NEET-PG 2013 Practice Questions

Q: 3 beta hydroxysteroid dehydrogenase deficiency causes increased production of -

DHEA. ***DHEA*** - The enzyme **3 beta-hydroxysteroid dehydrogenase (3β-HSD)** is crucial for converting **delta-5 steroids (pregnenolone, 17-OH-pregnenolone, and DHEA)** into **delta-4 steroids (progesterone, 17-OH-progesterone, and androstenedione)**. - A **deficiency** in 3β-HSD leads to the accumulation of its substrates, particularly **DHEA (dehydroepiandrosterone)** and **17-OH-pregnenolone**, due to the impaired conversion in the steroid synthesis pathway. - Among the accumulated substrates, **DHEA** has weak androgenic activity, making it clinically significant in this enzyme deficiency. *Progesterone* - **Progesterone** is a delta-4 steroid, which is synthesized from **pregnenolone** via the action of **3β-HSD**. - A deficiency in this enzyme would **decrease** the production of progesterone, not increase it, as the enzyme is required for its synthesis. *Deoxycortisol* - **Deoxycortisol (11-deoxycortisol)** is a precursor to cortisol, formed later in the adrenal steroid synthesis pathway from **17-hydroxyprogesterone**. - Its production would be **decreased** by a 3β-HSD deficiency, as the pathway is blocked upstream, reducing the formation of downstream products like cortisol and its precursors. *Estradiol* - **Estradiol** is an estrogen, synthesized from androgens (like testosterone) via the enzyme **aromatase**. - A deficiency in 3β-HSD would impair the production of androgens like androstenedione and testosterone, which are precursors for estradiol, thereby leading to a **decrease** in estradiol levels, not an increase.

Q: Isolated painful third nerve palsy is a feature of aneurysms of:

Aneurysm of the posterior communicating artery. ***Aneurysm of the posterior communicating artery*** - An aneurysm of the **posterior communicating artery (PCOM)** can compress the ipsilateral **oculomotor nerve (CN III)** as it exits the brainstem. - This compression typically affects the **superficial parasympathetic fibers** first, leading to a **dilated pupil** (mydriasis) along with ophthalmoplegia and ptosis, making the third nerve palsy "painful" and "isolated" without other focal neurological deficits. *Aneurysm of the anterior communicating artery* - Aneurysms of the **anterior communicating artery (ACoM)** are more commonly associated with **subarachnoid hemorrhage** and can cause **visual field defects** or **frontal lobe dysfunction**, but generally not isolated CN III palsy. - While rupture can lead to various neurological deficits, isolated painful third nerve palsy due to ACoM aneurysm is atypical. *Aneurysm of the vertebrobasillary artery* - Aneurysms in the **vertebrobasillar system** typically present with symptoms related to **brainstem compression** or ischemia, such as cranial nerve palsies beyond the third nerve, ataxia, or motor/sensory deficits. - Isolated third nerve palsy is an uncommon presentation for vertebrobasilar aneurysms compared to PCOM aneurysms. *Aneurysm of the ophthalmic artery* - **Ophthalmic artery aneurysms** are usually **intraorbital** and can cause **visual loss** due to direct compression of the **optic nerve (CN II)** or orbital structures. - They are less likely to cause isolated painful third nerve palsy, as the third nerve's course is generally not directly compromised by ophthalmic artery aneurysms.

Q: ECG image showing U wave. Patient is on furosemide and beta blocker. What is the most likely diagnosis?

Hypokalemia. ***Hypokalemia*** - The presence of **U waves** on an ECG is a classic sign of **hypokalemia**, often seen when serum potassium levels drop below 3.0 mEq/L. - The patient is taking **furosemide**, a loop diuretic, which commonly causes potassium loss and thus **hypokalemia**. *Hypocalcemia* - Hypocalcemia typically manifests on an ECG as a **prolonged QT interval**, not prominent U waves. - While furosemide can affect calcium, it usually leads to **hypercalcemia** due to volume contraction, not hypocalcemia. *Hyperkalemia* - Hyperkalemia is characterized by **tall, peaked T waves**, a **prolonged PR interval**, and a **widened QRS complex** on an ECG. U waves are absent. - Furosemide *causes* potassium excretion, making hyperkalemia an unlikely finding in this context. *Hypercalcemia* - Hypercalcemia typically causes a **shortened QT interval** on an ECG. U waves are not a feature. - While furosemide may sometimes lead to slight increases in calcium, it is not associated with U waves.

Q: In head injury, unilateral dilatation of the pupil is seen due to?

