Enlargement of the middle meningeal artery on MR angiography in chronic subdural hematoma

OBJECTIVE The middle meningeal artery (MMA) is suspected to play an important role in the development of chronic subdural hematoma (CSDH). The aim of this study was to clarify whether the MMA was enlarged in patients with CSDHs. METHODS The authors retrospectively assessed 55 patients in whom CSDH was diagnosed between 2010 and 2014 and who underwent MR angiography (MRA) after the onset of CSDH. The authors compared MMA diameters between hemispheres with and without CSDHs on MR angiograms. A case-control study was also performed with 55 sex- and age-matched patients with incidental unruptured aneurysms as controls. RESULTS In 55 patients with CSDHs, the diameters of the 79 MMAs on the CSDH side were significantly larger than the diameters of the 31 MMAs on the non-CSDH side (p < 0.05). In 24 patients with bilateral CSDHs, no significant difference was found between the MMA diameters on the larger hematoma side and those on the smaller hematoma side. In 13 patients who underwent MRA before the onset of the CSDH, the MMAs on MR angiograms acquired after onset of the CSDH were significantly larger than those on MR angiograms acquired before the CSDH onset (p < 0.05). The diameters of the MMAs in 55 patients with CSDHs were significantly larger than those of the MMAs in the 55 control patients (p < 0.05). CONCLUSIONS The MMA is enlarged with development of a CSDH. Information about the MMA observed on MRA in patients with CSDHs may be useful in developing a strategy for future treatment of CSDHs.