An Update on Idiopathic Hypertrophic Cranial Pachymeningitis for the Headache Practitioner

Purpose of Review We aim to review idiopathic hypertrophic cranial pachymeninigitis (IHCP), describe common head pain patterns and features associated with the disorder, suggest potential classification of head pain syndromes based on the recently published International Classification of Headache Disorders-3, explore pathophysiology found to be associated with cases of IHCP, and indicate common treatment for the disorder. Recent Findings It is suggested that a subset of IHCP is an IgG4-related autoimmune disorder. Patients with IHCP were found to have elevated cerebrospinal fluid (CSF) protein and lymphocytic pleocytosis. Corticosteroids are a mainstay of treatment. Other immunosuppressive agents and steroid sparing agents as add-on therapy may have utility in the treatment of cases refractory to corticosteroids alone. Summary Clinical manifestations of IHCP depend upon the location of the inflammatory lesions and compression of the adjacent nervous system structures. Headache and loss of cranial nerve function were the most common presenting features of hypertrophic cranial pachymeninigitis. Several headache diagnoses may result from IHCP. Gadolinium-enhanced MRI is the standard imaging modality for diagnosing. Although the pathophysiology is poorly understood, many cases of hypertrophic pachymeninigitis (HP) are thought to be closely related to inflammatory disorders. Cases of HP previously thought to be idiopathic may have IgG4 pathophysiology. CSF and serological studies are helpful. Treatment involves immunosuppressive agents. Advancement in neuroimaging, assays, tests, and further delineation of inflammatory disorders affecting the nervous system may provide further insight to the etiology of cases of HP previously considered and diagnosed as idiopathic.