The Chiari Severity Index

Abstract

Background To develop evidence-based treatment guidelines for Chiari Malformation Type 1 (CM-1), preoperative prognostic indices capable of stratifying patients for comparative trials are needed. Objective To develop a preoperative Chiari Severity Index (CSI) integrating the clinical and neuroimaging features most predictive of long-term patient-defined improvement in quality of life (QOL) after CM-1 surgery. Methods We recorded preoperative clinical (e.g. headaches, myelopathic symptoms) and neuroimaging (e.g. syrinx size, tonsillar descent) characteristics. Brief follow-up surveys were administered to assess overall patient-defined improvement in QOL. We used sequential sequestration to develop clinical and neuroimaging grading systems and conjunctive consolidation to integrate these indices to form the CSI. We evaluated statistical significance using the Cochran-Armitage test and discrimination using the c-statistic. Results Our sample included 158 patients. Sequential sequestration identified headache characteristics and myelopathic symptoms as the most impactful clinical parameters, producing a clinical grading system with improvement rates ranging from 81% (grade 1) to 58% (grade 3) (p=0.01). Based on sequential sequestration, the neuroimaging grading system included only the presence (55% improvement) or absence (74% improvement) of a syrinx ≥ 6 mm (p=0.049). Integrating the clinical and neuroimaging indices, improvement rates for the CSI ranged from 83% (grade 1) to 45% (grade 3) (p=0.002). The combined CSI had moderately better discrimination (c=0.66) than the clinical (c=0.62) or neuroimaging (c=0.58) systems alone. Conclusion Integrating clinical and neuroimaging characteristics, the CSI is a novel tool that predicts patient-defined improvement following CM-1 surgery. The CSI may aid preoperative counseling and stratify patients in comparative effectiveness trials.

Chiari malformation type 1 presenting as unilateral progressive foot drop: a case report and review of literature

“…Early diagnosis of Chiari malformation type-1 is pivotal as prognosis after the surgery depends on the extent of the neurological deficit prior to the surgery. Our patient is awaiting surgery and has an excellent prognosis [ 6 , 7 ]. In conclusion, this case highlights the importance of considering broad differential diagnosis for foot drop and value of the complete neurological examination including superficial reflexes in arriving at a diagnosis.…”

Resolution of Tonsillar Herniation and Syringomyelia Following Resection of a Large Anterior Frontal Parasagittal Meningioma

“…Specifically, the authors examined the differences in clinical outcomes for patients who underwent SOL resection with or without posterior fossa decompression. Decompression is most commonly done with suboccipital craniectomy and C1 laminectomy [1,9]. In nearly all cases in both surgical groups, as seen in our patient, syringomyelia resolved or improved with resection of the SOL without requiring a syrinx shunt [3].…”

Comparison of posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation type I in adult patients

“…In a study by Wu et al [ 24 ] the severity of the clinical symptoms did not correlate with the degree of cerebellar tonsillar herniation. However, Greenberg et al [ 25 ] developed a preoperative Chiari Severity Index that integrates the clinical and neuroimaging characteristics. This is a novel tool that predicts patient-defined improvement following CM-I surgery, aids in preoperative counseling, and stratifies patients in comparative effectiveness trials.…”