Figure 2.

Selective blood–brain barrier leakage overlaps with MR signal changes in the amygdala. (A–F) Staining for immunoglobulin in representative images of coronal brain sections in (A) normal controls, (B) epileptic controls, and in FEPSO at the level of (C) frontal cortex and nucleus accumbens, (D) amygdala and piriform lobe, (E) hippocampus, and (F) cerebellum. Immunoglobulin leakage is seen prominently in the hippocampus but also in the amygdala and adjacent regions. Scale bar corresponds to 5 mm. (G) Transverse T2-weighted MR image at the level of the hippocampus and piriform lobe in a 1-year-old female neutered European shorthair cat, orientated along the long axis of the hippocampus on a sagittal slice. The MR signal is bilaterally abnormally increased, and the area of the amygdala (arrow) appears bilaterally enlarged. (H) Optical density quantification of Ig leakage in FEPSO, epileptic, and normal control hippocampus. The hippocampi of FEPSO have higher values than normal controls. Data shown as median with interquartile range, LGI1 antibody-positive animals, are indicated in red and untested animals in black (**p < 0.01, Kruskal–Wallis test with Dunn’s post hoc correction, FEPSO n = 15, epileptic controls n = 7, normal controls n = 7). (I) Significant elevation of immunoglobulin signal in hippocampus and amygdala in FEPSO cats compared to other brain areas of the same cats. LGI1 antibody-positive animals are indicated in red and untested animals in black. Data shown as median with interquartile range (*p < 0.05, ***p < 0.001; Kruskal–Wallis test with Dunn’s post hoc correction, hippocampus n = 15, amygdala n = 9, basal ganglia n = 12, cortex n = 15, cerebellum n = 13).