Authors: Adele S. Budiansky et al.
Source: Journal of Neurosurgical Anesthesiology 37(4):335–340, October 2025. DOI: 10.1097/ANA.0000000000001046
This focused review outlines four major strategies used to achieve temporary intraoperative cerebral blood flow reduction during neurovascular surgery and endovascular procedures. Techniques reviewed include deep hypothermic circulatory arrest (DHCA), intravenous adenosine, rapid ventricular pacing (RVP), and endovascular balloon-assisted occlusion. Each approach serves to create a controlled reduction in blood flow to facilitate aneurysm clipping, arteriovenous malformation (AVM) embolization, or the management of intraoperative rupture.
Results and Discussion
DHCA, once a mainstay technique, has become largely obsolete due to high morbidity and mortality rates associated with hypothermia, coagulopathy, and the complex logistics of cardiopulmonary bypass. Intravenous adenosine provides a simple and rapid means of inducing brief circulatory arrest but exhibits variable hemodynamic responses and potential risks of arrhythmia or bronchospasm. RVP offers a predictable and tightly controlled reduction in mean arterial pressure by pacing the right ventricle at 150–200 beats per minute, allowing for repeated short episodes of reversible hypotension. Balloon-assisted occlusion, requiring a hybrid surgical–endovascular environment, provides localized control when proximal clip placement is not feasible and can be combined with systemic flow reduction techniques for enhanced effect.
The authors emphasize that no single technique has demonstrated superiority in safety or efficacy. The choice of flow reduction method should be individualized, based on lesion location, patient physiology, procedural requirements, and institutional expertise.
Key Points
- Flow reduction techniques are essential adjuncts in the management of complex neurovascular procedures, facilitating surgical microdissection and control during aneurysm clipping and endovascular embolization of arteriovenous malformations and other vascular shunt lesions.
- Deep hypothermic circulatory arrest has largely become obsolete in recent years, since alternative flow reduction strategies such as intravenous adenosine and rapid ventricular pacing can induce transient hypotension with more favorable side-effect profiles.
- Endovascular balloon-assisted occlusion provides localized flow control in anatomically challenging cases where access to the parent vessel is restricted, and can be combined with systemic techniques in hybrid procedures.
- Choice of technique should be individualized based on lesion anatomy, institutional expertise and available resources, and no single approach has demonstrated superiority in terms of efficacy or safety.
What You Should Know
• Flow reduction aids surgical control during aneurysm clipping and AVM embolization.
• DHCA is now rarely used due to its morbidity.
• Adenosine is effective for short, emergency-induced hypotension but lacks predictability.
• RVP provides controlled, repeatable hypotension suitable for planned interventions.
• Balloon-assisted occlusion enables localized control in hybrid or endovascular cases.
• Selection depends on anatomy, available expertise, and procedural context.
Thank you to the Journal of Neurosurgical Anesthesiology for publishing this comprehensive review of modern strategies for temporary cerebral flow reduction in neurovascular surgery.