Abnormality of the Central Canal of the Spinal Cord in Syringomyelia in a Patient With a Basal Skull Malformation (SYRCANAL)

The aim of this study is to analyze the association between a deformity of the cranial portion of the central spinal canal and syringomyelia in patients with a Chiari-type malformation of the craniocervical junction.

The investigators hypothesize that Chiari malformation, defined by the herniation of the cerebellar tonsils through the foramen magnum, may be responsible for a deformation of the cranial portion of the central spinal canal, and that this deformation is associated with the presence of syringomyelia in patients with this malformation.

Study Overview

• Status: Not yet recruiting
• Conditions: Syringomyelia; Chiari Malformation Type I
• Intervention / Treatment: Procedure: MRI

Detailed Description

Chiari Malformation Type I (CM-I) is a congenital anomaly characterized by downward displacement of the cerebellar tonsils through the foramen magnum, which may disrupt cerebrospinal fluid (CSF) circulation at the craniovertebral junction. The condition generally results from underdevelopment of the posterior cranial fossa, leading to insufficient space for the cerebellum. This anatomical abnormality can cause a wide range of heterogeneous symptoms, including occipital headaches triggered by coughing or exertion, neck pain, dizziness, balance disturbances, paresthesia, limb weakness, and swallowing difficulties.

One of the most concerning complications is syringomyelia/hydromyelia, which corresponds to the development of fluid-filled cavities within the spinal cord. These cavities may either be adjacent to the central canal (syringomyelia) or result from dilation of the central canal itself (hydromyelia). Associated spinal cord involvement may lead to specific neurological symptoms and is often a major indication for surgical treatment of Chiari malformation.

The decision to perform surgical decompression of the craniovertebral junction must balance the potential benefits against the associated risks. Furthermore, surgical outcomes remain variable and sometimes uncertain. Some symptoms may persist despite surgery, and syringomyelia regression is inconsistent. A better understanding of the pathophysiology of syringomyelia associated with Chiari malformation is therefore essential to improve patient selection and optimize surgical strategies.

Although the pathophysiology of syringomyelia in Chiari malformation has been investigated in several studies, it remains only partially understood. Recently, the position of the obex has been suggested to be associated with the presence of syringomyelia in patients with Chiari malformation. The obex is the neurological structure located at the cranial end of the central canal. Based on previous findings, investigators hypothesize that a low-lying obex may induce deformation of the central canal, creating a folding or kinking effect that could explain downstream canal dilation. Our primary hypothesis is therefore that the morphology of the central canal at the cervicomedullary junction (including angulation, folding, or compression) is a key factor influencing the presence or absence of associated hydromyelia/syringomyelia and, consequently, clinical severity.

Animal studies support a pathophysiological cascade involving initial mechanical deformation of the central canal followed by pericanal inflammation contributing to syringomyelia formation. According to this novel hypothesis, cerebellar tonsillar descent without associated central canal deformation would confer a lower risk of syringomyelia and unfavorable clinical progression than cases involving deformation of the cranial portion of the central canal.

In vivo visualization and morphological assessment of the cranial portion of the ependymal central canal using MRI therefore offer the potential to identify new risk markers for Chiari malformation that may ultimately assist surgical decision-making. However, when the canal is not dilated, visualization remains challenging, as does the identification of potential pericanal inflammation.

Several years ago, Tourdias et al. developed a specific MRI sequence known as White Matter-nulled (WMn) MPRAGE, which enhances contrast between structures of the central nervous system, including the thalamus, thereby improving the accuracy of thalamic assessment in pathological conditions. More recently, this group demonstrated that the WMn-MPRAGE sequence can be adapted for spinal cord imaging, maximizing the detection of spinal cord lesions. In collaboration with the Anatomy Laboratory of the University of Bordeaux, it was demonstrated that WMn-MPRAGE enables reliable visualization of the spinal cord central canal in healthy subjects when compared with previous anatomical specimen studies. Furthermore, recent advances in spinal cord diffusion MRI, particularly through artificial intelligence-based denoising methods, now enable detailed assessment of spinal cord microstructure and may allow quantification of biomarkers associated with pericanal inflammation.

