35 Questions
What is the cause of Internucleur Opthalmoplegia (INO)?
Demyelination of the medial longitudinal fasciculus
Convergence is usually affected in Internucleur Opthalmoplegia (INO).
False
What is aberrant regeneration?
A change in the actions of muscles supplied by the 3rd nerve due to regrowth of damaged nerve fibres following complete or severe 3rd nerve palsy.
In Internucleur Opthalmoplegia (INO), the lesion is in the _______________________.
medial longitudinal fasciculus (MLF)
What is the result of a lesion in the MLF?
Palsy of the medial rectus
Adduction can recover quickly in Multiple Sclerosis (MS) patients with Internucleur Opthalmoplegia (INO).
True
Match the following types of nystagmus with their characteristics:
Pendular = Rhythmic oscillations of the eyes Horizontal jerk = Fast movement in one direction, slow movement in the other direction See-saw = Alternate elevation and depression of the eyes Downbeat = Fast downward movement, slow upward movement
Yoke prisms can be used to reduce _______________________ and move images into the null zone.
head posture
What is One and a half syndrome?
Unilateral Internucleur Opthalmoplegia (INO) and ipsilateral horizontal gaze palsy.
Bilateral Internucleur Opthalmoplegia (INO) is most commonly caused by tumours.
False
What is the main purpose of Bielschowsky's Head Tilt Test?
To differentiate between a superior oblique and a contralateral superior rectus palsy
A positive Bielschowsky's Head Tilt Test result is always indicative of a superior oblique palsy.
False
What is the normal response of a healthy individual's eyes when they tilt their head?
The SO and SR muscles of the eye closest to the shoulder keep the eye level, and the IO and IR rectus muscles keep the other eye level.
Nystagmus is a repetitive oscillatory movement in one or both eyes, characterized by alternating smooth pursuits in one direction and a ______________________ movement in the other direction.
saccadic
What is a characteristic of congenital nystagmus?
No null position
Albinism is a common cause of congenital nystagmus.
True
What is the purpose of the cover test in Bielschowsky's Head Tilt Test?
To measure the degree of vertical deviation in the primary position and with the patient's head tilted maximally to the left and right.
What is the primary purpose of Bielschowsky's Head Tilt Test?
To differentiate between a superior oblique and a contralateral superior rectus palsy
A positive Bielschowsky's Head Tilt Test result is always indicative of a superior oblique palsy.
False
What is the characteristic of nystagmus that distinguishes it from other eye movements?
repetitive oscillatory movement
In a patient with a superior oblique palsy, the ______________ muscle's action is not counteracted by the superior oblique muscle.
superior rectus
What is a common cause of congenital nystagmus?
All of the above
Congenital nystagmus is always uniplanar.
False
Match the following types of nystagmus with their characteristics:
Congenital = May be uniplanar or not uniplanar Acquired = Worse at distance, less for near
What is the direction of the saccadic movement in nystagmus?
opposite direction
What is the primary usage of JavaScript?
Client-side scripting for web applications
In Internucleur Opthalmoplegia (INO), the lesion is in the pons.
True
What is the result of aberrant regeneration?
A change in the actions of muscles supplied by the 3rd nerve due to regrowth of damaged nerve fibres.
Baclofen can effectively stop _______________________ nystagmus.
periodic alternating
What is the purpose of yoke prisms in treating nystagmus?
To reduce head posture and move images into the null zone
Convergence is always affected in Internucleur Opthalmoplegia (INO).
False
Match the following types of nystagmus with their characteristics:
Pendular = Horizontal oscillations Horizontal jerk = Fast phase in one direction, slow phase in the other Vestibular = Caused by a problem with the balance organs in the inner ear See-saw = Alternating elevation and depression of the eyes
What is the result of a lesion in the MLF?
Deficit for adduction on the side of the MLF lesion
In Internucleur Opthalmoplegia (INO), the _______________________ is affected.
medial longitudinal fasciculus (MLF)
What is the characteristic of Internucleur Opthalmoplegia (INO) that helps differentiate it from other conditions?
