Vertical Deviations — MCQs
What conditions can be diagnosed using the cover-uncover test?
What is the action of the superior oblique muscle?
Vestibular evoked myogenic potential (VEMP) is a tool for evaluating which of the following?
Most common ocular movement affected in thyroid ophthalmopathy:
Bilateral ptosis is seen in all except which of the following?
All of the following are seen in 3rd nerve palsy except
Ataxia, nystagmus, and ophthalmoplegia are seen in which of the following conditions?
What type of diplopia is typically associated with sixth cranial nerve palsy?
In a patient with right vestibular neuronitis, what will be the finding on the head impulse test?
A 65-year-old male with a history of hypertension and diabetes presents to the OPD with complaints of diplopia and squint. On examination, the secondary deviation is more than the primary deviation. Which of the following is the most likely diagnosis?
Vertical Deviations Indian Medical PG Practice Questions and MCQs
Question 1: What conditions can be diagnosed using the cover-uncover test?
- A. Eye alignment disorders including strabismus and heterophoria (Correct Answer)
- B. Convergent strabismus (Esotropia)
- C. Latent misalignment (Heterophoria)
- D. Strabismus (Squint)
Explanation: ***Eye alignment disorders including strabismus and heterophoria*** - The **cover-uncover test** is a clinical procedure used to detect and differentiate both **strabismus** (manifest deviation) and **heterophoria** (latent deviation) by observing eye movements when vision is occluded and then re-exposed. - This test is a fundamental tool for assessing **ocular alignment** and binocular vision, revealing if an eye deviates and how it recovers. - **This is the most comprehensive answer** as it includes both manifest and latent deviations. *Convergent strabismus (Esotropia)* - Although the cover-uncover test can diagnose **esotropia** (a type of strabismus where the eye turns inward), this option is **too specific** and does not cover all the conditions assessable by this test. - The test can diagnose **all types of strabismus** (esotropia, exotropia, hypertropia, hypotropia) and heterophoria, not just convergent strabismus. - Esotropia is characterized by the **deviating eye failing to spontaneously realign** when uncovered, as it is a constant, manifest deviation. *Latent misalignment (Heterophoria)* - While the cover-uncover test **can detect heterophoria**, this option is **incomplete** as it does not include strabismus (manifest deviation). - Heterophoria manifests when the covered eye deviates and then **refixes** when uncovered, indicating a latent deviation normally controlled by fusion. - The alternate cover test is more sensitive for detecting heterophoria, but the cover-uncover test can identify it as well. *Strabismus (Squint)* - The cover-uncover test is used to diagnose **strabismus**, but this option is **incomplete** and does not include **heterophoria**, which is also diagnosable by the test. - Strabismus is identified when the eye that was *not* covered deviates, or the covered eye does not refixate upon uncovering, indicating a manifest turn. - This option only covers manifest deviations and misses latent deviations.
Question 2: What is the action of the superior oblique muscle?
- A. Intorsion, adduction, elevation
- B. Extorsion, adduction, elevation
- C. Extorsion, abduction, depression
- D. Intorsion, abduction, depression (Correct Answer)
Explanation: ***Intorsion, abduction, depression*** - The **superior oblique muscle** has three actions: **depression** (downward movement - primary action), **abduction** (movement away from the midline), and **intorsion** (medial/internal rotation of the globe) [1]. - The depressor action is most effective when the eye is **adducted** (turned inward), as the muscle's line of pull is then optimally aligned with the vertical axis. - Mnemonic: **SO-DAI** (Superior Oblique: Depression, Abduction, Intorsion) *Intorsion, adduction, elevation* - While **intorsion** is correct, this option incorrectly includes **adduction** and **elevation**. - The superior oblique causes **abduction** (not adduction) and **depression** (not elevation) [1]. - **Elevation** is performed by the superior rectus and inferior oblique muscles [1]. *Extorsion, adduction, elevation* - All three actions are incorrect for the superior oblique muscle. - The correct actions are **intorsion**, **abduction**, and **depression**. - **Extorsion** is performed by the inferior oblique and inferior rectus muscles [1]. *Extorsion, abduction, depression* - While **abduction** and **depression** are correct, **extorsion** is wrong. - The superior oblique causes **intorsion** (internal rotation), not extorsion (external rotation). - This is a common point of confusion - remember the superior oblique **intorts**, while the inferior oblique **extorts**.
