Persistent trigeminal artery terminating in the posterior inferior cerebellar artery: case report.

Objective: Persistent trigeminal arteries are rare and represent a remnant of the fetal carotid-basilar circulation. They typically extend from the internal carotid artery to the basilar artery. An unusual case of a patient with a trigeminal artery originating from the internal carotid artery and terminating as the dominant hemispheric branch of the posterior inferior cerebellar artery is presented.

Clinical Presentation: A 66-year-old woman presented to the emergency department with pulsatile tinnitus, increasing left eye pain, proptosis, conjunctival injection, diplopia, and decreased visual acuity. Conventional contrast-enhanced computed tomographic and magnetic resonance imaging demonstrated findings consistent with a left carotid-cavernous fistula. The patient underwent an emergency diagnostic cerebral angiogram. Besides an indirect carotid-cavernous fistula on the left side, a right-sided persistent trigeminal artery terminating as the dominant hemispheric trunk of the posteroinferior cerebellar artery was incidentally noted. The vermian branch of the right posteroinferior cerebellar artery arose from the ipsilateral vertebral artery, whereas duplicate superior cerebellar arteries supplied the left posteroinferior cerebellar artery region.

Intervention: The patient was treated for the indirect carotid-cavernous fistula with detachable platinum coils and N-butyl cyanoacrylate, resulting in the resolution of her symptoms.

Conclusion: We report a case of a persistent trigeminal artery supplying only the cerebellar hemisphere. The clinical significance of this anomaly relates to its role in endovascular therapeutic and surgical complications and the paradoxical lesions in the cerebellum that occur as a result of carotid disease. We also discuss the Saltzman classification of persistent trigeminal arteries and their variants.