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Computational Methodology to Estimate Resistance to Cerebrospinal Fluid Motion in the Spinal Canal for Chiari Patients with Specific and Nonspecific Symptoms

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2019, Master of Science in Engineering, University of Akron, Mechanical Engineering.
Chiari malformation type 1 (CMI) is a structural abnormality of the cerebellum at the craniospinal junction, the part of the brain primarily responsible for motor control. This malformation is radiologically described as a greater than 5 mm caudal displacement of the cerebellar tonsils below the foramen magnum (FM). However, cerebellar tonsillar position (CTP) does not always correlate with symptom severity. The conundrum arises because some individuals who meet the MR imaging criteria are asymptomatic, while individuals with less than 5 mm CTP have CMI symptoms. Hence, researchers have been seeking different measurement parameters to quantify CMI severity. An alternative method to quantify the impact of CTP is longitudinal impedance (LI), a scalar parameter used to quantify impedance or fluid flow blockage per unit length of a conduit such as the spinal canal. In this study we used LI as a parameter to determine the cerebrospinal fluid (CSF) flow blockage at the foramen magnum. CMI patients with different types of symptoms have been shown to have a different percentage change in CSF stroke volume. In this study, 24 symptomatic CMI patients with a mean age of 36 ± 8.8 years and CTP greater than 5 mm were studied. The patients were divided into two groups based on their symptom severity [ i.e. specific symptoms (S-CMI) and nonspecific symptoms (NS-CMI)] by neurosurgeons blinded to their magnetic resonance (MR) images prior to the study. The cervical spine of each patient was imaged with 3D T2- weighted MR imaging on a 3T scanner. The inner and outer boundaries of cervical spinal subarachnoid space between the FM and 60 mm caudal to the FM were segmented. The boundaries were smoothed and reconstructed, and both ends (FM & caudal end) of the 3D model were extruded 40 mm to allow the flow to be nearly fully developed inside the model. An unstructured tetrahedral mesh was created for computational fluid dynamics simulations. Finite volume solver software Fluent was utilized to run the fluid simulations, modelling CSF as water at 37 °C, 1.0 g/cm3, and µ = 0.001 P. LI was calculated by dividing the Fourier coefficients of pressure drop between the FM and a plane 25 mm in the caudal direction by Fourier coefficients of volume flow rate. Next, LI was integrated between one to eight Hz to get a characteristic value to compare each case. Statistical significance was evaluated as p < 0.05. Statistical analysis revealed a significant difference between mean LI for S-CMI and NS-CMI patients. The mean average values of S-CMI patients was 1.5 times larger than NS-CMI patients (816 ± 630 and 322 ± 155, p = 0.016 respectively). Finally, this thesis showed the use of computational simulations to estimate the CSF flow dynamics in the spinal canal. LI was shown to be a useful methodology to estimate the resistance of CSF flow in the spinal canal of Chiari patients with different symptomology. This technique may have the potential to quantify the CMI symptom severity and assist surgical planning for CMI patients. However, a larger study is required.
Francis Loth, PhD (Advisor)
Alex Povitsky, PhD (Committee Member)
Rouzbeh Amini, PhD (Committee Member)
150 p.

Recommended Citations

Citations

  • IBRAHIMY, A. (2019). Computational Methodology to Estimate Resistance to Cerebrospinal Fluid Motion in the Spinal Canal for Chiari Patients with Specific and Nonspecific Symptoms [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1574449883152461

    APA Style (7th edition)

  • IBRAHIMY, ALAADDIN. Computational Methodology to Estimate Resistance to Cerebrospinal Fluid Motion in the Spinal Canal for Chiari Patients with Specific and Nonspecific Symptoms. 2019. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1574449883152461.

    MLA Style (8th edition)

  • IBRAHIMY, ALAADDIN. "Computational Methodology to Estimate Resistance to Cerebrospinal Fluid Motion in the Spinal Canal for Chiari Patients with Specific and Nonspecific Symptoms." Master's thesis, University of Akron, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1574449883152461

    Chicago Manual of Style (17th edition)