Spectrum of non-ischemic oculomotor nerve palsies at a tertiary care centre - case series and literature review.

PURPOSE: Oculomotor nerve palsies (ONPs) have a varied range of clinical presentations. Though they are mainly divided into ischemic and non-ischemic variants, with the former being more common, a detailed clinic-radiological evaluation is needed in all cases to ascribe an etiology in all cases.

METHODS

We conducted a retrospective review of records to identify all patients with non-ischemic ONPs presenting to a tertiary care teaching hospital over 5 years.

RESULTS

Nineteen cases of non-ischemic ONP were found. The various causes of non-ischemic ONPs included congenital, malignancy-associated, impending transtentorial herniation, tuberculous meningitis, pinealoblastoma, subacute subdural hemorrhage, parasellar lesions (sphenoid wing meningioma, petro-sphenocavernous meningioma), post-neurosurgery for meningioma, internal carotid artery aneurysm, inflammatory, and infective cavernous sinus lesions, after coiling for carotico-cavernous fistula, IgG4-related disease, post-Herpes zoster ophthalmicus, post-traumatic, and idiopathic orbital inflammatory syndrome.

CONCLUSION

The unique neuroanatomy of the oculomotor nerve contributes to its varied and complex presentation. The nerve is particularly susceptible in its basilar and cavernous sinus segments. Although neuroimaging may be initially deferred in a pupil-sparing ONP in patients with vasculopathic risk factors, the "rule of pupil" may not always be followed. The 19 cases that we described are discussed in detail, along with a review of the literature. This wide spectrum of presentations helps to understand and correlate the nerve's anatomical course and highlights the importance of a detailed neurological evaluation to facilitate targeted imaging of the suspected region of pathology.