7 - Abnormal Ocular Motility or Diplopia Flashcards

Question

CN 3 Palsy Pupil-Sparing

Answer 1

1. Pupillary function normal with complete/partial motor dysfunction 2. Ischemic cranial neuropathy usual etiology and resolves within 6 months --- HTN, HLD, DMT2. **Usually pupil-sparing and complete**! 3. Acute isloated pupil-sparing and complete CN3 palsy in patients over 50 with known vascular risk factors and without hx of cancer does NOT necessarily require neuroimaging BUT general medical evaluation indicated to assess serum glucose, SBP, lipid levels. In older adults screening for vasculitis --- GCA with ESR, CRP, platelets 4. If other cranial neuropathies develop, progression occurs, no improvement within 3 months neuroimaging should be taken in search for a mass, infiltrative lesion at base of skull or within cavernous sinus. Lumbar puncture may be needed to detect carcinmatous meningitis, inflammation, or infection. 5. **Pupil-sparing and partial --- NOT AS BENIGN as complete oculomotor paresis given that many other fibers within CN3 are also spared. _Some partial CN3 palsies with normal pupillary function are due to compressive lesions, including aneurysm and may later progress to involve pupil_. MRA/CTA indicated to exclude aneurysm. If MRA/CTA negative and CN3 palsy has progressed, MRI of Brain and Orbits with gadolinium contrast should be obtained to search for anatomic lesion** 6. Pain may be present in vasculopathic palsies or anuerysms 7. Patients with partial CN3 palsy 2/2 aneurysm have better recovery of function than patients with complete CN3 palsy after undergoing same neurosurgery intervention

Answer 2

1. CN3 branches into superior and inferior divisions within cavernous sinus and superior orbital fissure 2. **Isolated involvement of either division → anterior cavernous sinus lesion or posterior orbit** 1. **Initial study should be cranial and orbital MRI with contrast and fat suppression + MRA. If normal, medical evaluation for HTN, BG, HLD, ESR, CRP, platelets (if necessary)** 2. Rare cases --- divisional CN3 palsy may be secondary to brainstem disease from small-vessel stroke or demyelination. Aneurysms much less common. Rare causes include tumors, inflammation (sarcoid), vasculitis, meningitis, lymphoma, trauma

Answer 3

1. May experience transient ophthalmoplegia after viral infection or vaccination 2. Although aneurysms rare in children, pupil-involving CN 3 palsy necessitates workup to exclude aneurysm 3. Recurrent painful oculomotor neuropathy term now in place of ophthalmoplegic migraine --- presents as a CN3 palsy. Ophthalmoplegia develops after onset of head pain. 1. MRI may show reversible thickening and enhancement of root exit zone of CN 3. CN 3 enhancement may persist after resolution of CN 3 palsy thus follow-up MRI indicated

Answer 4

1. **After nerve axons damaged, nerve fibers regrow to innervate muscles (of same CN) other than those they originally innervated. This produces synkinetic phenomenon --- co-contraction of muscles normally not activated together.** See eyelid retraction with adduction for example, or pupillary miosis with elevation/adduction/depression 2. 2/2 normal development unlike usual synkinesis with abnormal miswiring that is congenital

