Supranuclear And Internuclear Disorders Flashcards
Features of supranuclear disorders
- SN mobility disorders cause palsies of conjugate movement
- horozontal and vertical conjugate movements are controlled by separate gaze centres
Horozontal gaze centres - eye movements
- saccades = initiated by contralateral frontal pre-motor area
- pursuit = initiated by ipsilateral occipito-parietal area
- vestibular reflexes = vestibular nuclei in pons
Vertical gaze centres - lesion location and its impact
- key region for vertical movement lies in rostral mid brain
- riMLF is most important area for generating down gaze
- posterior commissure important for generating upgaze
What is parinauds syndrome
- lesion affecting upper mid brain
- usually pineal tumour
- hydrocephalus - dilution of 3rd nerve nucleus and compression of posterior commissure
- can be caused by atheroscleritis/embolism/vasculitis
Parinauds syndrome clinical signs
- loss of saccades with normal smooth pursuit movement vertical gaze palsy
- progressive causes loss of downgaze, and eventual complete vertical gaze paralysis
- dilated pupils
- convergence retraction nystagmus on upgaze
- disinhibition of the oculomotor nuclei, causing burst of co-fixing from EOMs
- upper lid retraction associated with lid lag
- loss of bells phenomenon
- globe retraction
- Light/near dissociation - dilated pupils that react only to accommodation and NOT to light
- Collier’s sign - bilateral upper eyelid retraction with lid lag (eyes have come down but lag of lids coming down)
- Papilledema - children more likely to have hydrocephalus (swelling in the brain) but can be present in adults too
What is Internuclear ophthalmoplegia and aetiology
- lesion in medial longitudinal fasiculus MLF
- type depends on location in MLF
- can be unilateral and bilateral
- most spontaneously recover
Causes
- MS most common in unilateral
- small vessel occlusion in older Px, unilateral
- tumour common in bilateral
Features of unilateral INO
- loss of adduction of affected MR on attempted conjugate gaze
- saccadic, pursuit and vestibular systems are all affected
- abducting gaze evoked nystagmus of the other eye
- diplopia worse at near
- slower saccades, useful in differentiating asymmetric bilateral INO
Bilateral INO features
- rarely complain of diplopia
- interneurons from both 6th nerve nuclei affected, often asymmetric
- gaze evoked vert nystagmus and impaired vert smooth pursuit
One and a half syndrome - paralytic pontine exotropia - aetiology, signs and symptoms
- lesions affect both horizontal gaze centre and adjacent MLF = INO + gaze palsy
- Unilateral INO and ipsilateral horizontal gaze palsy
- complete one and a half uncommon
- tumour likely cause
Signs
- conjugate horizontal gaze palsy and limited adduction of the ipsilateral eye
- ipsilateral eye can’t mover left or right
- contralateral eye can be exotropic with abduction nystagmus during lateral eye movements
Symptoms
- oscillopsia
- blurred vision
- diplopia
What is skew deviation
- vertical strabismus
- disruption of input to 3rd nerve and 4th nerve nuclei
- associated with CNS
Skew deviation features
- vertical strabismus from peripheral and central lesions
- diplopia
- torsional nystagmus
- head tilt with torsion
- peripheral/central lesions cause head tilt to affected side
- rostral lesion on MLF causes head tilt to unaffected side
- unable to fuse with prisms
- deviation less when Px lies Down
Treatment of one and a half
- patching
- treat underlying cause
- prisms to minimise diplopia
- EOM recession
What is progressive supranuclear palsy
- Degeneration of the Brainstem Reticular Formation
- Disease of later life (px’s are older when they come and see you)
Progressive supranuclear palsy - ocular signs
- Impaired/slowing of vertical saccades
- Different to Parinaud’s as instead of losing upgaze saccades you lose downgaze saccades
- Usually affecting downgaze initially then complete loss of vertical saccades
- Late stages may have horizontal gaze disorders, with complete Ophthalmoplegia (unable to move eyes at all)
- Frequent square-wave jerks have been noted/saccadic intrusions
- Difficulty in voluntary opening the eyelids (Apraxia of lid opening)
