A persistent pharyngohyostapedial artery: embryologic implications

Abstract

A 3-year-old child was examined because of otorrhagia. CT scans showed an unusual vessel, confirmed by angiography, related to a persistent pharyngohyostapedial artery. This embryonic persistent artery associated with the normal internal carotid artery would explain the "duplication" aspect of the internal carotid artery.

fig 1.

3-year-old girl with a persistent pharyngohyostapedial artery detected after second tympanotomy of the left ear. A–C, Axial CT scans from the skull base to the superior surface of the petrous bone. Enlarged inferior tympanic canaliculus is interposed between the carotid and jugular foramina (arrow, A). No ipsilateral foramen spinosum is identified. The bony canal along the promontory (arrow, B), where the hyoid artery crosses, has an appearance similar to a pair of glasses. The anterior tympanic segment of the facial nerve canal is enlarged (arrow, C), and a special opening is seen at the anterosuperior surface of the petrous bone lateral to the geniculate ganglion (arrowhead, C). D, Coronal CT scan shows enlargement of the anterior tympanic segment of the facial nerve canal (arrow) as compared with the labyrinthine segment. The bony canal containing the hyoid artery is enclosed in the promontory (arrowhead). C = carotid canal. E, Digital subtraction angiogram, oblique view, shows “duplication” aspect of the left internal carotid artery. The inferior tympanic artery courses parallel laterally and posteriorly to the internal carotid artery. Note the other branches of the ascending pharyngeal artery. F, Lateral subtraction angiogram of selective inferior tympanic artery from which the stapedial artery arises, further supplying the middle meningeal artery (arrow).

fig 2.

Diagram of persistent pharyngohyostapedial artery