Answer 5

1. Acute palsy causes diplopia worse in contralateral gaze, ipsilateral head tilt, downgaze 2. Most cases show grossly normal EOMs with some showing limited downgaze in adduction 3. Need to perform PACT or Maddox Rod tesiting to demonstrate hypertropia that worsens in contralateral gaze and ipsilateral head tilt 4. Ipsilateral head tilt worsens vertical strabismus and patients may subconsciously tilt their head to opposite side to avoid diplopia 5. Parks-Bielschowsky 3 step test for vertically acting muscles 1. **Find side of hypertropia in primary gaze** 2. **Determine hypertropia is greater on L or R gaze** 3. **Determine hypertropia greater on L or R head tilt** 6. Excyclotropia should be assessed by double Maddox rod testing 7. **Skew deviation may mimic CN 4 palsy → hypertropic eye intorted as opposed to extorted + patient in supine position reduces magnitude of hypertropia.** 8. Acquired vertical strabismus not from CN 4 often result of dysfunction of more than 1 muscle and will not generate positive 3 step-test --- TED, MG, multiple CN palsies can produce variety of nonspecific patterns of ocular misaligment. 9. Reliability of 3 step-test in identifying pattern of vertical strabismus lessens over time because of spread of comitance 10. Bilateral CN 4 Palsy 1. **Should be considered if unilateral CN 4 palsy diagnosed especially in head trauma** 2. **Crossed hypertropia --- R eye higher on left gaze and L eye higher on right gaze** 3. **Extorsion of \> 10 degrees** 4. **Large \> 25 PD V pattern esotropia (greater esotropia in downgaze than upgaze)** 5. **Chin-down posture (hypertropia decreases in down upgaze)** 11. Congenital CN 4 palsy 1. Most common cause 2. 2/2 anomalous SO tendon, anomalous insertion, defect in trochlea, schwannoma of nerve 3. May be asymptomatic until adulthood when vertical fusion amplitudes diminish and diplopia develops 4. Chronic head tilt seen on old phorographs 5. Long-standing CN 4 palsy may have relatively large vertical fusional amplitudes \> 3 PD 12. Older patients --- typically from microvascular ischemia. Usually function return in 6 months 1. Assess vascular risk factors --- HTN, HLD, DMT2, GCA. 13. May also be 2/2 closed head trauma given dorsal midbrain crossing anatomy, disease within cavernous sinus or subarachnoid space, TED, skew deviation in atypical cases as well as MG or partial CN 3 palsy 14. Diagnostic evaluation for isolated non-traumatic CN 4 palsy yields little information as most congenital, ischemic, idiopathic. 15. Lack of improvement in 3 months should prompt neuroimaging at skull base to search for mass lesion

Answer 6

1. May see divergence insufficiency or diolopia worse at distance as less abduction required on near vision 2. Most common cause is ischemic mononeuropathy 3. Cerebellopontine angle lesions (acoustic neuroma) may involve CN 6 + other CNs such as CN 5 (decreased facial sensation), CN 7 (facial paralysis), CN 8 (decreased hearing with vestibular signs). 4. Chronic inflammation of petrous bone may cause an ipsilateral abducens palsy and facial pain especially in children with recurrent middle ear infections → Gradenigo syndrome. 5. Susceptible to injury from shearing forces of head trauma or elevated ICP --- injury in these situations occurs where nerve enters the cavernous sinus through Dorello canal (the opening below the petroclinoid ligament). 6. Vulnerable to meningeal processess such as meningioma, nasopahryngeal carcinoma, chordoma, chondrosarcoma 7. Palsy after seemingly minor trauma --- should raise concern for preexisting pathology such as tumor compression that makes nerve more suceptible to injury. 8. **Congenital CN 6 palsy almost never occurs in isolation --- abduction paresis that is present early in life usually manifests as Duane syndrome (with narrowing of palpebral fissure)** 9. Older adults \> 50 --- usually ischemic, and resolves within 6 months. Some people recommend neuroimaging. Medical evaluation important. MRI mandatory if no improvement after 3 months. 1. May require LP, chest imaging, hematologic studies to identify underlying systemic process such syphilis, sarcoidosis, collagen vascular disease, GCA. Recovery does not always indicate a benign process. 10. Younger \< 50 --- requires careful scrutiny with neuroimaging. May be presenting sign of posterior-draining CCF (white eye syndrome). 1. Negative results --- assess for MG, TED, LP to look for meningeal disease 2. Leukemia and brainstem glioma important to consider in young children while demyelination may be seen in adolescents and young adults (MRI with FLAIR). 11. Mimics --- Duane Type 1, spasm of near reflex, MG, TED, medial orbital wall fracture with entrapment

Answer 7

1. Rare cause of episodic diplopia 2. **Prior skull-based radiation therapy for neoplasm most common. Months to years postradiation, patients experience episodic diplopia lasting 30-60 seconds** 3. May affect any of the oculomotor nerves 4. Diplopia triggered by activation of affected nerve in eccentric gaze with resultant sustained muscle contraction producing ocular misalignment (CN 6 neuromyotonia --- produces sustained lateral rectus muscle spasm). 5. Disorder responds well to carbamazepine

