Idiopathic hypertrophic cranial pachymeningitis is a rare chronic inflammatory and fibrosing process of unknown etiology. This entity is characterized by fibrosis and thickening of the dura mater and resulting in neurological syndrome. The authors report a 72 year-old woman who presented with progressive bifrontal headache, bilateral visual loss and transient episode of confusion. Neurological examination revealed bilateral optic atrophy, apathy and no focal neurological deficit. Investigations showed anemia of chronic disease, elevated erythrocyte sedimentation rate and polyclonal hypergammaglobulinemia. No specific inflammatory diseases or malignancy such as systemic lupus erythematosus, syphilis, hematologic malignancy were found. MRI of the brain revealed thickened and enhanced dura mater and leptomeninges at the inferior aspect of bilateral frontal lobes as well as vasogenic edema of the frontal lobes. Cerebrospinal fluid showed mild pleocytosis, high protein level and normal glucose level. Meningeal biopsy revealed nonspecific
inflammatory process of the dura and leptomeninges. There was no granuloma formation or evidence of vasculitis. Special stain for tuberculous bacilli, fungus and malignancy were all negative. The diagnosis of “idiopathic hypertrophic pachymeningitis” was made. The patient was treated with oral prednisolone 45 mg/day. Her headache was improved, but the profound vision loss in both eyes remained unchanged after 2 years of follow-up. Prednisolone was tapered within 18 months. Idiopathic hypertrophic cranial pachymeningitis usually involves dura at tentorium cerebelli, cavernous sinus and base of the skull. The extensive involvement at the anterior cranial fossa is extremely rare.

Keywords: Pachymeningitis, Headache, Optic neuropathy, Anterior cranial fossa