Implantable sensor measures intracranial pressure in shunt system of hydrocephalus patients
Urinary incontinence, a shuffling gait and fading cogitation are all signs for Parkinson’s or Alzheimer’s disease. It is also possible to have a pathological overpressure in the brain that is caused by a hydrocephalus. With this diagnosis the brain either produces too much brain fluid or can’t flush it sufficiently. The consequence: The pressure increases too much which causes the brain to suffer damages. The remedy is a shunt system which is implanted into the patient by doctors. There, the excess fluid is carried to, for example, the abdominal area. The centerpiece of this shunt system is the valve: If the pressure has risen above the threshold, the valve opens; if it sinks, it closes.
Until now, doctors could only perform a function control of the valve for the hydrocephalus treatment using complex and expensive computer and magnetic resonance imaging. This changes with a novel sensor that researchers at the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg developed in cooperation with Christoph Miethke GmbH and Aesculap AG. If the sensor is implanted together with the shunt system, doctors can read out intracranial pressure anytime using a handheld reader and without extensive examination.
When the patient has complaints, the doctor simply needs to hold the handheld reader up to the head of the hydrocephalus patient. The reader sends magnetic radio waves and supplies the sensor in the shunt system with energy – the implant is “activated”, measures temperature and pressure of the brain fluid and sends the data back to the handheld reader. If the measured pressure is not in the desired range, the doctor can adjust the valve of the shunt system accordingly from the outside and personalize it to the patient.
The researchers also developed the handheld reader for telemetric communication with the sensor which shows the measured values conveniently on a display. A particular challenge is the hermetic metal cover in which the implant is embedded: This forms an obstacle for the magnetic communication radio waves, but is indispensable for the biocompability of the implant.
The sensor system is ready for series production and CE-approved. Currently, the implant is distributed by Miethke and Aesculap. The sensor sets the basis for further development up to theranostics – a neologism created from the terms therapy and diagnostics. In several years the sensor could potentially not only measure intracranial pressure and assist the doctor in diagnosis, but also adjust the pressure autonomously through the shunt system and therefore support the attending physician actively in the individual therapy of the patient.