Abducens Nerve Palsy and Esotropia

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Questions and Answers

Which nerve is responsible for controlling the lateral rectus muscle that abducts the eye?

  • Trochlear (fourth cranial) nerve
  • Abducens (sixth cranial) nerve (correct)
  • Oculomotor (third cranial) nerve
  • Trigeminal (fifth cranial) nerve

What is the most common ocular motor paralysis in adults?

  • Trochlear (fourth cranial) nerve palsy
  • Trigeminal (fifth cranial) nerve palsy
  • Abducens (sixth cranial) nerve palsy (correct)
  • Oculomotor (third cranial) nerve palsy

What is the result of an abducens nerve palsy?

  • Exotropia
  • Hyperopia
  • Esotropia (correct)
  • Myopia

Where does the abducens nerve travel through before entering the orbit?

<p>Cavernous sinus and superior orbital fissure (A)</p> Signup and view all the answers

What is a risk factor for abducens nerve palsy in adults?

<p>Hypertension (C)</p> Signup and view all the answers

What is the significance of a sudden onset of abducens nerve palsy?

<p>It suggests a vascular etiology (D)</p> Signup and view all the answers

What is the anatomical location where the abducens nerve is tethered?

<p>Dorello’s canal (C)</p> Signup and view all the answers

What is the location of the nucleus of the abducens nerve?

<p>Pons (B)</p> Signup and view all the answers

What is the most common diagnostic procedure for abducens nerve palsy?

<p>Magnetic Resonance Imaging (MRI) with gadolinium and fat suppression (C)</p> Signup and view all the answers

In which patients is MRI recommended?

<p>All patients under the age of 50 years, those that present with non-isolated abducens nerve palsy, have a history of cancer, or have an absence of microvascular risk factors (A)</p> Signup and view all the answers

How is diplopia in myasthenia gravis characterized?

<p>Fluctuating and fatigable (C)</p> Signup and view all the answers

What is the primary treatment for underlying or systemic conditions in abducens nerve palsy?

<p>Treating the underlying condition (B)</p> Signup and view all the answers

How long do most patients with microvascular abducens nerve palsy recover?

<p>3-6 months (A)</p> Signup and view all the answers

What is the purpose of botulinum toxin injections in abducens nerve palsy?

<p>To weaken the medial rectus (C)</p> Signup and view all the answers

When is surgical intervention usually reserved for?

<p>After 6 months of stable orthoptic measurements (A)</p> Signup and view all the answers

What is the most likely complication following surgical correction of abducens nerve palsy?

<p>Over- or under-correction (B)</p> Signup and view all the answers

What determines the prognosis for abducens nerve palsy?

<p>Underlying etiology (A)</p> Signup and view all the answers

What suggests a demyelinating process?

<p>Subacute onset (A)</p> Signup and view all the answers

What is the most common presenting symptom of abducens nerve palsy?

<p>Diplopia (A)</p> Signup and view all the answers

What is the cardinal sign of abducens nerve palsy?

<p>Esotropia of the affected eye (D)</p> Signup and view all the answers

What is the location of the lesion in Millard-Gubler syndrome?

<p>Brainstem (B)</p> Signup and view all the answers

What is the purpose of cycloplegic refraction in the evaluation of abducens nerve palsy?

<p>To assess the refractive error of the patient (A)</p> Signup and view all the answers

Why is it important to test each eye independently in the evaluation of abducens nerve palsy?

<p>To avoid pseudo-restrictive effects of alternating monocular fixation and vergence (C)</p> Signup and view all the answers

What is the characteristic of esotropia in abducens nerve palsy?

<p>It is incomitant and greater at distance (C)</p> Signup and view all the answers

What is the usual method of diagnosis of abducens nerve palsy?

<p>Clinical examination (B)</p> Signup and view all the answers

What is the characteristic of diplopia in abducens nerve palsy?

<p>Horizontal and uncrossed (A)</p> Signup and view all the answers

What is the significance of slow saccadic velocity in side gaze?

<p>It is a diagnostic feature of abducens nerve palsy (B)</p> Signup and view all the answers

What is the primary reason why the affected eye turns medially in abducens nerve palsy?

