Diagnostic utility of parasagittal measurements of tonsillar herniation in Chiari I malformation

Abstract

Background and purpose Although the cerebellar tonsils are parasagittal structures, the extent of tonsillar herniation (ETH) in Chiari I malformation (CMI) is currently measured in the midsagittal plane. We measured the ETH of each cerebellar tonsil in the parasagittal plane and assessed their diagnostic utility by comparing them to the midsagittal ETH measurements in predicting cough-associated headache (CAH), an indicator of clinically significant disease in CMI. Methods Eighty-five CMI patients with 3D-MPRAGE images were included. Neurosurgeons determined the presence of CAH. Sagittal images were used to measure ETH in the midsagittal (MS_ETH) and parasagittal planes (by locating tonsillar tips on each side on reformatted coronal images). Given the parasagittal ETH (PS_ETH) asymmetry in the majority of cases, they were considered Smaller_PS_ETH or Larger_PS_ETH. The accuracy of ETH measurements was assessed by the receiver operating characteristic (ROC) curve. Results Of 85 patients, 46 reported CAH. ROC analysis showed an area under the curve (AUC) of 0.78 for Smaller_PS_ETH significantly better than 0.65 for MS-ETH in predicting CAH ( p = 0.001). An AUC of 0.68 for Larger_PS_ETH was not significantly different from MS_ETH. The sensitivity and specificity of predicting CAH were 87% and 28% for MS_ETH >6 mm versus 90% and 46% for Smaller_PS_ETH >6 mm, and 52% and 67% for MS_ETH >9 mm versus 48% and 87% for Smaller_PS_ETH >9 mm. At ETH >15 mm, no differences were seen between the measurements. Conclusions Diagnostic utility of ETH measurements in detecting clinically significant CMI can be improved by parasagittal measurements of the cerebellar tonsillar herniation.

The importance of precise plane selection for female adult Chiari Type I malformation midsagittal morphometrics

“…A recent study conducted measurements of tonsillar position in two parasagittal planes on each side of the brain by locating the tonsillar tips on the coronal plane [ 2 ]. Ebrahimzadeh et al assessed diagnostic utility by comparing parasagittal plane measurements to the midsagittal measurements in the prediction of cough-associated headache.…”

“…Chiari malformation type I (CMI) is a neurological condition characterized by cerebellar tonsils that extend below the foramen magnum at the base of the skull. CMI patients experience a range of symptoms, including headaches, retro-orbital pain, ocular disturbances, cough-associated headache, neck pain, cognitive dysfunction, depression, anxiety, balance problems, and numbness [1][2][3][4][5]. The current diagnosis process utilizes imaging of the cerebellar tonsils, patient-reported symptoms, and neurological signs.…”

“…The current diagnosis process utilizes imaging of the cerebellar tonsils, patient-reported symptoms, and neurological signs. One area of CMI research involves morphometric measurements evaluated on structural magnetic resonance images (MRI) [2,4,[6][7][8][9][10]. Eppelheimer et al illustrated the significance of morphometric measurements to identify prevalent conditions related to CMI morphometrics [8].…”