Diagnosis of Patients With Chiari Malformation

Publication Date: August 31, 2023
Last Updated: September 29, 2023

Summary of Recommendations

In patients with CIM diagnosed only with brain or cervical spine MRI, further imaging of the brain and spine may be helpful to evaluate for clinically relevant pathology such as hydrocephalus or spine syrinx. (C)

In patients with CIM, advanced imaging modalities such as Cine MRI may or may not predict benefit from surgical decompression. (C)

In patients with CIM, measurement of the clivoaxial angle, pB-C2, or C- C2 sagittal vertebral alignment (C-C2SVA) may predict future craniocervical instability and the need for surgical stabilization. ()

There is insufficient evidence to support the use of flexion-extension films to predict future craniocervical instability in this population. (Insufficient)

Recommendation Grading


  • CCOS: Chicago Chiari Outcome Scale
  • CIM: Chiari I Malformation
  • CSF: Cerebrospinal Fluid
  • IONM: Intraoperative Neuromonitoring
  • MRI: Magnetic Resonance Imaging
  • PFD: Posterior Fossa Decompression
  • PFDD: Posterior Fossa Decompression With Duraplasty
  • SDB: Sleep-disordered Breathing
  • SSEPs: Somatosensory Evoked Potentials


The information in this patient summary should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.



Patients With Chiari Malformation: Diagnosis

Authoring Organization

Publication Month/Year

August 31, 2023

Last Updated Month/Year

November 6, 2023

Document Type


Country of Publication


Document Objectives

Chiari I malformation (CIM) is characterized by descent of the cerebellar tonsils through the foramen magnum, potentially causing symptoms from compression or obstruction of the flow of cerebrospinal fluid. Diagnosis and treatment of CIM is varied, and guidelines produced through systematic review may be helpful for clinicians.

Target Patient Population

All patients with Chiari Malformation

Target Provider Population

Neurologists, neurosurgeons, and other allied clinicians treating adults and children with Chiari Malformation

Inclusion Criteria

Male, Female, Adolescent, Adult, Child, Infant, Older adult

Health Care Settings

Ambulatory, Outpatient

Intended Users

Nurse, nurse practitioner, physician, physician assistant


Diagnosis, Assessment and screening

Diseases/Conditions (MeSH)

D001139 - Arnold-Chiari Malformation


Chiari Malformation, Chiari I Malformation

Source Citation

Bauer DF, Niazi T, Qaiser R, Infinger LK, Vachhrajani S, Ackerman LL, Jackson EM, Jernigan S, Maher CO, Pattisapu JV, Quinsey C, Raskin JS, Rocque BG, Silberstein H. Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Patients With Chiari Malformation: Diagnosis. Neurosurgery. 2023 Oct 1;93(4):723-726. doi: 10.1227/neu.0000000000002633. Epub 2023 Aug 30. PMID: 37646512.