6th nerve palsy

Question 1

Pathway

Answer 1

starts at abdusence nerve in ther pons,
exits brain stem at junction between pons and medulla,
enters subarachnoid canal and runs along dorello’s canal,
passes above the tip of the petrous temporal bone,
enters the carvenous sinus where it runs along side its internal carotid artery,
enters the lateral aspect of the superior orbital fissure and passes anteriorly to innervate the lateral rectus.

Question 2

Aetiology in over 50s

Answer 2

most commonly due to:-
1. diabetes
2. hypertension
3. high cholesterol

other aetiology includes:-
1. trauma
2. Giant cell arthritis - EMERGENCY
3. Stroke

Question 3

Aetiology in under 50s

Answer 3

most common causes includes:-
1. MS
2. Raised ICP due to space occupying lesion
3. increased IIH
4. trauma
5. cavernous sinus mass
6. viral infection

Question 4

Aetiology in chidren

Answer 4

Most common causes in under 16s:-
1. congenital VI pasly
2. space occupying lesion
3. trauma
4. Idiopathic
5. hydrocephalus
6. viral infections effecting ears, nose or throat

Question 5

Clinical features

Answer 5

Esotropia in drimary position greather in distance fixation.
Esotropia increasing in size on attempted abduction on effected eye.
Limited abduction on affected eye.
Px coplains of increased diplopia.
Px may have to tue face to affected side.
Field of BSV moved towards unaffected eye.

Question 6

Diff Diagnosis

Answer 6

Myasthenia Gravis
Duanes retraction syndrome - Type 1
Infantile esotropia
Mobeius syndrome - combined 6th and 7th nerve pasly
Medial wall fracture

Question 7

Investigations

Answer 7

Assess distance vis covertest
Lateral version measurements to compare varying size of esotropia
Smooth pursuit will show limitation ofabduction of the affected eye
Saccades may show hypermetria
Lees screen supports smooth pursuit finding and allowing future comparison of pasly

Question 8

6th nerve pasly

Answer 8

Left esotropia in PP
On attemoted leave-version- Left eye does not reach midline, -5 underaction
On attempted dextro-version -RE does not fully abducted, -1 underaction
Showing long standing palsy with full muscle sequalae

Question 9

Case history

Answer 9

Depends on age of Px
presenting usually with hoozontal diplopia that is worse in the distance
may be aware of using a face-turn to achieve single vision (BSV)
question changes and when it started

Question 10

Orthoptic Management

Answer 10

Prism to join Diplopia and restore binocular single vision.
If deviation too large to control with prism, then occluding 1 eye will alleviate patients symptoms for diplopia.
Allow 6 months for recovery.
Only partial recovery before botox adminestration.

Question 11

moebius syndrome

Answer 11

Congenital
Bilateral 6th and 7th nerve palsies
No known genetic cause
insufficent lid closure
Volitational eye lid closure
Amblyopia
DVD

Question 12

Gradebigo’s syndrome

Answer 12

Incolvement of 6th nerve in combination with 5,7 and 8.
causes are inflamation of the petrous bone secondaary to middle ear infection.
Most likely in children.