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Dr. Ankit Agrawal, A19699, Dr. Bhagyajyothi B.K., Dr. Rekha B.K. Mudhol, Dr. Shalaka Kshirsagar, Dr. Sumeet Gupta


Abstract:

The aim of the study is to evaluate PRES Syndrome as an important cause of vision loss in patients with acute haemodynamic instability. Patients with acute haemodynamic instability like acute pre-eclampsia/eclampsia/severe PIH/accelerated hypertension and presenting with sudden visual impairment were examined. Five patients in which the anterior segment was found to be normal, normal pupillary reactions and clear lens, with no major fundus anomalies, were selected and sent for MRI of brain. MRI scanning showed T2 and FLAIR hyperintesities involving bilateral parieto-occipital regions in all the 5 patients, suggestive of PRES Syndrome.

Posterior Reversible Encephalopathy Syndrome (PRES), is an important cause of sudden painless visual loss in patients with acute haemodynamic instability and should be kept as a differential diagnosis when examining these cases. It is caused by vasogenic oedema, commonly in the parieto-occipital region, due to hyperperfusion.

Key-words:  Posterior reversible encephalopathy syndrome, PRES, eclampsia, hypertension, sudden vision loss, parieto-occipital, vasogenic edema

Key Messages :  PRES is an important cause of visual impairment in patients with acute haemodynamic instability like acute pre-eclampsia/eclampsia/severe PIH/accelerated hypertension. It is caused by vasogenic oedema, commonly in the parieto-occipital region. It is usually resolved completely with treatment of causative haemodynamic instability.

Introduction: 

Posterior reversible encephalopathy syndrome (PRES) [1, 2] is a clinic-radiological entity that was well described by Hinchey et al. [3] in 1996. PRES is characterized by variable associations of seizure activity, consciousness impairment, headaches, visual abnormalities, nausea/vomiting, and focal neurological signs. It occurs due to a number of causes, predominantly malignant hypertension, eclampsia, and medical treatments such as immunosuppressive therapy [4].

Diagnosis of PRES relies on history, clinical examination, and radiologic findings of symmetric bilateral hyper-intensities on T2- weighted magnetic resonance imaging (MRIs) representing vasogenic edema. This edema most commonly affects the posterior occipital and parietal lobes [5].

This syndrome is usually reversible once the underlying cause is treated or controlled. Management of PRES includes removal of any offending agents, blood pressure, and seizure management. [5].

The global incidence of PRES is unknown. It has been reported in patients ranging from 4 to 90 years of age, with most cases occurring in young-aged to middle-aged adults. A marked female preponderance is observed which may reflect some of the underlying causes. [6].

PRES may cause sudden diminution of vision or visual impairment in a patient due to any of the above mentioned causes. The patient presents with a normal anterior segment and fundus examination does not reveal any relevant major abnormality and thus the diagnosis becomes difficult. This case series will help us understand the importance of PRES as a differential diagnosis when faced with such a clinical picture.

Cases:

Patients presenting with complaints of sudden diminution of vision, and associated with acute pre-eclampsia, eclampsia, severe PIH and accelerated hypertension were screened in a tertiary care hospital from June 2016- May 2017.

Of these 5 patients were selected based on the following criteria:

Normal anterior segment.

No pupillary abnormality.

Normal Fundus.

Case 1- Female patient, 22 year old, primigravida, period of gestation 32 weeks, presented with complaints of sudden diminution of vision since morning. Patient didn’t give any history of visual impairment till one day back. The patient’s medical history was unremarkable. On examination, her blood pressure was found to be 170/100 mm of Hg. Proteinuria was present. The patient was diagnosed as severe pre-eclampsia. On ophthalmological examination, visual acuity was recorded as PL+ PR accurate in both eyes, the anterior segment and pupillary reflexes appeared normal.

Case 2- Male patient, 43 year old. Patient was a known case of hypertension and taking treatment since 5 years. Presented with complaints of giddiness and sudden diminution of vision. BP was recorded as 210/120 mm of Hg. The patient was diagnosed as accelerated hypertension. The visual acuity was recorded as PL-ve in both eyes.Anterior segment was normal and fundus examination showed grade 2 hypertensive retinopathy changes.

Case 3- Female patient, 27 years old, G2P2, period of gestation 34 weeks, presented with complaints of sudden diminution of vision since 1 day. Patient has a normal delivery previously and medical history was normal. On examination BP was 150/100 mm of Hg. No proteinuria was present.The patient was diagnosed as having PIH (pregnancy induced hypertension). The Visual Acuity was recorded as CF 3m in RE and 6/60 in LE.  Anterior segment was normal and fundus showed grade 1 hypertensive retinopathy changes.

Case 4- Female, 19 year old, primigravida, 28 week period of gestation. Presented with complaints of sudden diminution of vision since 3 – 4 hours. Patient had an unremarkable history. On examination the patient was found to be in altered sensorium. BP was 170/110. Proteinuria was present. The patient was diagnosed as having severe pre-eclampsia. The visual acuity was recorded as PL+ PR accurate in both eyes. Anterior segment was normal and fundus examination showed grade 1 hypertensive retinopathy changes.

Case 5- Female, 25 year old, G2P2, period of gestation 31 weeks, presented with complaints of sudden diminution of vision with hallucinations. The patient gave no prior history of similar complaints. BP was recorded as 180/100, and proteinuria was present. The patient was diagnosed as having pre-eclampsia. The visual acuity was recorded as PL-ve in both eyes. Anterior segment examination was normal while fundus examination showed grade 3 hypertensive retinopathy changes.

