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Transcalvarial brain herniation volume after decompressive craniectomy is the difference between two spherical caps
Chun-Chih Liao1, Yi-Hsin Tsai2, Yi-Long Chen3
1Institute of Biomedical Engineering, National Taiwan University, No.1, Sec.1, Ren'ai Rd., Taipei City 10051, Taiwan; Department of Neurosurgery, Taipei Hospital,Ministry of Health and Welfare, No.127, Siyuan Rd., New Taipei City 24213, Taiwan.
Medical Hypotheses
|January 14, 2015
Summary
This study introduces a new method to calculate transcalvarial herniation volume after decompressive craniectomy, aiding in better patient monitoring and surgical outcome comparisons.
Area of Science:
- Neurosurgery
- Biomechanical Engineering
- Medical Imaging
Background:
- Decompressive craniectomy (DC) is crucial for managing increased intracranial pressure (ICP).
- Transcalvarial herniation (TCH) is a common consequence of DC, where the brain protrudes through the skull defect.
- Current monitoring primarily focuses on ICP, neglecting intracranial volume (ICV) changes like TCH volume (V(TCH)).
Purpose of the Study:
- To develop a mathematical model for estimating V(TCH) following DC.
- To propose a simplified formula for rapid V(TCH) calculation.
- To enable quantitative volumetric comparisons of TCH and ICV.
Main Methods:
- Modeled the brain hemispheres as a sphere and TCH as a spherical cap.
- Derived V(TCH) based on the radius of the circular skull defect ('a') and height difference (Δh).
- Developed simplified estimation formulas for circular (Vˆ(TCH)=1/2A(2)Δh) and elliptical defects (Vˆ(TCH)=1/2ACΔh).
Main Results:
- The maximum estimated V(TCH) was 365.0 mL with specific 'a' and Δh values.
- The simplified formula showed a ratio between 0.77 and 1.27 compared to the calculated V(TCH) for 'a' between 0 and 7 cm.
- The formula was adapted for elliptical defects.
Conclusions:
- The proposed model and formulas allow for accurate V(TCH) calculation after DC.
- This facilitates volumetric comparisons between different DC procedures and skull sizes.
- Enables quantitative ICV assessment alongside ICP monitoring.
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