Posterior reversible encephalopathy syndrome-associated bilateral cortical blindness as presenting feature of severe pre-eclampsia

Abstract

© BMJ Publishing Group Limited 2021. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION A 24yearold primigravida (gravida 1, para 0), at 34 weeks of gestation, presented to the emergency department of our hospital with a sudden painless bilateral visual loss for 1 day associated with mild headache. She did not have any history of loss of consciousness, trauma, seizure, fever, hypertension, diabetes, thyroid disorder or any cardiovascular diseases. Her antenatal history was insignificant. Ocular examination revealed visual acuity of only light perception and intact pupillary light responses in both eyes. Fundus (figure 1A,B) was unremarkable bilaterally, except a single dot haemorrhage temporal to the fovea in the right eye. No disc oedema, retinal detachment or any retinal vascular abnormality was noted in either eye. Optical coherence tomography (figure 1C,D) showed bilateral normal foveal contour and retinal nerve fibre layer thickness. Her blood pressure was found to be 170/100 mm Hg, recorded multiple times. Obstetrical examinations including fetal assessment and other systemic evaluations were normal. Laboratory investigations including complete haemogram, liver function test, renal function test, serum electrolytes and coagulation profile were unremarkable, except hypocalcaemia (6.5 mg/dL) and raised serum alkaline phosphatase levels (454.8 U/L). Urinalysis revealed 2+ proteinuria and elevated levels of 24hour urinary protein. Considering severe preeclampsia, treatment with magnesium sulfate (according to Pritchard regimen) and antihypertensive medication (labetalol) was initiated. An urgent MRI of the brain with venography revealed areas of T2/fluidattenuated inversion recovery hyperintensities (figure 2A–F) in bilateral parietooccipital lobes and cerebellar hemispheres, suggesting posterior reversible encephalopathy syndrome (PRES). A diagnosis of bilateral cortical blindness due to severe preeclampsiaassociated PRES (PEPRES) was made, and an emergency caesarean section was performed. The perinatal period was uneventful with a healthy mother and child. One week postoperatively, her visual acuity gradually restored to 20/20 in both eyes. Preeclampsia and eclampsia are among the most common conditions associated with PRES, others being blood pressure fluctuations, renal failure, autoimmune diseases, cytotoxic drugs and organ transplants. PRES is characterised by reversible vasogenic cerebral oedema, often presenting with seizures, encephalopathy, headache or visual disturbances. 2 Various mechanisms, including failure of cerebral autoregulation, endothelial injury by sudden blood pressure changes and direct cytokine effects on endothelium, have been postulated. All of these factors can lead to blood–brain barrier breakdown and consequent brain oedema. As parietal and occipital lobes are preferentially involved, visual symptoms are common in PRES. Lifson et al have reported visual complaints in 27% of patients diagnosed with PRES. However, Figure 1 Fundus photograph of both eyes (A,B) showing normal fundus except tiny retinal haemorrhage temporal to the fovea in the right eye. Optical coherence tomography demonstrating normal foveal contour (C,D) with insets showing normal retinal nerve fibre layer thickness bilaterally. Figure 2 Brain MRI showing hyperintensities on T2weighted images and fluidattenuated inversion recovery images in bilateral parietal (A and D), occipital (B and E) and cerebellar hemispheres (C and F).