Transcranial optical monitoring for detecting intracranial pressure alterations in children with benign external hydrocephalus: a proof-of-concept study

Abstract

Significance: Benign external hydrocephalus (BEH) is considered a self-limiting pathology with a good prognosis. However, some children present a pathological intracranial pressure (ICP) characterized by quantitative and qualitative alterations (the so-called B-waves) that can lead to neurological sequelae.

Aim: Our purpose was to evaluate whether there were cerebral hemodynamic changes associated with ICP B-waves that could be evaluated with noninvasive neuromonitoring.

Approach: We recruited eleven patients (median age 16 months, range 7 to 55 months) with BEH and an unfavorable evolution requiring ICP monitoring. Bedside, nocturnal monitoring using near-infrared time-resolved and diffuse correlation spectroscopies synchronized to the clinical monitoring was performed.

Results: By focusing on the timing of different ICP patterns that were identified manually by clinicians, we detected significant tissue oxygen saturation ( ${\mathrm{StO}}_2$ ) changes ( $p=0.002$ ) and blood flow index (BFI) variability ( $p=0.005$ ) between regular and high-amplitude B-wave patterns. A blinded analysis looking for analogs of ICP patterns in BFI time traces achieved 90% sensitivity in identifying B-waves and 76% specificity in detecting the regular patterns.

Conclusions: We revealed the presence of ${\mathrm{StO}}_2$ and BFI variations-detectable with optical techniques-during ICP B-waves in BEH children. Finally, the feasibility of detecting ICP B-waves in hemodynamic time traces obtained noninvasively was shown.

Keywords: benign enlargement of subarachnoid spaces; hydrocephalus; intracranial pressure monitoring; optical techniques; pathophysiology.