Etiology of Oculomotor Nerve Paralysis

  • Abdul-Reza Tabassi Tehran University of Medical Sciences, Tehran, Iran
  • Ali-Reza Dehghani Isfahan University of Medical Sciences, Isfahan, Iran
  • Hamid Mosayebi Tehran University of Medical Sciences, Tehran, Iran


Purpose: To determine the etiology of oculomotor nerve paralysis over a one year period at a university-based hospital.

Methods: This observational case series was conducted on consecutive patients with a clinical diagnosis of isolated oculomotor nerve paresis who were referred to the neuro-ophthalmology clinic at Farabi Eye Hospital, Tehran, Iran during 2001-2002. All patients were evaluated for hypertension and diabetes. In patients with confirmed diabetes mellitus or hypertension, oculomotor nerve palsy was diagnosed as ischemic. However if no recovery was observed up to four months, the patient underwent MRI and MRA. The etiology of oculomotor nerve palsy was classified into six categories including ischemia, trauma, aneurysm, neoplasm, miscellaneous and idiopathic.

Results:  During the period of the study, 28 eyes of 28 patients (17 male and 11 female subjects) with mean age of 50.5 years were enrolled. Blepharoptosis was observed in 89.3%. Pupil reaction was normal in 50%, sluggish in 14.3% and absent in 35.7%. Pupil size was normal in 57.1% and mydriatic in 42.9%. The paralysis was ischemic in 42.8%, traumatic in 14.3%, aneurysmal in 7.1%, neoplastic in 7.1%, miscellaneous in 10.7% and idiopathic in 17.8% of the cases.

Conclusion: In the present series, ischemia was the most common cause of oculomotor nerve palsy in which the most prevalent underlying disorder was diabetes mellitus.

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