Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?
OBJECTIVE
Periventricular lucency (PVL) is often observed in the hydrocephalic brain on CT or MRI. Earlier studies have proposed the extravasation of ventricular CSF into the periventricular white matter or transependymal CSF absorption as possible causes of PVL in hydrocephalus. However, there is insufficient evidence for either theory to be conclusive.


METHODS
A finite element (FE) model of the hydrocephalic brain with detailed anatomical geometry was constructed to investigate the possible mechanism of PVL in hydrocephalus. The initiation of hydrocephalus was modeled by applying a transmantle pressure gradient (TPG). The model was exposed to varying TPGs to investigate the effects of different geometrical characteristics on the distribution of PVL. The edema map was derived based on the interstitial pore pressure.


RESULTS
The model simulated the main radiological features of hydrocephalus, i.e., ventriculomegaly and PVL. The degree of PVL, assessed by the pore pressure, was prominent in mild to moderate ventriculomegaly. As the degree of ventriculomegaly exceeded certain values, the pore pressure across the cerebrum became positive, thus inducing the disappearance of PVL.


CONCLUSIONS
The results are in accordance with common clinical findings of PVL. The degree of ventriculomegaly significantly influences the development of PVL, but two factors were not linearly correlated. The results are indicative of the transependymal CSF absorption as a possible cause of PVL, but the extravasation theory cannot be formally rejected.
Departments of 1 Brain and Cognitive Engineering, and.
Hakseung
H
Kim
Biomedical Engineering, Korea University, Seoul, South Korea;
Eun-Jin
EJ
Jeong
Departments of 1 Brain and Cognitive Engineering, and.
Dae-Hyeon
DH
Park
Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, United Kingdom.
Zofia
Z
Czosnyka
Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, California;
Byung C
BC
Yoon
Department of Rehabilitation, Seoul National University Hospital, College of Medicine, Seoul, South Korea; and.
Keewon
K
Kim
Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, United Kingdom.
Marek
M
Czosnyka
Departments of 1 Brain and Cognitive Engineering, and.
Dong-Joo
DJ
Kim
D000328:Adult; D001696:Biomechanical Phenomena; D001921:Brain / Q000473:pathology; D001929:Brain Edema / Q000473:pathology; D002552:Cerebral Ventricles / Q000473:pathology*; D065634:Cerebrospinal Fluid Leak / Q000175:diagnosis*; D003198:Computer Simulation; D004805:Ependyma / Q000378:metabolism; D020342:Finite Element Analysis; D006801:Humans; D006849:Hydrocephalus / Q000473:pathology*; D007427:Intracranial Pressure; D008297:Male; D008953:Models, Anatomic; D066127:White Matter / Q000378:metabolism
FE = finite element; ICP = intracranial pressure; ISF = interstitial fluid; PVL = periventricular lucency; TPG = transmantle pressure gradient; biomechanics; finite element model; hydrocephalus; intracranial pressure; periventricular lucency; transmantle pressure gradient