Teaching Video NeuroImages: Is it III alone, or III and IV?
Stephen G. Reich
Neurology May 22, 2007; 68 (21)
RESIDENT AND FELLOW SECTION http://n.neurology.org/content/68/21/E34
Series editor: Mitchell S.V. Elkind MD, MS, Section Editor
The most important questions, when confronted with an oculomotor (III) palsy are:
1) Is the pupil spared?
2) Is it complete aside from pupil sparing? and
3) Is it in isolation?
A “no” answer to any makes a benign, ischemic III palsy less likely.1
In the presence of a III palsy, the traditional method of testing the trochlear nerve (IV) at the bedside by asking the patient to depress the adducted eye cannot be performed. Instead, the patient should be instructed to abduct the eye and then look down; if IV is intact, there will be intorsion.2
Confirming that IV is intact in the presence of a III palsy is important because the combination of an oculomotor and trochlear palsy suggests a lesion in the cavernous sinus.
A 56-year-old man presented with a complete, pupil-sparing right oculomotor palsy (video E-1). The evaluation was negative, and the palsy resolved within 1 month.
Video
The video demonstrates a pupil-sparing but otherwise complete right oculomotor palsy.
There is ptosis. The eye is down, out, and unable to adduct, depress, or elevate. With attempted down gaze, there is intorsion, confirming that IV is intact. Although not demonstrated in the video, this primary action of IV should be tested by first having the patient abduct and then attempt to depress the eye. Intorsion is best appreciated by observing a medial conjunctival vessel.
ACKNOWLEDGMENT The author thanks Dr. Neil Miller for assistance.
Footnotes Disclosure: The author reports no conflicts of interest.
REFERENCES
1. Trobe JD. Isolated third nerve palsies. Sem Neurol 1986;6:135–141.
2. Ansons AM, Davis H. Diagnosis and management of ocular motility disorders. 3rd ed. Oxford: Blackwell Science Ltd, 2001:359–360.