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Clinical Ophthalmology > Neuro 2.1 > Flashcards

Neuro 2.1 Flashcards

1
Q

Internuclear Ophthalmoplegia

A
  • Lesion of the Medial Longitudinal Fasciculus (MLF)
  • Palsy of the MR
  • With dissociated gaze evoked nystagmus of the abducting eye (Ataxic Nystagmus)
  • Unilateral or bilateral
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2
Q

INO - Pathways Involved

A
  • To look to the left, the right frontal eye field sends a signal to the left PPRF
  • The left PPRF innervates the left VI (abducens) nucleus, which controls the left LR and causes the LE to abduct (Gaze left)
  • Also, the left VIN nucleus innervates the right IIIN (oculomotor) nucleus, which controls the right MR muscle, causing the RE to adduct (Gaze left)
  • PPRF - paramedian pontine reticular formation - horizontal gaze centre
  • The MLF is the tract connecting the R LR and L MR and the same on the opposite side where it is connecting the L LR and R MR
  • In INO there is damage to the MLF giving a deficit in adduction
  • Convergence is usually still intact
    • No convergence - lesion higher up the MLF
    • Convergence intact - lesion lower down MLF
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3
Q

INO - Causes

A
  • MS (most common)
  • Stroke - basilar artery occlusion
  • Tumour (rarely)
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4
Q

INO - Signs

A
  • Exophoria/tropia
    • If exotropia, px will tell you of diplopia when reading
    • Any exo deviation will be greater at near than at distance
  • Deviation will increase on attempted adduction
  • Impaired/slowed saccades useful when differentiating unilateral INO from asymmetric Bilateral INO
  • Ataxic nystagmus on lateral gaze (bobbing effect - only when nystagmus is in one eye - not a true nystagmus hence why ataxic)
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5
Q

INO - Differential Diagnosis

A
  • Myasthenia Gravis
    • Look for fatigue, variability, ptosis, Cogan’s lid twitch, involvement of the vertical muscles
  • Medial Wall BO fracture
    • History of trauma, enophthalmos, mechanical restriction of abduction
  • Duane’s Retraction Syndrome
    • Looking for restriction of abduction and characteristic palpebral fissure changes
    • Infranuclear MR palsy (partial 3rd nerve palsy)
    • Very rare
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6
Q

INO - Brief Summary

A
  • Ipsilateral MR palsy (MR palsy in one eye e.g. R MR palsy - R INO, lesion in R MLF)
  • Saccades more affected than smooth pursuit
  • Convergence may be intact
  • Ataxic nystagmus
  • Skew Deviation - ipsilateral hypertropia
  • Bilateral has gaze evoked vert nystagmus and impaired vert smooth pursuit
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7
Q

INO - Recovery

A
  • Adduction can recover quite quickly in MS patients
  • Ataxic nystagmus may take longer
  • This can be a sign when examining a px with previous episodes of INO
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8
Q

One and a half Syndrome

A
  • Unilateral INO and ipsilateral horizontal gaze palsy
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9
Q

One and a half Syndrome - Causes

A
  • Extensive lesion of the lower Pons
  • Affecting the horizontal gaze centre and the adjacent MLF
  • Bilateral MR Palsy and one LR Palsy (Gaze palsy + INO)
  • MS, stroke, tumour
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10
Q

One and a half Syndrome - Signs

A
  • Unilateral INO
  • Ipsilateral gaze palsy
  • Preserved abduction of contralateral eye
  • Ataxic nystagmus
  • Intact vertical motility and convergence
  • VOR (vestibulo-ocular reflex) usually intact - if px’s head is moved their eyes move in the opposite direction
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11
Q

Parinaud’s Syndrome

A
  • Also known as ‘Dorsal Midbrain Syndrome’
  • Posterior Commissure Syndrome
  • Sylvian Aqueduct Syndrome
  • Nystagmus Retractorius Syndrome
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12
Q

Parinaud’s Syndrome - Clinical Features

A
  • Loss of upward saccadic movement with normal vertical pursuit
  • Convergence Retraction ‘Nystagmus’ – best seen using OKN drum on downward rotation, characteristic rhythmical convergence movement of both eyes with retraction of the globe
  • 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
  • Convergence insufficiency
  • Accommodative insufficiency
  • Skew deviation
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13
Q

Parinaud’s Syndrome - Extensive Lesions

A
  • Pineal mass will compress superior colliculi restricting upward saccades
  • Edinger-Westphal Nucleus (rostral portion of 3rd nerve) causing light near dissociation of the pupils
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14
Q

Progressive Supranuclear Palsy

A
  • Degeneration of the Brainstem Reticular Formation
  • Disease of later life (px’s are older when they come and see you)
  • Also known as Steele-Richardson Syndrome
  • The vertical gaze palsy differentiates the condition from other Parkinsonian disorders
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15
Q

Progressive Supranuclear Palsy - Ophthalmic Signs

A
  • 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)
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16
Q

Progressive Supranuclear Palsy - Neurological Signs

A
  • History of early falls
  • Dysphagia with choking
  • Symmetrical akinetic rigidity
  • Absence of tremor
  • Frontal lobe deficits (will affect personality)
  • Difficulty seeing food on their plate
  • Trouble walking downstairs
  • Combination of vertical gaze palsy and axial rigidity limiting neck movement
  • Dementia and death approx. 10yrs after onset
17
Q

Myasthenia Gravis

A
  • Myogenic disorder of the muscles
18
Q

Myasthenia Gravis - Causes

A
  • Autoimmune disorder
  • Formation of acetylcholine receptor site antibodies
  • The antibodies prevent acetylcholine from binding and reduce effectiveness of neurotransmitter, hence minimal muscle contraction
  • Acetylcholine continues to be released
  • This maintains the striated muscle contracture until the stores are drained.
  • This then shows the classic early muscle fatigue
19
Q

