Hello colleagues, I hope everyone is doing well and keeping safe. I'm John, a fourth year medical student from the National University of Singapore and it is my pleasure to share with you the findings of our study on the proposed prognostic scoring system for bilateral chronic subdural hematoma. I have no conflicts of interest to disclose. Chronic subdural hematoma is a bread and butter condition in neurosurgery and it affects mainly the elderly. As the world population is ageing, incidence of CSDH is expected to rise. Up to 35% of the time, CSDH occurs bilaterally. However, current management of bilateral CSDH remains controversial. Let's take a look at these two patients. The first patient is an elderly gentleman who presents after a fall with a headache and altered mental state. CT imaging shows large bilateral CSDH with significant mass effect on the underlying cerebral hemispheres. Patient 2 has the same set of clinical history and symptoms. However, CT scan shows that the left CSDH is significantly larger than the right side. Evidently, most of the mass effect is from the left CSDH as shown by the large degree of midline shift. Will your management be the same? In current practice, bilateral CSDH is evacuated unilaterally when the contralateral side is small and asymptomatic. However, this decision is not based on objective, evidence-based guidelines but rather on the surgeon's experience. This has a few issues. First, in patients with unilateral evacuation, re-operation rates for the contralateral side can go up to as high as 20%. Second, a recent nationwide multicenter study in Denmark found that unilateral evacuation had higher re-operation rates than bilateral evacuation. Therefore, we aimed to compare the outcomes of unilateral and bilateral evacuation for bilateral CSDH patients as well as to propose a scoring system to pre-operatively assess the risk of re-operation for contralateral CSDH growth in patients undergoing unilateral drainage. This is a multicenter cohort study using a database from a previous study that we just published recently. Data were collected from three tertiary hospitals in Singapore across an 8-year period. All consecutive CSDH patients 21 years and older were included in this database. For this current study, we looked only at those with bilateral CSDH. A total of 621 consecutive CSDH patients were reviewed retrospectively. 240 had bilateral CSDH and were included in our study. 98 patients had unilateral drainage. These are the baseline characteristics of patients within the unilateral and bilateral evacuation groups. Most are fairly comparable at baseline. The only differences were that for bilateral evacuation patients, there was a smaller amount of midline shift and a larger width of the smaller hematoma, which is what we would expect. In terms of post-operative outcomes, we compared re-operation rate, 6-month modified Rankine scale, 30-day mortality, post-operative infection, and length of stay between unilateral and bilateral evacuation groups. No significant difference was found in any of these measured outcomes after adjusting for craniotomy versus burr-hole cases. Moving on, we used this subgroup of 98 patients who had unilateral drainage to develop a pronostic scoring system to assess the risk of re-operation for contralateral CSDH growth. We grouped our outcomes into unfavorable and favorable outcomes, with all outcomes defined as occurring within 6 months of the initial surgery. Unfavorable outcomes were used to identify bad pronostic factors, and these were the two unfavorable outcomes we used. First, re-operation for contralateral CSDH, and second, growth of contralateral CSDH with or without re-operation. For both of these outcomes, pre-operative use of anticoagulants was the only significant predictor. All risk factors were identified with multivariable logistic regression with selection of the multivariable model using backward elimination. The favorable outcome we looked at was complete spontaneous resolution of the non-evacuated CSDH. We found on multivariable analysis that the pre-operative maximum axial width of the non-evacuated CSDH was the only significant predictor. Looking further at the predictive value of this pre-operative maximum width, we plotted the ROC curve and found that a cut-off value of 9 mm produced a sensitivity of 73.2% and a specificity of 54.4%. We found using logistic regression that patients with pre-operative maximum axial width of 9 mm or less were 4 times as likely to have complete resolution of the contralateral CSDH. Therefore, using these factors, we proposed the Singapore Risk of Contralateral Surgery score or Singapore RCSS. This score comprises pre-operative use of anticoagulants and maximum axial thickness on CT imaging. Points were allocated based on the strength of association of each factor as demonstrated by the odds ratios. Patients were then classified into four risk categories. Using this proposed risk score, we performed internal validation on our series of patients. We found that with each increase of 1 in the risk level, patients were 4 times as likely to undergo a re-operation for contralateral CSDH growth. There are certain caveats to our proposed scoring system. First, the score has only been internally validated in our cohort of 98 local patients, hence we do not know if it produces similar results in different populations with different methods of CSDH evacuation. Second, this is a retrospective study and the indication for contralateral re-operation was subjective, taking into account clinical symptoms and signs as well as mass effect of the hematoma. Finally, the prognostic score does not give an absolute recommendation for or against surgery, but instead serves as an adjunct to clinical decision making. On the other hand, the strengths of our study are that we are the first to propose a comprehensive risk score to address this clinical quandary. We are also the first to report the use of anticoagulants as a risk factor for re-operation of contralateral CSDH. Lastly, our score uses routinely assessed variables, hence it can be easily applied to everyday clinical practice. In conclusion, unilateral evacuation of bilateral CSDH can be as effective as bilateral evacuation, but patients should be carefully selected and followed up. The Singapore RCSS may be used as an adjunct for clinical decision making in the management of bilateral CSDH patients, bearing in mind the limitations with which it has been developed. Further external validation of the Singapore RCSS will be helpful in clarifying our findings. I would like to thank my mentor and principal investigator of this study, Professor Vincent Ng from the National University Hospital of Singapore, who has given me tremendous guidance on this study. I would also like to thank the other members of the study team as well as the neurosurgery divisions of the participating institutions. Thank you all for your time in listening to my presentation and I wish you all the best and stay safe.

prognostic scoring system

bilateral chronic subdural hematoma

unilateral and bilateral evacuation

Singapore Risk of Contralateral Surgery score

clinical decision making