent or diminished deep tendon reflexes) indicates a **Lower Motor Neuron (LMN)** lesion. **1. Why Spinal Muscular Atrophy (SMA) is correct:** SMA Type 1 (Werdnig-Hoffmann disease) is the most common cause of "Floppy Infant Syndrome" due to the degeneration of anterior horn cells. * **Intrauterine signs:** Decreased fetal movements and polyhydramnios (due to poor fetal swallowing) are classic indicators of severe prenatal onset. * **Clinical features:** Severe generalized hypotonia, a "frog-leg" posture, and **absent reflexes**. Tongue fasciculations are a pathognomonic finding. **2. Why other options are incorrect:** * **Congenital Myasthenia:** This is a disorder of the neuromuscular junction. While it presents with hypotonia and ptosis, reflexes are typically **preserved**, and symptoms often fluctuate. * **Congenital Myotonia:** This involves delayed muscle relaxation (myotonia). It does not typically present with severe neonatal hypotonia or hyporeflexia; symptoms usually manifest later in childhood. * **Muscular Dystrophy:** Duchenne Muscular Dystrophy (DMD) rarely presents in the neonatal period. Congenital Muscular Dystrophies can cause hypotonia, but they are less common than SMA and often associated with brain malformations or contractures (arthrogryposis). **Clinical Pearls for NEET-PG:** * **SMA Genetics:** Autosomal recessive; mutation in the **SMN1 gene** on chromosome **5q**. * **Reflex Rule:** In a floppy infant, **absent reflexes** point to SMA (Anterior Horn Cell), while **exaggerated reflexes** point to Central Nervous System causes (e.g., Ataxic Cerebral Palsy). * **Sensation:** In SMA, despite profound motor weakness, sensory involvement is absent, and extraocular muscles are spared.

Q: A 6-month-old child presents with multiple episodes of focal seizures, developmental delay, learning difficulties, and ADHD. Examination reveals macrocephaly, hemianopsia, a facial lesion, glaucoma with buphthalmos, and conjunctival and episcleral hemangiomas. Which of the following genes is most likely mutated?

GNAQ. ### Explanation The clinical presentation described is a classic case of **Sturge-Weber Syndrome (SWS)**, also known as encephalofacial angiomatosis. The hallmark features include a facial capillary malformation (Port-wine stain/Nevus flammeus), leptomeningeal angiomas (leading to seizures, hemianopsia, and developmental delay), and ocular involvement (glaucoma and buphthalmos). **1. Why GNAQ is correct:** Sturge-Weber Syndrome is caused by a **somatic activating mutation** in the **GNAQ gene** (located on chromosome 9q21). This gene encodes the Gαq protein, which is involved in G-protein coupled receptor signaling. The mutation occurs post-zygotically, meaning it is not inherited (sporadic) and results in mosaicism. This leads to abnormal vascular development in the skin, brain, and eyes. **2. Why the other options are incorrect:** * **RAS:** Mutations in the RAS pathway (e.g., *KRAS, HRAS*) are typically associated with "RASopathies" like Noonan syndrome or Costello syndrome, or specific vascular malformations like Schimmelpenning syndrome, but not SWS. * **FGF:** Fibroblast Growth Factor mutations are primarily associated with craniosynostosis syndromes (e.g., Apert or Pfeiffer syndrome) and achondroplasia. * **MYC:** This is a proto-oncogene frequently associated with malignancies like Burkitt lymphoma, not neurocutaneous syndromes. **Clinical Pearls for NEET-PG:** * **Port-wine stain:** Usually follows the distribution of the Trigeminal nerve (V1 and V2 branches). * **Radiology:** Skull X-ray or CT shows **"Tram-track" calcifications** (gyriform calcifications) in the leptomeninges. * **Management:** Seizure control is the priority; glaucoma requires lifelong monitoring. * **Key Association:** SWS is a **Phakomatosis** (neurocutaneous syndrome) that, unlike Neurofibromatosis or Tuberous Sclerosis, is **not inherited**.

Q: Which one of the following is the most common cause of congenital hydrocephalus?