Question 3: Vestibular evoked myogenic potential (VEMP) is a tool for evaluating which of the following?
- A. Superior vestibular nerve disorders
- B. Cochlear nerve lesions
- C. Auditory nerve function
- D. Inferior vestibular nerve disorders (Correct Answer)
Explanation: ***Inferior vestibular nerve disorders*** - **VEMP** uses **loud acoustic stimuli** or **bone vibration** to activate the **saccule**, with the response pathway: saccule → inferior vestibular nerve → vestibular nucleus → vestibulospinal tract → muscle response. - **Cervical VEMP (cVEMP)** is recorded from the **sternocleidomastoid muscle**, while **ocular VEMP (oVEMP)** is recorded from **extraocular muscles**; absent or delayed responses indicate **saccular or inferior vestibular nerve dysfunction**. *Superior vestibular nerve disorders* - The **superior vestibular nerve** innervates the **utricle** and **semicircular canals**, which are assessed by **head impulse test** and **caloric testing**, not VEMP. - **VEMP** is the only clinical test specifically assessing **otolith (saccule) function** and does not evaluate semicircular canal pathways. *Cochlear nerve lesions* - **Cochlear nerve** assessment requires **pure tone audiometry**, **auditory brainstem response (ABR)**, and **otoacoustic emissions**. - **VEMP** evaluates vestibular pathways through **muscle reflexes**, not auditory nerve conduction or cochlear function. *Auditory nerve function* - **VEMP** is a vestibular test that evaluates **otolith organs** and their neural pathways, not auditory function. - While VEMP uses **acoustic stimuli** to trigger the response, it measures **vestibulospinal or vestibulo-ocular reflexes**, not hearing or auditory nerve conduction.
Question 4: Most common ocular movement affected in thyroid ophthalmopathy:
- A. Elevation (Correct Answer)
- B. Adduction
- C. Abduction
- D. Depression
Explanation: ***Elevation*** - **Restrictive myopathy** of the **inferior rectus muscle** is the most common cause of impaired eye elevation in thyroid ophthalmopathy. - This typically leads to **diplopia** on upward gaze, known as **Graves' ophthalmopathy**. - The inferior rectus is the **most frequently affected** muscle, followed by medial rectus, superior rectus, and lateral rectus (mnemonic: "I'M SLow"). *Adduction* - Impaired adduction (inward movement) is less common and usually associated with **medial rectus restriction**. - While it can occur (second most common muscle involvement), it is not the most frequent manifestation of thyroid ophthalmopathy. *Abduction* - Impaired abduction (outward movement) suggests **lateral rectus involvement**, which is the least common in thyroid ophthalmopathy. - **Sixth nerve palsy** would also cause impaired abduction but is not typically directly caused by thyroid ophthalmopathy. *Depression* - Impaired depression (downward movement) is uncommon in thyroid ophthalmopathy. - Depression is primarily controlled by the **inferior rectus** (which is commonly affected but causes elevation problems, not depression problems) and inferior oblique. - Superior rectus involvement would cause impaired elevation, not depression.
Question 5: Bilateral ptosis is seen in all except which of the following?
- A. Trauma
- B. Hyperthyroidism (Graves' disease) (Correct Answer)
- C. Congenital
- D. Myotonic dystrophy
Explanation: ***Hyperthyroidism (Graves' disease)*** - **Hyperthyroidism** causes eyelid retraction, leading to a **stare** or **lid lag**, rather than **ptosis**. - **Graves' ophthalmopathy** can cause proptosis (bulging eyes) and conjunctival injection, but does not typically manifest as ptosis. *Congenital* - **Congenital ptosis** is often present at birth due to improper development of the **levator palpebrae superioris muscle**. - It can be **bilateral** and is usually isolated, without other systemic symptoms. *Trauma* - **Traumatic ptosis** can occur if the **levator muscle**, **aponeurosis**, or **third cranial nerve** is damaged. - This can be **bilateral** depending on the nature and extent of the head trauma. *Myotonic dystrophy* - **Myotonic dystrophy** is a **hereditary muscle disorder** characterized by progressive muscle weakness. - **Bilateral ptosis** is a very common early sign of **myotonic dystrophy**, often accompanied by **facial weakness** and **myotonia**.
