Continuous, noninvasive wireless monitoring of flow of cerebrospinal fluid through shunts in patients with hydrocephalus

Siddharth Krishnan ,Aaron Banks,Matthew B Potts,Manish Patel,Kaan Börekçi,Marcus Mims,Juliet Freudman,Matthew C Tate ,Tord D Alden ,Hsuan Ming Chen ,Kyeongha Kwon,Yujun Deng,Amit Ayer ,Zachary A Abecassis ,Diana Ostojich,Yonggang Huang,Heling Wang,Joshua M Rosenow ,Hany Arafa ,Chun Ju Su ,Robert Loza,Kun Hyuck Lee ,Izabela Stankiewicz,Mitchell Mims,Jonathan T Reeder,John A Rogers

doi:10.1038/s41746-020-0239-1

Abstract

Hydrocephalus is a common disorder caused by the buildup of cerebrospinal fluid (CSF) in the brain. Treatment typically involves the surgical implantation of a pressure-regulated silicone tube assembly, known as a shunt. Unfortunately, shunts have extremely high failure rates and diagnosing shunt malfunction is challenging due to a combination of vague symptoms and a lack of a convenient means to monitor flow. Here, we introduce a wireless, wearable device that enables precise measurements of CSF flow, continuously or intermittently, in hospitals, laboratories or even in home settings. The technology exploits measurements of thermal transport through near-surface layers of skin to assess flow, with a soft, flexible, and skin-conformal device that can be constructed using commercially available components. Systematic benchtop studies and numerical simulations highlight all of the key considerations. Measurements on 7 patients establish high levels of functionality, with data that reveal time dependent changes in flow associated with positional and inertial effects on the body. Taken together, the results suggest a significant advance in monitoring capabilities for patients with shunted hydrocephalus, with potential for practical use across a range of settings and circumstances, and additional utility for research purposes in studies of CSF hydrodynamics.

Highlights

Hydrocephalus is a common and debilitating condition caused by the excess production or impaired resorption of cerebrospinal fluid (CSF) in the ventricles of the brain
The results presented in the following extend these concepts into a user-friendly, fully wireless system that enables continuous, noninvasive monitoring of CSF flow performed by patients output voltages, (iii) a BLE-SoC and its associated timers and antenna to digitize and transmit these data, and to support wireless two-way communication, (iv) power management electronics and a rechargeable lithium polymer (Li-Po) battery to supply power to the various sub-systems, (v) a flexible printed circuit board substrate to support and interconnect the components, and (vi) packaging and insulation layers to protect the device from the environment
The increases in temperature downstream (TDS) from the actuator are larger than those at an equal distance upstream (TUS). Temperature sensors record these differences as a function of time after supplying power to the actuator

Summary

INTRODUCTION

Hydrocephalus is a common and debilitating condition caused by the excess production or impaired resorption of cerebrospinal fluid (CSF) in the ventricles of the brain. The findings from clinical trials of the ShuntCheck system include relatively high numbers of false positives, as patent shunts regularly experience intermittent flow[25] Each of these methods requires immobilization of the patient and yields only instantaneous measurements during brief examinations by trained care providers in hospital settings. The fPCB has a thickness (~115 μm) that yields low flexural rigidity (4 × 10−4 N-m) and sufficient degrees of flexibility to conform and bond to the curved surface of the skin with a mild adhesive where the shunt is most superficial, typically near the neck or the clavicle This mechanics follows from an island-bridge configuration, designed to localize bending strains to the interconnected structures and away from the electronic components.

RESULTS AND DISCUSSION

METHODS

CODE AVAILABILITY