A nationwide survey of hypertrophic pachymeningitis in Japan.
OBJECTIVES
To clarify the prevalence, frequent causes and distinct features of hypertrophic pachymeningitis (HP) according to background conditions in a nationwide survey in Japan.


METHODS
The study began with a preliminary survey to determine the approximate number of HP patients diagnosed from 1 January 2005 to 31 December 2009, and was followed by a questionnaire survey for clinical and laboratory findings. HP was defined as a condition with thickening of the cranial or spinal dura mater with inflammation, evidenced by MRI or histology.


RESULTS
Crude HP prevalence was 0.949/100 000 population. The mean age at onset was 58.3±15.8 years. Among 159 cases for whom detailed data were collated, antineutrophil cytoplasmic antibody (ANCA)-related HP was found in 54 cases (34.0%) and IgG4/multifocal fibrosclerosis (MFS)-related HP in 14 cases (8.8%). Seventy cases (44.0%) were classified as 'idiopathic' and 21 (13.2%) as 'others'. ANCA-related HP cases showed a female preponderance, a higher age of onset, and higher frequencies of otological symptoms and elevated systemic inflammatory biomarkers, but lower frequencies of diplopia compared with idiopathic HP. IgG4/MFS-related HP cases showed a marked male predominance; all had cranial HP while none had isolated spinal HP or decreased sensation.


CONCLUSIONS
HP is not extremely rare. ANCA-related HP is the most frequent form, followed by IgG4/MFS-related HP. Both forms have unique features, which may help to differentiate background causes.
['Yonekawa|Tomomi|T|', 'Murai|Hiroyuki|H|', 'Utsuki|Satoshi|S|', 'Matsushita|Takuya|T|', 'Masaki|Katsuhisa|K|', 'Isobe|Noriko|N|', 'Yamasaki|Ryo|R|', 'Yoshida|Mari|M|', 'Kusunoki|Susumu|S|', 'Sakata|Kiyomi|K|', 'Fujii|Kiyotaka|K|', 'Kira|Jun-ichi|J|']
D000367:Age Factors D001921:Brain D003625:Data Collection D005260:Female D006801:Humans D006984:Hypertrophy D007564:Japan D008279:Magnetic Resonance Imaging D008297:Male D008581:Meningitis D008875:Middle Aged D059906:Neuroimaging D049268:Positron-Emission Tomography D015995:Prevalence D012737:Sex Factors D013116:Spinal Cord D015899:Tomography, Emission-Computed, Single-Photon
MRI Bacteriology Immunology Infectious Diseases