The objective of the paper is to review the state-of-the-art in medical robotic systems used for different surgical applications, and to position and evaluate their concepts according to the design requirements of an innovative, robotized neurosurgical system, capable of performing tumor ablation or electrode positioning. A few other non-medical systems, which have interesting concepts, will also be discussed. The overall aim is to determine the robotic concept (structure, actuation, etc.) most applicable to specific tasks in neurosurgery. The first section of the article describes the requirements of the task and each important aspect is expressed by an evaluation criterion. Then, 59 systems are described, according to the fields of medical applications and the robotic concepts. An evaluation of the different systems is conducted, based on the five most significant criteria. However, the main characteristic assessed is the deployment capability of the system i.e. extension and retraction. The final section presents an overview of concepts transferable to neurosurgical applications. Continuum concepts, such as "elephant trunks", seem to be the most adapted solutions, utilizing pneumatic and/or spring and/or cable actuations. Pneumatics offer deployment forces and cables can control and guide the deployment. The design of a new neurosurgical device should take into account these observations as a base.