Persistent trigeminal artery. A method for its demonstration.

Abstract

Quain (1) first described a carotidbasilar anastomosis in 1844. Because of its close relationship to the gasserian ganglion and the fifth cranial nerve, this anastomosis has been called a persistent trigeminal artery (2). In the 3-mm. human embryo the entire brain receives arterial blood from the internal carotid artery system; the forebrain by the cephalad branches and the hindbrain mainly by the trigeminal artery. With the formation of the vertebral-basilar system to supply the hindbrain, the trigeminal artery is no longer necessary and usually regresses. This process is complete by the time the embryo reaches the 14-mm. stage (thirty-fifth day). Persistence of the artery in the adult may have clinical significance. The primary purpose of this paper is to describe a method which may aid in the visualization of the persistent trigeminal artery during angiography. Case I: M. M., 34-year-old white woman, was brought to the hospital because of acute alcoholism. No other history was obtained. Physical examination revealed numerous bruises about the head. The right pupil was larger than the left and reacted sluggishly to light; the corneal reflexes were diminished bilaterally. There were horizontal nystagmus, with the fast component to the left, and a left central facial paresis. Deep reflexes were increased in all extremities, and a left hemiparesis with bilateral Hoffman and Babinski signs was noted. The patient's temperature was 104°. The white blood count was 21,500 per cubic centimeter. On the day following admission, a right carotid angiogram was obtained. Before the lateral view was made, the x-ray tube was inadvertently displaced and tilted toward the vertex of the skull. The top of the cranium was not visualized on the films. A persistent trigeminal artery, in addition to a normal-sized posterior communicating artery, was demonstrated (Fig. 1). With x-ray tube then positioned for a direct lateral exposure, the examination was repeated. This time the anomalous vessel was hidden by the density of the bone at the base of the skull (Fig. 2). The remainder of the study was negative. Case II: L. B., a 48-year-old Negro woman, was admitted to the hospital in a stuporous condition, because of a sudden onset of unconsciousness. For many years she had been known to be hypertensive. Examination revealed a soft-tissue swelling over the right forehead, slight nuchal rigidity, early bilateral papilledema, a left homonymous hemianopsia, depression of the left corneal reflex, a left flaccid hemiplegia, and a left Babinski sign. A right carotid angiogram was at first considered to be essentially normal. It was noted, however, that the basilar artery, the posterior cerebral arteries, and the superior cerebellar arteries were opacified despite the presence of a normal posterior communicating artery (Fig. 3).