Quantitative assessment of post-operative recurrence of chronic subdural haematoma using mean haematoma density.

PURPOSE: The purpose of this study was to establish a quantitative method with which to assess the post-operative recurrence of chronic subdural haematoma (CSDH). METHODS: CT scans were reviewed from 44 consecutive patients with CSDHs who underwent burr hole drainage between July 2008 and January 2012. The area of the haematoma was quantified according to the mean haematoma density (MHD) using computer-based image analysis of pre-operative brain CT scans. MHD as well as other variables of patients with and without post-operative recurrences was statistically compared. RESULTS: Post-operative recurrence was noted in six of the 44 patients that underwent surgical procedures. Among these variables, high MHD, separated type and bilateral and skull base involvement of CSDHs were shown to be significantly related to post-operative recurrence (p < 0.05). Controlling for separated type in logistic regression analysis revealed the OR of MHD as statistically significant indicators with a p value of less than 0.05 (OR = 1.243; 95% CI = 1.003-1.54). CONCLUSION: This study provides statistical proof that MHD is a significant, independent, prognostic factor for the post-operative recurrence of CSDH. As such, consideration of MHD could aid in the prediction of post-operative prognosis of CSDHs.

Verifying three-dimensional skull model reconstruction using cranial index of symmetry.

BACKGROUND: Difficulty exists in scalp adaptation for cranioplasty with customized computer-assisted design/manufacturing (CAD/CAM) implant in situations of excessive wound tension and sub-cranioplasty dead space. To solve this clinical problem, the CAD/CAM technique should include algorithms to reconstruct a depressed contour to cover the skull defect. Satisfactory CAM-derived alloplastic implants are based on highly accurate three-dimensional (3-D) CAD modeling. Thus, it is quite important to establish a symmetrically regular CAD/CAM reconstruction prior to depressing the contour. The purpose of this study is to verify the aesthetic outcomes of CAD models with regular contours using cranial index of symmetry (CIS). MATERIALS AND METHODS: From January 2011 to June 2012, decompressive craniectomy (DC) was performed for 15 consecutive patients in our institute. 3-D CAD models of skull defects were reconstructed using commercial software. These models were checked in terms of symmetry by CIS scores. RESULTS: CIS scores of CAD reconstructions were 99.24±0.004% (range 98.47-99.84). CIS scores of these CAD models were statistically significantly greater than 95%, identical to 99.5%, but lower than 99.6% (p<0.001, p = 0.064, p = 0.021 respectively, Wilcoxon matched pairs signed rank test). These data evidenced the highly accurate symmetry of these CAD models with regular contours. CONCLUSIONS: CIS calculation is beneficial to assess aesthetic outcomes of CAD-reconstructed skulls in terms of cranial symmetry. This enables further accurate CAD models and CAM cranial implants with depressed contours, which are essential in patients with difficult scalp adaptation.