Myasthenia Gravis - Types

A
  • Systemic - eyes also affected
  • Ocular - won’t have generalised systemic problem, only EOM’s affected
20
Q

Myasthenia Gravis - Signs

A
  • Characterised by excessive fatiguability of striated muscle
  • EOM, facial (can’t contain a smile), bulbar, neck, limb girdle, distal limb and trunk muscles
  • When the respiratory muscles are severely affected can be fatal
  • EOM’s - mostly affected as they have a very high concentration of receptors and increased sensitivity of the Neuromuscular junction
  • May be associated with other autoimmune diseases such as diabetes, Graves’ Orbitopathy and rheumatoid arthritis
21
Q

Myasthenia Gravis - Systemic Signs

A
  • Dependant on which muscle groups are affected
  • Ensure that you ask for signs of general MG in case history
  • Difficulty chewing/swallowing (jaw muscles)
  • Difficulty speaking (bulbar muscles)
  • Breathlessness (respiratory muscles)
  • Fatigue climbing stairs or holding arms up high shows a weakness of the (limb girdle muscle)
  • Lack of facial expression (facial muscles)
22
Q

Myasthenia Gravis - Symptoms

A
  • Symptoms increase as day goes on (fatigue on muscles has not kicked in yet)
  • May be symptom free in morning and only complain of fatigue by the evening
23
Q

Myasthenia Gravis - Ocular Symptoms

A
  • Ptosis
  • Diplopia (may not have in morning)
  • Inadequate lid closure
24
Q

Myasthenia Gravis - Assessment of Ptosis

A
  • Ptosis should increase on continued elevation or repeated up and down gaze
    • Extreme cases - lids may drop on continued gaze in the primary position
  • Positive Cogan’s Lid Twitch
  • Px look down for 15 secs, then refixate in primary position, twitch seen in upper lid as it overshoots the midline and returns to ptotic position
  • “Flutter type” upper lid movements due to lid twitches
  • If you hold the most affected eyelid open, innervational drive to both upper eyelids is reduced and the ptosis on the other, less affected eye increases
  • Frontalis overaction in an attempt to raise the eyelids - apparent upperlid retraction
25
Q

Myasthenia Gravis - Assessment of Diplopia

A
  • Dip can be hor/ver/both, and will vary throughout the day
  • MG can cause any type of muscle palsy
  • Limited elevation is the most common
  • Pseudo INO
  • Isolated IR palsy
  • Pseudo gaze palsy (can’t look to the right)
  • Pseudo 3rd, 4th, 6th nerve palsies
  • Can mimic any EOM condition
  • Orbicularis weakness
  • Ask px to close eyes tightly, examiner tries to open them whilst they keep them shut
26
Q

Myasthenia Gravis - Classification

A
  • Neonatal - rare
  • Congenital - infants may be affected with both ocular and systemic MG
  • Juvenile - from Birth to Puberty similar to the adult cases
  • Adults - most common
  • Ocular - if doesn’t become generalised within 2 yrs, will likely remain ocular
27
Q

Myasthenia Gravis - Investigations

A
  • Ice pack test
    • Lowering temp can improve symptoms
    • Ice pack applied to eyelid can improve ptosis
  • Sleep test
    • Ask px to nap - lid position will improve if MG
  • Serum blood testing for acetylcholine receptor site antibodies
    • 80-90% seen in General MG
    • 40-50% seen in Ocular MG
    • Do not exclude MG if negative blood result
  • Electromyography
    • To record electrical activity of skeletal muscles
    • Single or multiple muscle fibres may be tested
    • Nerve supply to the muscles electronically stimulated and muscle activity recorded
28
Q

Myasthenia Gravis - Management

A
  • The Ophthamologist may trial a longer acting antichoinesterase drug
  • CT scan of the thymus gland (can be enlarged in MG)
  • If gland is enlarged (Thymoma), can be removed
29
Q

Myasthenia Gravis - Ocular Management

A
  • Fresnel prisms (change prisms frequently)
  • Ptosis props (allow lid to be lifted in evening, no need in morning)
  • Occlusion (to prevent diplopia)
  • Strabismus surgery under local anaesthesia with adjustables (only when things are very stable)
30
Q

Chronic Progressive External Ophthalmoplegia (CPEO)

A
  • Mitochondrial disorder characterised by ptosis and slowly progressive bilateral ocular immobility
  • Associated with ‘Kearns Sayre Syndrome’
31
Q

CPEO - Clinical Features

A
  • Progressive symmetrical loss of motility
  • Upgaze usually first affected
  • Ptosis and orbicularis weakness
  • Normal pupils and accommodation
  • Diplopia not commonly complained of as symmetrical and very slowly progressive
  • Final stages have virtually no eye movements with positive FDT (force duction test? - eye is physically moved with callipers holding the conj anf if unable to move eye this is) due to secondary fibrosis
32
Q

CPEO - Kearns Sayre Syndrome

A
  • CPEO (n childhood)/child with extreme ptosis or palsies etc
    • Fine pigmentary retinopathy
    • Mild visual impairment
    • Can be connected with a heart conduction block
33
Q

CPEO - Differential Diagnosis

A
  • Myasthenia gravis
  • Graves’ disease (TED)
  • Supranuclear gaze palsy
  • Multiple nerve palsies
34
Q

CPEO - Management

A
  • Fundoscopy
  • ECG
  • Orthoptic assessment to include UFOF
  • Ptosis Props/Fresnels

Clinical Ophthalmology (10 decks)

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