Special Forms of Strabismus — MCQs
Inability to abduct left eye with LMN fascial palsy on same side. The lesion is in
Which of the following is NOT a feature of Moebius syndrome?
Most common ocular movement affected in thyroid ophthalmopathy:
Ataxia, nystagmus, and ophthalmoplegia are seen in which of the following conditions?
Which of the following is not a component of Brown-Sequard syndrome?
Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.
Which of the following is a hallmark feature of Duane retraction syndrome?
Obstacles in concomitant squint are:
Esotropia is commonly seen in which type of refractive error?
A patient presents with convergent squint in one eye. Vision in the squinting eye is 6/60, and vision in the non-squinting eye is also 6/60. What is the most appropriate next step in management?
Special Forms of Strabismus Indian Medical PG Practice Questions and MCQs
Question 1: Inability to abduct left eye with LMN fascial palsy on same side. The lesion is in
- A. Left pons (Correct Answer)
- B. Cerebellar lesions
- C. CP angle tumor
- D. Right pons
Explanation: ***Left pons*** - A lesion in the **left pons** can affect both the **left abducens nucleus** (leading to inability to abduct the left eye) and the **left facial nucleus or nerve fibers** (causing left lower motor neuron facial palsy). [2] - This specific combination of ipsilateral (same-sided) symptoms is characteristic of a brainstem lesion, particularly within the pons where these cranial nerve nuclei are in close proximity. [1] *Cerebellar lesions* - **Cerebellar lesions** primarily cause symptoms like **ataxia**, dysmetria, and nystagmia, but typically do not cause isolated cranial nerve palsies of the abducens and facial nerves. [1] - While coordinating movements, the cerebellum does not house the nuclei for direct eye abduction or facial muscle control. *CP angle tumor* - A **cerebellopontine (CP) angle tumor** can affect cranial nerves VI and VII, but it typically presents with other symptoms like **vestibulocochlear nerve (VIII) dysfunction (hearing loss, vertigo)** early on due to its anatomical location. - While it can eventually compress the abducens and facial nerves, the combination of **isolated abducens and facial palsy** without VIII nerve involvement points more directly to an intraparenchymal pontine lesion. *Right pons* - A lesion in the **right pons** would cause **right-sided inability to abduct the eye** and **right-sided LMN facial palsy**, not left-sided as described in the case. - Brainstem lesions typically produce ipsilateral cranial nerve deficits due to the close proximity of the nuclei and fascicles before decussation of some pathways.
Question 2: Which of the following is NOT a feature of Moebius syndrome?
- A. Bilateral facial paralysis
- B. Impaired lateral eye movement
- C. Unilateral or bilateral abducens nerve involvement
- D. Decreased chest movements (Correct Answer)
Explanation: ***Decreased chest movements*** - **Decreased chest movements** are not a characteristic feature of **Moebius syndrome**, which primarily affects cranial nerves, particularly the **facial and abducens nerves**. - While other systemic issues can coexist, respiratory problems like decreased chest movements are not considered a direct or defining symptom of this condition. *Bilateral facial paralysis* - **Bilateral facial paralysis** is a hallmark of **Moebius syndrome**, resulting from congenital underdevelopment or absence of the **facial (VII) cranial nerves**. - This leads to a characteristic **mask-like facial expression**, difficulty with smiling, frowning, and other facial movements. *Impaired lateral eye movement* - **Impaired lateral eye movement** is a common feature due to involvement of the **abducens (VI) cranial nerves**, which control the **lateral rectus muscle**. - Patients often present with **esotropia** (crossed eyes) and are unable to move their eyes past the midline when looking to the side. *Unilateral or bilateral abducens nerve involvement* - **Unilateral or bilateral abducens (VI) nerve involvement** is a core diagnostic criterion for **Moebius syndrome**. - This leads to the characteristic deficit in **lateral gaze**, as the abducens nerve innervates the **lateral rectus muscle**.
Question 3: 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 4: 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 5: Which of the following is not a component of Brown-Sequard syndrome?
