Clinical, Hydrodynamic And Prospective Study Of ETV In The Treatment Of Chiari Type I Malformation Complicated With Hydrocephalus

Part ?: Endoscopic Third Ventriculostomy for Chiari I Malformation and Associated Hydrocephalus: Primary Experience and Literature ReviewObjective: This retrospective study was conducted to analyze the clinical outcome and radiological changes of Chiari type I malformation(CIM)and associated hydrocephalus after endoscopic third ventriculostomy(ETV)to identify its efficacy.Method: The data were collected from the medical records between July 2013 and July 2018 and from the published literature on remedying the Chiari I malformation and associated hydrocephalus with ETV.Postoperative symptoms and radiological outcome,according to Evan's index(EI),transverse diameter of the third ventricle,sagittal diameter of the fourth ventricle,extent of tonsillar herniation and syrinx,were recorded.Results: Our primary eleven patients experienced improvements of symptoms after ETV,especially the conditions of hydrocephalus.Ventricular dilatation and tonsillar hernia had been reduced by the time of the last imaging examination(p<0.05).Only one patient required posterior fossa decompression due to persisting CIM symptoms.The results of the literature review were similar to those of our experience.Conclusion: ETV is proved to be a superior treatment for hydrocephalus associated with CIM.Part ?: Endoscopic Third Ventriculostomy for Treatment of Chiari I Malformation and Hydrocephalus: A Hydrodynamics ModelObjective: To show how ETV treatment may lead to recovery of herniated tonsil in patients with CIM and associated hydrocephalus.Methods: A hydrodynamics model of CIM and hydrocephalus was then developed to simulate the procedure.Anatomy magnetic resonance images(MRI)of the mid-sagittal segmentation of a CIM and hydrocephalus patient were obtained to reconstruct flow fields.The Foramen of Monro was prescribed as the inlet boundary,with ETV was modeled as a 6 mm diameter hole in the anterior wall of the third ventricle.Results: The simulation showed that ETV changes the characteristics of CSF hydrodynamics,especially around the cranio-cervical junction.Further theoretical analysis revealed that intracranial pressure redistributed after the procedure,as a result of hydrodynamics changes.Pressure difference around cranio-cervical junction reduced from 13 Pa preoperatively to 0 Pa postoperatively.Considering the cerebellar tissue as hyperelastic material in Mooney-Rivlin model,a 0.5mm quasistatic deformation caused by pressure changes occurs in cerebellar tonsil after ETV,which validated the hypothesis.Conclusion: We developed a hydrodynamics model of endoscopic third ventriculostomy for treatment of Chiari I malformation and hydrocephalus.The simulation revealed quasi-static velocity and pressure redistribution during perioperative time in ETV procedure.Then hypothesis that considering cerebellar tonsil as ‘hyperelastic plug' obstructed at foramina magnum plane may provide an explanation how herniation relived after this procedure.Part ?: Endoscopic Third Ventriculostomy for Treatment of Chiari I Malformation and Hydrocephalus: A Prospective ResearchObjective: This study further explored the CSF hydrodynamic characteristics of Chiari I malformation with hydrocephalus with time-resolved three-dimensional magnetic resonance velocity imaging(4D flow MRI),and observed the clinical therapeutic effect of ETV on CIM with hydrocephalus,and the effect of ETV on CSF hydrodynamics.Methods: The study was designed as a multi-center,single-group and observational test.The subjects were patients who were treated in neurosurgery of Eastern Theater General Hospital after March 2019 due to Chiari I deformity and hydrocephalus.Patients were screened according to the inclusion and exclusion criteria,the selected patients were routinely examined by imaging and 4 D flow MRI.Results: A total of 7 eligible patients were included,of which 4 were male and 3were female,with an average age of 37 years and an average hospital stay of 20.6days.Six patients developed headache symptoms,three patients developed limb numbness,two patients developed decreased upper limb muscle strength,and one patient developed neck discomfort.The corresponding symptoms of patients with headache improved significantly before discharge,and other symptoms improved to varying degrees.Imaging improvement is basically the same as retrospective analysis of cases in Part I.4D flow MR suggest complex and uneven CSF flow signals from the cisterna interpeduncularis to the ventral brainstem and to the ventral side of the spinal cord in the sagittal position.The CSF flow above the foramen magnum plane is still complicated after ETV procedure.But after entering the spinal canal,it is obvious that the complexity of CSF flow decreases.CSF flow velocity is also inhomogeneous in the foramen magnum plane,and the flow is mainly obvious in the anterolateral side of both sides,and the velocities there are higher.After ETV surgery,weak cerebrospinal fluid flow signals can be seen at the outlet of the fourth ventricle.At the lower edge of the tonsil,the CSF distribution was also superior at the anterolateral sides.Bilateral CSF flow signals are missing due to neural structure.The cerebrospinal fluid flow velocity in the ventral SAS of the spinal cord decreased significantly after ETV operation.Quantitative analysis showed that the flow through the foramen magnum plane and c1 plane decreased.Conclusion: The results of this study further verified the efficacy of ETV in the treatment of Chiari I malformation with hydrocephalus.4D flow MRI techniques can visualize and quantify CSF flow and better understand the hydrodynamic alteration characteristics CSF in patients with CIM and hydrocephalus.