Question 6: All of the following are seen in 3rd nerve palsy except
- A. Ptosis
- B. Pupillary dilatation
- C. Loss of abduction (Correct Answer)
- D. Exotropia and hypotropia
Explanation: ***Loss of abduction*** - The **lateral rectus muscle**, responsible for **abduction** of the eye, is innervated by the **abducens nerve (CN VI)**, not the oculomotor nerve (CN III). - Therefore, a third nerve palsy would not directly cause a loss of abduction. *Ptosis* - **Ptosis** (drooping of the upper eyelid) is a common finding in **CN III palsy** due to paralysis of the **levator palpebrae superioris muscle**. - This muscle is innervated by the oculomotor nerve. *Pupillary dilatation* - The **oculomotor nerve (CN III)** carries **parasympathetic fibers** that constrict the pupil. - Damage to these fibers in a CN III palsy results in **unopposed sympathetic activity**, leading to a dilated pupil that is poorly reactive to light. *Exotropia and hypotropia* - **Exotropia** (eye turned outward) occurs due to unopposed action of the **lateral rectus muscle**. - **Hypotropia** (eye turned downward) is due to the unopposed action of the **superior oblique muscle**.
Question 7: Ataxia, nystagmus, and ophthalmoplegia are seen in which of the following conditions?
- A. 3rd nerve palsy
- B. Wernicke encephalopathy (Correct Answer)
- C. Myasthenia gravis
- D. Chronic progressive external ophthalmoplegia
Explanation: ***Wernicke encephalopathy*** - This condition is characterized by the classic triad of **ataxia**, **nystagmus**, and **ophthalmoplegia** (often presenting as external ophthalmoplegia), alongside confusion [2]. - It results from a **thiamine (vitamin B1) deficiency** [2], [3], commonly seen in chronic alcoholics or individuals with severe malnutrition. *Myasthenia gravis* - This is an **autoimmune disorder** affecting the neuromuscular junction, leading to fluctuating muscle weakness that worsens with activity [1]. - While it can cause **ophthalmoplegia** (especially ptosis and diplopia), it does not typically present with ataxia or nystagmus. *3rd nerve palsy* - A **third nerve palsy** specifically affects the oculomotor nerve, causing a constellation of symptoms including ptosis, pupillary dilation, and inability to move the eye up, down, or medially. - While it causes **ophthalmoplegia** affecting one eye, it does not typically cause nystagmus or ataxia. *Chronic progressive external ophthalmoplegia* - This is a mitochondrial disorder characterized by **slowly progressive weakness** of the extraocular muscles, leading to bilateral ptosis and limitation of eye movements. - It causes a specific type of **ophthalmoplegia** but is not typically associated with nystagmus or prominent ataxia.
Question 8: What type of diplopia is typically associated with sixth cranial nerve palsy?
- A. Crossed diplopia
- B. Uncrossed diplopia (Correct Answer)
- C. No diplopia
- D. Vertical diplopia
Explanation: ***Uncrossed diplopia*** - **Sixth cranial nerve palsy** affects the **lateral rectus muscle**, causing the affected eye to deviate inwards (**esotropia**) [1], [2]. - When the eye is turned inward, the image from the affected eye falls on the **nasal retina**, which is perceived as coming from the temporal visual field, leading to **uncrossed diplopia** (the image from the right eye is seen on the right, and the image from the left eye is seen on the left) [1]. *Crossed diplopia* - **Crossed diplopia** occurs when the eyes are exotropic (turned outward), such as in **third cranial nerve palsy** with loss of medial rectus function [1], [2]. - In this case, the image from the right eye is seen on the left, and the image from the left eye is seen on the left. *Vertical diplopia* - **Vertical diplopia** is typically associated with **fourth cranial nerve palsy**, which affects the **superior oblique muscle**, or sometimes with ocular motor nerve palsies (third nerve) affecting superior and inferior recti [2]. - This results in a vertical separation of images, where one image appears above the other [1]. *No diplopia* - **Diplopia** is a hallmark symptom of **ocular motor nerve palsies** because the eyes are misaligned, causing the brain to receive two distinct images [1]. - The absence of diplopia would indicate properly aligned eyes or a mechanism of suppression in chronic conditions.
