Inductive passive sensor for intraparenchymal and intraventricular monitoring of intracranial pressure

Accurate measurement of intracranial hypertension is crucial for the management of elevated intracranial pressure (ICP). Catheter-based intraventricular ICP measurement is regarded as the gold standard for accurate ICP monitoring. However, this method is invasive, time-limited, and associated with complications. In this paper, we propose an implantable passive sensor that could be used for continuous intraparenchymal and intraventricular ICP monitoring. Moreover, the sensor can be placed simultaneously along with a cerebrospinal fluid shunt system in order to monitor its function. The sensor consists of a flexible coil which is connected to a miniature pressure sensor via an 8-cm long, ultra-thin coaxial cable. An external orthogonal-coil RF probe communicates with the sensor to detect pressure variation. The performance of the sensor was evaluated in an in vitro model for intraparenchymal and intraventricular ICP monitoring. The findings from this study demonstrate proof-of-concept of intraparenchymal and intraventricular ICP measurement using inductive passive pressure sensors.

I. Introduction

Intracranial hypertension (IH) is a neurological complication which is commonly observed following severe traumatic brain injury (TBI), disturbances of CSF flow, and idiopathic IH [1]. Treatment of elevated ICP through a variety of interventions is believed to prevent secondary brain damage. In clinical settings, the placement of an intraventricular catheter and fluid-coupled measurement of ICP is considered the gold standard [2]. There are alternative devices that consist of fiber-optic catheter-tip pressure transducers that can be inserted into the ventricle or brain parenchyma to measure ICP. These devices by themselves do not allow CSF drainage. However, both methods are time-limited, and require a direct connection through the scalp to an external device. In addition, the insertion of a ventricular catheter carries the potential risk of infection and intracranial hemorrhage [3], [4]. In patients with hydrocephalus, treatment often requires the placement of a shunt to divert excessive CSF from the brain to the peritoneal cavity (a ventriculo-peritoneal, or VP shunt). The common problems with VP shunts are obstruction, mechanical failure and over/under drainage [5]. Direct measurement of ICP with most shunt systems is impossible. To detect these complications, implantable intraventricular ICP sensors can be introduced along with the shunt systems to continuously monitor their function.