Kathryn Busch submits her PhD thesis, which reveals that the measurement of brain venous pulsatility may predict detrimental events following certain types of brain surgery
Opening up the head to perform surgery is an awe inspiring challenge and it is incredible to see the skill and surgical advances that are giving so many patients truly life changing treatments. In a minority of cases, however, outcomes for the patient are not positive. In some of these cases, if early warning signs could be seen, more aggressive pharmacological treatments may prevent problems from occurring.
Kathryn Busch has discovered a blood flow feature that could be measured during following surgery that may be such a warning sign. Brain arteriovenous malformations are a joining of the arteries to the veins in the brain in a network of vessels that carries risk of rupturing, causing disability or death. Professor Michael Morgan found that aggressive blood pressure lowering following surgical removal of the arteriovenous malformation meant that fewer patients had problems following surgery. But some patients still had bleeding events following surgery. There was no way to predict which patients would have these bleeding events. Professor Michael Morgan set Kathryn Busch the task of investigating if a predictor could be found, with the hypothesis that looking at blood flow in the brain vessels might provide an early marker.
A huge challenge, given the low incidence of the condition (limited number of patients to study), and the number of time points and blood vessels to investigate. In this needle in a haystack, Kathryn found that the veins in the brain, which usually have a smooth even blood flow, can become highly pulsatile (periods of low flow and high flow within each beat of the heart). Through the study of these patients with arteriovenous malformation, other brain surgery patients, and extensive use of the literature, Kathryn has put forward a new hypothesis on post-surgery management for brain vascular surgery. Ultrasound tools that allow both visualising the blood vessels, and accurately measuring the blood flow within those vessels, when applied specifically to the veins in the brain, may give information that predicts bleeding events before they happen.
There has been so much work to get to this stage. But more work will be needed before this is integrated as a treatment solution. The journey of discovery of pulsatility in veins in the brain has been a fascinating one, and not one without controversy. There has been robust discussions between surgeons on the presence of this pulsatility, and the meaning and cause of it.
Congratulations to Kathryn Busch for the work that has gone into this project, and pulling it together to form a highly informed PhD thesis. The thesis has just been submitted for examination and will be available to the public later this year. If you would like to see some of the work now, Kathryn has published most of the work in journals:
Busch, K., Kiat, H., Stephen, M., Simons, M., Avolio, A. & Morgan, M. K. Cerebral hemodynamics and the role of transcranial Doppler applications in the assessment and management of cerebral arteriovenous malformations. Journal of Clinical Neuroscience 30, 24–30 (2016).
Busch, K., Kiat, H., Avolio, A., Butlin, M. & Davidson, A. Obstructive hydrocephalus due to an unruptured brain arteriovenous malformation: demonstrating transcranial colour duplex confirmation of cerebral venous hemodynamic alterations and colour duplex ultrasound confirmation of shunt patency. Cureus 11(11), [e6181], (2019).
Busch, K., Davidson, A., Di Ieva, A., Avolio, A., Butlin, M. & Kiat, K. Significant venous flow alterations following brain arteriovenous malformation surgery: assessment by transcranial colour duplex. Journal of Clinical Neuroscience. 99,268-274 (2022).
Busch, K., Chandra, R., Buckenham, T. & Kiat, H. Detection of anomalous cervical internal carotid artery branches by colour duplex ultrasound. European Journal of Vascular and Endovascular Surgery 53, 776–782 (2017).