Volume measurement with magnetic resonance imaging of hippocampus-amygdala formation in patients with anorexia nervosa

The purpose of our work was to evaluate the volume of hippocampus-amygdala formation (HAF) in patients with anorexia nervosa (AN), being this structure a crucial target for the glucocorticoid action in the adaptative stress-response. AN patients have biochemical hypercortisolism associated to normal ACTH levels, but do not develop the characteristic clinical features of glucocorticoid hypersecretion. Furthermore, in these patients cortisol levels usually do not suppress after dexametasone challenge. Twenty AN females (aged 30.0±5.1) with 10.5±4.2 yr of disease underwent a brain magnetic resonance (MR) examination during the recovery phase; an age-matched control group (CG) of 20 healthy female volunteers was also studied. Two interleaved T1-weighted spin-echo sequences for 46 contiguous 2-mm coronal slices (pixel 0.98² mm) were used. The volumes of both right and left HAFs were calculated with manual contouring from the third ventricle to the Sylvian aqueduct. IGF-I, T₃, gonadotropins, 24-h urine free cortisol, and BMI were obtained for both patients (on admission and on present evaluation) and CG. Mann-Whitney, Wilcoxon and Spearman tests were used. AN patients showed a significant (p=0.0001) reduction of total (right plus left) HAF volume (6.6±1.3 cm³) when compared with CG (8.9±1.1). No significant difference was found between right and left HAF in both patients and CG. In AN patients, no significant correlation was found between the HAF and all the hormonal parameters or BMIs, while a trend towards significance was observed with duration of the disease (r=-0.398; p=0.082). MR imaging demonstrated a significant volume reduction of HAF in AN patients during the recovery phase of the disease, suggesting a possible causal role in the pathogenesis of the disease.