Dolichoectatic Carotid Arterial Compression of the Optic Nerve: The Unusual Suspect in the Setting of a Coexisting Incidental Pituitary Adenoma

Background: Anatomic compression of the optic nerve secondary to a dolichoectatic cerebrovascular compression is a rare clinical entity. Because of the limited number of published cases and variable clinical presentation, the natural history remains ambiguous and no consensus exists regarding management. In addition, there is an ongoing debate regarding whether a dolichoectatic cerebral blood vessel can actually cause optic neuropathy, or it merely represents an incidental finding. As a result, it is thought that a diagnosis of compressive optic neuropathy from an adjacent dolichoectatic internal carotid artery (ICA) should be considered only after other possible etiologies are excluded. Although this might seem straightforward, the clinical scenario becomes complex if the patient is also found to have additional incidental pituitary lesions. Such coexistence has not been reported previously in the literature.

Case description: A 52-year-old left-handed man presented to us with intermittent headache and painless progressive visual deterioration in the right eye for 1 month. Screening magnetic resonance imaging (MRI) scan revealed a 9-mm eccentrically placed pituitary adenoma with right optic nerve compression because of dolichoectatic ICA. He underwent microvascular decompression of the right optic nerve. On follow-up, significant vision improvement was noticed and MRI scan revealed no change in the size of the pituitary adenoma.

Conclusions: The compression of the optic nerve by dolichoectatic ICA is commonly thought to be a diagnosis of exclusion. However, the presence of a coexisting pathology should not prompt the exclusion in every case and a case-based approach is highly recommended to correctly manage this rare clinical condition.