Oculomotor nerve compression. Oculomotor nerve compression - Unilateral pupillary dilation, often referred to as a **blown pupil**, is a classic sign of **oculomotor nerve (CN III) compression** due to increased intracranial pressure, typically from a **herniating uncus** [1]. - The parasympathetic fibers responsible for pupillary constriction run on the superficial aspect of the oculomotor nerve and are thus vulnerable to extrinsic compression [1], [2]. *Ophthalmic N. compression* - The **ophthalmic nerve (CN V1)** is a sensory nerve responsible for sensation to the forehead, scalp, upper eyelid, and cornea, not pupillary control. - Compression of this nerve would cause **sensory deficits** in its distribution and potentially abolish the **corneal reflex**, but not pupillary dilation. *Trigeminal N. compression* - The **trigeminal nerve (CN V)** is primarily responsible for sensation to the face and motor control of the muscles of mastication. - Compression would lead to **facial numbness or pain** and **weakness in chewing**, with no direct impact on pupillary size. *None of the options* - This option is incorrect because oculomotor nerve compression is a well-established cause of unilateral pupillary dilation in head injuries [1].

Q: Binocular single vision is tested by?

Synoptophore. ***Synoptophore*** - The **synoptophore** is an ophthalmic instrument used to diagnose and treat various binocular vision anomalies, including **strabismus** and suppression. - It allows for the precise measurement and assessment of the eyes' ability to **fuse images** from both eyes into a single perception, which is the essence of **binocular single vision**. *Amsler grid* - The **Amsler grid** is primarily used to detect central visual field defects, such as those caused by **macular degeneration** or other retinal pathologies. - It does not directly assess the brain's ability to fuse images from both eyes into a single vision. *Cardboard test* - The "cardboard test" is not a standard ophthalmic test for binocular single vision. - It may refer to various informal or rudimentary tests, but it lacks the precision and standardization required for accurate assessment of binocular functions. *Maddox rod* - The **Maddox rod** is used to detect and measure **heterophoria** (latent strabismus) or **heterotropia** (manifest strabismus). - It dissociates the images seen by each eye, preventing fusion and revealing the deviation of the eyes, rather than directly testing the ability to achieve binocular single vision.

Q: Foster Kennedy syndrome is

I/L Optic atrophy C/L papilloedema. ***I/L Optic atrophy C/L papilloedema*** - **Foster Kennedy syndrome** is characterized by the combination of **ipsilateral optic atrophy** and **contralateral papilledema**. - This constellation of signs is typically caused by a **frontal lobe mass** (e.g., meningioma or glioma) that directly compresses the ipsilateral optic nerve, leading to atrophy, while also causing increased **intracranial pressure** that manifests as papilledema in the contralateral eye. *I/L Papilloedema with C/L optic atrophy* - This describes the reverse of Foster Kennedy syndrome and is not a recognized clinical entity associated with a specific pathological process. - Papilledema is due to **increased intracranial pressure**, and optic atrophy is due to nerve damage; these would typically manifest in specific patterns related to the location and timing of the insult. *I/L Optic atrophy with papilloedema* - This option describes both conditions occurring in the **same (ipsilateral) eye**, which contradicts the characteristic presentation of Foster Kennedy syndrome. - While an eye can have both optic atrophy and papilledema (e.g., resolving papilledema or an underlying condition), it is not the defining feature of Foster Kennedy syndrome. *UL Papilloedema C/L papilitis* - This option mentions **papilledema** in one eye (unilateral or ipsilateral is implied) and **papillitis** in the other. - **Papillitis** is an inflammatory condition of the optic nerve head, while papilledema is due to increased intracranial pressure. This combination is not characteristic of Foster Kennedy syndrome, which specifically involves atrophy and papilledema due to a mass lesion.

Q: Normal level of visual acuity is attained at which age

6 years. ***6 years*** - **Normal adult visual acuity (20/20 or 6/6)** is typically achieved around the age of **6 years** as the visual system fully matures. - This age allows for the complete development of **foveal vision** and **binocular functions**. *6 months* - At 6 months of age, an infant's visual acuity is still developing and is typically around **20/200 to 20/400**. - While significant visual development occurs by this age, including **face recognition and tracking objects**, it is not yet at adult levels. *1 year* - By one year, visual acuity improves to approximately **20/50 to 20/100**. - Infants at this age are able to **distinguish fine details** and have improved **depth perception**, but full maturity is still some years away. *3 years* - At 3 years of age, visual acuity is generally around **20/30 to 20/40**. - Children at this stage are able to perform **visual tasks** like drawing and recognizing letters, but subtle refinements are still ongoing.

Q: Saturday night palsy is which type of nerve injury?

Neuropraxia. ***Neuropraxia*** - This is the mildest form of nerve injury, involving a **temporary conduction block** without axonal disruption, often due to **compression** or mild stretching. - **Saturday night palsy**, caused by prolonged compression of the radial nerve, is a classic example, characterized by rapid and complete recovery, typically within days to weeks. *Axonotemesis* - This involves **axon damage** and Wallerian degeneration distal to the injury, but the **endoneurium and connective tissue sheaths remain intact**. - Recovery is slower and often incomplete, as it requires axonal regeneration through the preserved connective tissue tubes, taking months. *Neurotmesis* - This is the most severe type of nerve injury, involving **complete transection of the nerve fiber**, including the axon, myelin, and all connective tissue sheaths. - Recovery is often poor and requires surgical intervention to attempt re-approximation of the nerve ends. *Complete section* - This term is largely synonymous with **neurotmesis**, indicating a full anatomical disruption of the nerve. - It involves the severance of all nerve components, leading to complete loss of function distal to the injury and the poorest prognosis for spontaneous recovery.

