Angiographic Evolution of Direct Bypass in Moyamoya Disease: Vascular Adaptations Over Time

Sunday, May 5, 2024

4:25 PM – 4:27 PM CT

Location: S405a

Presenting Author(s)

Jorge Rios Zermeno, MD

Research Fellow
Mayo Clinic Florida
Jacksonville, FL, US

Co-Author(s)

IA

Iman Ahrari, MD

Research Fellow
Mayo Clinic
Jacksonville, Florida, United States
Abdul Karim Ghaith, MD

Research Fellow- PhD candidate
Mayo clinic- rochester-mn
Rochester, MN, US
JK

Jeyan S. Kumar, MD

Neurovascular Fellow
Mayo Clinic
Charlottesville, Virginia, United States
RT

Rabih Tawk, MD

Cons-Neurointerventional Neurosurgery
Department of Neurological Surgery, Mayo Clinic
Jacksonville, Florida, United States

Disclosure(s):

Jorge Rios Zermeno, MD: No financial relationships to disclose

Abdul Karim Ghaith, MD: No financial relationships to disclose

Introduction: Revascularization through Extracranial-Intracranial (EC-IC) bypass is the primary intervention in managing Moyamoya disease (MMD), aimed at augmenting cerebral blood flow in symptomatic patients. However, the long-term angiographic changes of the EC-IC bypass remain insufficiently characterized. This study aims to delineate the angiographic progression of the EC-IC bypass to understand the postoperative evolution of the bypass in MMD patients.

Methods: We performed a retrospective review from 2011 and identified MMD patients who underwent EC-IC bypass. Angiograms were used for measurements. Statistical comparisons of anatomical parameters were conducted between preoperative and follow-up (FU) measurements using T-test and Chi-square. The analysis was performed using Python.

Results: Out of an initial cohort of 54 patients, 32 met the inclusion criteria, contributing to 44 anastomoses for the study. Among them, 20 (62.5%) underwent a single-barrel bypass. Encephalodurosynangiosis (EDS) was the most common indirect component of combined bypasses, performed in 75% of patients. At the final follow-up, all patients, except one (96.87%), had at least one patent anastomosis. Six anastomoses (18.75%) experienced occlusion, 5 in double barrel bypasses.
A significant increase in the diameter of the Superficial Temporal Artery (STA) and its frontal and parietal branches from preop to first postoperative angiogram was observed. This was followed by a gradual reduction until stabilizing at near-initial size at 18 months of FU and persisting this way until the final FU (5 years). The territory supplied by the direct bypass decreased over time and was greater throughout FU for double barrel bypasses. The median time for indirect bypass appearance was 267 days, while the median time for anastomosis occlusion was 441 days.

Conclusion : This work shows the anatomical changes induced by MMD in the supplying vasculature after EC-IC bypass, including the timing of the first appearance of the indirect component and occlusion of the anastomoses.