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

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.

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Posterior Fossa Measurements in Patients With and Without Chiari I Malformation

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s0317167100011860 ◽

2011 ◽

Vol 38 (3) ◽

pp. 452-455 ◽

Cited By ~ 27

Author(s):

John A. Dufton ◽

Syed Yaser Habeeb ◽

Manraj K. S. Heran ◽

David J. Mikulis ◽

Omar Islam

Keyword(s):

Pearson Correlation ◽

Foramen Magnum ◽

Chiari I Malformation ◽

Magnetic Resonance Images ◽

Tonsillar Herniation ◽

Anteroposterior Diameter ◽

Cerebellar Tonsillar Herniation ◽

Study Population ◽

Chiari I ◽

Tonsillar Descent

Purpose:To determine if there is a correlation between cerebellar tonsillar descent in patients with and without Chiari I malformation and three skull morphometric measurements: clivus length, anteroposterior diameter of the foramen magnum, and Boogard's angle.Methods:Cerebellar tonsillar descent, clivus length, anteroposterior diameter of the foramen magnum, and Boogard's angle were measured in mid-sagittal T1-weighted magnetic resonance images of 188 patients. The study included 81 patients with Chiari I malformations (CMI). Without identifiable pathology, 107 patients served as a comparison group. Two-sample t-tests were used to assess for significance. A Pearson correlation matrix was constructed to assess the strength of linear dependence between measured parameters for the study population.Results:A negative correlation was found between tonsillar herniation and clivus length (r = -0.30, P < 0.001), while a positive correlation was found between tonsillar herniation and foramen magnum size (r = 0.15, P = 0.0431), and Boogard's angle (r = 0.23, P = 0.0014). Clivus length was shorter (P = 0.0009) in CMI patients (4.02 cm ± 0.45) than comparison patients (4.23 cm ± 0.42). In addition, the anteroposterior diameter of the foramen magnum was wider (P = 0.0412) (3.74 cm ± 0.40 compared to 3.63 ± 0.30) and Boogard's angle was larger (P = 0.0079) (123.58 degrees ± 8.27 compared to 120.62 degrees ± 6.79) with CMI.Conclusion:A greater degree of cerebellar tonsillar herniation is associated with a shorter clivus length, a wider anteroposterior diameter of foramen magnum, and a wider Boogard's angle.

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Hypothesis on the pathophysiology of syringomyelia based on analysis of phase-contrast magnetic resonance imaging of Chiari-I malformation patients

F1000Research ◽

10.12688/f1000research.72823.1 ◽

2021 ◽

Vol 10 ◽

pp. 996

Author(s):

Han Soo Chang

Keyword(s):

Subarachnoid Space ◽

Phase Contrast ◽

Foramen Magnum ◽

Chiari I Malformation ◽

Cerebellar Tonsil ◽

Active Movement ◽

Theoretical Problem ◽

Velocity Waveform ◽

Mri Scans ◽

Chiari I

Background: Despite a number of hypotheses, our understanding of the pathophysiology of syringomyelia is still limited. The current prevailing hypothesis assumes that the piston-like movement of the cerebellar tonsils drives the cerebrospinal fluid (CSF) into the syrinx through the spinal perivascular space. However, it still needs to be verified by further experimental data. A major unexplained problem is how CSF enters and remains in the syrinx that has a higher pressure than the subarachnoid space. Methods: I analyzed phase-contrast MRI scans of 18 patients with Chiari-I malformation with syringomyelia undergoing foramen magnum decompression and 21 healthy volunteers. I analyzed the velocity waveforms of the CSF and the brain in various locations. The obtained velocity waveforms were post-processed using a technique called synchronization in situ. I compared between the preoperative data and the control data (case-control study), as well as between the preoperative and postoperative data (cohort study). Results: The syrinx shrank in 17 (94%) patients with good clinical improvement. In Chiari-I patients, the velocity of the tonsil was significantly larger than controls, but was significantly smaller than that of the CSF in the subarachnoid space, suggesting passive rather than active movement. The abnormal tonsillar movement disappeared after surgery, but the velocity waveform of the spinal subarachnoid CSF did not change. These results, contradicting the above mentioned hypothesis, required an alternative explanation. I thus hypothesized that there is a CSF channel between the fourth ventricle and the syrinx. This channel assumes one-way valve function when mildly compressed by the cyclical movement of the cerebellar tonsil. The decompression of the tonsils switches off the one-way valve, collapsing the syrinx. Conclusions: My hypothesis reasonably explained my data that clearly contradicted the existing hypothesis, and successfully addressed the above-mentioned theoretical problem. It will serve as a working hypothesis for further study of syringomyelia pathophysiology.

