Back to Basics: Oculomotor Palsy

60 yo w/ hx insulin dependent diabetes, HTN, HLD, presents to the ED complaining of double vision and drooping eyelid for 3 days. POC glucose 359. CTH w/o and CTA head negative. What's the diagnosis and likely cause for this patient?

CN3 (Oculomotor) palsy

  • CN3 innervates superior, medial and inferior rectus muscles, inferior oblique & levator palpebrae > Palsy causes eye to deviate lateral and down
  • Parasympathetic - pupillary sphincter and ciliary muscle
    • Sparing of pupil - likely ischemic
    • Abnormal pupil - likely compressive cause (aneurysm)
  • Binocular diplopia - double vision stops when cover either eye
  • DDx: aneurysm, ischemia, trauma, neoplasm, cavernous sinus thrombosis, giant cell arteritis, myasthenia gravis
  • CTA head imaging modality of choice +/- MRI/A
  • Ischemic causes tend to resolve in 4-8 weeks

Most likely cause for this patient:

This patient with pupil sparing CN3 palsy was felt to have an ischemic etiology w/ hx of uncontrolled diabetes after negative imaging


Want a refresher on other causes of diplopia?  Check out our prior post from Dr. Ginty




Margolin E, and Freund P. "A Review of Third Nerve Palsies". International Ophthalmology Clinics, vol. 59, no. 3, July 2019, pp. 99–112. doi: 10.1097/IIO.0000000000000279.

Capo, H., M.D., Warren, F., M.D., Kupersmith, M. , M.D. Evolution of Oculomotor Nerve Palsies. J Clin Neuroophthalmol. 1992 Mar;12(1):21-5