# The efficacy of the simple bypass protocol for chronic cerebral arterial occlusion and moyamoya disease

## TL;DR

This study shows that a simple bypass surgery improves outcomes for patients with chronic cerebral arterial occlusion, especially where advanced diagnostic tools are unavailable.

## Contribution

The study demonstrates the efficacy of using mean transit time and a single-barrel bypass protocol in resource-limited settings for treating chronic cerebral arterial occlusion.

## Key findings

- 80% of patients who underwent the simple bypass protocol showed symptomatic improvement.
- Only one complication (brainstem infarction) occurred among 30 patients.
- The protocol is effective in areas lacking advanced diagnostic tools like acetazolamide or CO2 challenge tests.

## Abstract

Ischemic strokes represent a significant public health concern, with a prevalence of 2.5% in the United States and over 250,000 new cases annually in Thailand, where strokes remain the leading cause of mortality. Chronic cerebral arterial occlusion and moyamoya disease are specific subtypes of ischemic stroke. In certain regions, advanced diagnostic tools are often inaccessible. Simple bypass protocols, which utilize mean transit time (MTT) in conjunction with surgical interventions such as the single-barrel bypass, are valuable for enhancing patient outcomes in these settings. The objective of this study is to elucidate the efficacy of MTT as a diagnostic tool and to evaluate the single-barrel bypass as a therapeutic intervention for chronic cerebral arterial occlusion.

This retrospective study assessed the utility of MTT as a selection criterion and evaluated the efficacy of the single-barrel bypass procedure for chronic cerebral arterial occlusion. Conducted at Rajavithi Hospital, the study included patients treated between 2010 and 2024 with complete medical records. Outcomes measured were changes in neurological function, alterations in MTT, and the incidence of surgical complications within one month postoperatively.

Among the 30 patients who underwent the simple bypass protocol, 80% (24/30) demonstrated symptomatic improvement and better Modified Rankin Scale scores. Only one complication was reported—a brainstem infarction in a single patient.

The simple bypass protocol is an effective intervention for patients exhibiting prolonged MTT and is particularly useful in regions where stress tests such as acetazolamide or CO2 challenge testing are unavailable.