Neuro-Ophthalmology Flashcards

Question

What is anisocoria

Answer 1

Anisocoria refers to the presence of asymmetrical pupillary size between the two eyes Can be either pathological or physiological 20% of general population has the physiological type

Answer 2

● Ptosis: Mild eyelid drooping due to Müller muscle dysfunction. ● Miosis: Due to dysfunction of the dilator pupillae. The pupil reacts to light and near stimuli. ● Ipsilateral facial anhidrosis: Not present in third-order neuron lesions. ● The affected iris in congenital Horner syndrome has a lighter colour.

Answer 3

First order: Lateral medullary syndrome and syringomyelia. ● Second order: Pancoast tumour and neck trauma. ● Third order: Internal carotid dissection (painful), cluster headache and cavernous sinus lesions Also look at passmed split

Answer 4

Topical aproclonidine: Causes pupillary dilation Topical cocaine: Will dilate Horner's pupil less than a normal pupil Topical hydroxyamphetamine: Will dilate pupil in first and second order neuron lesions Will fail to dilate if third order (postganglionic). CT/MRI: If tumours or carotid dissection/aneurysm are suspected.

Answer 5

A unilateral condition characterized by loss of postganglionic parasympathetic innervation to the iris sphincter and ciliary muscle. FEATURES ● A large pupil with poor response to light but intense pupillary response (miosis) to near stimuli with slow re-dilation (light-near dissociation: pupil reaction to a near stimulus is greater than its reaction from a light stimulus). ● Holmes-Adie syndrome: Associated diminished deep tendon reflex of lower limbs. INVESTIGATIONS ● Slit lamp: Vermiform movements of pupillary borders. ● Pharmacological: 0.1% (low dose) of topical pilocarpine into both eyes causes constriction of the affected pupil due to denervation hypersensitivity

Answer 6

Characterized by bilateral, irregular small pupils. Both pupils do not react to light; however, they constrict normally on accommodation (light-near dissociation). The most common cause is diabetes; it was previously neurosyphilis

Answer 7

● Ptosis. ● Abduction and depression of the eye in primary position (‘down and out’) with ophthalmoplegia (only abduction of the eye is fully normal). ● Dilated pupil and accommodation abnormalities.

Answer 8

Medical - Diabetes and Hypertension (usually pupil sparing) Surgical - Posterior communicating artery aneurysm, trauma, and uncal herniation.

Answer 9

● CNIII palsy ● Contralateral hemiparesis (damage to the cerebral peduncle)

Answer 10

● Vertical diplopia: Worse on walking downstairs or looking down. ● Hypertropia: The affected eye is higher than the contralateral eye. It is made worse on tilting the head to the ipsilateral shoulder. ● Depression of the eye is limited: Most noted on adduction. ● Compensatory head posture to avoid diplopia: Patients tend to develop a contralateral head tilt and face turn. ● Bilateral CNIV palsies can present with compensatory depressed chin posture and crossed hypertropia

Answer 11

- Congenital CN IV palsy - Closed head trauma - Microvascular ischaemia

Answer 12

The Park-Bielschowsky three-step test can be used to identify a superior oblique palsy. Note that the complete three steps may not always be all positive (6). The three steps are: 1. Identify hypermetropic eye in primary position. 2. Eyes are examined in left and right gazes. Hypertropia increases on opposite gaze in CNIV palsy (worse on opposite gaze [WOOG]). 3. With the patient fixating at a target ahead, assess hypertropia on right and left head tilts. Hypertropia gets better on contralateral head tilt in CNIV palsy (better on opposite tilt [BOOT]).

Answer 13

Microvascular ischaemia Trauma Idiopathic ICP

Answer 14

● Horizontal double vision: Worse on looking at distant targets. ● Esotropia in primary position. ● Abduction is limited.

Answer 15

● Lesion to the MLF, commonly caused by demyelination or stroke. ● Defective adduction of the eye ipsilateral to the lesion and abducting nystagmus of the contralateral eye. ● Patients may complain of horizontal diplopia

Answer 16

● Lesion to the dorsal midbrain. ● Causes: Pinealoma or aqueductal stenosis in children and vascular problems in adults. ● Supranuclear upgaze palsy. ● Lid retraction (Collier sign). ● Convergence-retraction nystagmus. ● Large pupil with light-near dissociation (not reactive to light but constrict on accommodation)

Answer 17

● Lesion to the PPRF and MLF on the same side, commonly caused by a stroke. ● The only movement left is the abduction of the contralateral eye.

Answer 18

A neurodegenerative progressive disorder characterized by vertical gaze palsy, slowing of vertical saccades, postural instability and parkinsonism

Answer 19

Nystagmus is an involuntary rapid and repetitive oscillation of the eye which can be physiological or pathological.

Answer 20

End-point nystagmus: Nystagmus at extreme gaze. Optokinetic nystagmus: Nystagmus due to fast-moving repetitive objects.

