Differentiations

Question 1

Whats the differentiations between mechanical and neurogenic palsy?

Answer 1

Mechanical:
- Small deviation in PP
- Ductions equal to versions
- Ceasing of movement; abrupt
- Pain
- Reversal or diplopia
- Upshoots/downshoots

Neurogenic:
- Large deviation PP
- Ductions better than versions
- Gradual failure in movement
- No pain
- No upshoots/downshoots

Question 2

Whats the muscle sequelae between mechanical and neurogenic palsy?

Answer 2

• Mechanical : Partial, only overaction of contralateral synergist
- Hess chart pointed/squished

• Neurogenic: Full muscle sequalae
- Hess chart more filled

Question 3

Whats the differentiations between long standing and acquired deviations?

Answer 3

Longstanding:
- AHP: Fixed and pt usually unaware
- No diplopia
- Enlarged fusion ranges
- Gradual onset of symptoms
- Amblyopia
- Suppression

Newly acquired:
- AHP: Px aware of AHP/uncomfortable
- Diplopia
- Recent onset
- No enlarged fusion ranges

Question 4

Whats the differentiations between SO and SR palsy?

Answer 4

SO:
• Eso deviation more typical
• AHP - chin depression
• V eso pattern
• Greater vertical deviation at near
• Bielchowsky +ve
• Diplopia greatest on depression

SR:
• Exo deviation more typical
• AHP - chin elevation
• V exo pattern
• Greater deviation in distance
• Bielchowsky-ve
• May have history of ptosis
• Diplopia greatest on elevation

Question 5

Investigations to differentiate a 6th nerve palsy?

Answer 5

• Assess Far Distance (cover test and measurements)
• Lateral Version measurements to compare varying size of esotropia
• Smooth Pursuits will show limitation of abduction of affected eye
• Saccades may show hypometria of affected eye
• Lee’s screen will support smooth pursuit findings and allow comparison of palsy at future visits

Question 6

Further investigations for 6th nerve palsy?

Answer 6

• If Px has no high risks factors indicating microvascular incident, patient most likely requires neuro-imaging to determine cause
• Important to find aetiology of palsy, rule out anything sinister such as space occupying lesion/multiple sclerosis

Question 7

What is unilateral INO?

Answer 7

• Interneurones from one 6th nerve nucleus affected, loss of adduction of the affected MR on attempted conjugate gaze.
• Saccadic, pursuit and vestibular systems are all affected.
• Also get abducting nystagmus of the other eye (reason for this is not clear)
• Convergence can remain intact

Question 8

What is Bilateral INO?

Answer 8

• Bilateral: interneurones from both 6th nerve nuclei affected. Often asymmetric
• Patients rarely complain of diplopia
• Cause; MS is the commonest cause of unilateral (&often bilateral) INO in the younger patient
• In the older patient, small blood vessel occlusion is likely in unilateral INO, and tumour is a possibility in bilateral
• Most spontaneously recover, except if tumour

Question 9

Parinauds syndrome case?

Answer 9

• Lesions in uppermidbrain
• Pineal tumours more common adolescents males
• Metastases and gliomas
• Hydrocephalous
• Artherosclerosis
• Embolism, vasculitis

Question 10

Parinauds syndrome signs?

Answer 10

• Vertical gaze palsy, loss of saccades first
- Absence of OKN when stripes are rotated upwards due to lack of saccades, but normal downwards
• Progressive : Loss of downgaze with eventual complete vertical gaze palsy
• Both pupils dilated

• MR is most powerful muscle, resulting in retraction of globe
• Upper eyelid retraction - Colliers sign

Question 11

Clinical characteristics of browns syndrome?

Answer 11

• Limitation of elevation in adduction
• Down drift of affected eye on contralateral version
• o/action of contralateral SR
• A or V pattern &
• Discomfort on attempted elevation in adduction
• Improvement on repeated testing - ‘click’ syndrome
• AHP
• + ve Forced Duction Test