Thus, the pathophysiology of Chiari Malformation Type I remains incompletely understood. Investigators hypothesize that analysis of the morphology of the cranial portion of the ependymal central canal using WMn-MPRAGE imaging, combined with assessment of the adjacent spinal cord microstructure, may provide novel biomarkers of associated syringomyelia risk and clinical severity.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Jean-Rodolphe VIGNES, Pr; Phone Number: +33 05 57 95 54 43; Email: jean-rodolphe.vignes@chu-bordeaux.fr
• Study Contact Backup: Name: Paul ROBLOT, Dr; Phone Number: +33 05 56 79 55 43; Email: paul.roblot@chu-bordeaux.fr

Study Locations

• France
  • Bordeaux, France
    • Bordeaux University Hospital
    • Contact: Jean-Rodolphe VIGNES, PR; Phone Number: +33 05 56 79 55 43; Email: jean-rodolphe.vignes@chu-bordeaux.fr
    • Principal Investigator: Jean-Rodolphe VIGNES, Pr
    • Sub-Investigator: Paul ROBLOT, Dr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adult patients being treated for Chiari malformation or syringomyelia at Bordeaux University Hospital
• Patients admitted for an initial surgical consultation regarding Chiari malformation with or without syringomyelia at Bordeaux University Hospital
• Individuals enrolled in or covered by a social security program.
• Free, informed, and express consent (confirmed in writing) (no later than the day of enrollment and prior to any examination required by the study).

Exclusion Criteria:

• Pregnant or breastfeeding patients
• Contraindications to MRI
• Individuals deprived of their liberty by judicial or administrative order,
• Adults subject to legal protective measures (guardianship, conservatorship, judicial protection).
• Patients who have previously undergone surgery for a Chiari malformation or a posterior fossa malformation

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Patients with Chiari malformation with associated syringomyelia	Procedure: MRI; Magnetic Resonance Imaging (MRI) using T1, T2, White-Matter nulled (WMn), and diffusion sequences
Experimental: Patients with Chiari malformation without associated syringomyelia	Procedure: MRI; Magnetic Resonance Imaging (MRI) using T1, T2, White-Matter nulled (WMn), and diffusion sequences

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Deformation of the central canal of the spinal cord	The central canal deformation index of the spinal cord, calculated based on the angle of the curves and the length of each segment between two curves.	At inclusion (D0)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Protrusion of the cerebellar tonsils	Protrusion of the cerebellar tonsils into the foramen magnum on T2-weighted MRI. Commonly accepted definition of Chiari malformation Type I: cerebellar tonsils extending more than 5 mm below the McRae line on MRI. The McRae line is defined as the anatomical line connecting the basion and the opisthion, corresponding to the anterior and posterior margins of the foramen magnum.	at inclusion (day 0)
Presence and dimensions of syringomyelia	The presence and dimensions of syringomyelia on MRI using T2 and WMn-MPRAGE sequences	At inclusion (day 0)
Distance between the obex and the foramen magnum	Distance between the obex and the foramen magnum on T2-weighted and WMn-MPRAGE MRI sequences	At inclusion (Day 0)
Diffusion MRI parameter (1)	Diffusion MRI parameter (mean diffusivity) in the pericanalicular region	At inclusion (Day 0)
Diffusion MRI parameter (2)	Diffusion MRI (anisotropy fraction) in the pericanalicular region	At inclusion (Day 0)

Collaborators and Investigators

• Sponsor: University Hospital, Bordeaux
• Collaborators: University of Bordeaux

Study record dates

Study Major Dates

• Study Start (Estimated): September 30, 2026
• Primary Completion (Estimated): September 30, 2029
• Study Completion (Estimated): September 30, 2029

Study Registration Dates

• First Submitted: June 8, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: MR; spinal cord; syringomyelia; Chiari malformation; central canal
• Additional Relevant MeSH Terms: Central Nervous System Diseases; Nervous System Diseases; Congenital Abnormalities; Spinal Cord Diseases; Nervous System Malformations; Neural Tube Defects; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Syringomyelia; Arnold-Chiari Malformation
• Other Study ID Numbers: CHUBX 2026/003

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No