Neurological Disorders — MCQs
Identify the visual field defect shown in the image.
What is the condition characterized by a relative afferent pupillary defect?
Which of the following is NOT typically seen in 3rd nerve palsy?
Which of the following is NOT a feature of Horner's syndrome?
All of the following are seen in the Horner's syndrome, Except
Anterior ischemic optic neuropathy is characterized by:
Nystagmus is associated with all except:
Isolated painful third nerve palsy is a feature of aneurysms of:
Retinitis pigmentosa is a feature of all except which of the following?
An otherwise healthy 43-year-old woman comes to the physician because of several episodes of involuntary movements of her head over the past few months. They are sometimes associated with neck pain and last minutes to hours. Neurologic examination shows no abnormalities. During examination of the neck, the patient's head turns horizontally to the left. She states this movement is involuntary, and that she is unable to unturn her head. After 5 minutes, her head re-straightens. Which of the following best describes this patient's disorder?
Neurological Disorders Indian Medical PG Practice Questions and MCQs
Question 1: Identify the visual field defect shown in the image.
- A. Binasal hemianopia
- B. Bitemporal hemianopia (Correct Answer)
- C. Homonymous hemianopia
- D. Altitudinal defect
Explanation: ***Bitemporal hemianopia*** - The image shows loss of vision in the **temporal (outer) halves of both visual fields**, which is characteristic of bitemporal hemianopia. - This defect typically results from a lesion at the **optic chiasm**, compressing the crossing nasal retinal fibers, often due to a **pituitary tumor**. *Binasal hemianopia* - This condition involves visual loss in the **nasal (inner) halves of both visual fields**, which is the opposite of what is depicted. - It is a rare defect that can be caused by lesions affecting the **uncrossed temporal retinal fibers** on both sides, such as from bilateral carotid artery aneurysms. *Homonymous hemianopia* - A homonymous hemianopia involves the **same half of the visual field in both eyes** (e.g., right visual field loss in both eyes), resulting from a lesion posterior to the optic chiasm. - The image clearly shows different halves affected in each eye (temporal fields), not the same half. *Altitudinal defect* - An altitudinal defect involves the **loss of vision in the upper or lower half of the visual field** in one or both eyes, respecting the horizontal midline. - The visual field loss shown in the image is vertical, affecting the temporal halves, not the upper or lower halves.
Question 2: What is the condition characterized by a relative afferent pupillary defect?
- A. Efferent pathway defect
- B. Cerebral lesion
- C. Total afferent pupillary defect
- D. Marcus Gunn pupil (Correct Answer)
Explanation: ***Marcus Gunn pupil, a defect in the afferent pathway of the eye*** - A **Marcus Gunn pupil**, also known as a **relative afferent pupillary defect (RAPD)**, occurs due to a lesion or dysfunction in the **afferent (sensory) pathway** of one eye. - This results in an asymmetric response to light, where the pupil of the affected eye appears to dilate paradoxically when light is swung from the unaffected to the affected eye during the **swinging flashlight test**. *Efferent pathway defect* - An **efferent pathway defect** (e.g., in the oculomotor nerve, CN III) would cause a **fixed, dilated pupil** with impaired direct and consensual light reflexes, rather than an RAPD. - Such a defect would typically affect the motor response of the pupil, causing it to be unable to constrict. *Cerebral lesion* - While certain cerebral lesions can affect pupillary responses, a **relative afferent pupillary defect** specifically points to an issue in the direct sensory input from the retina to the brainstem. - Large **cerebral lesions** are more likely to cause other neurological signs or abnormalities in the motor control of the eye. *Total afferent pupillary defect* - A **total afferent pupillary defect**, often seen in **amaurotic pupil** (blind eye without light perception), would result in no direct or consensual light response in the affected eye. - In a RAPD, there is still some, albeit reduced, response to light, making it a **relative** defect rather than a total absence of afferent signaling.
Question 3: Which of the following is NOT typically seen in 3rd nerve palsy?
- A. Mydriasis
- B. Ptosis
- C. Loss of abduction (Correct Answer)
- D. Loss of light reflex
Explanation: ***Loss of abduction*** - The **oculomotor nerve (CN III)** controls adduction, elevation, and depression of the eye, but **not abduction**. [2] - **Abduction** is primarily controlled by the **abducens nerve (CN VI)**, so its loss would indicate a CN VI palsy. *Mydriasis* - The **oculomotor nerve (CN III)** innervates the **parasympathetic fibers** to the pupillary constrictor muscles. [3] - Palsy of these fibers leads to unopposed action of the sympathetic dilator muscles, causing **mydriasis (pupil dilation)**. [4] *Ptosis* - The **oculomotor nerve (CN III)** innervates the **levator palpebrae superioris muscle**, which lifts the eyelid. - Dysfunction of this nerve leads to **ptosis (drooping of the eyelid)**. [1] *Loss of light reflex* - The **efferent pathway** for the **pupillary light reflex** travels via the **oculomotor nerve (CN III)** to constrict the pupil. [3] - A 3rd nerve palsy, particularly affecting the parasympathetic fibers, **impairs pupillary constriction**, resulting in a loss of the direct and consensual light reflex in the affected eye. [4]
Question 4: Which of the following is NOT a feature of Horner's syndrome?