Q: Which of the following is the principal mode of heat exchange in an infant incubator?

Convection. ***Convection*** - In an infant incubator, **convection** is the primary method of heat transfer where a fan circulates warm air around the infant. - This controlled circulation of warm air helps maintain a stable thermal environment for the neonate. *Radiation* - **Radiation** involves heat transfer through electromagnetic waves, and while it occurs, it's not the primary mode in a typical closed incubator, which aims to minimize radiant heat loss to cooler surfaces. - Radiant warmers, used for open care, primarily rely on radiation, but these are distinct from closed incubators. *Evaporation* - **Evaporation** is the loss of heat through the conversion of liquid (sweat or insensible water loss) to vapor, but incubators aim to minimize this by maintaining optimal humidity. - Excessive evaporative heat loss can be significant in premature infants, but it is a mode of *heat loss*, not the principal *mode of heat exchange* for maintaining warmth in an incubator. *Conduction* - **Conduction** is direct heat transfer through physical contact, such as between the infant's skin and the mattress. - While incubators have warm mattresses to prevent conductive heat loss, the circulating warm air (convection) is the main mechanism for overall temperature control.

Q: Which of the following is an example of a clean surgery?

Hernia surgery. ***Hernia surgery*** - **Clean surgeries** involve no entry into hollow viscera (e.g., gastrointestinal, genitourinary, or respiratory tract) and are characterized by **no inflammation** or infection. Hernia repair typically fits this description. - The risk of **surgical site infection** (SSI) is usually less than 2% in clean cases, making it a benchmark for surgical infection control. *Gastric surgery* - This involves entry into the **gastrointestinal tract**, which is considered a **contaminated** or **clean-contaminated** procedure due to the presence of bacteria. - The risk of infection is higher than in clean surgeries, often requiring prophylactic antibiotics. *Cholecystectomy* - This procedure involves the **gallbladder**, which is part of the biliary system, often considered a **clean-contaminated** wound if bile spills or if there's no evidence of active infection. - If performed for **acute cholecystitis** (inflammation/infection), it would be classified as **contaminated** or **dirty**. *Rectal surgery* - This involves the **rectum**, which is part of the lower **gastrointestinal tract** and contains a high bacterial load. - Procedures involving the rectum are classified as **contaminated** or **dirty** due to the high risk of bacterial contamination.

Question 1

3 beta hydroxysteroid dehydrogenase deficiency causes increased production of -

Accepted Answer

DHEA

Answer

Progesterone

Answer

Deoxycortisol

Answer

Estradiol

Question 2

Isolated painful third nerve palsy is a feature of aneurysms of:

Accepted Answer

Aneurysm of the posterior communicating artery

Answer

Aneurysm of the anterior communicating artery

Answer

Aneurysm of the vertebrobasillary artery

Answer

Aneurysm of the ophthalmic artery

Question 3

ECG image showing U wave. Patient is on furosemide and beta blocker. What is the most likely diagnosis?

Accepted Answer

Hypokalemia

Answer

Hypocalcemia

Answer

Hyperkalemia

Answer

Hypercalcemia

Question 4

In head injury, unilateral dilatation of the pupil is seen due to?

Accepted Answer

Oculomotor nerve compression

Answer

Ophthalmic N. compression

Answer

Trigeminal N. compression

Answer

None of the options

Question 5

Binocular single vision is tested by?

Accepted Answer

Synoptophore

Answer

Amsler grid

Answer

Cardboard test

Answer

Maddox rod

Question 6

Foster Kennedy syndrome is

Accepted Answer

I/L Optic atrophy C/L papilloedema

Answer

I/L Optic atrophy with papilloedema

Answer

I/L Papilloedema with C/L optic atrophy

Answer

I/L Papilloedema C/L papilitis

Question 7

Normal level of visual acuity is attained at which age

Accepted Answer

6 years

Answer

6 months

Answer

1 year

Answer

3 years

Question 8

Saturday night palsy is which type of nerve injury?

Accepted Answer

Neuropraxia

Answer

Axonotemesis

Answer

Complete section

Answer

Neurotmesis

Question 9

Which of the following is the principal mode of heat exchange in an infant incubator?

Accepted Answer

Convection

Answer

Radiation

Answer

Evaporation

Answer

Conduction

Question 10

Which of the following is an example of a clean surgery?

Accepted Answer

Hernia surgery

Answer

Cholecystectomy

Answer

Rectal surgery

Answer

Gastric surgery

NEET-PG 2013

Biochemistry

Internal Medicine

Ophthalmology

Orthopaedics

Pediatrics

Surgery