Cerebrovascular Responses in a Patient with Lundberg B Waves Following Subarachnoid Haemorrhage Assessed with a Novel Non-Invasive Brain Pulse Monitor: A Case Report

Abstract

Subarachnoid haemorrhage (SAH) can trigger a range of poorly understood cerebrovascular responses that may play a role in delayed cerebral ischemia. The brain pulse monitor is a novel non-invasive device that detects a brain photoplethysmography signal that provides information on intracranial pressure (ICP), compliance, blood flow and tissue oxygen saturation. We monitored the cerebrovascular responses in a patient with Lundberg B waves following a SAH. The patient presented with a Fischer grade 4 SAH that required urgent left posterior communicating artery aneurysm coiling and ventricular drain insertion. On hospital day 4 oscillations or spikes on the invasive ICP were noted, consistent with Lundberg B waves. Brain pulse monitoring demonstrated concurrent pulse waveform features consistent with reduced brain compliance and raised ICP over both brain hemispheres. Oxygen levels also demonstrated slow oscillations correlated with the ICP spikes. Brief infrequent episodes of reduced and absent brain pulses were also noted over the right hemisphere. Our findings suggest that the brain pulse monitor holds promise for early detection of delayed cerebral ischemia and could offer insights into the vascular mechanisms at play. Plain Language Summary: In this study, we examined a patient with a serious brain bleed, known as subarachnoid hemorrhage (SAH). Patients with SAH can suffer from vasospasm and consequent delayed cerebral ischemia (DCI), which can happen from 4 to 14 days after the initial bleeding. Detecting and treating DCI early is difficult because methods are imperfect, discontinuous and technically difficult. We used a new, non-invasive device that can monitor various features of brain health. This device helps us understand the pressure inside the skull, blood flow, and the oxygen saturation on the surface of the brain. In this patient, we found evidence of: ● Brain pulse signals that were directly related to acute changes in the invasive intracranial pressure. ● Specific brain pulse patterns that may indicate a local reduction in brain blood flow. ● Signs of a breakdown in the brain’s ability to regulate blood flow in the injured hemisphere. ● The oxygen saturation levels in the brain that related to pressure changes. These results are promising because they suggest the new device could help us identify when someone’s brain condition is getting worse. This ability could guide the development of improved care protocols, and aid clinical decision-making. Further research is needed in this patient population with additional forms of monitoring to understand the generalizability of our findings.