Brain Cooling in Surgery

Brain cooling, often referred to as hypothermia, is a hot topic in the world of neuroprotective strategy during neurosurgery. The idea behind the argument for this process is that lowering brain temperature decreases the patient’s metabolic demand, helps account for blood flow decrease, and reduces cell death due to freezing. While early clinical trials in animals and humans show promise, it remains inconclusive. However, it presents an intriguing look into the future of neurosurgery.

During the incision of the bran, several factors threaten its function; reduced blood flow during vessel constriction, injury, fluctuations, or hemorrhage. Hypothermia aims to protect the brain during these periods by lowering oxygen consumption. What this does is that since the brain is quite literally freezing, the membranes and circuits become stabilized, thus inhibiting threatening conditions that stem from the operation including apoptosis and excitotoxicity (No Evidence That Cooling Patients Undergoing Brain Surgery Helps to Either Reduce Death and Severe Disability or Increase Harm | Cochrane, 2015).

Techniques for brain cooling include systemic or selective freezing. Systemic refers to reducing core body temperature (thus freezing the “system”) in an effort to equalize the body temperature across the board. Systemic hypothermia carries risks of infection, arrhythmia, and delayed recovery, since so much of the body is being impacted (No Evidence That Cooling Patients Undergoing Brain Surgery Helps to Either Reduce Death and Severe Disability or Increase Harm | Cochrane, 2015). Selective methods, on the other hand, attempt to target the brain directly while limiting systemic complications. Selective brain freezing methods include cooling helmets, hypothermic cardiopulmonary bypasses, and topical saline irrigation (Wass et al., 1998). 

One study showed that irrigating brain tissue with saline at around 30°C reduced parenchymal temperature by 1.6°C, although the temperature returned to base within minutes (Iatrou et al., 2002). Another trial of mild hypothermia (around 33°C) during aneurysm surgery found no statistically significant difference compared with the normal temperature (Todd et al., 2005). Similarly, a Cochrane review concluded that hypothermia during neurosurgery didn’t obviously reduce mortality or disability, though evidence of harm was also weak (No Evidence That Cooling Patients Undergoing Brain Surgery Helps to Either Reduce Death and Severe Disability or Increase Harm | Cochrane, 2015).

Challenges remain in determining the best extent, duration, and timing of brain cooling. Maintaining hypothermia during operations without compromising surgical access is very hard but important (No Evidence That Cooling Patients Undergoing Brain Surgery Helps to Either Reduce Death and Severe Disability or Increase Harm | Cochrane, 2015). Despite these limitations, selective cooling continues to be refined and holds potential for neuroprotection in the future.  

In conclusion, brain cooling is an experimental but promising method that could drastically reduce the chances for surgery-related brain damage. Current evidence suggests that it is not ready for routine use, but research continues into safer and more targeted strategies.

Written by Saket Parayil at Incisionary

References

Cochrane. (n.d.). Cooling for cerebral protection during brain surgery. Retrieved from https://www.cochrane.org/CD006638/ANAESTH_no-evidence-that-cooling-patients-undergoing-brain-surgery-helps-to-either-reduce-death-and-severe-disability-or-increase-harm

Dietrich, W. D., et al. (2002). The effect of selective brain cooling on intracerebral temperature during craniotomy. Journal of Neurosurgery, 96(2), 302-309. https://pubmed.ncbi.nlm.nih.gov/12002923

Mayo Clinic. (n.d.). Selective convective brain cooling during hypothermic cardiopulmonary bypass. Annals of Thoracic Surgery. https://mayoclinic.elsevierpure.com/en/publications/selective-convective-brain-cooling-during-hypothermic-cardiopulmo

Todd, M. M., Hindman, B. J., Clarke, W. R., & Torner, J. C. (2005). Mild intraoperative hypothermia during surgery for intracranial aneurysm. New England Journal of Medicine, 352(2), 135-145. https://www.nejm.org/doi/full/10.1056/NEJMoa040975