- A. Contralateral loss of pain and temperature sensation
- B. Contralateral posterior column involvement (Correct Answer)
- C. Ipsilateral extensor plantar response
- D. Ipsilateral loss of proprioception
Explanation: ***Contralateral posterior column involvement*** - **Brown-Séquard syndrome** is caused by hemisection of the spinal cord, affecting pathways as they ascend or descend. [1] - The **posterior columns** (involved in proprioception, vibration, and fine touch) transmit sensory information **ipsilaterally**, meaning symptoms would be on the same side as the lesion, not contralateral. [1] *Ipsilateral extensor plantar response* - This is a feature of **upper motor neuron (UMN) damage** affecting the corticospinal tract, which descends ipsilaterally before crossing in the medulla. - In Brown-Séquard syndrome, the **ipsilateral corticospinal tract** is damaged, leading to UMN signs below the lesion. [1] *Ipsilateral loss of proprioception* - **Proprioception** is carried by the posterior columns, which ascend **ipsilaterally** in the spinal cord. [2] - Damage to the posterior column on one side of the spinal cord (as in a hemisection) results in **ipsilateral loss** of proprioception, vibration, and discriminative touch. [1] *Contralateral loss of pain and temperature sensation* - The **spinothalamic tracts** carry pain and temperature sensations and cross within one or two spinal cord segments after entering. [2] - Therefore, a lesion on one side of the spinal cord will result in **contralateral loss** of pain and temperature sensation, typically a few segments below the level of the lesion. [1]
Question 6: Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.
- A. Statements 1 & 2 are correct, 2 is not explaining 1 (Correct Answer)
- B. Statements 1 and 2 are correct and 2 is the correct explanation for 1
- C. Statements 1 and 2 are incorrect
- D. Statement 1 is incorrect
Explanation: ***Correct: Statements 1 & 2 are correct, 2 is not explaining 1*** **Analysis of Statement 1:** - A 59-year-old patient with **flaccid bullae** and **suprabasal acantholytic split** on histopathology is the classic presentation of **Pemphigus vulgaris** - The flaccid (easily ruptured) nature of bullae distinguishes it from tense bullae seen in bullous pemphigoid - The suprabasal location of the split (just above the basal layer) with acantholysis (loss of cell-to-cell adhesion) is pathognomonic - **Statement 1 is CORRECT** ✓ **Analysis of Statement 2:** - The **"row of tombstones" or "tombstone appearance"** is indeed a diagnostic histopathological feature of Pemphigus vulgaris - This appearance results from basal keratinocytes remaining attached to the basement membrane while suprabasal cells separate due to acantholysis - The intact basal cells standing upright resemble a row of tombstones - **Statement 2 is CORRECT** ✓ **Does Statement 2 explain Statement 1?** - Statement 2 describes a **histopathological appearance** (tombstone pattern) that is a **consequence** of the suprabasal split - However, it does NOT explain the **underlying cause** of the flaccid bullae or the suprabasal split - The true explanation involves **IgG autoantibodies against desmoglein 3 (and desmoglein 1)**, which attack intercellular adhesion structures (desmosomes), causing **acantholysis** - Therefore, **Statement 2 does NOT explain Statement 1** ✗ *Incorrect: Statement 2 is the correct explanation for Statement 1* - While both statements describe features of Pemphigus vulgaris, the tombstone appearance is a descriptive finding, not an explanatory mechanism *Incorrect: Statements 1 and 2 are incorrect* - Both statements are medically accurate descriptions of Pemphigus vulgaris features *Incorrect: Statement 1 is incorrect* - Statement 1 correctly describes the cardinal clinical and histopathological features of Pemphigus vulgaris
Question 7: Which of the following is a hallmark feature of Duane retraction syndrome?
- A. Hyperopia
- B. Retraction of globe (Correct Answer)
- C. Head tilt
- D. None of the options
Explanation: ***Retraction of globe*** - **Globe retraction** upon attempted adduction and/or abduction is a classic sign due to co-contraction of the antagonistic rectus muscles. - This abnormal innervation causes the eye to pull back into the orbit and narrow the palpebral fissure. *Hyperopia* - **Hyperopia** (farsightedness) is a refractive error and not a primary diagnostic feature of Duane retraction syndrome. - While it can co-occur, it is not a hallmark of the syndrome's motor abnormalities. *Head tilt* - A **head tilt** can be adopted by patients with Duane syndrome to compensate for the limited eye movements and maintain binocular vision, but it is a compensatory mechanism, not a hallmark feature itself. - It's a secondary sign that helps manage the primary problem of ocular motility impairment. *None of the options* - This option is incorrect because **globe retraction** is indeed a hallmark feature of Duane retraction syndrome.