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Cystic Degeneration of Cerebellar Tonsil 1 Year After Chiari I Malformation Surgery: A Case Report and Review of the Literature

World Neurosurgery ◽

10.1016/j.wneu.2019.04.241 ◽

2019 ◽

Vol 128 ◽

pp. 501-505

Author(s):

Firooz Salehpour ◽

Moslem Shakeri ◽

Farhad Mirzaei ◽

Behrooz Shokouhi ◽

Mohammad Kazemzadeh ◽

...

Keyword(s):

Case Report ◽

Chiari I Malformation ◽

Cerebellar Tonsil ◽

Cystic Degeneration ◽

Review Of The Literature ◽

Chiari I

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Obex position is associated with syringomyelia and use of posterior fossa decompression among patients with Chiari I malformation

Journal of Neurosurgery Pediatrics ◽

10.3171/2020.2.peds19486 ◽

2020 ◽

Vol 26 (1) ◽

pp. 45-52

Author(s):

Gabe Haller ◽

Brooke Sadler ◽

Timothy Kuensting ◽

Nivan Lakshman ◽

Jacob K. Greenberg ◽

...

Keyword(s):

Posterior Fossa ◽

Area Under The Curve ◽

Retrospective Chart Review ◽

Severity Index ◽

Basilar Invagination ◽

Foramen Magnum ◽

Chiari I Malformation ◽

Posterior Fossa Decompression ◽

Radiological Measurements ◽

Chiari I

OBJECTIVEChiari I malformation (CM-I) has traditionally been defined by measuring the position of the cerebellar tonsils relative to the foramen magnum. The relationships of tonsillar position to clinical presentation, syringomyelia, scoliosis, and the use of posterior fossa decompression (PFD) surgery have been studied extensively and yielded inconsistent results. Obex position has been proposed as a useful adjunctive descriptor for CM-I and may be associated with clinical disease severity.METHODSA retrospective chart review was performed of 442 CM-I patients with MRI who presented for clinical evaluation between 2003 and 2018. Clinical and radiological variables were measured for all patients, including presence/location of headaches, Chiari Severity Index (CSI) grade, tonsil position, obex position, clival canal angle, pB-C2 distance, occipitalization of the atlas, basilar invagination, syringomyelia, syrinx diameter, scoliosis, and use of PFD. Radiological measurements were then used to predict clinical characteristics using regression and survival analyses, with performing PFD, the presence of a syrinx, and scoliosis as outcome variables.RESULTSAmong the radiological measurements, tonsil position, obex position, and syringomyelia were each independently associated with use of PFD. Together, obex position, tonsil position, and syringomyelia (area under the curve [AUC] 89%) or obex position and tonsil position (AUC 85.4%) were more strongly associated with use of PFD than tonsil position alone (AUC 76%) (Pdiff = 3.4 × 10−6 and 6 × 10−4, respectively) but were only slightly more associated than obex position alone (AUC 82%) (Pdiff = 0.01 and 0.18, respectively). Additionally, obex position was significantly associated with occipital headaches, CSI grade, syringomyelia, and scoliosis, independent of tonsil position. Tonsil position was associated with each of these traits when analyzed alone but did not remain significantly associated with use of PFD when included in multivariate analyses with obex position.CONCLUSIONSCompared with tonsil position alone, obex position is more strongly associated with symptomatic CM-I, as measured by presence of a syrinx, scoliosis, or use of PFD surgery. These results support the role of obex position as a useful radiological measurement to inform the evaluation and potentially the management of CM-I.

