a retrospective review of clinical records of late postpartum eclampsia patients who had presented with acute onset of visual and/or neurological symptoms to the emergency department of a medical college hospital in south india between april 2009 and may 2013 was done .
all patients had underwent mri with diffusion weighted imaging ( dwi ) and apparent diffusion coefficient ( adc ) mapping to differentiate vasogenic from cytotoxic cerebral edema .
patient records were analyzed for presence of visual symptoms , peak systolic and diastolic blood pressures , associated neurological symptoms , location of mri lesions and time taken for recovery .
the mr images were graded for extent and severity of cortex and white matter vasogenic edema , degree of confluence , mass effect and ventricular distortion on a scale from 1 to 5 .
statistical analysis was performed using chi - square test and a p value of less than 0.05 was considered to be statistically significant .
clinical and imaging findings are summarized in table 1 . clinical profile of patients with pres the 10 patients ranged in age from 21 to 32 years ( average-26  3.49 years ) .
mean peak systolic and diastolic blood pressures were 144  21.71 and 93  9.19 mm of hg , respectively .
bilateral visual loss was noted in five patients of whom three patients were able to perceive hand movements and two patients had only perception of light .
the most common abnormality noted on mri included bilateral symmetrical hyperintensities on t2-weighted images and fluid attenuated inversion recovery ( flair ) sequences in the parieto - occipital regions [ figs . 1 and 2 ] .
dwi showed high signal intensity with no areas of restricted diffusion while adc mapping did not show corresponding low signal intensity thus suggesting vasogenic edema .
axial mr image ( fluid attenuated inversion recovery ) showing confluent edema in subcortical and deep white matter ( grade 4 ) seen as hyperintensities in bilateral parieto - occipital lobes ( patient 6 ) axial mr image ( fluid attenuation inversion recovery ) showing edema in subcortical white matter ( grade 2 ) seen as hyperintensities in bilateral occipital lobes ( patient 9 ) five patients had additional abnormalities in the cerebellar hemispheres and three patients had involvement of frontal lobes . average time taken for visual recovery was 2.6  1.34 days .
follow - up mri in four patients after 1 month revealed complete resolution of these abnormalities . in the remaining , clinical symptoms and signs
follow - up scans were not performed due to financial constraints . the extent of cerebral edema in patients with and without visual loss was compared and results summarized in table 2 .
posterior reversible encephalopathy syndrome ( pres ) is a rare neurotoxic state that presents with altered mental status , headache , seizures , and visual disturbances along with neuroimaging features of vasogenic edema involving the posterior cerebral circulation .
although several cases of pres have been reported in neurology and neuroradiology literature , exposure in ophthalmic literature has been rather limited .
the causes of pres are diverse and include pre - eclampsia , eclampsia , renal insufficiency , solid organ transplantation and immunosuppressive therapy .
hypertensive encephalopathy is said to be the cause of this syndrome which has been demonstrated by various clinical and experimental studies .
patients with hypertensive encephalopathy have the same clinical signs as those with pres and they also have rapid resolution of clinical and imaging abnormalities once the blood pressure is lowered .
the most widely accepted theory states that sudden elevation of blood pressure causes failure of autoregulation in the cerebral blood vessels leading to hyperperfusion , breakdown of blood brain barrier , and vasogenic edema . the posterior circulation is preferentially affected since it has less sympathetic innervation than the carotid circulation , thus rendering it less able to adjust to blood pressure fluctuations . however , this theory is not comprehensive because pres can affect normotensives .
high degree of suspicion is required in these patients of late postpartum eclampsia because it occurs between 48 hours postpartum and 1 month after delivery frequently in women who have had a normal pregnancy and delivery and no signs of a pre - eclamptic syndrome .
alternative theory implicates endothelial dysfunction as the cause for occurrence of pres in eclampsia and sepsis .
this is supported by the fact that elevations in markers of endothelial dysfunction such as lactate dehydrogenase and abnormal red blood cell fragmentation have been reported in pres .
vasospasm with subsequent ischemia has also been hypothesized to cause loss of integrity of the blood brain barrier in eclampsia .
although reversible by definition early recognition and prompt treatment is essential to prevent secondary complications like intracerebral hemorrhage and infarction .
a large retrospective study of pres in diverse clinical situations revealed the occurrence of visual symptoms in 20% and headache in 26% while seizures was observed in 74% of cases .
the visual disturbances reported with pres include cortical blindness , visual neglect , homonymous hemianopia and blurred vision .
cortical visual loss was observed in five of our patients ( 50% ) while the remaining denied any visual disturbances .
our findings are in line with liman et al . , who observed that visual disturbances like cortical blindness , blurred vision and hemianopia are more common in eclampsia related pres ( 50% ) .
patients with pres due to other etiologies more often present with severe symptoms like altered mental status or neurological deficit and lesser visual disturbances ( 27.8% ) .
roth et al . , have also reported a higher percentage of disturbed vision in pre - eclampsia - eclampsia - related pres .
this could be because of the younger age and lesser associated comorbidities in these patients as compared to patients with pres due to other etiologies .
all patients ( with / without visual loss ) demonstrated bilateral symmetrical hyperintensities in the parieto - occipital regions on t2-weighted images .
this feature along with predominant involvement of the white matter distinguishes this syndrome from bilateral posterior cerebral artery territory infarction .
although several studies have reported visual symptoms of varying degrees in pres , to the best of our knowledge no study has attempted to correlate the visual symptoms with imaging abnormalities .
the limitations of our study include its retrospective design , and smaller sample size of postpartum eclampsia patients .
we conclude that there is a higher prevalence of cortical visual loss in patients with pres associated with late postpartum eclampsia .
patients with higher degree of vasogenic edema of the posterior cerebral white matter might present with visual loss .
ophthalmologists should be aware of this clinical entity since it is reversible and readily treated by controlling the blood pressure .
further prospective studies comprising larger sample size and different etiologies of pres are warranted in this regard .
 the purpose of this study was to determine the prevalence of visual disturbances in patients with posterior reversible encephalopathy syndrome ( pres ) associated with late postpartum eclampsia . 
 we retrospectively reviewed the clinical records of late postpartum eclampsia patients with features of pres for the presence of visual disturbances and location of radiological abnormalities . 
 we found a higher prevalence of cortical visual loss in patients with pres associated with late postpartum eclampsia . 
 bilateral symmetrical vasogenic edema of the parieto - occipital lobe was the most common magnetic resonance imaging ( mri ) abnormality noted . 
 no significant differences were observed in the extent of edema in patients with and without visual loss . 