The monitoring and control of increased intracranial pressure (ICP) are the major requirements for the diagnosis and treatment of patients suffering from traumatic brain injury (TBI) or hydrocephalus. Widely used commercially available ICP measuring devices require the use of a tethered fiber optic probe, which can cause complications, such as infection and hemorrhage. The use of a probe also prohibits immediate (at the time of induced injury) and long-term measurements of ICP. Therefore, we have developed and tested a small fully embedded wireless ICP sensor, incorporating a novel antenna and packaging arrangement. Evaluations were performed in-vitro and in-vivo to demonstrate the robustness of this microwave pressure-monitoring system. This is the first report of in-vivo tests in a dynamic study of continuous (every 6 s) wireless ICP measurements in a swine model of closed-head rotational-acceleration induced TBI using a digital device. In particular, our device measured extreme changes in ICP immediately upon rapid head rotation that persisted for hours after the injury. The readings matched well those obtained from a commercially available tethered monitor. Our device can be utilized in the future as a tool to diagnose and track long-term ICP changes.