Ogden type of hyperelastic constitutive law has recently emerged in modeling ventricular enlargement in hydrocephalic brain with finite element method, but this material property for brain tissue has not been investigated in a patient-specific setting in hydrocephalus. Consequently, the accuracy of the simulated ventricular enlargement using this hyperelastic tissue property remains unknown. In this study, we evaluated this brain material model in four patients with communicating hydrocephalus under a small trans-mantle pressure difference (TPMD) between brain ventricle and subarachnoid space (<1mmHg). Based upon changes in ventricular geometries obtained with sequential MRI, we found that this hyper-elastic model has a great flexibility and accuracy in modeling ventricular enlargement (with errors less than 1mm). Our study supports the utility of this hyperelastic constitutive law for future hydrocephalus modeling and suggests that the observed ventricular enlargement in these patients may be caused by a slight increase in TMPD.