Unilateral agenesis of internal carotid artery with intercavernous anastomosis: a rare case report

Abstract

Unilateral agenesis of internal carotid artery (ICA) with intercavernous anastomosis is a rare congenital anomaly. We present a case of a 25-year-old female with 2-month history of holocranial headache. Neurological examination was unremarkable. Magnetic resonance imaging (MRI) with magnetic resonance angiography (MRA) showed absence of left ICA with an abnormal intercavernous vessel in the sella. Computed tomography (CT) showed absence of the left carotid canal. Doppler ultrasonography (USG) showed high resistance flow in the left common carotid artery (CCA). Since no hemorrhage or aneurysm was seen, patient was managed conservatively and is on regular follow-up. Based on our knowledge, this is the first case to demonstrate the features of unilateral agenesis of ICA with intercavernous anastomosis in X-ray, Doppler USG, CT, and MRI scans of the brain.

Keywords: Aplasia; internal carotid artery; unilateral agenesis.

Figure 1

25-year-old female presented with holocranial headache and was diagnosed with unilateral agenesis of internal carotid artery with intercavernous anastomosis. Axial CT scan (a and b) Two consecutive sections at the base of skull show absent bony carotid canal on the left side (arrows).

Figure 2

25-year-old female presented with holocranial headache and was diagnosed with unilateral agenesis of internal carotid artery with intercavernous anastomosis (a and b) Time of flight (TOF) MRA with maximum intensity projection (MIP) of the neck vessels and the intracranial arteries show complete absence of the cervical and petrous part of the left ICA with left common carotid artery continuing as external carotid artery (arrow in a). MRA with MIP of intracranial arteries shows an abnormal vessel (arrow in b) seen arising from the cavernous segment of the right ICA and reconstituting the cavernous and supraclinoid segments of the left ICA, and continuing as the left MCA. A1 segment of left ACA is not seen (Dotted arrow) suggesting aplasia.

Figure 3

25-year-old female presented with holocranial headache and was diagnosed with unilateral agenesis of internal carotid artery with intercavernous anastomosis. (a) Axial T2-weighted sequence shows an abnormal vessel running across the sella (White arrow). (b) Sagittal T1-weighted sequence shows abnormal flow void (arrow) in the floor of sella and mildly bulging into the sphenoid sinus, representing the intercavernous anastomotic vessel, which can cause devastating complication during a transphenoidal pituitary surgery.

Figure 4

25-year-old female presented with holocranial headache and was diagnosed with unilateral agenesis of internal carotid artery with intercavernous anastomosis (a-d) Duplex Doppler scans with spectral waveform of the (a) right CCA, (b) left CCA, (c) right ICA, and (d) left ECA show high velocity and low resistance flow in the right ICA because it has to compensate for the absent left ICA. Low resistance flow is also seen in the right CCA. High resistance flow with externalization is seen in the left CCA.

Figure 5

(a) 25-year-old female presented with holocranial headache and was diagnosed with unilateral agenesis of internal carotid artery with intercavernous anastomosis. (a) Lateral radiograph of the skull (zoomed image) and (b) sagittal reformated CT scan (bone window) show a well defined lytic area (arrows) in the anteroinferior aspect of the sella due to the abnormal intercavernous vessel traversing across it.