[Study of the hypoplasic internal carotid artery by use of multislice spiral computed tomography. Two case reports].

INTRODUCTION: Hypoplastic internal carotid artery (HICA) is a rare benign congenital malformation. Its angiographic image string sign is shared by entities that may be either medically or surgically treated. We report two cases diagnosed by helical computerized tomography (HCT).

CASE REPORTS: Case 1: woman diagnosed clinically and by magnetic resonance (MR) of Chiari I malformation with associated syringomyelia. An HCT of the craniocervical junction was done to rule out osseous malformations. An hypoplastic posterior fossa (PF) with small right carotid foramen was diagnosed. An arteriography with HCT was done that showed the carotid string sign. Case 2: a 82 years old hypertensive woman with left hemiparesia and homonymous hemianopsia was diagnosed of right temporooccipital infarct. An HCT arteriography disclosed occlusion of the right posterior cerebral artery, calcification of the left carotid siphon and stenosis of the right siphon. Bi and tridimensional reconstructions of the circle of Willis, cranial base and distal cervical carotid arteries showed an hypoplastic right carotid artery and foramen.

CONCLUSIONS: Multislice HCT is a recently incorporated diagnostic tool that allows a volumetric study in a short period of time, seconds. An angiographic study can be done intravenously in cases of vascular anomaly suspiction, hypoplastic carotid artery in the reported cases. HCT is the only current imaging tool that can diagnose this anomaly without the aid of other imaging studies.