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Idiopathic Hypertrophic Pachymeningitis: A Report of Two Patients and Review of the Literature

Purpose: We report the treatment and follow-up, including MRI, of two patients with idiopathic hypertrophic pachymeningitis and review the English language literature, with emphasis on management and outcome in this rare disorder. Methods and Materials: The files of two patients were reviewed, with relevant histopathology and imaging (MRI). The first patient has been followed for sixteen years (the longest MRI-documented postoperative course reported for this condition) and the second for two years. The English language literature was reviewed, including a summary of all reported patients that have been followed with MRI or CT imaging. Results: Despite extensive investigation, no underlying etiology was determined in either patient. Histopathological studies revealed a chronic inflammatory dural infiltrate in both patients, with granulomas in the first but not the second patient. The first patient underwent surgery twice and has remained stable for sixteen years, despite persistent neurologic deficits. The second patient was managed with dexamethasone after a surgical biopsy, and experienced complete resolution of all neurological deficits and abnormalities seen with MRI. Conclusion: Although prompt and extensive surgery has been recommended for this condition, the results from our second patient indicate that complete remission can be achieved in some patients with biopsy and steroid therapy. This also supports the view that autoimmune mechanisms underlie idiopathic hypertrophic pachymeningitis. The first patient illustrates that extensive laminectomies may be an effective therapeutic option but chronic discomfort may result. If extensive surgery must be performed, laminoplasty should be done because of the potential for reduced pain and improved long-term spinal stability.