Diplopia Flashcards
(33 cards)
ductions v versions
ductions monocular eye movements, versions binocular eye movements
light seen under red line in Maddox rod testing?
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)
use of double Maddox rod testing?
to quantify cyclodeviation when vertical dilopia is present
most common causes of restrictive strabismus
TED and trauma
increase in IOP by 5 mm Hg or more on upgaze?
suggests restricted inferior rectus (often seen in TED)
comitant v incomitant deviations
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
only cranial nerve to innervate contralateral side?
CN IV (trochlear)
differentiate clinically between skew and bilateral 4th nerve palsy
skew: the abducting eye is elevated in conjugate gaze
bilateral 4th: the adducting eye is elevated
findings in ocular tilt reaction
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
what type of misalignment do thalamic lesions generally cause
esotropia
findings in 6th nerve nuclear lesion
ipsilateral gaze palsy (affects ipsilateral abduction as well as contralateral adduction by way of interneurons), and often involves ipsilateral CN VII fascicle
structure damaged in INO? cardinal sign of INO? two most common causes?
ipsilateral MLF. slowing of ipsilateral adducting saccades. also see contralateral abducting nystagmus. demyelinating lesions (in younger patients) and stroke (older patients)
findings in right INO?
bilateral INO?
right one-and-a-half? most common cause?
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
Findings in Weber, Benedikt, Nothnagel, and Claude syndromes
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
Findings in Foville and Millard-Gubler syndromes
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
typical time course for ischemic cranial neuropathy
+/- pain, symptoms worsen for7-10 days, then slowly improve. progression beyond 2 weeks or failure to improve by 3 months warrants additional workup
findings in complete CN III palsy?
affected eye down and out + ptosis + mydriasis
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?
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
different affects on third nerve from compressive v ischemic insult?
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
cutoff for physiologic anisocoria? prevalence?
no more than 1 mm of anisocoria; 20% prevalence
isolated involvement of either superior or inferior division of CN II localizes lesion to ____. workup for divisional 3rd nerve palsy?
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
aberrant regeneration of third nerve involves aberrant connections from ___ to ____ and occurs in what situations?
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
common presenting symptom of fourth nerve palsy
diplopia while reading (diplopia worse in downgaze)
Bielchowsky 3-step findings in right 4th palsy. what head positions may the patient adopt?
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