Question 9: In a patient with right vestibular neuronitis, what will be the finding on the head impulse test?
- A. Head turned to right, corrective saccade to the left (Correct Answer)
- B. Head turned to left, corrective saccade to the right
- C. Head turned to right, no corrective saccade
- D. Head turned to left, no corrective saccade
Explanation: ***Head turned to right, corrective saccade to the left*** - In **right vestibular neuronitis**, the right vestibular apparatus is impaired, affecting the **vestibulo-ocular reflex (VOR)** on that side. - During the head impulse test, when the head is rapidly turned **to the right** (toward the affected side), the impaired VOR cannot maintain eye fixation on the target. - The eyes initially move **with the head** (to the right), then a visible **corrective saccade** (catch-up saccade) brings them **back to the left** to refixate on the target. - This corrective saccade is the **hallmark positive finding** in head impulse test for right vestibular dysfunction. *Head turned to left, corrective saccade to the right* - This would indicate a **left vestibular lesion**, not right vestibular neuronitis. - When turning the head to the left with left vestibular dysfunction, a corrective saccade to the right would be observed. *Head turned to right, no corrective saccade* - This would indicate **normal VOR function** on the right side. - A normal response shows no corrective saccade because the eyes maintain fixation throughout the head turn. - This is the **opposite** of what is expected in right vestibular neuronitis. *Head turned to left, no corrective saccade* - This indicates normal VOR function on the left side. - In right vestibular neuronitis, turning the head to the left (away from the affected side) typically shows **normal VOR** with no corrective saccade needed.
Question 10: A 65-year-old male with a history of hypertension and diabetes presents to the OPD with complaints of diplopia and squint. On examination, the secondary deviation is more than the primary deviation. Which of the following is the most likely diagnosis?
- A. paralytic squint (Correct Answer)
- B. concomitant strabismus
- C. restrictive strabismus
- D. pseudo strabismus
Explanation: ***Paralytic squint*** The key finding of **secondary deviation being greater than primary deviation** is a classic sign of **paralytic strabismus**. This occurs because the paretic eye (due to neurological deficit) has to work harder to fixate, leading to an exaggerated innervation to the yoked muscle in the healthy eye, causing a larger deviation (Hering's law of equal innervation). The patient's age and history of **hypertension and diabetes** increase the risk of **cranial nerve palsies** (e.g., oculomotor, trochlear, abducens), which are common causes of paralytic squint due to microvascular ischemia. *Concomitant strabismus* In **concomitant strabismus**, the degree of deviation remains constant in all directions of gaze, meaning **primary and secondary deviations are equal**. This contradicts the clinical finding in the patient. Concomitant strabismus often presents in childhood and is typically non-paralytic, with no underlying neurological deficit affecting muscle action. *Restrictive strabismus* **Restrictive strabismus** is characterized by physical limitation of eye movement due to mechanical restriction of an extraocular muscle, often seen in conditions like **thyroid eye disease** or **orbital trauma**. While restrictive strabismus can cause diplopia and reduced eye movement, it typically involves a **limited range of motion** and usually does not present with secondary deviation being greater than primary deviation in the same manner as a paralytic squint. *Pseudo strabismus* **Pseudo strabismus** is an apparent misalignment of the eyes where the eyes are actually straight. This can be due to features like a **wide epicanthal fold** or a **small interpupillary distance**. In pseudo strabismus, there is **no true deviation** on cover-uncover testing, and therefore, the concepts of primary and secondary deviation do not apply, nor would there be actual diplopia.
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