55 Questions
Which nerve is responsible for controlling the lateral rectus muscle that abducts the eye?
Abducens (sixth cranial) nerve
What is the most common ocular motor paralysis in adults?
Abducens (sixth cranial) nerve palsy
What is the result of an abducens nerve palsy?
Esotropia
Where does the abducens nerve travel through before entering the orbit?
Cavernous sinus and superior orbital fissure
What is a risk factor for abducens nerve palsy in adults?
Hypertension
What is the significance of a sudden onset of abducens nerve palsy?
It suggests a vascular etiology
What is the anatomical location where the abducens nerve is tethered?
Dorello’s canal
What is the location of the nucleus of the abducens nerve?
Pons
What is the most common diagnostic procedure for abducens nerve palsy?
Magnetic Resonance Imaging (MRI) with gadolinium and fat suppression
In which patients is MRI recommended?
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
How is diplopia in myasthenia gravis characterized?
Fluctuating and fatigable
What is the primary treatment for underlying or systemic conditions in abducens nerve palsy?
Treating the underlying condition
How long do most patients with microvascular abducens nerve palsy recover?
3-6 months
What is the purpose of botulinum toxin injections in abducens nerve palsy?
To weaken the medial rectus
When is surgical intervention usually reserved for?
After 6 months of stable orthoptic measurements
What is the most likely complication following surgical correction of abducens nerve palsy?
Over- or under-correction
What determines the prognosis for abducens nerve palsy?
Underlying etiology
What suggests a demyelinating process?
Subacute onset
What is the most common presenting symptom of abducens nerve palsy?
Diplopia
What is the cardinal sign of abducens nerve palsy?
Esotropia of the affected eye
What is the location of the lesion in Millard-Gubler syndrome?
Brainstem
What is the purpose of cycloplegic refraction in the evaluation of abducens nerve palsy?
To assess the refractive error of the patient
Why is it important to test each eye independently in the evaluation of abducens nerve palsy?
To avoid pseudo-restrictive effects of alternating monocular fixation and vergence
What is the characteristic of esotropia in abducens nerve palsy?
It is incomitant and greater at distance
What is the usual method of diagnosis of abducens nerve palsy?
Clinical examination
What is the characteristic of diplopia in abducens nerve palsy?
Horizontal and uncrossed
What is the significance of slow saccadic velocity in side gaze?
It is a diagnostic feature of abducens nerve palsy
What is the primary reason why the affected eye turns medially in abducens nerve palsy?
Due to the unopposed action of the medial rectus muscle
Where does the abducens nerve begin its course?
In the dorsal pons
What is the significance of a slowly progressive onset of abducens nerve palsy?
It suggests a compressive etiology
What is the characteristic of esotropia in abducens nerve palsy?
It is incomitant and greater at near than at distance
What is the anatomic location where the abducens nerve is tethered?
In Dorello's canal
What is the most common presenting symptom of abducens nerve palsy in children?
Diplopia
What is the risk factor for abducens nerve palsy in adults?
All of the above
What is the characteristic of the abducens nerve course?
It has the longest intracranial course
What is the most common underlying etiology of abducens nerve palsy in children?
Neoplasm
What is the significance of palpebral fissure widening upon abduction effort in abducens nerve palsy?
It is a sign of attempted abduction
What is the characteristic of esotropia in abducens nerve palsy?
It is greater at distance than at near
What is the significance of slow saccadic velocity in side gaze in abducens nerve palsy?
It is a diagnostic feature of abducens nerve palsy
What is the purpose of measuring fusional amplitudes in the evaluation of abducens nerve palsy?
To assess the quality of binocular vision
What is the characteristic of diplopia in abducens nerve palsy?
It is horizontal and uncrossed
What is the significance of a head turn toward the affected eye in abducens nerve palsy?
It is a compensatory mechanism to avoid diplopia
What is the significance of raised intracranial pressure in abducens nerve palsy?
It is a symptom of headache and pain around the eyes
What is the characteristic of the deviation in abducens nerve palsy?
It is greater at distance than at near
What is the importance of evaluating ductions and versions in the diagnosis of abducens nerve palsy?
It is helpful in determining incomitance
What is the primary purpose of MRI in the diagnosis of abducens nerve palsy?
To rule out underlying etiologies
Which of the following conditions may present with unilateral symptoms including proptosis and inflammation?
Thyroid eye disease
What is the significance of a 6-month period in the management of abducens nerve palsy?
The time required for orthoptic measurements to stabilize
What is the purpose of forced duction test in the management of abducens nerve palsy?
To assist with surgical planning
What is the most common complication following surgical correction of abducens nerve palsy?
Over- or under-correction
What is the significance of the presence of microvascular risk factors in patients with abducens nerve palsy?
It may affect the decision to perform MRI
What is the purpose of occlusion using a Bangerter filter or patch in the management of abducens nerve palsy?
To eliminate diplopia and confusion
What is the characteristic of diplopia in patients with myasthenia gravis?
It is fluctuating and fatigable
In which patients may the diagnostic yield of MRI be relatively low?
Elderly patients with isolated abducens nerve palsy and vasculopathic risk factors
What is the primary goal of treatment for underlying or systemic conditions in patients with abducens nerve palsy?
To treat the underlying condition
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