Royal Australasian College of Physicians Examinations/Resources/Clinical Exam/Short Cases/Example Cases/3rd Nerve Palsy

The 3rd Nerve Palsy
Stem: ''This patient presents with a headache. Please examine his eyes.''

Key Features

 * dilated pupil
 * abducted and depressed eye with reduced movement
 * ipsilateral ptosis

Look for

 * IV nerve palsy (tilt head towards side of lesion)
 * V nerve palsy  (corneal reflex, sensation V1 / V2)
 * VI nerve palsy (lateral rectus palsy)
 * Contralateral UMN signs in Limbs = Weber's D

Example presentation
This patient has a left 3rd nerve palsy, evidenced by a dilated pupil, and an abducted and depressed globe, with paralysis of movement and ptosis. There are no other cranial nerve abnormalities. The cause may be a berry aneurysm, causing headache and compressing the nerve. I would also consider a diabetic 3rd nerve palsy, or hypertension – although these would spare the pupil; or also a stroke in the midbrain, which would usually be accompanied by contralateral pyramidal signs; or a lesion in the cavernous sinus.

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