Evaluating the effect of hydrocephalus cause on the manner of changes in the effective parameters and clinical symptoms of the disease.

In the present study, the heads of 11 normal subjects and 21 patients affected by hydrocephalus due to three different causes were simulated using fluid-structure interaction (FSI). To validate the results, the calculated diagram of CSF velocity in aqueduct of Sylvius (AS) was compared with the similar velocity diagram measured using Cine PC-MRI for the same subject. After ensuring the agreement of results, other outputs such as CSF pressure were calculated non-invasively using FSI. The intracranial pressure and CSF pressure in AS and behind the optic nerve sheath were in patients 5-5.3 times the value in normal subjects and the ventricular system volume in patients was 10.2-11.1 times the value in normal subjects. However, the difference between the coefficient of variation and the maximum value of pressure and volume in different types of hydrocephalus was small. Furthermore, the difference between CSF stroke volumes in various types of hydrocephalus patients was less than 4.4%. Results showed that the intensity of clinical symptoms was similar in patients with similar CSF pressure and the cause of the hydrocephalus disease didn't have any significant effect on the intensity of patients' clinical symptoms and the manner of changes in effective parameters on disease. It was also found that the relation of CSF pressure and volume was 16.7% greater in patients with non-communicating hydrocephalus than in patients with communicating hydrocephalus. These results enhance the insight into hydrocephalus bio-mechanism and can help to choose the proper treatment method for hydrocephalus patients.

Effects of lumbar drainage on CSF dynamics in subarachnoid hemorrhage condition: A computational study.

Lumbar drainage is considered a therapeutic measure in treatment of subarachnoid hemorrhage. However, the evidence on the effectiveness of this method is still inconclusive. In this study, a subject-specific three dimensional model of the cerebrospinal fluid (CSF) pathways and compartments was developed. The ventricular and the cranial and spinal subarachnoid spaces were reconstructed using magnetic resonance images. Occurrence of subarachnoid hemorrhage was modeled. Since the presence of blood in the CSF spaces is known to be the cause of complications such as cerebral vasospasm, concentration of blood in these spaces was investigated. Two cases of lumbar drains that were different in the drainage rate were studied. Temporal variations of concentration of blood in CSF spaces were calculated. It was observed that lumbar drainage accelerates the clearance of blood and, thereby, the spasmogens present in the cranial and spinal subarachnoid space. Higher clearance rates were observed at higher drainage rates.

Safety and possible outcome assessment of autologous Schwann cell and bone marrow mesenchymal stromal cell co-transplantation for treatment of patients with chronic spinal cord injury.

BACKGROUND AIMS: Cell replacement therapy has become a promising issue that has raised much hope in the regeneration of central nervous system injury. Evidence indicates that successful functional recovery in patients with spinal cord injury will not simply emphasize a single therapeutic strategy. Therefore, many recent studies have used combination strategies for spinal cord regeneration. METHODS: We assessed the safety and feasibility of a bone marrow mesenchymal stromal cell and Schwann cell combination for the treatment of patients with chronic spinal cord injury. Eight subjects who received a complete traumatic spinal cord injury (American Spinal Injury Association [ASIA] classification A) enrolled in this study. The patients received this autologous combination of cells directly into the injury site. The mean duration of follow-up was approximately 24 months. RESULTS: No magnetic resonance imaging evidence of neoplastic tissue overgrowth, syringomyelia or psuedomeningocele in any of the patients was seen during the study. There was no deterioration in sensory or motor function in any of the patients during the course of the study. Three patients had negligible improvement in ASIA sensory scale. No motor score improvement and no change in ASIA classification was seen. The patients had widely subjective changes in the course of the study such as urination and defecation sensation and more stability and trunk equilibrium in the sitting position. CONCLUSIONS: There were no adverse findings at least 2 years after autologous transplantation of Schwann cell and mesenchymal stromal cell combination into the injured spinal cord. It appears that the use of this combination of cells is safe for clinical application to spinal cord regeneration.

Mathematical modeling of CSF pulsatile hydrodynamics based on fluid-solid interaction.

Intracranial pressure (ICP) is derived from cerebral blood pressure and cerebrospinal fluid (CSF) circulatory dynamics and can be affected in the course of many diseases. Computer analysis of the ICP time pattern plays a crucial role in the diagnosis and treatment of those diseases. This study proposes the application of Linninger et al.'s [IEEE Trans. Biomed. Eng., vol. 52, no. 4, pp. 557-565, Apr. 2005] fluid-solid interaction model of CSF hydrodynamic in ventricular system based on our clinical data from a group of patients with brain parenchyma tumor. The clinical experiments include the arterial blood pressure (ABP), venous blood pressure, and ICP in the subarachnoid space (SAS). These data were used as inputs to the model that predicts the intracranial dynamic phenomena. In addition, the model has been modified by considering CSF pulsatile production rate as the major factor of CSF motion. The approximations of ventricle enlargement, CSF pressure distribution in the ventricular system and CSF velocity magnitude in the aqueduct and foramina were obtained in this study. The observation of reversal flow in the CSF flow pattern due to brain tissue compression is another finding in our investigation. Based on the experimental results, no existence of large transmural pressure differences were found in the brain system. The measured pressure drop in the ventricular system was less than 5 Pa. Moreover, the CSF flow pattern, ICP distribution, and velocity magnitude were in good agreement with the published models and CINE (phase-contrast magnetic resonance imaging) experiments, respectively.

A novel model for biomechanical behavior of human brain in epidural hematoma injuries.

To obtain an appropriate model for the simulation of the biomechanical behavior of brain tissue and the deformation of ventricles, in particular, we have developed a novel computerized plain strain finite element model. For optimum results, a multiple loading solutions approach using various tissue parameters for the simulation of epidural hematoma have been tested. For this purpose, CT-Scan of a patient with traumatic epidural hematoma has been modeled. By changing the tissue parameters (E and nu) and increasing intraventricular pressure gradient, the displacement of similar points in the modeled ventricle was compared with the true values obtained from patient's CT-Scan taken 3 months later after the resolution of hematoma. The magnitudes leading to least errors were determined. Best solutions were obtained with E=11-12 kPa and DeltaP=1.25-1.5 kPa (7.5-9.4 mmHg), which were consistent with the patient's clinical condition. Biomechanical modeling of unilateral displacement loadings, which are the conditions similar to surgical navigation systems, without considering ventricular geometry and their internal pressure resulted in unacceptable results.