Arachnoid involved in idiopathic hypertrophic pachymeningitis

The cerebrospinal fluid (CSF) shows inflammatory changes in patients with idiopathic hypertrophic pachymeningitis (IHP), which is a rare disorder. However, systemic CSF research including immunoglobulins in patients with IHP are substantially lacking. In the study, clinical, laboratory, neuroradiologic and therapeutic data from 9 patients with IHP were retrospectively studied, and CSF changes were analyzed. Intracranial pressure was elevated in 4 patients. Protein levels in CSF were elevated in 5 patients (< 1 g/L). IgA was elevated in 7 patients (> 0.5 mg/dL), IgG was elevated in 8 patients (> 3.4 mg/dL) and IgM was elevated in 6 patients (> 0.13 mg/dL) with IHP. CSF immunoglobulins, including IgA, IgG and IgM, were significantly elevated compared with levels in the control (P = 0.021, 0.018, 0.019). There were no linear correlations between IgG, IgM and protein in CSF, but there was a linear correlation between IgA and protein. In conclusion, CSF in IHP shows inflammatory changes, and protein levels are low to moderately elevated. CSF immunoglobulins, including IgA, IgG and IgM, also increased. The arachnoid is involved in IHP, a proportion of immunoglobulins may originate from the blood because of damage to the blood-CSF barrier at the arachnoid. Other intrathecal synthesis of immunoglobulins may be a secondary change due to alteration in the CSF's content to stabilize the internal environment or may be secreted by activated immune memory cells in the brain, which need further research.