High prevalence of incidental brain findings in primary dysmenorrhoea

Primary dysmenorrhoea (PDM) is inexorably common. PDM women suffer from cramping pain in the lower abdomen that starts with menstruation and lasts for 24-72 h. Up to 90% of adolescent girls and more than 50% of menstruating women worldwide report suffering from it. Ten to 20% of PDM women describe their suffering as severe and distressing. However, nothing is known regarding the association of PDM with possible brain anomalies or abnormalities.

High-resolution T1-weighted anatomical brain magnetic resonance images (MRI) were acquired for each subject and inspected for incidental findings (normal variants and abnormalities) as a routine procedure in our PDM-related multimodal neuroimaging studies. Altogether, 330 right-handed young women [otherwise healthy PDMs = 163; non-PDM healthy controls (HCs) = 167] were enrolled during the period of 2006-2014. Binomial proportion test was performed for between-group comparisons.

PDMs demonstrated significantly higher prevalence of overall incidental brain MRI findings (PDMs: n = 18, 11.0%; HCs: n = 6, 3.6%; p = 0.005) that should be ascribed to a preponderance of normal variants (PDMs: n = 16, 9.8%; HCs: n = 3, 1.8%; p = 0.001), especially cavum septum pellucidum. No significant between-group difference of abnormal findings was found (PDMs: n = 2, 1.2%; HCs: n = 3, 1.8%; p = 0.336).

We report here that otherwise healthy PDMs are associated with high prevalence of normal variants but not brain abnormalities. Our observations invite further epidemiological and neuroscientific studies.