Research Findings

2025.04.01

Long-Term Clinical Landscapes of Spinal Hypertrophic Pachymeningitis With Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis

Neurology. 2025 Apr 22;104(8):e213420. doi: 10.1212/WNL.0000000000213420. Epub 2025 Mar 19.

Nakajima A1, Hokari M1, Yanagimura F1,2, Saji E1,3, Shimizu H4, Toyoshima Y4,5, Yanagawa K1, Arakawa M1,6, Yokoseki A1,7, Wakasugi T1,8, Okamoto K9, Watanabe K10,11, Minato K10, Otsu Y1, Nozawa Y12, Kobayashi D12, Sanpei K13, Kikuchi H14, Hirohata S15,16, Awamori K17, Nawata A18, Yamada M19, Takahashi H4,20, Nishizawa M1,21, Igarashi H22, Sato N23,24, Kakita A4, Onodera O1, Kawachi I1,24.

  1. Department of Neurology, Brain Research Institute, Niigata University.
  2. Department of Neurology, NHO Niigata National Hospital.
  3. Department of Neurology, Niigata City General Hospital.
  4. Department of Pathology, Brain Research Institute, Niigata University.
  5. Department of Neurology, Brain Disease Center, Agano Hospital.
  6. Musashi Clinic.
  7. Department of Neurology, Niigata Medical Center.
  8. Department of Neurology, NHO Nishiniigata Chuo Hospital.
  9. Department of Neurosurgery, Brain Research Institute, Niigata University.
  10. Department of Orthopaedic Surgery, Niigata University Medical and Dental Hospital.
  11. Niigata Spine Surgery Center, Kameda Daiichi Hospital.
  12. Division of Clinical Nephrology and Rheumatology, Graduate School of Medical and Dental Sciences, Niigata University.
  13. Department of Neurology, Sado General Hospital.
  14. Department of Internal Medicine, Teikyo University School of Medicine.
  15. Department of Rheumatology, Nobuhara Hospital.
  16. Department of Rheumatology and Infectious Diseases, Kitasato University School of Medicine.
  17. Department of Neurology, Kaetsu Hospital.
  18. Department of Pathology and Oncology, School of Medicine, University of Occupational and Environmental Health.
  19. Department of Brain Disease Research, Shinshu University School of Medicine.
  20. Department of Pathology and Laboratory Medicine, Niigata Neurosurgical Hospital.
  21. Niigata University of Health and Welfare.
  22. Center for Integrated Human Brain Science, Brain Research Institute, Niigata University.
  23. Division of Anatomy, Graduate School of Medical and Dental Sciences, Niigata University.
  24. Medical Education Center, Graduate School of Medical and Dental Sciences, Niigata University.

Background and objectives

Spinal hypertrophic pachymeningitis (HP) is an extremely rare disorder characterized by the thickening of the spinal dura mater, which harbors distinct repertoires of immune cells due to the unique partitioning of the arachnoid blood-CSF barrier. The objectives were to identify the pathogenesis and therapeutic strategies for spinal HP.

Methods

This retrospective cohort study analyzed the clinical and pathologic profiles of patients with idiopathic/immune-mediated HP including spinal HP.

Results

Among 61 patients with idiopathic/immune-mediated HP, all 6 Japanese patients with spinal HP, with a median observation period of 88.8 months, were myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA)-seropositive. The MPO-ANCA+ spinal HP cohort had the following characteristics: (1) a predominance of older women; (2) all patients were classified as having microscopic polyangiitis based on the 2022 American College of Rheumatology/European League Against Rheumatism criteria; (3) 83% of patients developed subacute/chronic myelopathy due to extramedullary spinal cord compression; (4) 50% of patients had lesion extension to the epidural compartment and vertebral column; (5) 50% of patients presented with chronic sinusitis, otitis media, or mastoiditis; (6) 33% of patients had involvement of the lower airways or kidneys; (7) a higher disease activity of the nervous system was noted based on the Birmingham Vasculitis Activity Score (BVAS), in contrast to MPO-ANCA+ cranial HP; (8) granulomatous inflammation with myofibroblasts, immune cells including granulocytes, and B-cell follicle-like structures were observed in the thickened dura mater; (9) immunotherapies (with or without surgical decompression) were effective in reducing the modified Rankin Scale score and reduced BVAS during the first active insults; (10) combined immunotherapies with glucocorticoids and cyclophosphamide/rituximab helped in reducing relapses in the long term; and (11) surgical decompression, including laminectomy and duraplasty, was necessary for compressive myelopathy. These data suggest that MPO-ANCA+ spinal HP shares common features with MPO-ANCA+ cranial HP (1, 2, 6, 8, 9, and 10), but also has unique clinical features (3, 4, 5, 7, and 11).

Discussion

Our findings highlight the significant pathogenic role of ANCA in spinal HP. MPO-ANCA+ spinal HP, as an organ-threatening disease, should be positioned as having unique characteristics, whether limited to the CNS or as part of a generalized form in ANCA-associated vasculitis.

Reprinted under a CC BY NC ND 4.0 license.

Paper summary (in Japanese)
School of Medicine, Niigata University.

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