Answer 8

1. **Benign microvascular disease rarely causes simultaneous involvement of more than ocular motor CN.** 2. **Simultaneous involvement of unilateral CNs 3, 4, 5, 6 and sympathetic nerves then strongly suspect cavernous sinus lesion** 3. Bilateral involvement of CNs --- suggests diffuse process such as infiltrative disease (carcinoma, leukemia, lymphoma) or midline mass that extends bilaterally (chondroarcoma, nasopharyngeal carcinoma, chordoma), meningeal based process, inflammatory polyneuropathy (GBS or Miller-Fisher, sarcoidosis), MG 4. Neuroimaging should be done --- if normal then LP with cytopathology should be considered. Special testing for cancer-associated protein markers may be helpful. 5. Idiopathic multiple cranial neuropathy syndrome should be considered after neuroimaging, CSF analysis, extendend observation have excluded neoplastic, inflammatory, infectious causes

Answer 9

1. Ipsilateral CN dysfunction involving combination of CN 3, 4, 5, 6, and sympathetic fibers hallmark of ophthalmoplegia secondary to cavernous sinus lesion 2. **If only 1 CN involved then usually CN 6 which is only CN NOT protected within lateral dural wall of cavernous sinus → Abducens Bathed in Blood!!** 3. Aggressive lesions of cavernous sinus --- may cause engorgment of ocular surface vessels from compromised venous outflow, orbital venous congestion, increased intraocular pressure, increased ocular pulse pressure 4. Difficult to distinguish cavernous sinus lesions from those involving superior orbital fissure --- sometimes called sphenocavernous syndrome or parasellar syndrome 5. If offending lesion extends toward optic canal into orbital apex and optic nerve compromised then ---- orbital apex syndrome applied

Answer 10

1. **Idiopathic, sterile inflammation affecting cavernous sinus** 2. Severe boring pain almost always present + ophthalmoplegia 3. Neuroimaging may show enhancing mass within cavernous sinus 4. Pain responds rapidly to corticosteroid therapy but may also be seen in a neoplastic process especially lymphoma 5. Sometimes found that painful ophthalmoplegia in patients initially diagnosed with Tolosa-Hunt syndrome due to neoplasm 6. **Diagnosis of exclusion** 7. Other causes of cavernous sinus lesions --- aneurysm, meningioma, lymphoma, schwannoma, pituitary adenoma, CCF, metastasis, sarcoidosis, cavernous sinus thrombosis

Answer 11

1. Abnormal connection between cavernous sinus and carotid artery or its branches introduce high arterial pressure into normally low-pressure venous circulation of cavernous sinus. Causes reverse blood flow within SOV and produces venous congestion within orbit. 1. See arterialization of conjunctival vessels 2. Direct high-flow connections between ICA and cavernous sinus 1. 2/2 severe head trauma with cranial bruit 3. Dural low-flow connections between small arterial feeders off ICA or ECA and cavernous sinus 1. Spontaneously and usually in older woman 4. Cannot distinguisn between high-flow or low-flow besides cranial bruit 5. MRA, CTA or cerebral angiography necessary to make diagnosis 6. See elevated IOP and proptosis and other signs: 1. Diplopia from CN palsy or orbital congestion 2. **Arterial or venous compromise to retina and eye** 3. **Ischemic optic neuropathy** 4. Choroidal effusions 5. Ocular Pain (may be partly from dry surface from proptosis) 6. Cerebral Venous infarction resulting from venous hypertension 7. Pulsatile tinnitus 7. **Compression of CN 6 due to posteriorly draining fistula can cause an isolated CN 6 palsy** 8. Dural fistula may close spontaneously 9. CCF either high/low flow may be treated with IR techniques

Answer 12

1. Produces variable diplopia, variable ptosis with pupil-sparing painless ocular misalignment 2. Never produces sensory symptoms, pain or pupil dysfunction

