PhD Defence Marlous Verhulst | The Brain Beyond Heartbeat | Neuroimaging the injured brain after cardiac arrest

The Brain Beyond Heartbeat | Neuroimaging the injured brain after cardiac arrest

Marlous is Verhulst is a PhD student in the department Clinical Neurophysiology. (Co)Promotors are prof.dr. J. Hofmeijer and dr. R. Helmich from the faculty of Science & Technology, University of Twente.

Brain injury is a major challenge after cardiac arrest. While some patients remain comatose, others wake up but still face significant cognitive problems. Being able to predict neurological outcome is important, not only to support decision-making in comatose patients, but also to identify those who may benefit from early cognitive rehabilitation. To improve such predictions, we need a better understanding of the underlying brain injury mechanisms and how to capture these with clinical tools.

In the first part, we investigated whether MRI in the acute phase can identify patients at risk of long-term cognitive problems. Functional changes in brain networks were mainly associated with short-term impairments, such as delirium, but had limited value for long-term outcomes. In contrast, lower brain volume was more strongly linked to poorer cognitive performance at twelve months, highlighting the importance of structural imaging in prognostic models.

The second part focuses on comatose patients, combining different MRI modalities with clinical markers to predict recovery of consciousness. Structural abnormalities, such as reduced diffusivity and increased brain volume indicative of edema, were found only in patients with poor outcomes and provided robust predictive value. Functional network alterations were present in both outcome groups and may help identify patients with potential for recovery.

In the third part we explored the mechanisms underlying postanoxic encephalopathy. The findings show that structural and functional brain injury follow partly independent pathways, with different implications and timelines. Understanding these processes can contribute to the development of targeted treatments in both the acute and later recovery stages after cardiac arrest.

This thesis demonstrates that brain injury after cardiac arrest results from multiple, evolving processes with varying reversibility. By integrating structural and functional imaging, it lays the groundwork for a multimodal, mechanism-based approach to improve diagnosis, personalized prognostication, and targeted treatment, advancing our understanding of the brain beyond heartbeat.