Morphological Parameters Associated With Middle Cerebral Artery Aneurysms

BACKGROUND: Morphological factors contribute to the hemodynamics of the middle cerebral artery (MCA). OBJECTIVE: To identify image-based morphological parameters that correlated with the presence of MCA aneurysms. METHODS: Image-based anatomic parameters obtained from 110 patients with and without MCA bifurcation aneurysms were evaluated with Slicer, an open-source image analysis software, to generate 3-dimensional models of the aneurysms and surrounding vascular architecture. We examined segment lengths, diameters, and vessel-to-vessel angles of the parent and daughter vessels at the MCA bifurcation. In order to reduce confounding by genetic and clinical risk factors, 2 control groups were selected: group A (the unaffected contralateral side of patients with unilateral MCA bifurcation aneurysms) and group B (patients without intracranial aneurysms or other vascular malformations). Univariate and multivariate analyses were performed to determine statistical significance. RESULTS: One hundred ten patients who were evaluated from 2007 to 2014 were analyzed (73 patients with MCA aneurysms and 37 control patients). Multivariate analysis revealed that a smaller parent artery diameter (group A: odds ratio [OR] 0.20, P < .01, group B: OR 0.23, P < .01) and a larger daughter-to-daughter branch angle (group A: OR 1.01, P = .04, group B: OR 1.02, P = .04) were most strongly associated with MCA aneurysm presence after adjusting for other morphological factors. CONCLUSION: Smaller parent artery diameter and larger daughter-to-daughter branch angles are associated with the presence of MCA bifurcation aneurysms. These easily measurable parameters may provide objective metrics to assess aneurysm formation and growth risk stratification in high-risk patients.

Differential conduction at axonal bifurcations. I. Effect of electrotonic length

1. Frequency-dependent differential conduction of action potentials into one daughter branch of the squid giant axon is demonstrated. 2. This differential conduction arises from differences in the electrotonic length of the daughters, rather than inhomogeneities in membrane properties. 3. It may therefore be a more general phenomenon in the nervous system than is differential conduction which does depend upon membrane inhomogeneities.