This document surveys recent event-driven routing protocols for wireless sensor networks (WSNs) that facilitate efficient data transmission triggered by specific events. It compares various protocols based on parameters like reliability, congestion control, and energy efficiency, while also discussing challenges in routing design such as node deployment, energy consumption, and fault tolerance. The paper highlights key protocols such as ESRT, LTRES, RRRT, SMESRT, and CODAR, emphasizing their advantages and limitations in managing event detection and transmission.