Diplopia

Question 1

ductions v versions

Answer 1

ductions monocular eye movements, versions binocular eye movements

Question 2

light seen under red line in Maddox rod testing?

Answer 2

left hyperdeviation (right eye has maddox rod. a light seen under the red line seen by the right eye means the left eye is up too high)

Question 3

use of double Maddox rod testing?

Answer 3

to quantify cyclodeviation when vertical dilopia is present

Question 4

most common causes of restrictive strabismus

Answer 4

TED and trauma

Question 5

increase in IOP by 5 mm Hg or more on upgaze?

Answer 5

suggests restricted inferior rectus (often seen in TED)

Question 6

comitant v incomitant deviations

Answer 6

comitant: deviation equal in all fields of gaze. usually congenital and does not cause diplopia
incomitant: deviaiton changes with gaze. usually acquired and causes diplopia

Question 7

only cranial nerve to innervate contralateral side?

Answer 7

CN IV (trochlear)

Question 8

differentiate clinically between skew and bilateral 4th nerve palsy

Answer 8

skew: the abducting eye is elevated in conjugate gaze

bilateral 4th: the adducting eye is elevated

Question 9

findings in ocular tilt reaction

Answer 9

patient perceives world as rotated, so head tilt is adopted. however, head tilt in these patients is associated with hyperdeviation and incyclotorsion of the eye opposite the side of tilt (opposite of normal head tilt). usually caused by a central lesions causing decreased otolithic input to the interstitial nucleus of Cajal

Question 10

what type of misalignment do thalamic lesions generally cause

Answer 10

esotropia

Question 11

findings in 6th nerve nuclear lesion

Answer 11

ipsilateral gaze palsy (affects ipsilateral abduction as well as contralateral adduction by way of interneurons), and often involves ipsilateral CN VII fascicle

Question 12

structure damaged in INO? cardinal sign of INO? two most common causes?

Answer 12

ipsilateral MLF. slowing of ipsilateral adducting saccades. also see contralateral abducting nystagmus. demyelinating lesions (in younger patients) and stroke (older patients)

Question 13

findings in right INO?
bilateral INO?
right one-and-a-half? most common cause?

Answer 13

right INO: impaired right eye adduction + left eye abducting nystagmus

bilateral INO: impaired adduction OU + bilateral abducting nystagmus

right one-and-a-half: right horizontal gaze palsy (right PPRF or 6th nerve nucleus) and right INO

• impaired right eye adduction + left eye abducting nystagmus from right INO
• impaired right eye abduction and left eye adduction
• *contralateral ABDuction is only preserved horizontal eye movement
• MCC is stroke

Question 14

Findings in Weber, Benedikt, Nothnagel, and Claude syndromes

Answer 14

All are midbrain lesions with ipsilateral CN III palsy

Weber: + contralateral hemiparesis (cerebral peduncle)
Benedikt: + contralateral tremor (red nucleus)
Nothnagel: + contralateral cerebellar ataxia
Claude = Benedikt + Nothnagel

Question 15

Findings in Foville and Millard-Gubler syndromes

Answer 15

Foville: 6th nuclear + 7th fascicular + nucleus solitarius (trigeminal) leading to ipsilateral horizontal gaze palsy, ipsilateral Bell’s, and ipsilateral loss of taste and facial sensation

Millard-Gubler: CN VI + CNVII + corticospinal tract = ipsilateral horizontal gaze palsy, ipsilateral facial paralysis, and contralateral hemiplegia

Question 16

typical time course for ischemic cranial neuropathy

Answer 16

+/- pain, symptoms worsen for7-10 days, then slowly improve. progression beyond 2 weeks or failure to improve by 3 months warrants additional workup

Question 17

findings in complete CN III palsy?

Answer 17

affected eye down and out + ptosis + mydriasis

Question 18

when do you not need to image a patient with an acute third nerve palsy? what imaging do you order and what vessels are of specific interest?

Answer 18

complete, non-pupil involving 3rd in patient 50 or older with microvascular risk factors. everybody else needs MRI/MRA to look for mass and particularly for PCOM aneurysm (at junction of ICA). Will need non-con CT first if acute with headache or concern for SAH

Question 19

different affects on third nerve from compressive v ischemic insult?

Answer 19

compression: first affects parasympathetic fibers traveling more superficially in nerve (causes mydriasis)
ischemic: first affects more internal oculomotor nerve fibers since they are further form blood supply

Question 20

cutoff for physiologic anisocoria? prevalence?

Answer 20

no more than 1 mm of anisocoria; 20% prevalence

Question 21

isolated involvement of either superior or inferior division of CN II localizes lesion to ____. workup for divisional 3rd nerve palsy?

Answer 21

anterior cavernous sinus or posterior orbit. MRI with contrast and fat suppression is initial test of choice (not angiography). If imaging normal, then lab workup for medical causes

Question 22

aberrant regeneration of third nerve involves aberrant connections from ___ to ____ and occurs in what situations?

Answer 22

involves only connections from the third nerve to the third nerve (i.e. MR to LPS or IR to pupillary constrictors). Common after trauma or compression but does NOT occur after microvascular third nerve palsies

Question 23

common presenting symptom of fourth nerve palsy

Answer 23

diplopia while reading (diplopia worse in downgaze)

Question 24

Bielchowsky 3-step findings in right 4th palsy. what head positions may the patient adopt?

Answer 24

right hypertropia that is worse in left gaze and worse in right head tilt. therefore patient may adopt left head turn and left head tilt. patient may also adopt chin-down position since hypertropia is worse on downgaze

Question 25

findings in bilateral 4th nerve palsy

Answer 25

• crossed hypertropia (right eye elevated on leftgaze and vice versa)
• large (> 25 D) V pattern strabismus (may have slight eso, which is worse in downgaze)
• chin-down posture
• excyclotorsion of 10 degrees or worse

Question 26

nerve most susceptible to injury in closed-head trauma

Answer 26

CN IV

Question 27

chronic ear infection and ipsilateral abducens palsy

Answer 27

Gradenigo syndrome; chronic petrous bone inflammation

Question 28

workup for CN VI palsy?

Answer 28

older than 50 with risk factors: none
younger than 50: MRI brain/orbits. if negative, consider acetylcholine antibody titers, edrophonium testing, TSH, and free T4

Question 29

patient with prior skull-base radiation a year ago, presents with episodic diplopia lasting 30-60 seconds: diagnosis and treatment

Answer 29

neuromyotonia; carbamazepine

Question 30

distinguishing characteristic between cavernous sinus syndrome and orbital apex syndrome

Answer 30

optic nerve involved in orbital apex syndrome but not cavernous sinus syndrome

Question 31

nerve most commonly involved in mononeuropathic cavernous sinus sundrome

Answer 31

CN VI

Question 32

severe boring monocular pain accompanied by multiple ipsilateral cranial neuropathies that responds very well to steroids?

Answer 32

Tolosa-Hunt syndrome (idiopathic, sterile inflammation of cavernous sinus)

Question 33

pattern of ophthalmoplegia seen after some retrobulbar injections?

Answer 33

usually affects inferior rectus, initially with paresis causing hypertropia, but later leading to fibrosis causing a restrictive hypotropia worse in upgaze