8.1.7 Flashcards
What is essential to include in a thorough patient history for incomitant deviations?
Onset, duration, progression of symptoms; presence of diplopia; associated systemic conditions; history of trauma; neurological symptoms
Systemic conditions include diabetes and hypertension.
What symptoms may patients report when assessing incomitant deviations?
Diplopia, ptosis, difficulty moving the eye in certain directions
Ptosis refers to drooping eyelid.
What does motility assessment evaluate in clinical examination?
Range of eye movements in all directions of gaze
Helps identify limitations and patterns suggestive of specific nerve involvement.
What tests can be performed to determine the presence and magnitude of deviations?
Cover-uncover and alternate cover tests
These tests are performed in various gaze positions.
Which cranial nerve innervates the superior rectus muscle?
Third Nerve (Oculomotor)
It controls most eye movements and also supplies muscles for eyelid elevation and pupil constriction.
What is the role of the Fourth Nerve (Trochlear)?
Innervates the superior oblique muscle, responsible for depression and intorsion of the eye (down and towards the nose)
Important for maintaining head posture.
What is the function of the Sixth Nerve (Abducens)?
Innervates the lateral rectus muscle, responsible for abduction of the eye
This muscle allows outward movement of the eye.
What are common causes of Third Nerve Palsy?
- Microvascular causes (diabetes, hypertension)
- Aneurysms
- Trauma
- Tumors or lesions
Particularly, posterior communicating artery aneurysms can compress the nerve.
What clinical features are associated with Third Nerve Palsy?
- Ocular misalignment (downward and outward deviation)
- Ptosis
- Pupil involvement (dilation, loss of reflex)
If parasympathetic fibers are affected, mydriasis may occur.
What diagnostic evaluations are essential for Third Nerve Palsy?
- Neuroimaging (MRI or CT scans)
- Laboratory tests (blood glucose, blood pressure)
Helps identify structural causes and assess microvascular risk factors.
What management strategies are recommended for Third Nerve Palsy?
- Address underlying causes (manage diabetes, hypertension)
- Symptomatic relief (prism glasses, ptosis crutches)
- Surgical options (strabismus surgery, eyelid surgery)
Recovery depends on the etiology.
What is the prognosis for microvascular Third Nerve Palsy?
Often improves over weeks to months
Traumatic or compressive causes may have variable outcomes.
What referral urgency is indicated for acute onset of incomitant deviations?
Urgent referral to rule out life-threatening causes like aneurysms
Especially with pupil involvement.
What is the anatomy and function of the Trochlear Nerve (CN IV)?
Exits dorsally from the brainstem, innervates the superior oblique muscle for eye depression and intorsion
It decussates, meaning a right CN IV lesion affects the left eye.
What are the clinical features of Fourth Nerve Palsy?
- Vertical diplopia
- Exacerbated when looking down and in
- Compensatory head tilt
Head tilt is towards the opposite side of the palsy.
What management options are available for Fourth Nerve Palsy?
- Observe congenital cases
- Fresnel prisms for diplopia
- Surgery if persistent misalignment
Superior Oblique Tuck surgery may be performed.
What is the anatomy and function of the Abducens Nerve (CN VI)?
Arises from the pons, innervates the lateral rectus muscle for abduction of the eye
It runs through the cavernous sinus before entering the orbit.
What are common causes of Sixth Nerve Palsy?
- Raised intracranial pressure
- Microvascular causes
- Trauma
- Brainstem lesions
Commonly due to tumors or idiopathic intracranial hypertension.
What clinical features are associated with Sixth Nerve Palsy?
- Horizontal diplopia
- Esotropia in primary gaze
- Inability to abduct the affected eye
Diplopia worsens when looking towards the affected side.
What is the management for microvascular Sixth Nerve Palsy?
Observe, resolves in 3–6 months
Urgent referral needed for high ICP.
What condition affects the extraocular muscles in Thyroid Eye Disease?
Graves’ Orbitopathy
Causes swelling of orbital fat and muscles, leading to mechanical restriction.
What are clinical features of Duane’s Syndrome?
- Limited or absent abduction
- Adduction limitation
- Upshoot or downshoot on attempted movement
- Narrow palpebral fissure
Involves abnormal development of the abducens nerve.
What management options exist for Convergence Insufficiency?
- Vision therapy (orthoptic exercises)
- Prism glasses
- Near-vision exercises
Aimed at improving convergence strength.
What may cause horizontal and vertical rectus muscle palsies?
- Trauma
- Neurological disorders
- Mechanical restriction or orbital disease
Examples include stroke or tumors.
What is mechanical strabismus?
Results from physical restriction of eye movement
Can be due to trauma or orbital disease.
What is orbital disease?
Conditions affecting the orbit, including orbital fractures and tumors.