- A. Anhidrosis
- B. Enophthalmos
- C. Hyperchromatic iris (Correct Answer)
- D. Miosis
Explanation: ***Hyperchromatic iris*** - The iris in Horner's syndrome typically presents as **heterochromia iridis**, where the affected eye's iris is **hypochromatic (lighter)** compared to the healthy eye due to reduced melanin synthesis from sympathetic denervation - This occurs particularly with congenital or early-onset Horner's syndrome (before age 2 years) - A **hyperchromatic (darker) iris is NOT a feature** of Horner's syndrome, making this the correct answer *Anhidrosis* - **Anhidrosis** (decreased sweating) on the affected side of the face and neck is a classic feature of Horner's syndrome - Results from disruption of postganglionic sympathetic fibers supplying sweat glands in the ipsilateral facial and neck regions - Pattern of anhidrosis helps localize the lesion (central, preganglionic, or postganglionic) *Enophthalmos* - **Mild enophthalmos** (sunken eyeball appearance) occurs in Horner's syndrome - Due to paralysis of **Müller's muscle** (superior tarsal muscle), which normally helps maintain globe position - Combined with ptosis, this creates the characteristic sunken appearance of the affected eye *Miosis* - **Miosis** (pupillary constriction) is a hallmark feature of Horner's syndrome - Results from paralysis of the **iris dilator muscle** due to interrupted sympathetic innervation - Leads to unopposed parasympathetic activity, causing the characteristic small pupil - Dilation lag can be demonstrated with dim lighting or cocaine test
Question 5: All of the following are seen in the Horner's syndrome, Except
- A. Dilated pupil (Correct Answer)
- B. Drooping of upper eyelid
- C. Enophthalmos
- D. Loss of sweating on same side of face
Explanation: ***Dilated pupil*** - **Horner's syndrome** results from damage to the sympathetic pathway, leading to **miosis** (constricted pupil) due to unopposed parasympathetic activity [2]. - A **dilated pupil** would be indicative of a different pathology, such as oculomotor nerve palsy [3]. *Drooping of upper eyelid* - This symptom, known as **ptosis**, is a classic feature of Horner's syndrome due to the paralysis of the **superior tarsal muscle** (Müller's muscle), which is innervated by the sympathetic nervous system [1], [2]. - The degree of ptosis is typically mild to moderate. *Enophthalmos* - **Enophthalmos**, or the apparent sinking of the eyeball into the orbit, is often seen in Horner's syndrome. - This is partly an illusion caused by the ptosis and sometimes attributed to a loss of tone in the **orbitalis muscle** (if present and sympathetically innervated). *Loss of sweating on same side of face* - This is known as **anhydrosis** and occurs on the **ipsilateral side of the face and neck** due to the disruption of sympathetic innervation to the sweat glands. - The extent of anhydrosis depends on the level of the lesion along the sympathetic pathway [4].
Question 6: Anterior ischemic optic neuropathy is characterized by:
- A. Centrocaecal scotoma
- B. Altitudinal hemianopia (Correct Answer)
- C. Ring scotoma
- D. Increased blood supply
Explanation: ***Altitudinal hemianopia*** - **Anterior ischemic optic neuropathy (AION)** typically causes **sudden, painless vision loss** in one eye, often presenting as **altitudinal visual field defects**. - This pattern results from **ischemia** to the **optic nerve head**, affecting the superior or inferior retinal nerve fiber layers. *Centrocaecal scotoma* - A **centrocaecal scotoma** is a visual field defect that encompasses both the **central vision** and the **blind spot**. - This pattern is more characteristic of **toxic or nutritional optic neuropathies**, not typically AION. *Ring scotoma* - A **ring scotoma** is a circular defect around the **central visual field**, sparing the fovea. - This type of scotoma is commonly seen in diseases like **retinitis pigmentosa**, which affects peripheral and mid-peripheral retina rather than the optic nerve head as seen in AION. *Increased blood supply* - **Anterior ischemic optic neuropathy** is fundamentally caused by a **reduced or insufficient blood supply** to the optic nerve head, leading to **ischemia and infarction**. - Increased blood supply would be beneficial and would not cause the vision loss characteristic of AION.
