Pregnancy-induced brain magnetic resonance imaging changes in women with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, affecting the brain, spinal cord and optic nerves. MS presents in two main clinical forms: relapsing MS, manifesting with inflammatory attacks causing acute deterioration of neurological symptoms, and progressive MS, defined as the constant worsening of neurological function. Some MS patients might experience only minor symptoms while others could stop seeing, writing, or moving around. Infection with Epstein–Barr virus, lack of ultraviolet radiation, repeated exposure to organic solvents, physical and emotional stress are considered to be the major risk factors of MS for genetically predisposed individuals. However, all of the possible causes have one thing in common: the body’s immune system attacks its own nervous tissue. MS frequently manifests in women at a time when many are considering pregnancy, and raising children can be expected to occur at a time of increasing disability. Despite this, little is known about the effect of pregnancy on disease progression or the disease process on pregnancy outcome.

Magnetic resonance imaging (MRI) has become the single most useful paraclinical measure for the diagnosis of MS; MRI is sensitive to brain changes which are seen in MS. Classically, the MRI shows lesions in the white and grey matter of the brain and spinal cord especially near the cerebrospinal fluid spaces. Both the mother and the baby are unharmed by the test. Recent trial reports have supported the use of MRI as a prognostic tool in patients experiencing their first episode of demyelination symptoms. MRI can detect changes in the brain associated with MS disease activity, such as abnormal tissue changes (also known as lesions) and brain tissue loss (also called atrophy).

Previous research has found an increase in the number of new or contrast-enhancing lesions on brain MRI shortly after birth. Very few previous studies in healthy women found brain volume loss (BVL) during pregnancy. Given that prior research were done on small sample size studies of healthy women, there is limited understanding of the dynamics of pregnancy-induced BVL alterations in women with neurological diseases such as MS. Furthermore, it is unclear whether pregnancy-induced BVL alterations are related with past disease activity or whether they are clinically meaningful. Therefore, it is critical to gain a better knowledge of the dynamics of brain changes in MS during pregnancy.

To find out answer to the above question, researchers Dr. Tomas Uher, Eva Havrdova, Karolina Vodehnalova, Jan Krasensky, Vaclav Capek, Manuela Vaneckova, and Dana Horakova from the Charles University in Czech Republic conducted a clinical observational study examine lesion activity and BVL during pregnancy and the postpartum period, as well as to assess their clinical significance in women with relapsing-remitting MS (RR-MS). The research work is now published in European Journal of Neurology.

In order to comprehend the dynamics of lesion activity and brain volume changes during pregnancy and postpartum, the authors performed extensive brain MRI analysis from 62 women with relapsing-remitting MS and correlated the MRI data with clinical symptoms and disability. Data from MRI (221 scans) as well as clinical visits at baseline (24 and > 6 months before), pre-pregnancy (6 months before), postpartum (3 months after), and follow-up (> 12 and 24 months after delivery) were included. The authors found that postpartum period was associated with an increase in T2 lesion volume and accelerated brain volume loss in a significant proportion of women. However, in the study, 70.7% of women still had lower brain volume 12–24 months after delivery compared with the prepregnancy period. This incomplete brain volume recovery following pregnancy cannot be explained only by accelerated brain volume loss in MS, because women had a higher rate of brain volume loss during the postconception phase (between prepregnancy and follow-up) than during the preconception phase (between baseline and prepregnancy). We propose several possible interpretations, including physiological phenomenon as observed in the recent study on healthy women. The level of disability, however, remained the same throughout both the pregnancy and the postpartum periods. The majority of women had mild disability and short disease duration (median 5.5 years).

In summary, the findings of Dr. Tomas Uher and colleagues imply that MRI lesion and brain volume changes may become more pronounced during the postpartum period. The study may have an important impact on the choice of the treatment strategy and monitoring of disease activity of pregnant patients with MS Although we observed pregnancy-induced brain volume loss in the majority of women, these changes may be physiological, as observed in adolescence. Hence, clinically stable and effectively treated women should continue to perceive pregnancy as safe.