Aberrant course of the precavernous-cavernous junction of the internal carotid artery.

We present an extremely rare case of an aberrant course of the precavernous-cavernous junction of the internal carotid artery (ICA), which was observed by magnetic resonance (MR) angiography. The patient was a 67-year-old woman with no symptoms related to the anomalous ICA. The anomalous segment of the ICA was stenotic and formed a loop postero-supero-laterally. We found no similar cases in the relevant English-language literature. Segmental agenesis of the ICA with collateral formation, probably via the proximal segment of the primitive trigeminal artery, may be associated with the development of this variation.