Disturbed temporal lobe circulation due to compression by pituitary adenoma

The objective of this study was to clarify the pathophysiology of temporal lobe-related symptoms in pituitary adenoma by investigating temporal lobe circulation in pituitary adenoma with single photon emission computed tomography (SPECT). The subjects were 37 patients with pituitary adenoma (74 regions in the bilateral temporal lobes) who underwent 123I-iofetamine (IMP) SPECT before treatment. Using imaging analysis software 3D-SSP, the temporal lobes were evaluated in the bottom view on SPECT using the following method. Regions of interest (ROI) were established in the anteromedial (AM), posteromedial (PM), anterolateral (AL), and posterolateral (PL) regions of the temporal lobe, and the activity ratio (AR) of the counts/pixel in each ROI to those throughout the entire brain was determined. The AR in the 37 patients was compared with that in 37 healthy volunteers. Furthermore, the temporal lobes in patients with pituitary adenoma were classified according to the presence or absence of compression caused by the tumor, pituitary apoplexy, and hormone production, and evaluated. The AR in the AM and AL was significantly lower in the pituitary adenoma than in the healthy group (both, p<0.001). In the pituitary adenoma group, the AR in the AM, AL, and PL was significantly lower in the compression than in the non-compression group (p<0.05, p<0.05, and p<0.01, respectively). Classification based on the presence or absence of pituitary apoplexy or hormone production did not significantly differ with the AR values. We conclude that pituitary adenoma causes hypoperfusion in the temporal lobe at a high frequency, and direct compression by the tumor is a cause of regional cerebral blood flow (rCBF) reduction. (author)