Investigating the Immune Landscape and Clinical Features of Spinal Adhesive Arachnoiditis

Authors

  • SA Graff
  • HV Nalluri
  • D Maric
  • DB McGavern
  • M Quezado
  • JD Heiss

Abstract

Arachnoiditis is the inflammation of the arachnoid membrane, triggered by infection, chemical exposure, surgery, or traumatic injury. This inflammation can cause an excessive accumulation of extracellular matrix (ECM) components, produced by fibroblasts, leading to permanent scarring of the arachnoid membrane. The inflammatory response may extend beyond the arachnoid membrane to the dura mater, spinal cord, and nerve roots, resulting in complications such as tethering of the spinal cord to the dura, constriction of spinal cord arterial blood supply, and obstruction of normal cerebrospinal fluid (CSF) circulation. A disruption in normal CSF flow may lead to the development of syringomyelia. The course of patients with arachnoiditis is variable. Patients with widespread arachnoiditis generally have a worse prognosis than those with focal arachnoiditis. In this natural history study, we aimed to collect tissue samples and patient data to better understand how arachnoiditis changes over time and explore mechanisms by which arachnoiditis causes neurological and quality-of-life deficits. Nine patients underwent neurosurgical treatment for syringomyelia associated with arachnoiditis. Multiplex-immunohistochemical (MP-IHC) staining of arachnoid tissue samples collected during surgery revealed mean immune cell densities as follows: CD4: 3.4 ± 3.8 cells/mm2, CD8: 4.4 ± 7.5 cells/mm2, CD20: 0.97 ± 1.2 cells/mm2, CD68: 10 ± 12.7 cells/mm2, IBA1+CD68: 11.5 ± 13.9 cells/mm2. Subjects with a higher infiltration of immune cells also showed increased levels of ECM components such as collagen and fibrinogen. Surgical pathology confirmed the presence of arachnoid scars and fibrous tissue. These subjects also had a history of multiple surgeries for recurrent syringomyelia.

Scientific Focus Area: Clinical Research

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