Correlation of Petrous Carotid Canal Diameter with Severity of Ipsilateral Moyamoya Disease

Introduction/Background: Moyamoya disease is a cerebrovascular disorder that consists of progressive narrowing of arteries in the anterior circulation of the brain. Comparing high-resolution CT imaging of 45 adult moyamoya patients with age-, sex-, and race-matched ischemic stroke controls at our institution, we found in a previous study that carotid canal diameter is statistically significantly smaller in moyamoya patients. We do not think this is a secondary change. We hypothesized that patients with smaller carotid canal diameters were more likely to present with advanced disease based on angiographic Suzuki grading scale.

Methods: We studied 45 adult patients diagnosed with moyamoya disease at our institution from 2010 to 2018. We excluded pediatric patients and patients with Trisomy 21. We calculated bilateral carotid canal diameters and bilateral angiographic Suzuki grades at the time of clinical presentation on cerebral angiography. We then performed regression analysis on the data to calculate Spearman’s Rho correlation and p-value to determine if there was a relationship between carotid canal size and disease severity, determined as a higher angiographic Suzuki grade on initial presentation. We also calculated a Spearman’s Rho correlation and p-value to determine if there was a relationship with right and left carotid canal diameters.

Results: The right petrous carotid canal diameter was negatively correlated with the right hemispheric Suzuki grade with a weak strength of correlation (Spearman’s = −0.20). The p-value for this association was not statistically significant (p = 0.181). The left petrous carotid canal diameter was negatively correlated with the left hemispheric Suzuki grade with a weak strength of correlation (Spearman’s = −0.34). The p-value for this association was statistically significant (p = 0.028). In addition, we noted that having a small right carotid canal diameter is strongly correlated with having a small left carotid canal diameter and having a small left carotid canal diameter is strongly correlated with having a small right carotid canal diameter (Spearman’s = 0.71), even though the angiographic intracranial vascular disease may only be unilateral. This p-value for the association of the bilateral carotid canal diameters was statistically significant with a p-value <0.00001.

Conclusion: Carotid canal diameter is correlated to severity of disease at presentation as determined by Suzuki grade on diagnostic angiography at the time of clinical presentation in moyamoya patients. Decreasing carotid canal diameters are correlated with increasing ipsilateral Suzuki grades and smaller contralateral carotid canal diameters. These measurements were obtained at one point in time. Further studies may elucidate the time course of these changes, whether or not they are affected by revascularization surgery, and whether or not they are associated with more rapid progression of disease after clinical presentation.

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