Idiopathic hypertrophic pachymeningitis.

BACKGROUND: Hypertrophic pachymeningitis is an uncommon disorder that causes a localized or diffuse thickening of the dura mater and has been associated with rheumatoid arthritis, syphilis, Wegener's granulomatosis, tuberculosis, and cancer. Few series of the idiopathic variety have been described, particularly with respect to MRI correlation to clinical outcome and treatment.

OBJECTIVE: To investigate the clinical and laboratory evaluation, course, and treatment of patients with idiopathic hypertrophic pachymeningitis (IHP), to correlate the MRI findings with the clinical course, and to review the literature on IHP.

METHODS: Retrospective case series of 12 patients (9 men, 3 women), with a mean age of 55 years (range 39 to 88 years), who had IHP by imaging studies, meningeal or orbital biopsy, or both. The clinical features, laboratory evaluation, contrast-enhanced MRI, treatment, and clinical outcome were documented for each case. The mean duration of follow-up was 3.5 years (range 3 months to 16 years).

RESULTS: The main clinical features at presentation were headache (11 cases), loss of vision (7 cases), diplopia (4 cases), papilledema (2 cases), other cranial nerve involvement (3 cases), ataxia (2 cases), and seizures (1 case). On the initial MRI, the location of abnormal enhancement of the dura mater correlated with the clinical findings and the sphenoid wing area was affected in all patients. The sedimentation rate was elevated in five cases. The CSF had increased protein in six cases and lymphocytosis in four cases. Biopsy of the dura mater in five cases and the orbital soft tissue in one case showed infiltrates of small mature lymphocytes, plasma cells, and epithelioid histiocytes, but no neoplasia, vasculitis, or infectious agents. Cultures of the CSF and biopsy material remained sterile. Corticosteroid therapy improved the vision in 7 of 8 cases and controlled headache in 10 of 11 cases. Five cases had partial improvement of other neurologic symptoms and signs. Recurrence developed with steroid tapering in six cases. One case had progressive deterioration and died. In four cases methotrexate or azathioprine was added with reduction of the steroid dose. Follow-up MRI performed in 11 patients correlated 80% with the clinical state (p = 0.01).

CONCLUSION: IHP can be suspected on MRI and defined pathologically on biopsy. Untreated, the clinical course is usually marked by severe headache and progressive neurologic deterioration and vision loss. Although initially steroid-responsive, clinical manifestations frequently recur with corticosteroid taper, requiring the addition of immunosuppressive agents in some cases.