Hemodynamic and histopathological changes in the early phase of the development of an intracranial aneurysm

Hiroharu Kataoka, Takanobu Yagi, Taichi Ikedo, Hirohiko Imai, Koichi Kawamura, Kazumichi Yoshida, Masanori Nakamura, Tomohiro Aoki, Susumu Miyamoto

Research output: Contribution to journalArticle

Abstract

Hemodynamic stress and chronic inflammation are closely associated with the pathogenesis of intracranial aneurysms (IAs). However, the hemodynamic and biological mechanisms triggering IA formation remain to be elucidated. To clarify them, computational fluid dynamics (CFD) and histopathological analyses in the early phase of IA development using an experimentally induced IA model in rats were con-ducted. Histological changes in the early phase of IA development were observed under a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Using data from 7-T magnetic resonance angiography (7T-MRA), CFD analyses were performed to determine wall shear stress (WSS) and wall pressure (WP) at the prospective site of IA. A bump-like protrusion named an “intimal pad” was located in the anterior cerebral artery (ACA) immediately distal to the apex of the bifurcation. TEM showed the degeneration of the internal elastic lamina (IEL) and longitudinally elongated smooth muscle cells (SMCs) that switched from the contractile to the proliferative phenotype and penetrated between two divided layers of the degenerated IEL in the prospective site of the IA. However, no inflammatory cells were observed. CFD analyses showed no particular pattern of WSS and WP at the prospective IA site. IEL degeneration and the phenotypic change and longitudinal elongation of SMCs were identified as the early events in IA development. CFD analyses and TEM data suggest that these biological events may be derived from increased circumferential wall stress due to increased blood pressure and increased longitudinal wall strain due to the existence of the intimal pad.

Original languageEnglish
Pages (from-to)319-328
Number of pages10
JournalNeurologia Medico-Chirurgica
Volume60
Issue number7
DOIs
Publication statusPublished - 2020

Keywords

  • Hemodynamics
  • Internal elastic lamina
  • Intracranial aneurysm
  • Smooth muscle cell

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology

Fingerprint Dive into the research topics of 'Hemodynamic and histopathological changes in the early phase of the development of an intracranial aneurysm'. Together they form a unique fingerprint.

  • Cite this

    Kataoka, H., Yagi, T., Ikedo, T., Imai, H., Kawamura, K., Yoshida, K., Nakamura, M., Aoki, T., & Miyamoto, S. (2020). Hemodynamic and histopathological changes in the early phase of the development of an intracranial aneurysm. Neurologia Medico-Chirurgica, 60(7), 319-328. https://doi.org/10.2176/nmc.st.2020-0072