Question 7: Nystagmus is associated with all except:
- A. Vestibular disease
- B. Cochlear disease (Correct Answer)
- C. Arnold-Chiari malformation
- D. Cerebellar disease
Explanation: ***Cochlear disease*** - **Cochlear disease** primarily affects **hearing** through damage to the cochlea, the auditory part of the inner ear [3]. - It does not directly involve the vestibular system, which controls balance and eye movements, and therefore is not associated with nystagmus. *Vestibular disease* - **Vestibular disease** affects the **balance system** of the inner ear and can cause nystagmus, often accompanied by vertigo and dizziness [2], [4]. - Examples include **benign paroxysmal positional vertigo (BPPV)**, **Meniere's disease**, and **vestibular neuronitis**. *Arnold-Chiari malformation* - **Arnold-Chiari malformation** involves structural defects in the cerebellum and brainstem, which can disrupt the normal control of eye movements. - This often leads to **downbeat nystagmus** or other forms of central nystagmus due to compression of the **brainstem** and **cerebellum**. *Cerebellar disease* - The **cerebellum** plays a crucial role in coordinating smooth eye movements and maintaining gaze stability. - **Cerebellar disease** can cause various types of nystagmus, such as **gaze-evoked nystagmus** and **rebound nystagmus**, due to impaired motor control [1].
Question 8: Isolated painful third nerve palsy is a feature of aneurysms of:
- A. Aneurysm of the posterior communicating artery (Correct Answer)
- B. Aneurysm of the anterior communicating artery
- C. Aneurysm of the vertebrobasillary artery
- D. Aneurysm of the ophthalmic artery
Explanation: ***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.
Question 9: Retinitis pigmentosa is a feature of all except which of the following?
- A. NARP
- B. Refsum's disease
- C. Hallervorden-Spatz disease (Correct Answer)
- D. Abetalipoproteinemia
Explanation: ***Hallervorden-Spatz disease*** - Also known as **Pantothenate kinase-associated neurodegeneration (PKAN)**, this disorder primarily causes **extrapyramidal symptoms** such as dystonia and parkinsonism due to iron accumulation in the basal ganglia. - While it is a neurodegenerative disorder affecting the brain, **retinitis pigmentosa** is not a characteristic feature of Hallervorden-Spatz disease. *Refsum's disease* - This is an **autosomal recessive peroxisomal disorder** characterized by the accumulation of **phytanic acid**, which is toxic to various tissues. - **Retinitis pigmentosa** is a classic symptom, often presenting with night blindness and progressive vision loss, along with **ataxia**, **polyneuropathy**, and **ichthyosis**. *NARP* - **NARP (Neuropathy, Ataxia, Retinitis Pigmentosa)** is a rare mitochondrial disorder caused by mutations in the **MT-ATP6 gene**, leading to energy production deficits. - **Retinitis pigmentosa** is a core feature, contributing to visual impairment, alongside **sensory neuropathy**, **ataxia**, and **developmental delay**. *Abetalipoproteinemia* - This is an **autosomal recessive disorder** characterized by the inability to synthesize **apolipoprotein B**, essential for the formation of chylomicrons and VLDL, leading to severe **malabsorption of fat-soluble vitamins** (A, D, E, K). - Prolonged deficiency of **vitamin E** can result in progressive neurological dysfunction, including **ataxia** and **retinitis pigmentosa**, due to oxidative damage to photoreceptors and nervous tissue.
Question 10: An otherwise healthy 43-year-old woman comes to the physician because of several episodes of involuntary movements of her head over the past few months. They are sometimes associated with neck pain and last minutes to hours. Neurologic examination shows no abnormalities. During examination of the neck, the patient's head turns horizontally to the left. She states this movement is involuntary, and that she is unable to unturn her head. After 5 minutes, her head re-straightens. Which of the following best describes this patient's disorder?
- A. Dystonia (Correct Answer)
- B. Athetosis
- C. Akathisia
- D. Hemiballismus
- E. Chorea
Explanation: ***Dystonia*** - This patient presents with **sustained, involuntary muscle contractions** causing repetitive, twisting movements and abnormal postures [1], which are characteristic features of **dystonia**, specifically **cervical dystonia (torticollis)**. - The description of the head turning involuntarily to the left and inability to unturn it, lasting minutes to hours, fits the pattern of intermittent or spasmodic dystonia. *Athetosis* - **Athetosis** involves slow, sinuous, **writhing involuntary movements**, particularly affecting distal limbs [1]. - These movements are often continuous and slow, unlike the more sudden, sustained contractions seen in the patient. *Akathisia* - **Akathisia** is characterized by an internal feeling of **restlessness** and a strong urge to move, often described as an inability to sit still. - It results in fidgeting and pacing, rather than sustained, involuntary posturing of a specific body part. *Hemiballismus* - **Hemiballismus** involves **large-amplitude, involuntary, flinging movements** of one side of the body [1]. - This symptom typically arises from lesions in the **subthalamic nucleus** and is distinct from the sustained, twisting movements described [1]. *Chorea* - **Chorea** presents as **brief, irregular, rapid, and unpredictable involuntary movements** that flow randomly from one body part to another [1]. - Unlike the sustained, fixed posturing seen in dystonia, choreiform movements are often described as "dance-like" and are not maintained.
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