Idiopathic intracranial hypertrophic pachymeningitis: two case reports and review of the literature.

In 1949, Naffziger et al. first described idiopathic intracranial hypertrophic pachymeningitis (IIHP) as an aseptic, diffuse inflammatory disease that causes thickening of the dura mater and often headache and progressive multiple nerve palsies due to fibrous entrapment or ischemic damage of neurovascular structures. Pachymeningeal thickening can be diffuse or nodular. We report two cases of IIHP; one was affected by diffuse IIHP, while the other presented focal IIHP mimicking a convexity meningioma. We examine the differential diagnosis between IIHP and other known causes of hypertrophic pachymeningitis. We also discuss the clinical bases of treatment.