Magnetic resonance spectroscopy in pre-eclampsia: evidence of cerebral ischaemia.

OBJECTIVE: To establish whether there are changes in the maternal brain in pre-eclampsia detectable by magnetic resonance angiography and spectroscopy.

DESIGN: A prospective, observational study.

SETTING: Obstetric and Radiology Departments, Queen's Medical Centre, Nottingham.

SAMPLE: Fourteen healthy, nulliparous non-pregnant women, 9 healthy primiparous pregnant women and 10 women with pre-eclampsia.

METHODS: Magnetic resonance angiography and proton magnetic resonance spectroscopy of the brain was performed on each woman. Non-pregnant women were each studied twice. Healthy pregnant women were studied three times during pregnancy and once postnatally. Subjects with pre-eclampsia were studied once antenatally and twice postnatally. Magnetic resonance angiograms were examined for signs of vessel narrowing. On magnetic resonance spectroscopy, the ratios of the dominant peaks of the spectrum: N-acetyl aspartate (NAA), choline, creatine and lactate were compared.

MAIN OUTCOME MEASURE: Comparison of spectroscopic indices in non-pregnant, normal pregnant and pre-eclamptic women.

RESULTS: On magnetic resonance angiography, there was no evidence of vessel narrowing in any of the three groups. NAA/choline ratio was higher at all stages of pregnancy compared with the non-pregnant group (P < 0.05) associated with lower choline. NAA/choline increased gradually during healthy pregnancy associated with a decrease in choline. NAA/choline was significantly lower in the pre-eclampsia group compared with the healthy pregnant women at similar gestation (P < 0.01), associated with higher choline. There were no differences between the groups postnatally. Lactate was not detected. These changes are similar to those found in patients with carotid stenosis without cerebral infarction.

CONCLUSIONS: Narrowing of vessels detectable on magnetic resonance angiography does not occur commonly in pre-eclampsia. Magnetic resonance spectroscopy results suggest that there is relative cerebral ischaemia in pre-eclampsia compared with healthy pregnancy.