Analysis of Potential Determinants of a Reduced Intercarotid Distance in Patients Undergoing Endoscopic Transsphenoidal Surgery

Objectives: (1) Evaluate the anatomic variability of the distance between the internal carotid arteries (ICA) at the paraclival, intracavernous, and paraclinoid segments in normal variants and in patients with sellar or parasellar lesions. (2) Identify clinicopathologic factors associated with a reduced intercarotid distance (ICD) and identify subgroups at higher risk for ICA injury during endoscopic skull base surgery. Methods: A retrospective case-control study was performed at an academic tertiary care center. The smallest distance between the ICAs at the paraclival, intracavernous. and paraclinoid segments on coronal T2-weighted magnetic resonance imaging was measured in patients with sellar or parasellar tumors and in nontumor controls. Factors such as demographic profiles, cephalometric measurements, tumor dimensions, and sphenoid configuration were assessed as potential predictors of the ICD. Results: In total, 154 cases and 34 controls were analyzed. Patients with growth hormone (GH) secreting adenomas had a markedly reduced ICD at the paraclival segment as compared to controls (1.59 cm and 1.77 cm, respectively; P = .02; 95% confidence interval [CI] [0.03-0.32]). The paraclinoid ICD was reduced in patients with a planum sphenoidale meningioma (1.09 cm and 1.33 cm, respectively; P = .04; 95% CI [0.01-0.45]). The transverse dimension of pituitary adenomas was linearly correlated to the ICD (P < .001). No narrowing of the ICD was associated with sphenoid configuration or cephalometric measurements. Conclusions: Patients with a GH secreting adenoma or planum sphenoidale meningioma had a reduced ICD. Identifying these populations can help surgeons recognize constraints imposed by a reduced ICD to endoscopic access of the skull base and avoid inadvertent ICA injury.