Question 8: Obstacles in concomitant squint are:
- A. Sensory obstacles
- B. Motor obstacles
- C. Central obstacles
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Concomitant squint** involves **sensory obstacles** (e.g., amblyopia, eccentric fixation), **motor obstacles** (e.g., muscle imbalance, inadequate fusional vergence), and **central obstacles** (e.g., defective brain processing of visual information). - All these factors interact to cause and maintain the misalignment of the eyes. *Sensory obstacles* - These include conditions like **amblyopia** (lazy eye) due to suppression of the deviated eye's image, and **eccentric fixation**, where the fovea is not used for central vision. - While significant, sensory obstacles alone do not fully explain concomitant squint, as motor and central components are also crucial. *Motor obstacles* - These involve issues with the **extraocular muscles**, such as imbalance in muscle tone, or problems with the **neural control** of eye movements, leading to a deviation that is relatively constant in all gaze positions. - Motor obstacles are a key component but are often influenced by central and sensory factors. *Central obstacles* - These refer to problems within the brain's visual pathways and centers responsible for **fusion**, **vergence**, and maintaining **ocular alignment**. - Defective processing of visual input or an inability to maintain binocular vision can directly contribute to squint, highlighting the brain's role in coordinating eye movements.
Question 9: Esotropia is commonly seen in which type of refractive error?
- A. Myopia
- B. Hypermetropia (Correct Answer)
- C. Astigmatism
- D. Presbyopia
Explanation: ***Hypermetropia*** - **Esotropia**, or convergent strabismus, is commonly associated with **uncorrected hypermetropia**, especially in children. - The constant effort to **accommodate** to see clearly for hypermetropic individuals can lead to excessive convergence, causing the eye to turn inward. *Myopia* - Myopia, or **nearsightedness**, rarely causes esotropia. - In some cases, high myopia can be associated with **exotropia** (divergent strabismus) due to reduced accommodative effort. *Astigmatism* - **Astigmatism** causes blurry vision at all distances due to an irregularly shaped cornea or lens, but it is not directly linked to specific forms of strabismus like esotropia or exotropia. - While it can contribute to **amblyopia** if severe and uncorrected, it does not typically cause the eyes to turn inward. *Presbyopia* - **Presbyopia** is an age-related loss of the eye's ability to focus on nearby objects due to stiffening of the lens. - It affects accommodation but does not cause strabismus such as esotropia; it typically begins around age 40.
Question 10: A patient presents with convergent squint in one eye. Vision in the squinting eye is 6/60, and vision in the non-squinting eye is also 6/60. What is the most appropriate next step in management?
- A. Glasses
- B. Refraction and treat underlying cause of poor vision (Correct Answer)
- C. Squint surgery
- D. Botulinum toxin
Explanation: ***Refraction and treat underlying cause of poor vision*** - When **both eyes have equally poor vision (6/60)** with a convergent squint, this suggests a **bilateral pathology** affecting visual acuity, not simply a refractive accommodative esotropia. - The **first step** is comprehensive **cycloplegic refraction** to determine if refractive error contributes to the poor vision. - **Equally important** is identifying the **underlying cause** of bilateral vision loss (6/60 in both eyes), which could be: - **Bilateral amblyopia** (though unusual to have equal severity) - **Uncorrected high refractive error** (hypermetropia causing accommodative esotropia) - **Cataracts** (congenital or developmental) - **Retinal pathology** or **optic nerve disorders** - Only after identifying and treating the underlying cause can definitive management of the squint be planned. *Glasses* - While **glasses** may be part of the treatment if refractive error is found, **prescribing glasses alone** without first performing refraction and investigating why both eyes have 6/60 vision is incomplete management. - This option is too narrow and doesn't address the need to identify the underlying pathology causing bilateral poor vision. *Squint surgery* - **Squint surgery** addresses ocular misalignment but does **not improve vision**. - Surgery should only be considered **after** refractive correction, treatment of amblyopia (if present), and management of any underlying pathology. - Operating without addressing the cause of poor vision would be premature. *Botulinum toxin* - **Botulinum toxin** is used for certain types of strabismus as a temporary or alternative to surgery. - Like surgery, it addresses alignment but **not visual acuity**. - The priority is to improve vision and identify the underlying cause before considering alignment procedures.
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