Neurology Practice Questions

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: Neurofibromatosis type 2 is associated with which of the following?

All of the above. **Explanation:** Neurofibromatosis Type 2 (NF2), also known as **MISME syndrome** (Multiple Inherited Schwannomas, Meningiomas, and Ependymomas), is an autosomal dominant neurocutaneous disorder. * **Bilateral Acoustic Neuroma (Vestibular Schwannoma):** This is the **hallmark** and most specific clinical feature of NF2. It typically presents with progressive hearing loss, tinnitus, and imbalance in the second or third decade of life. * **Cafe-au-lait spots:** While more characteristic and numerous in NF1, cafe-au-lait spots **do occur** in NF2, though they are usually fewer in number and lighter in color. * **Chromosome 22 deletion:** The NF2 gene is located on the long arm of **chromosome 22 (22q12)**. It encodes the protein **Merlin** (also called Schwannomin), which acts as a tumor suppressor. Mutations or deletions in this gene lead to the development of characteristic tumors. **Why "All of the above" is correct:** NF2 is a multisystem genetic disorder. Since it involves the 22q12 locus, presents with bilateral vestibular schwannomas, and can manifest with cutaneous markers like cafe-au-lait spots, all three individual options are clinically accurate. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for NF2:** "22" — Chromosome **22**, Bilateral (two) acoustic neuromas, and the protein Merlin (2 syllables). * **Ocular Finding:** Juvenile posterior subcapsular lenticular opacities (cataracts) are an early diagnostic sign in NF2. * **NF1 vs. NF2:** NF1 (von Recklinghausen) is on Chromosome **17** and is associated with Lisch nodules and Optic Gliomas; NF2 lacks Lisch nodules and is associated with Meningiomas.

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: Hypotonia with brisk tendon reflexes is typically seen in which condition?

Hypotonic cerebral palsy. **Explanation:** The clinical combination of **hypotonia** (low muscle tone) and **brisk tendon reflexes** (hyperreflexia) is a hallmark of an **Upper Motor Neuron (UMN) lesion** during the acute or specific evolutionary phases. 1. **Why Hypotonic Cerebral Palsy (CP) is correct:** Cerebral Palsy is a non-progressive UMN disorder. While most CP cases eventually manifest as spasticity, the **Hypotonic (Atonic) variant** presents with persistent low tone. Because the lesion is in the brain (central), the inhibitory control over the spinal reflex arc is lost, leading to **brisk deep tendon reflexes (DTRs)** and often a positive Babinski sign, despite the floppy muscles. 2. **Why the other options are incorrect:** * **Guillain-Barré Syndrome (GBS):** This is a Lower Motor Neuron (LMN) disorder affecting peripheral nerves. It presents with hypotonia and **absent or diminished reflexes** (areflexia/hyporeflexia). * **Spinal Muscular Atrophy (SMA):** This involves destruction of the anterior horn cells (LMN). It is characterized by profound hypotonia ("floppy infant") and **absent reflexes**. * **Infantile Tremor Syndrome (ITS):** Typically presents with tremors, anemia, and regression of milestones. While hypotonia can occur, it is not classically associated with brisk reflexes in the same diagnostic manner as UMN lesions. **High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of Thumb":** Hypotonia + Brisk Reflexes = Central/Brain pathology (UMN). Hypotonia + Absent Reflexes = Peripheral/Nerve/Muscle pathology (LMN). * **Evolution of CP:** Many infants who later develop spastic CP pass through a transient "hypotonic phase" (Dystonic/Athetoid types). * **Differential for Hypotonic CP:** Always consider Benign Congenital Hypotonia, but reflexes would be normal there, not brisk.

Q: Which of the following statements about hydrocephalus is true?

Macewen sign is seen. **Explanation:** Hydrocephalus in infants is characterized by an abnormal accumulation of cerebrospinal fluid (CSF), leading to increased intracranial pressure (ICP) and macrocephaly. **1. Why Option A is correct:** The **Macewen sign** (also known as the "cracked-pot sign") is a classic clinical finding in infants with hydrocephalus. Due to increased ICP, the cranial sutures separate. When the skull is percussed near the junction of the frontal, temporal, and parietal bones, it produces a resonant, hollow sound similar to a cracked pot. **2. Why the other options are incorrect:** * **Option B:** While the **Sun-setting sign** (downward deviation of the eyes with the sclera visible above the iris) is indeed a classic sign of hydrocephalus, the question structure requires identifying the *most* accurate statement or evaluating if "All of the above" applies. * **Option C:** The most common cause of congenital hydrocephalus is **Aqueductal Stenosis** (stenosis of the Aqueduct of Sylvius), not Dandy-Walker malformation. * **Option D:** Since Option C is factually incorrect, "All of the above" cannot be the answer. **Clinical Pearls for NEET-PG:** * **Transillumination Test:** Often positive in severe hydrocephalus or hydranencephaly. * **Cushing’s Triad:** A late sign of increased ICP consisting of bradycardia, hypertension, and irregular respirations. * **Dandy-Walker Malformation:** Characterized by the triad of cystic dilation of the 4th ventricle, cerebellar vermis hypoplasia, and an enlarged posterior fossa. * **Chiari II Malformation:** Frequently associated with myelomeningocele and obstructive hydrocephalus.

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.

Question 1

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 2

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 3

Neurofibromatosis type 2 is associated with which of the following?

Accepted Answer

All of the above

Answer

Bilateral acoustic neuroma

Answer

Cafe-au-lait spots

Answer

Chromosome 22 deletion

Question 4

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 5

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 6

Foster's test is used in the diagnosis of which condition?

Accepted Answer

Spastic type of cerebral palsy

Answer

Hypotonic cerebral palsy

Answer

Choreoathetotic cerebral palsy

Answer

Myasthenia gravis

Question 7

Which of the following leads to communicating hydrocephalus?

Accepted Answer

Choroid plexus papilloma

Answer

Arnold-Chiari malformation

Answer

Dandy-Walker malformation

Answer

Vein of Galen malformation

Question 8

Hypotonia with brisk tendon reflexes is typically seen in which condition?

Accepted Answer

Hypotonic cerebral palsy

Answer

Guillain-Barré syndrome

Answer

Spinal muscular atrophy

Answer

Infantile tremor syndrome

Question 9

Which of the following statements about hydrocephalus is true?

Accepted Answer

Macewen sign is seen

Answer

Sun-setting sign of the eyes is seen

Answer

The most common cause is Dandy-Walker malformation

Answer

All of the above

Question 10

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

Neurology — MCQs

Neurology — MCQs

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