Aqueductal stenosis. **Explanation:** **Aqueductal Stenosis (Option D)** is the most common cause of congenital hydrocephalus, accounting for approximately **43% of cases**. The Aqueduct of Sylvius is the narrowest point in the ventricular system, connecting the third and fourth ventricles. Obstruction here (due to gliosis, forking, or septum formation) leads to **non-communicating (obstructive) hydrocephalus**, characterized by dilation of the lateral and third ventricles with a normal-sized fourth ventricle. **Analysis of Incorrect Options:** * **Malformations of the great vein of Galen (Option A):** While these arteriovenous malformations can cause hydrocephalus due to venous hypertension or direct compression of the aqueduct, they are a rare vascular cause. * **Craniosynostosis (Option B):** This is the premature fusion of cranial sutures. While it can lead to increased intracranial pressure, it is not a primary cause of hydrocephalus; rather, it limits the skull's ability to expand. * **Intrauterine meningitis (Option C):** Infections (like Toxoplasmosis or CMV) can cause hydrocephalus via inflammatory debris blocking the subarachnoid space (communicating) or aqueduct (obstructive), but statistically, idiopathic or genetic aqueductal stenosis remains more frequent. **High-Yield Clinical Pearls for NEET-PG:** * **X-linked Hydrocephalus:** The most common genetic form, caused by mutations in the **L1CAM gene**, often presenting with aqueductal stenosis and thumb adduction (clasped thumb). * **Dandy-Walker Malformation:** Characterized by a triad of cystic dilation of the 4th ventricle, cerebellar vermis hypoplasia, and an enlarged posterior fossa. * **Chiari II Malformation:** Almost always associated with myelomeningocele and is a major cause of hydrocephalus in neonates. * **Clinical Sign:** "Setting-sun" eye phenomenon (downward gaze) due to pressure on the midbrain tectum.

Q: A 7-year-old boy, who gets easily distracted in class with poor academic performance, experiences a seizure episode after hyperventilation. What is the diagnosis suggested by the EEG findings shown in the image?

Absence seizures. ***Absence seizures*** - **Childhood absence epilepsy** typically presents with **inattentiveness** and **poor academic performance** that can mimic ADHD, along with brief episodes of staring and unresponsiveness. - Seizures are characteristically **precipitated by hyperventilation** and show classic **3 Hz generalized spike-and-wave discharges** on EEG. *Myoclonic seizures* - Present with sudden, brief **muscle jerks** affecting arms, legs, or entire body, not the subtle behavioral changes described. - EEG shows **polyspike-and-wave complexes** rather than the typical 3 Hz pattern seen in absence seizures. *Atonic seizures* - Characterized by sudden **loss of muscle tone** causing **drop attacks** where the child falls to the ground. - EEG patterns are different from absence seizures and typically show **slow spike-and-wave** or **polyspike-and-wave** discharges. *Myotonia* - This is **not a seizure disorder** but a **muscle disorder** characterized by delayed muscle relaxation after contraction. - Associated with conditions like **myotonic dystrophy** and does not involve altered consciousness or EEG abnormalities.

Q: A 10-year-old girl develops ataxia and hydrocephalus. A CT scan shows a midline cerebellar mass. Which of the following is the most likely diagnosis?

Medulloblastoma. ### Explanation **Correct Answer: B. Medulloblastoma** **Why it is correct:** Medulloblastoma is the most common malignant brain tumor in children. It characteristically arises from the **vermis (midline)** of the cerebellum. Because of its location in the roof of the fourth ventricle, it frequently causes obstructive hydrocephalus by compressing the ventricular system, leading to symptoms of increased intracranial pressure (headache, vomiting) and truncal ataxia. On imaging, it typically appears as a solid, enhancing midline mass in the posterior fossa. **Why the other options are incorrect:** * **A. Meningioma:** These are typically slow-growing, extra-axial tumors common in adults, not children. They usually arise from the arachnoid cap cells and are rarely found in the posterior fossa in a pediatric patient. * **C. Neurofibroma:** These are benign nerve sheath tumors associated with Neurofibromatosis Type 1. They typically involve peripheral nerves or the spinal cord, not the cerebellar midline. * **D. Astrocytoma:** While Pilocytic Astrocytoma is the most common pediatric brain tumor overall, it usually arises in the **cerebellar hemispheres** (lateral) rather than the midline and often presents as a cystic lesion with an enhancing mural nodule on imaging. **NEET-PG High-Yield Pearls:** * **Location Rule:** Midline cerebellar tumors (Vermis) → Medulloblastoma (Truncal ataxia). Lateral cerebellar tumors (Hemispheres) → Astrocytoma (Limb ataxia/dysmetria). * **Histology:** Look for **Homer-Wright rosettes** and small round blue cells. * **Drop Metastasis:** Medulloblastoma has a high propensity to spread via CSF; always screen the entire neuraxis (spine) with MRI. * **Genetic Association:** Associated with **Turcot Syndrome** (Type 2) and Gorlin Syndrome.

Q: What is the most common age group for febrile seizures?

