Anomalous internal carotid artery in a patient with pituitary adenoma

This 26-year-old woman presented with amenorrhea and was found to suffer from hyperprolactinemia. Gadolinium-enhanced magnetic resonance (MR) imaging revealed an abnormally enhanced tumor in the left intrasellar region and fenestration of the left internal carotid artery (ICA) adjacent to the lesion (Fig. 1). Angiography demonstrated no tumor blush but did reveal a fenestration of the left ICA at the cavernous portion (Fig. 2). Furthermore, the left persistent otic artery was present. The mass was removed via the transsphenoidal approach. Special care was taken not to injure the fenestrated portion, and surgical manipulation in any portion of the blind operative field was restricted. Histological investigation revealed the tumor to be the diffuse type of pituitary adenoma. The patient’s postoperative course was uneventful except for transient diabetes insipidus. Hemorrhage from the ICA is potentially fatal and the most feared complication of transsphenoidal surgery. 2 The surgeon should be aware of the potential vagaries of the ICA’s location. Magnetic resonance imaging proved to be useful in determining the landmarks for location of the ICA. Fenestration of the intracranial ICA is an extremely rare anomaly. To date only five cases have been reported. 1,3,5 Such an anomaly presumably originated during the 4-mm embryonic stage, in which the primitive ICA divides into cranial and caudal branches. 4 The ob