An avoidable methodological failure in intracranial pressure monitoring using fiberoptic or solid state devices.

Failure of intraventricular pressure (IVP) measurement in case of catheter blockage is believed to be eliminated by using intraventricular microtransducers. We report about an avoidable methodological error, which may affect the reliability of IVP measurement with these devices. Intraventricular fiberoptic or solid state devices were implanted in 43 patients considered to be at risk for catheter occlusion. Two different types were used: devices where the transducer is placed inside the ventriculostomy catheter (Type A), and devices where the transducer is integrated in the external surface of the catheter (Type B). Of the 15 patients treated with Type A devices, no reliable pressure recording could be obtained in three patients where ventricular puncture was not successful. In four cases of the remaining 12 patients, periods of erroneous pressure readings were revealed. After opening of CSF drainage, all Type A devices failed to reflect real IVP. In patients treated with Type B devices, no erroneous pressure recording could be identified, irrespective if CSF drainage was performed or not. Transducers, which are simply placed inside the ventriculostomy catheter require fluid coupling. They may fail, either during CSF drainage or when the catheter is blocked or placed within the parenchyma.