Answer 13

1. Most common cause of **_restrictive_** strabismus in adults 2. **Most commonly Inferior Rectus and Medial Rectus** 1. Will see hypotropia worse on upgaze and esodeviation that increases on lateral gaze 3. Forced duction testing may provide support for diagnosis 4. Diagnosis of TED straightforwards if associated with proptosis, chemosis, eyelid retraction, lid lag 5. Neuroimaging reveals enlargement of EOM bellies with sparing of tendons

Answer 14

1. Blowout fractures of orbit may cause diplopia 2. Especially orbital floor with entrapment of inferior rectus 3. Paretic swelling from swelling may also occur in acute phase --- as swelling resolves so may diplopia thus decisions about surgery for orbital fractures must be made judiciously

Answer 15

1. May see binocular diplopia from injury or inflammation to inferior rectus or other muscles **after retrobulbar or peribulbar injection for cataract or other ocular surgery. Onset of diplopia immediately following surgery suggests nerve damage or nyotoxicity from local anesthetic.** 2. **Over time, initiial paretic or myotoxic effect evolves into extraocular muscle fibrosis leading to overaction or a restricted eye movement.** 1. **If inferior rectus affected --- involved eye transitions from hypertropic (paretic) to hypotropic (restricted)** 3. Restrictive diplopia may also be seen in: pterygium excision, SB placement, episcleral plaque brachytherapy, tube shunt procedures

Answer 16

1. Idiopathic inflammation of 1 or more EOMs may produce ophthalmoplegia and pain often with associated conjunctival hyperemia, chemosis, sometimes proptosis 2. Pain may be intense and exacerbated by eye movements 3. **If inflammation confined to posterior orbit, eye may appear to be white and quiet** 4. CT or MRI may show enlargement of 1 or more EOMs with tendon involvement with extension of inflammation into orbital fat 5. Pain responds to corticosteroids whereas diplopia may take longer to resolve 6. Usually an isolated phenomenon but may be associated with systemic disease: 1. GPA, SLE, sarcoidosis, IgG4, lymphoma, metastatic disease 7. EOM Bx should be done in cases of recurrent orbital myositis with steroid taper

Answer 17

1. If cancer infiltrates orbit from surrounding paranasal sinuses, **eye movements may be impaired either due to muscle infiltration or involvement of ocular motor CNs**.

Answer 18

1. Restrictive ocular motor disorder = **limited upgaze when eye adducted** 2. Usually congenital (short SO tendon) but may be acquired 3. Acquired → RA, idiopathic orbital inflammatory disease, trauma, iatrogenic trauma, focal neoplastic metastasis to superior oblique muscle

Answer 19

1. AKA strabismus fixus 2. Results in **progressive esotropia and hypotropia in high myopes (limited abduction and limited supraduction) → superotemporal shift of staphylomatous globe posteriorly with medial displacement of SR and inferior displacement of LR. Intervening connective tissue band also degenerates** 3. Neuroimaging required to confirm muscle slippage 4. Initial treatment is bilateral loop myopexy between SR and LR to restore normal anatomy

Answer 20

1. Can be seen in older patients without myopia 2. **Presents with mild-moderate angle esotropia at distance (divergence insufficiency), full lateral gaze, minimal hypotropia with limited supraduction** 3. **LR-SR band degenerates → inferior displacement of LR with _NO globe prolapse_.** 4. **Often with degenerative changes that can cause deep superior sulci, high lid crease, prosus from levator aponeurosis dehiscence.** 5. Usually etiology of divergence insufficiency in elderly.

Answer 21

1. In patients with childhood strabismus, **diplopia may be induced by refractive procedures that cause a change in fixation preference to the nondominant eye** (monovision correction, cataract surgery on an amblyopic eye prior to dominant eye, noncycloplegic refraction leading to undercorrected hyperopia and fixation with amblyopic eye) → "Fixation switch diplopia" resolves with appropriate optical correction to reestablish fixation with dominant eye

Answer 22

1. Foveal displacement syndrome from macular disease or surgery can result in typically vertical or oblique binocular diplopia that cannot be corrected with prisms 2. May be 2/2 to ERM

Answer 23

1. LPS and SR congenital agenesis of nuclei