title: Cerebrospinal fluid flow impedance is elevated in Type I Chiari malformation.
abstract: Diagnosis of Type I Chiari malformation (CMI) is difficult because the most commonly used diagnostic criterion, cerebellar tonsillar herniation (CTH) greater than 3-5 mm past the foramen magnum, has been found to have little correlation with patient symptom severity. Thus, there is a need to identify new objective measurement(s) to help quantify CMI severity. This study investigated longitudinal impedance (LI) as a parameter to assess CMI in terms of impedance to cerebrospinal fluid motion near the craniovertebral junction. LI was assessed in CMI patients (N = 15) and age-matched healthy controls (N = 8) using computational fluid dynamics based on subject-specific magnetic resonance imaging (MRI) measurements of the cervical spinal subarachnoid space. In addition, CTH was measured for each subject. Mean LI in the CMI group (551 ± 66 dyn/cm5) was significantly higher than in controls (220 ± 17 dyn/cm5, p &lt; 0.001). Mean CTH in the CMI group was 9.0 ± 1.1 mm compared to -0.4 ± 0.5 mm in controls. Regression analysis of LI versus CTH found a weak relationship (R2 = 0.46, p &lt; 0.001), demonstrating that CTH was not a good indicator of the impedance to CSF motion caused by cerebellar herniation. These results showed that CSF flow impedance was elevated in CMI patients and that LI provides different information than a standard CTH measurement. Further research is necessary to determine if LI can be useful in CMI patient diagnosis.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Shaffer
authors.forename: Bryn A
authors.initials: BA
authors.lastname: Martin
authors.forename: Brandon
authors.initials: B
authors.lastname: Rocque
authors.forename: Casey
authors.initials: C
authors.lastname: Madura
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.forename: Bermans J
authors.initials: BJ
authors.lastname: Iskandar
authors.forename: Stephen
authors.initials: S
authors.lastname: Dombrowski
authors.forename: Mark
authors.initials: M
authors.lastname: Luciano
authors.forename: John N
authors.initials: JN
authors.lastname: Oshinski
authors.forename: Francis
authors.initials: F
authors.lastname: Loth
mesh_terms: D000293:Adolescent; D000328:Adult; D001139:Arnold-Chiari Malformation / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology*; D002555:Cerebrospinal Fluid / Q000502:physiology*; D002574:Cervical Vertebrae / Q000503:physiopathology*; D003198:Computer Simulation; D003217:Conductometry / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008365:Manometry / Q000379:methods; D008875:Middle Aged; D008954:Models, Biological; D011312:Pressure; D015203:Reproducibility of Results; D012212:Rheology / Q000379:methods; D012680:Sensitivity and Specificity; D014783:Viscosity; D055815:Young Adult