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Rapid development of Chiari I malformation in an infant with Seckel syndrome and craniosynostosis

Journal of Neurosurgery ◽

10.3171/jns.2003.98.5.1113 ◽

2003 ◽

Vol 98 (5) ◽

pp. 1113-1115 ◽

Cited By ~ 25

Author(s):

Timothy E. Hopkins ◽

Stephen J. Haines

Keyword(s):

Mr Imaging ◽

Posterior Fossa ◽

Rapid Development ◽

Chiari I Malformation ◽

Tonsillar Herniation ◽

Seckel Syndrome ◽

Content Type ◽

Chiari I ◽

Csf Diversion ◽

Fine Print

✓ To illustrate the rapidity with which a child can develop a severe, symptomatic Chiari I malformation, the authors present the case of a 3-month-old infant with Seckel syndrome (microcephaly, micrognathia, craniosynostosis, and multiple other abnormalities) and posterior sagittal and bilateral lambdoid synostosis. The infant underwent magnetic resonance (MR) imaging shortly after birth; the initial image demonstrated the cerebellar tonsils in the posterior fossa, with no herniation. He subsequently developed severe apneic episodes and bradycardia; repeated MR imaging at 3 months demonstrated severe tonsillar herniation with compression of the brainstem. The child underwent posterior fossa remodeling surgery, including release of the posterior sagittal and lambdoid sutures and decompression of the Chiari I malformation. The patient's apnea gradually improved; however, he died of complications of pneumonia and sepsis several weeks later. The authors identified from the literature 21 patients in whom there was a documented MR image or other neuroimage that did not reveal evidence of a Chiari I malformation, followed by a subsequent study with clear documentation of the presence of Chiari I malformation. The interval between the initial study and the development of the tonsillar herniation ranged from 11 days to 18.5 years. In most cases, a lumbar cerebrospinal fluid (CSF) diversion had been performed. This patient developed a severely symptomatic Chiari I malformation during a 3-month period. These reports illustrate that the Chiari I malformation can develop rapidly in the face of increased intracranial pressure, craniosynostosis, and spinal CSF diversion.

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Resolution of Syringomyelia and Chiari I Malformation by Ventriculoatrial Shunting in a Patient with Pseudotumor Cerebri and a Lumboperitoneal Shunt

Neurosurgery ◽

10.1227/00006123-198804000-00022 ◽

1988 ◽

Vol 22 (4) ◽

pp. 744-747 ◽

Cited By ~ 44

Author(s):

Lawrence P. Sullivan ◽

John C. Stears ◽

Steven P. Ringel

Keyword(s):

Complete Resolution ◽

Pseudotumor Cerebri ◽

Chiari I Malformation ◽

Resonance Imaging ◽

Ventriculoatrial Shunt ◽

Tonsillar Herniation ◽

Arm Pain ◽

Chiari I ◽

Magnetic Resonance Imaging Mri ◽

The Relationship

Abstract A sneeze caused acute left arm pain in a 36-year-old woman with a lumboperitoneal (LP) shunt that had been placed 3 years earlier for relief of headaches caused by pseudotumor cerebri. Numbness progressed up the left arm, neck, and back of the head and finally into the left face along with weakness of the hand and arm. Magnetic resonance imaging (MRI) and computed tomography revealed new tonsillar herniation and a large eccentric syrinx extending from C2 to T6. The functioning LP shunt was clamped, and a ventriculoatrial shunt was placed. Pain lessened and motor function improved slightly. MRI revealed complete resolution of the syrinx and resolution of the tonsillar herniation. Theories of syringomyelia formation, the relationship to Chiari I malformation, and the implications of this case are discussed.

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