Dysgenesis of the internal carotid artery associated with transsphenoidal encephalocele: a neural crest syndrome?

Abstract

We describe two original cases of internal carotid artery dysgenesis associated with a malformative spectrum, which includes transsphenoidal encephalocele, optic nerve coloboma, hypopituitarism, and hypertelorism. Cephalic neural crest cells migrate to various regions in the head and neck where they contribute to the development of structures as diverse as the anterior skull base, the walls of the craniofacial arteries, the forebrain, and the face. Data suggest that the link between these rare malformations is abnormal neural crest development.

fig 1.

23-year-old man with progressive headaches. A, CT scan obtained through the midcranial skull base in the axial plane shows a transsphenoidal encephalocele (black arrows) and complete absence of the right carotid canal. The left carotid canal can be seen (white arrow). B, Cerebral MR imaging. Sagittal spin-echo T1-weighted sequence, 480/14/4 (TR/TE/excitations), shows a transsphenoidal encephalocele (open arrows). The bone defect involves the basipresphenoid, leaving intact the basipostsphenoid (black arrow). Atrophied optic chiasm pulled down into the bone defect can be seen (curved arrow). Unidentifiable adenohypophysis with ectopic neurohypophysis are shown (straight white arrow). C, Angiogram of the right common carotid artery. Lateral view shows filling of the right external carotid artery alone.

fig 2.

37-year-old man with progressive bitemporal visual field defect. A, CT scan of the midcranial skull base in the axial plane shows a transsphenoidal encephalocele (white arrows) and a narrow right carotid canal (black arrow). B and C, MR angiograms obtained using the 3-D time-of-flight technique with 40/7/1, flip angle of 15°, 64 sections, and 1.2-mm section thickness. B, Axial source image shows the narrow diameter of the right ICA within the carotid canal (arrow). C, Maximum-intensity projection reconstruction in the anteroposterior view shows signal loss of the right distal ICA (curved arrow). The large left ICA (straight solid arrow) and anterior cerebral artery (open arrow) caused by the collateral blood supply to the right middle cerebral artery and to the right anterior cerebral artery provided by the left carotid system via the anterior communicating artery can be seen.