Dissociated gaze evoking nystagmus of the abducting eye
Study Notes
Bielschowsky's Head Tilt Test (BHTT)
- Differentiates between superior oblique and contralateral superior rectus palsy
- Patient fixates on a target 3m away, cover test is performed in primary position and with head tilted maximally to left and right
- Increase in vertical deviation when head tilted to affected side indicates superior oblique palsy
Principles of BHTT
- In healthy individuals, superior oblique (SO) and superior rectus (SR) muscles of the eye closest to the shoulder keep the eye level when head is tilted
- Inferior oblique (IO) and inferior rectus (IR) muscles keep the other eye level
- In patients with SO palsy, SR muscle's action is not counteracted by SO muscles, leading to vertical deviation of the affected eye when head is tilted towards the affected eye
Nystagmus
- Repetitive oscillatory movement in one or both eyes
- Can be horizontal, vertical, and rotary direction
- Classified into congenital and acquired
- Congenital nystagmus: uniplanar, null position, compensated head nodding, worsened at distance
- Acquired nystagmus: not uniplanar, no null position, no compensated head nodding, not worse at distance
- Causes of congenital nystagmus: albinism, aniridia, optic nerve, chiasm, rods and cones, methadone
- Causes of acquired nystagmus: optic chiasm tumors, posterior fossa tumors
Classification of Nystagmus
- Congenital: manifest, latent, and latent-manifest
- Acquired: pendular, horizontal jerk, gaze-evoked, vestibular, see-saw, downbeat/upbeat, periodic alternating
Treatment of Nystagmus
- Baclofen effectively stops periodic alternating nystagmus
- Therapeutic approaches: contact lens, drugs, surgeries, and low vision rehabilitation
- Surgery can move eyes in the direction of a null zone
- Yoke prisms can reduce head posture and move images into the null zone
Aberrant Regeneration
- Change in actions of muscles supplied by the 3rd nerve due to regrowth of damaged nerve fibers following complete or severe 3rd nerve palsy
- May occur weeks to months after the onset of the 3rd nerve paresis
- Factors underlying aberrant regeneration are unclear, may involve central or peripheral response
- Investigations: cover test, ptosis, pupil, and retraction of globe
Internuclear Ophthalmoplegia (INO)
- Supranuclear disorder affecting the medial longitudinal fasciculus (MLF)
- Lesion of the MLF causes deficit for adduction on the side of the MLF lesion
- Convergence is usually intact
- Results in palsy of the medial rectus with dissociated gaze-evoking nystagmus of the abducting eye
Types of INO
- Unilateral: affects interneurons from only one 6th nerve nucleus, causing loss of adduction of the affected MR on attempted conjugate gaze
- Bilateral: affects interneurons running in both MLFs, causing bilateral adduction loss with bilateral ataxic nystagmus of the abducting eye
Pathways Involved in INO
- Normal pathway: right frontal eye field sends a signal to the left PPRF, which innervates the left 6th nerve nucleus, controlling the left lateral rectus and causing the left eye to abduct
- Normal pathway: left 6th nerve nucleus innervates the right third nerve nucleus, controlling the medial rectus, causing the eye to adduct
Recovery from INO
- Adduction can recover quickly in MS patients
- Ataxic nystagmus may take longer
One and a Half Syndrome
- Unilateral INO and ipsilateral horizontal gaze palsy
- Extensive lesion of the caudal (lower) lesions of the pons, affecting the horizontal gaze centre and adjacent MLF
- Bilateral medial rectus palsy and one lateral rectus palsy (gaze palsy and INO)
Features of One and a Half Syndrome
- Unilateral INO and ipsilateral gaze palsy
- Preserved abduction of contralateral eye
- Ataxic nystagmus at the working lateral rectus
- Paralytic pontine exotropia
- Intact vertical motility and convergence
- VOR usually intact
Treatment of One and a Half Syndrome
- Occlusion to remove diplopia and Oscillopsia
- Botulinum toxin and strabismus surgery for adduction deficit and exotropia
Bielschowsky's Head Tilt Test (BHTT)
- Differentiates between superior oblique and contralateral superior rectus palsy
