Idiopathic Hypertrophic Cranial Pachymeningitis With Chiari Type I Malformation: Case Report and Review of the Literature.

Idiopathic hypertrophic cranial pachymeningitis (IHCP) is a rare chronic inflammatory disease characterized by diffuse thickening of the dura mater. Although IHCP mostly presents as a diffuse lesion, it may also occur as focal tumour-like lesions. Here we present the first reported case of IHCP associated with a Chiari type I malformation (CMI). A 65-year-old man presented with a one-year history of chronic headache and vertigo exacerbated by standing and neck flexion. The neurological examination was unremarkable except for tongue wasting and fasciculations. MRI demonstrated features of CMI and findings suggestive of IHCP. Posterior fossa decompression resulted in significant symptomatic improvement and the diagnosis of IHCP was confirmed on histopathology. Though there is no consensus about the management of IHCP in this case, we advocate surgical decompression with prolonged steroid therapy.