Clinical and Radiologic Spectrum and Outcomes of Myelopathy Associated with Spinal Cord Displacement: A Single-center Cohort Study
Eoin Flanagan1, Andreu Vilaseca-Jolonch1, Timothy Kaufmann1, William Krauss1, Brian Weinshenker2
1Mayo Clinic, 2University of Virginia Health System
Objective:
To characterize clinical and radiologic features of intrathecal spinal cord displacement and to develop a diagnostic algorithm. To evaluate outcomes, including disability progression and reoperation rates, in this population.
Background:
Myelopathies associated with intrathecal spinal cord displacement are uncommon and frequently misdiagnosed. The most common etiologies are spinal cord herniation (SCH), arachnoid web (AW), and arachnoid cyst (AC). Comparative analyses stratified by etiology and treatment (surgical or non-surgical) remain limited.
Design/Methods:
Retrospective cohort study of adults (≥18 years) evaluated at Mayo Clinic (1996–2017) for myelopathy with imaging evidence of intrathecal spinal cord displacement. Exposures were classified by diagnosis (SCH, AC, or AW) and by surgical intervention, and outcomes included diagnosis confirmed surgically or by MRI features, disability status (Expanded Disability Status Scale [EDSS], ambulatory function), and postoperative worsening.
Results:
Fifty-nine patients were included: 30 AC (50.8%), 15 SCH (25.4%), and 14 AW (23.7%). Logistic regression identified imaging features with high diagnostic accuracy: short C-shaped displacement of the cord, extradural fluid and preserved CSF pulsation in SCH (AUC 0.942); smooth, long cord displacement with disrupted pulsation and CSF plane between dura and the cord in AC (AUC 0.973); and sharp “scalpel-like” deformity of the cord with preserved pulsation in AW (AUC 0.876). Thirty-six patients (61%) underwent surgery. SCH had worse disability nadir (median EDSS 4.0) than AC (2.5) or AW (1.5; p=0.024), and worse long-term recovery (p=0.021). Superficial siderosis was found in 4/9 SCH patients with brain imaging (44%). Postsurgical worsening risk was higher in SCH (HR 3.2; 95% CI 1.2–8.7), independent of age, EDSS, surgical delay, or intramedullary T2 lesions.
Conclusions:
Despite clinical overlap, radiology robustly discriminates AW, AC, and SCH. SCH is associated with higher disability and worse outcomes than AC or AW at surgery and follow-up, likely reflecting diagnostic delay, worse cord pathology and surgical complexity.
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