NON - COMITANT STRABISMUS AND ITS UNDERLYING CAUSES Flashcards
Diplopia can be caused by the disease of?
- Eye
- Orbit
-EOM’s - Neuromuscular junction
- Ocular motor nerves
- Brain
What does non-concomitant strabismus involve?
Limitations of eye movements in specific directions of gaze
- Strabismus magnitude changes with gaze direction
What are the causes of non-concomitant strabismus?
- Neurogenic dysfunction (cranial nerve palsy)
- Mechanical restriction
- Myogenic dysfunction (defect of muscle)
- Inter & supranuclear disorders
What is a neurogenic dysfunction?
It is an isolated nerve palsies tend to present with relatively predictable motility patterns
can be partial paresis (partially paralyzed)
What is 4th nerve palsy?
This is the most common cause of non-strabismus
Head injury, even if its is minor can cause damage
What is the clinical presentation of 4th nerve palsy?
- Hypertropia in primary gaze, increases in adduction
- Relative extorsion of the eye, which is difficult to observe (Maddox rod can help)
- Head tilt to opposite side
- Head turn to opposite side
What is 6th nerve palsy?
Occurs when the 6th nerve (abducens nerve) is damaged
It can also be paresis
What is the aetiology of 6th nerve palsy?
- Vascular in older px (diabetes, CVA)
- Brain Stem tumour in young px
- Diplopia: non concomitant pattern and may be transient
What is the clinical presentation of 6th nerve palsy?
- Esotropia in primary gaze
- Limited abduction on affected side
- Head turn to affected side
What is 3rd nerve palsy ?
This is damage to the third nerve (oculomotor nerve)
- Presents with a large exotropia and mild hypertropia
- Ptosis occurs due to the levator palpebrae involvement
- Possible fixed dilated pupil
What is Duane syndrome?
It is neuro-development disorder and resultant EOM restriction
- Causes retraction of the globe on attempted adduction
- LE more affected
- Females affected > than males
What are the three types of duane syndrome?
Type 1 - Abduction limitation & retraction on adduction
Type 2 - Adduction limitation & retraction on attempt
Type 3 - Abduction & adduction limitation, retraction on attempted adduction
What is the clinical presentation of Duane’s syndrome?
- Limitation of abduction
- May have esotropia in primary gaze
- Remote NPC
What is Brown syndrome?
This is when the tendon cannot move effectively through the trochlea
Causes restrictions of the SO release which inhibits IO action
What is the clinical presentation of brown’s syndrome?
Limited elevation on adduction
Hypertropia on adduction
Increased divergence in up gaze