6 months to 5 years. **Explanation:** **Febrile seizures** are the most common convulsive disorder in the pediatric population. By definition, they occur in children between **6 months and 5 years (60 months) of age**, associated with a fever (>38°C or 100.4°F) that is not caused by a central nervous system (CNS) infection or metabolic imbalance, and in children without a history of prior afebrile seizures. **Why Option B is Correct:** The peak incidence occurs between **12 to 18 months**. The brain in this age group (6 months to 5 years) is uniquely vulnerable to seizures triggered by a rapid rise in temperature due to an immature thermoregulatory system and developing neuronal excitability. **Analysis of Incorrect Options:** * **Option A & D:** Seizures occurring before 6 months of age are rarely "simple" febrile seizures. In infants younger than 6 months, a seizure with fever mandates a workup for **meningitis or encephalitis**, as the clinical signs of meningeal irritation are often absent in this age group. * **Option C:** While many febrile seizures occur before age 2, the clinical definition and risk period extend up to 5 years. Stopping at 2 years would exclude a significant portion of the affected population. **High-Yield Clinical Pearls for NEET-PG:** * **Simple Febrile Seizure:** Generalized tonic-clonic, lasts 15 minutes, or recurs within 24 hours. * **Risk of Recurrence:** Approximately 30% overall; higher if the first seizure occurs before 1 year of age. * **Management:** Reassurance is key. Long-term anticonvulsants are **not** recommended. For abortive therapy (if seizure lasts >5 mins), **Intranasal/IV Midazolam** or **Rectal Diazepam** is used.

Question 1

Sudden onset of tics and obsessive-compulsive symptoms in a child after Scarlet fever is most likely due to which of the following mechanisms?

Accepted Answer

Autoimmune response

Answer

Meningitis

Answer

Misdiagnosis of initial infection

Answer

Bacterial emboli

Question 2

A 12-year-old girl presents with headache, unsteadiness, and hearing loss that has worsened over the past 5 years. Her father has a history of brain surgery and has been deaf since age 35. What is the most likely diagnosis in the child?

Accepted Answer

Neurofibromatosis 2

Answer

Optic glioma

Answer

Tuberous sclerosis

Answer

Late onset congenital deafness

Question 3

A 12-year-old boy presents with progressive muscular weakness and is unable to get up from a squatting position. He is diagnosed with a hereditary muscular disorder. What is the mode of inheritance in this disorder?

Accepted Answer

X-linked recessive

Answer

Autosomal dominant

Answer

Mitochondrial

Answer

X-linked dominant

Question 4

An infant presents with hypotonia and hyporeflexia. During the intrauterine period, there was polyhydramnios and decreased fetal movements. What is the most probable diagnosis?

Accepted Answer

Spinal muscular atrophy

Answer

Congenital myasthenia

Answer

Congenital myotonia

Answer

Muscular dystrophy

Question 5

Which of the following is NOT a characteristic of typical febrile seizures?

Accepted Answer

EEG shows persistent abnormality

Answer

Commonest cause of seizures in children

Answer

Seizures do not last for more than 15 minutes

Answer

No postictal neurological deficit

Question 6

A 6-month-old child presents with multiple episodes of focal seizures, developmental delay, learning difficulties, and ADHD. Examination reveals macrocephaly, hemianopsia, a facial lesion, glaucoma with buphthalmos, and conjunctival and episcleral hemangiomas. Which of the following genes is most likely mutated?

Accepted Answer

GNAQ

Answer

RAS

Answer

FGF

Answer

MYC

Question 7

Which one of the following is the most common cause of congenital hydrocephalus?

Accepted Answer

Aqueductal stenosis

Answer

Malformations of great vein of Galen

Answer

Craniosynostosis

Answer

Intrauterine meningitis

Question 8

A 7-year-old boy, who gets easily distracted in class with poor academic performance, experiences a seizure episode after hyperventilation. What is the diagnosis suggested by the EEG findings shown in the image?

Accepted Answer

Absence seizures

Answer

Myoclonic seizures

Answer

Atonic seizures

Answer

Myotonia

Question 9

A 10-year-old girl develops ataxia and hydrocephalus. A CT scan shows a midline cerebellar mass. Which of the following is the most likely diagnosis?

Accepted Answer

Medulloblastoma

Answer

Meningioma

Answer

Neurofibroma

Answer

Astrocytoma

Question 10

What is the most common age group for febrile seizures?

Accepted Answer

6 months to 5 years

Answer

1 month to 1 year

Answer

6 months to 2 years

Answer

2 months to 5 years

Neurology — MCQs

Neurology — MCQs

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