AAV Linked to Inflammation, Thickening of Brain Membranes in Case Study

A rare case of ANCA-associated vasculitis (AAV) causing thickening of the dura mater — a protective membrane of the central nervous system (CNS) — was found in a person previously treated for ANCA-associated interstitial lung disease.

The case report was detailed in the study, “A Rare Case of Central Nervous System Vasculitis in a Patient with Perinuclear Antineutrophil Cytoplasmic Antibodies-associated Interstitial Lung Disease,” which was published in the journal Cureus.

Pachymeningitis is a rare inflammatory disorder that leads to thickening of the dura mater, the outermost of three layers forming the meninges, which provide protection and support to the brain and spinal cord.

This disorder has been linked to diseases such as syphilis, tuberculosis, and cancer, but may also be caused by autoimmune diseases including AAV — in which case it is known as chronic hypertrophic pachymeningitis (CHP).

Researchers described a 76-year-old woman with AAV-associated pachymeningitis, who had been previously diagnosed and treated for ANCA-associated interstitial lung disease, or lung scarring.

She arrived at a hospital three years after her first diagnosis, complaining of forgetfulness, depression, and personality changes that had been progressing in the past weeks. At that time, her lung function was stable. But brain imaging analyses were indicative of dura mater thickening and small-vessel vascular disease.

Blood tests revealed that the woman had ANCA antibodies targeting the myeloperoxidase (MPO) protein, as well as high levels of the inflammatory markers erythrocyte sedimentation rate and C-reactive protein, and of rheumatoid factor. This factor, an antibody against healthy tissue, is found in some autoimmune diseases.

Results of a spinal tap revealed higher than normal white blood cell counts, as well as excessive levels of proteins.

After a biopsy showed thickening of meningeal tissue accompanied by inflammation and blood vessel damage, her medical team attributed the pachymeningitis to MPO-associated AAV.

The woman was then treated with corticosteroids,  which led to a “dramatic improvement in her alertness,” the researchers wrote. She was subsequently treated with rituximab — which she had previously used for her lung disease — and her meningeal thickening completely resolved after three months. Her family also reported better cognition.

As of the study’s completion, the woman was in an assisted living facility.

CHP is a rare disease that needs to be diagnosed early to prevent irreparable brain damage, the researchers said. Diagnosis may be aided by ANCA antibodies measures, brain imaging scans, and meningeal biopsies.

While treatment for this condition is often the same as that for systemic AAV, “more studies are needed to assess the most effective and safest immunosuppressive therapy for ANCA-associated CNS vasculitis,” the team wrote.