Answer 21

CONGENITAL NYSTAGMUS ● The nystagmus is horizontal, pendular or jerky and disappears during sleep. It often has a null point – a position of gaze where nystagmus is minimal. ● Common causes include sensory deprivation (e.g. bilateral cataracts), optic nerve hypoplasia or foveal hypoplasia (e.g. albinism). ACQUIRED NYSTAGMUS Latent nystagmus ● Horizontal and jerky nystagmus, but only becomes present on monocular occlusion (direction is away from the covered eye). ● Most commonly associated with infantile esotropia. Convergence-retraction nystagmus ● Co-contraction of horizontal muscles on attempted upgaze causing the globe to retract. ● The medial rectus is the most powerful EOM. This causes eye convergence. ● Caused by dorsal midbrain lesions (e.g. Parinaud syndrome). Upbeat nystagmus Downward drifting of the eye followed by a fast upward corrective saccade or beat. Caused mainly due to medulla lesions. Downbeat nystagmus Upward drifting of the eye followed by a fast downward corrective saccade or beat. Caused mainly due to lesions at the craniocervical junction such as Arnold Chiari malformations. Peripheral vestibular nystagmus A conjugate horizontal and jerky nystagmus that occurs due to a vestibular lesion (e.g. labyrinthitis). There is a slow drifting of the eyes towards the side of the lesion followed by a fast corrective saccade in the other direction

Answer 22

An autoimmune disease affecting the post-synaptic nicotinic acetylcholine receptors (AChR) at neuromuscular junctions, leading to muscle fatigability. It typically presents in the third decade of life and has a female predominance. It affects voluntary muscles, and smaller muscles are affected first. Ocular involvement is commonly the presenting feature

Answer 23

● Ptosis: Bilateral (can be unilateral initially), worse at end of the day or after prolonged upgaze. ● Cogan lid twitch: A brief upshoot of the lid elicited by making patient look downwards then upwards. ● Diplopia. ● Ophthalmoplegia. ● Fatigability and weakness of muscles of facial expression and proximal limb muscles. ● Respiratory depression.

Answer 24

● Ice test: Ptosis improves after applying ice for 2 minutes. ● Antibodies: Anti-AChR antibody and anti-muscle-specific kinase (MUSK) antibody. ● Repetitive nerve stimulation (decrement of muscle action potential amplitudes). ● CT thorax: Can reveal a thymoma

Answer 25

● Acetylcholinesterase inhibitors (e.g. pyridostigmine), steroids and immunomodulators. ● Thymectomy if thymoma is present

Answer 26

Myotonic dystrophy is characterised by abnormal muscular relaxation and muscle wasting. It is an AD condition due to tri-nucleotide repeats on chromosome 19. FEATURES ● Inability of muscle relaxation. ● Early-onset cataract: Polychromatic opacities on the lens resembling a ‘Christmas tree’ cataract. ● Ptosis. ● Ophthalmoplegia

Answer 27

A rare variant of Guillain-Barre syndrome. Anti-GQ1b antibodies may be present. It presents with a tetrad of ataxia, areflexia, ophthalmoplegia and facial diplegia

Answer 28

Neurofibromatosis type 1 (NF1) is an AD multisystem genetic disorder due to a mutation in the Neurofibromin 1 gene on chromosome 17. FEATURES ● Café-au-lait spots: Brownish spots most commonly found on the trunk. ● Axillary freckling. ● Ophthalmic ● Optic nerve glioma. ● Bilateral Lisch nodules (iris hamartomas) ● Plexiform neurofibromas: ‘Bag of worms’ sensation in the eyelids ● Choroidal naevi: Patients with this have a higher risk of choroidal melanoma

Answer 29

Neurofibromatosis type 2 (NF2) is less common than NF1. It occurs as a result of a mutation to the Neurofibromin 2 gene on chromosome 22. FEATURES ● Posterior subcapsular cataracts. ● Bilateral/unilateral acoustic neuromas causing decreased sensorineural hearing loss, tinnitus and loss of corneal reflex. ● Meningiomas

Answer 30

● Facial angiofibroma. ● Ash-leaf spots: Hypopigmented macules on the skin. ● Seizures. ● Cognitive impairment. ● Multiple intracranial and/or retinal astrocytic hamartomas ● Glial tumours of retinal fibre layer that arise from astrocytes. ● They are commonly referred to as mulberry lesions due to their multinodular appearance. On fundoscopy they appear as well-defined elevated creamy white lesions. ● Associations– Tuberous sclerosis (most common association)– Neurofibromatosis– Retinitis pigmentosa (less common; lesions are non-calcified)

Answer 31

A bilateral idiopathic condition characterized by involuntary contraction of the orbicularis oculi muscle due to basal ganglia dysfunction. Presentation is in the sixth decade of life, with a female predominance. Blepharospasm and oromandibular dystonia can occur together in Meige syndrome

Answer 32

● Artificial tears for dry eyes. ● Botulinum toxin injection to orbicularis oculi. Side effects: Ptosis, dry eye, diplopia, lagophthalmos and corneal exposure. ● Surgical myectomy if the above does not work