Idiopathic hypertrophic pachymeningitis with intracranial hypotension and distension of anterior internal vertebral venous plexus are associated with positional headaches but not sufficient in the diagnosis

Idiopathic hypertrophic pachymeningitis (IHP) is a very infrequent disorder that causes a localized or diffuse thickening of the dura mater. The main clinical features of IHP at presentation include headache, cranial nerve involvement, ataxia, transient ischemic attacks (TIA) and seizures. Intracranial hypotension (ICH) and distension of anterior internal vertebral venous plexus (IVVP) have not previously been reported as the main clinical manifestations. We report a unique case with these characteristics as the main clinical findings, and investigate the internal relationship between these characteristics. This study highlights the heterogeneity of IHP, in terms of clinical, imaging, and pathological features. We recommend that dural biopsies should be considered in patients with clinically typical orthostatic headache and (or) diffuse pachymeningeal enhancement on magnetic resonance imaging (MRI) for the diagnosis of IHP.