Invention of a non-invasive intracranial pressure (ICP) monitoring system - an enlightenment from a hydrocephalus study.

Background: Mechanical obstruction is the most common cause of shunt failure for hydrocephalic patients. However, the diagnosis is extremely challenging and often requires invasive testing methods. Thus, a simple and non-invasive technique is in urgent need to predict the intracranial pressure (ICP) of hydrocephalic patients during their post-surgical follow-up, which could help neurosurgeons to determine the conditions of the shunt system.

Materials And Methods: Two groups of patients were enrolled in the current study. In group I, patients were enrolled as they were diagnosed with high ICP hydrocephalus and received shunt surgery. The shunt valve pressures were taken for their post-surgical ICP. Meanwhile, the participants of group II exhibited abnormally increased lumbar puncture opening pressure (LPOP; from 180 to 400 mmHO). Both the ICP and LPOP were used to match with their corresponding tympanic membrane temperature (TMT).

Results: When patients' ICP were in the normal range (group I, from 50 to 180 mmHO), the TMT correlated with ICP in a linear regression model (=0.59, <0.001). Interestingly, when patients exhibited above-normal ICP (LPOP was from 180 to 400 mmHO), their TMT fit well with the ICP in a third-order polynomial regression (=0.88). When the ICP was 287.98 mmHO, the TMT approached the vertex, which was 38.54 °C. Based on this TMT-ICP algorithm, we invented a non-invasive ICP monitor system. Interestingly, a tight linear correlation was detected between the ICP data drawn from the non-invasive device and Codman ICP monitoring system (=0.93, <0.01).

Conclusions: We believe the TMT-ICP algorithm (the Y-Jiang model) could be used for preliminary prediction of shunt malfunction as well as monitoring ICP changes.