Orbital diseases can lead to various visual impairments due to their impact on eye movements and alignment.
What is incomitant deviation?
Deviation of the eye that varies depending on which muscle is affected.
Incomitant deviations are often associated with specific muscle dysfunction.
What is diplopia?
Double vision that worsens in certain gaze positions.
Diplopia can significantly affect quality of life and may indicate underlying ocular conditions.
What are the clinical features of orbital disease?
Incomitant deviation, diplopia, restricted gaze or inability to move the eye in one direction.
These features depend on the specific muscles or structures involved.
What is the management for orbital disease?
Prism therapy and surgical intervention (strabismus surgery) for significant deviations.
Management strategies aim to improve alignment and reduce diplopia.
What is mechanical strabismus?
Strabismus resulting from physical restriction of eye movement due to orbital or muscle involvement.
This type of strabismus can be due to various anatomical changes or injuries.
What are the causes of mechanical strabismus?
- Orbital fractures following trauma
- Orbital tumors compressing extraocular muscles
- Orbital myositis
- Fibrosis of the muscle due to previous surgery or trauma
Each cause leads to specific clinical manifestations and management strategies.
What are the clinical features of mechanical strabismus?
Diplopia with fixed, incomitant deviation and restricted movements in one or more directions of gaze.
The degree of restriction depends on the location of the mechanical issue.
What is the management for mechanical strabismus?
Surgical treatment to relieve muscle restriction or realign the eyes; prism therapy or glasses may help.
The choice of management depends on the severity and cause of the strabismus.
What is intermittent exotropia (IXT)?
A condition characterized by intermittent outward deviation of the eye when eye muscles fail to maintain alignment.
IXT typically manifests during periods of fatigue or distraction.
What are the clinical features of intermittent exotropia?
Intermittent outward deviation, exophoria when eyes are aligned, diplopia when misaligned.
These features may vary based on the patient’s state of fatigue or attention.
What is the management for intermittent exotropia?
- Prism glasses
- Strabismus surgery for realignment
- Vision therapy to strengthen convergence
Management aims to improve binocular vision and reduce the frequency of outward deviation.
What is Duane’s syndrome?
A congenital condition where the abducens nerve fails to develop properly, leading to limited eye movements.
What are the three types of Duane’s syndrome?
- Type 1: Limited abduction of the affected eye
- Type 2: Limited adduction of the affected eye
- Type 3: Limitation in both abduction and adduction
Which muscle is primarily affected in Type 1 Duane’s syndrome?
Lateral rectus muscle
What is a common clinical feature of Type 1 Duane’s syndrome?
Esotropia (eye turned in when trying to look to the affected side)
In Type 2 Duane’s syndrome, which muscle is affected?
Medial rectus muscle
What is a common clinical feature of Type 2 Duane’s syndrome?
Exotropia (eye turned outward when attempting to look towards the affected side)
What condition is also known as Graves’ Orbitopathy?
Thyroid Eye Disease (TED)
Which muscles are commonly affected in Thyroid Eye Disease?
- Inferior rectus
- Medial rectus
- Superior rectus
- Lateral rectus
What is proptosis?
Forward displacement of the eye causing bulging eyes.
What are common clinical features of Thyroid Eye Disease?
- Restriction in gaze
- Diplopia
- Proptosis
- Periorbital swelling and redness
- Abnormal head posture
What does the third cranial nerve control?
- Superior rectus
- Medial rectus
- Inferior rectus
- Inferior oblique
- Levator palpebrae superioris
What is a symptom of third cranial nerve palsy?
Ptosis (drooping of the eyelid)
What is the typical eye position in third cranial nerve palsy?
Downward and outward
What is the primary muscle affected by the fourth cranial nerve?
Superior oblique muscle
What is a common symptom of fourth cranial nerve palsy?
Vertical diplopia
What compensatory position might a patient adopt with fourth cranial nerve palsy?
Compensatory head tilt
Which muscle does the sixth cranial nerve innervate?
Lateral rectus muscle
What is the effect of sixth cranial nerve palsy on eye position?
The affected eye remains turned inward (esotropia)
What is a management option for sixth cranial nerve palsy?
Prism glasses to reduce diplopia
What are the effects of third nerve palsy?
- Ptosis
- Ocular misalignment
- Diplopia
- Possible pupil dilation (mydriasis)
What type of diplopia is associated with sixth nerve palsy?
Horizontal diplopia
What is the management approach for fourth cranial nerve palsy?
- Prism correction
- Orthoptic exercises
- Strabismus surgery in severe cases
Fill in the blank: Thyroid Eye Disease primarily affects the _______ muscles.
[extraocular]
Fill in the blank: The third cranial nerve is responsible for controlling the _______ muscle.
[most of the eye movements]
True or False: The inferior rectus muscle is commonly affected in Thyroid Eye Disease.
True