- Patient fixates on a target 3m away, cover test is performed in primary position and with head tilted maximally to left and right
- Increase in vertical deviation when head tilted to affected side indicates superior oblique palsy
Principles of BHTT
- In healthy individuals, superior oblique (SO) and superior rectus (SR) muscles of the eye closest to the shoulder keep the eye level when head is tilted
- Inferior oblique (IO) and inferior rectus (IR) muscles keep the other eye level
- In patients with SO palsy, SR muscle's action is not counteracted by SO muscles, leading to vertical deviation of the affected eye when head is tilted towards the affected eye
Nystagmus
- Repetitive oscillatory movement in one or both eyes
- Can be horizontal, vertical, and rotary direction
- Classified into congenital and acquired
- Congenital nystagmus: uniplanar, null position, compensated head nodding, worsened at distance
- Acquired nystagmus: not uniplanar, no null position, no compensated head nodding, not worse at distance
- Causes of congenital nystagmus: albinism, aniridia, optic nerve, chiasm, rods and cones, methadone
- Causes of acquired nystagmus: optic chiasm tumors, posterior fossa tumors
Classification of Nystagmus
- Congenital: manifest, latent, and latent-manifest
- Acquired: pendular, horizontal jerk, gaze-evoked, vestibular, see-saw, downbeat/upbeat, periodic alternating
Treatment of Nystagmus
- Baclofen effectively stops periodic alternating nystagmus
- Therapeutic approaches: contact lens, drugs, surgeries, and low vision rehabilitation
- Surgery can move eyes in the direction of a null zone
- Yoke prisms can reduce head posture and move images into the null zone
Aberrant Regeneration
- Change in actions of muscles supplied by the 3rd nerve due to regrowth of damaged nerve fibers following complete or severe 3rd nerve palsy
- May occur weeks to months after the onset of the 3rd nerve paresis
- Factors underlying aberrant regeneration are unclear, may involve central or peripheral response
- Investigations: cover test, ptosis, pupil, and retraction of globe
Internuclear Ophthalmoplegia (INO)
- Supranuclear disorder affecting the medial longitudinal fasciculus (MLF)
- Lesion of the MLF causes deficit for adduction on the side of the MLF lesion
- Convergence is usually intact
- Results in palsy of the medial rectus with dissociated gaze-evoking nystagmus of the abducting eye
Types of INO
- Unilateral: affects interneurons from only one 6th nerve nucleus, causing loss of adduction of the affected MR on attempted conjugate gaze
- Bilateral: affects interneurons running in both MLFs, causing bilateral adduction loss with bilateral ataxic nystagmus of the abducting eye
Pathways Involved in INO
- Normal pathway: right frontal eye field sends a signal to the left PPRF, which innervates the left 6th nerve nucleus, controlling the left lateral rectus and causing the left eye to abduct
- Normal pathway: left 6th nerve nucleus innervates the right third nerve nucleus, controlling the medial rectus, causing the eye to adduct
Recovery from INO
- Adduction can recover quickly in MS patients
- Ataxic nystagmus may take longer
One and a Half Syndrome
- Unilateral INO and ipsilateral horizontal gaze palsy
- Extensive lesion of the caudal (lower) lesions of the pons, affecting the horizontal gaze centre and adjacent MLF
- Bilateral medial rectus palsy and one lateral rectus palsy (gaze palsy and INO)
Features of One and a Half Syndrome
- Unilateral INO and ipsilateral gaze palsy
- Preserved abduction of contralateral eye
- Ataxic nystagmus at the working lateral rectus
- Paralytic pontine exotropia
- Intact vertical motility and convergence
- VOR usually intact
Treatment of One and a Half Syndrome
- Occlusion to remove diplopia and Oscillopsia
- Botulinum toxin and strabismus surgery for adduction deficit and exotropia
This quiz assesses your understanding of Bielschowsky's Head Tilt Test (BHTT), a diagnostic tool used to differentiate between superior oblique and contralateral superior rectus palsy. It involves a series of steps, including fixation and cover testing, to measure vertical deviation. Learn more about BHTT and its applications in ophthalmology.
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