<p>Due to the unopposed action of the medial rectus muscle (A)</p> Signup and view all the answers

Where does the abducens nerve begin its course?

<p>In the dorsal pons (B)</p> Signup and view all the answers

What is the significance of a slowly progressive onset of abducens nerve palsy?

<p>It suggests a compressive etiology (B)</p> Signup and view all the answers

What is the characteristic of esotropia in abducens nerve palsy?

<p>It is incomitant and greater at near than at distance (B)</p> Signup and view all the answers

What is the anatomic location where the abducens nerve is tethered?

<p>In Dorello's canal (B)</p> Signup and view all the answers

What is the most common presenting symptom of abducens nerve palsy in children?

<p>Diplopia (A)</p> Signup and view all the answers

What is the risk factor for abducens nerve palsy in adults?

<p>All of the above (D)</p> Signup and view all the answers

What is the characteristic of the abducens nerve course?

<p>It has the longest intracranial course (B)</p> Signup and view all the answers

What is the most common underlying etiology of abducens nerve palsy in children?

<p>Neoplasm (A), Trauma (D)</p> Signup and view all the answers

What is the significance of palpebral fissure widening upon abduction effort in abducens nerve palsy?

<p>It is a sign of attempted abduction (C)</p> Signup and view all the answers

What is the characteristic of esotropia in abducens nerve palsy?

<p>It is greater at distance than at near (B)</p> Signup and view all the answers

What is the significance of slow saccadic velocity in side gaze in abducens nerve palsy?

<p>It is a diagnostic feature of abducens nerve palsy (C)</p> Signup and view all the answers

What is the purpose of measuring fusional amplitudes in the evaluation of abducens nerve palsy?

<p>To assess the quality of binocular vision (A)</p> Signup and view all the answers

What is the characteristic of diplopia in abducens nerve palsy?

<p>It is horizontal and uncrossed (A)</p> Signup and view all the answers

What is the significance of a head turn toward the affected eye in abducens nerve palsy?

<p>It is a compensatory mechanism to avoid diplopia (B)</p> Signup and view all the answers

What is the significance of raised intracranial pressure in abducens nerve palsy?

<p>It is a symptom of headache and pain around the eyes (C)</p> Signup and view all the answers

What is the characteristic of the deviation in abducens nerve palsy?

<p>It is greater at distance than at near (B)</p> Signup and view all the answers

What is the importance of evaluating ductions and versions in the diagnosis of abducens nerve palsy?

<p>It is helpful in determining incomitance (C)</p> Signup and view all the answers

What is the primary purpose of MRI in the diagnosis of abducens nerve palsy?

<p>To rule out underlying etiologies (D)</p> Signup and view all the answers

Which of the following conditions may present with unilateral symptoms including proptosis and inflammation?

<p>Thyroid eye disease (D)</p> Signup and view all the answers

What is the significance of a 6-month period in the management of abducens nerve palsy?

<p>The time required for orthoptic measurements to stabilize (B)</p> Signup and view all the answers

What is the purpose of forced duction test in the management of abducens nerve palsy?

<p>To assist with surgical planning (A)</p> Signup and view all the answers

What is the most common complication following surgical correction of abducens nerve palsy?

<p>Over- or under-correction (D)</p> Signup and view all the answers

What is the significance of the presence of microvascular risk factors in patients with abducens nerve palsy?

<p>It may affect the decision to perform MRI (D)</p> Signup and view all the answers

What is the purpose of occlusion using a Bangerter filter or patch in the management of abducens nerve palsy?

<p>To eliminate diplopia and confusion (D)</p> Signup and view all the answers

What is the characteristic of diplopia in patients with myasthenia gravis?

<p>It is fluctuating and fatigable (A)</p> Signup and view all the answers

In which patients may the diagnostic yield of MRI be relatively low?

<p>Elderly patients with isolated abducens nerve palsy and vasculopathic risk factors (D)</p> Signup and view all the answers

What is the primary goal of treatment for underlying or systemic conditions in patients with abducens nerve palsy?

<p>To treat the underlying condition (C)</p> Signup and view all the answers

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