All these patients were sent for MRI scanning of brain to find out any neurological cause of visual impairment, the results of which showedT2 and FLAIR hyperintesities involving bilateral parieto-occipital regions, suggestive of Posterior Reversible Encephalopathy Syndrome.

They were started on respective anti-hypertensive medications to control their hemodynamic status, and BP monitoring and visual acuity was recorded at regular intervals.

After a period of 24-48 hours of start of treatment, the best corrected visual acuity of all 5 patients was 6/6.

MRI Brain of all these patients was repeated 1 week after start of treatment, and the results showed resolution of hyperintensities in all the cases.

Visual fields of the patients was tested using Zeiss Humphrey Visual Field Analyser after 1 week of start of treatment and found to be within normal limits in all 5 cases.

Table 1:

Table 2:

Discussion:

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.

The most common visual abnormality is cortical blindness, but homonymous hemianopia, visual neglect, and blurred vision also occur.

Cortical visual impairment was noted in all 5 patients in this study. The resolution of patients’ visual impairment and MRI findings after start of anti-hypertensives support the clinical diagnosis of PRES secondary to acute haemodynamic instability.

These symptoms are thought to result from cerebral edema. The mechanism behind the development of angiogenic edema and CT and MR imaging appearance of PRES is not known. Two opposite hypotheses are commonly reported: 1. severe hypertension leads to failing autoregulation, subsequent hyperperfusion, with endothelial injury/vasogenic edema; and 2. vasoconstriction and hypoperfusion lead to brain ischemia and subsequent vasogenic edema [2].

The pathogenesis of this syndrome is poorly understood. Hypertensive encephalopathy is said to be the cause of this syndrome which has been demonstrated by various clinical and experimental studies[7]. 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.[8]

The syndrome is reversible, but early and prompt treatment is required to prevent complications like cerebral infarct, which may lead to permanent visual loss or other sensory-motor abnormalities.

Early recognition of PRES is important for prompt treatment by eliminating factors that cause PRES, such as uremia, hypertension, cytotoxic and immunosuppressive drugs.[9].

It is important for an ophthalmologist to recognize the symptoms and signs of PRES and correlate it the patients’ other clinical findings. Various differential diagnosis of sudden diminution of vision in acute haemodynamic changes include optic neuritis, papilledema, central retinal artery occlusion and serous retinal detachment. It is important to differentiate PRES from these conditions.

References :

  1. Bartynski WS (2008) Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features. AJNR Am J Neuroradiol 29: 1036–1042
  2. Bartynski WS (2008) Posterior reversible encephalopathy syndrome, part 2: controversies surrounding pathophysiology of vasogenic edema. AJNR Am J Neuroradiol 29: 1043–1049
  3. Hinchey J, Chaves C, Appignani B, Breen J, Pao L, Wang A ,et al (1996). A reversible posterior leukoencephalopathy syndrome. N Engl J Med 334: 494–500
  4. Cherniawsky Hannah, Merchant Neesha, Sawyer Micheal, Ho Maria. A case report of posterior reversible encephalopathy syndrome in a patient receiving gemcitabine and cisplatin. Medicine (2017) 96:8.
  5. Granata G, Greco A, Iannella G, Granata M, Manno A, Savastano E, et al. Posterior reversible encephalopathy syndrome—insight into pathogenesis, clinical variants and treatment approaches. Autoimmun Rev 2015;14:830–6.
  6. Legriel S, Pico F, Azoulay E. Understanding posterior reversible encephalopathy syndrome. Annual update in intensive care and emergency medicine 2011. Springer, 2011:631–53
  7. Byrom FB. The pathogenesis of hypertensive encephalopathy and its relation to the malignant phase of hypertension:Experimental evidence from the hypertensive rat.Lancet.1954;267:201–11
  8. Divya Karuppannasamy, K Vikrant, A Raghuram, T M Sathish Kumaar. Indian J Ophthalmol. 2014 May; 62(5): 635–638. doi: 10.4103/0301-4738.133525
  9. Shin, H.-Y., Kim, S. H., Lee, M. Y., Yoon, S. A., Kim, S. Y., & Lee, Y. C.. Sudden bilateral vision loss as the sole manifestation of posterior reversible encephalopathy syndrome from acute uremia: Clinical case report. Medicine, 96(27), e7424.

Table 1: Visual acuity of patients (by Snellen’s Chart)

 

 

 

 BCVA on presentation BCVA at 6 hours after start of treatment BCVA at 12 hours after start of treatment BCVA at 24 hours after start of treatment BCVA at 48 hours after start of treatment
Case 1 PL+ PR acc CF 3m 6/60 6/6 6/6
Case 2 PL-ve CF 1m 6/60 6/24 6/6
Case 3 CF 3m, 6/60 CF 3m, 6/36 6/36, 6/9 6/6,6/6 6/6
Case 4 PL+ PR acc CF 3m CF 3m 6/36 6/6
Case 5 PL -ve PL+ve PR acc CF 3m 6/6 6/6
BP at Presentation BP at 6 hours after start of treatment BP at 12 hours after start of treatment BP at 24 hours after start of treatment BP at 48 hours after start of treatment
Case 1 170/100 160/90 150/90 140/80 140/80
Case 2 210/120 180/100 160/90 150/90 140/90
Case 3 150/100 140/90 140/90 130/80 130/80
Case 4 170/110 170/100 150/90 140/90 140/90
Case 5 180/100 160/90 150/80 150/80 140/80

Table 2: BP measurement at intervals. (in mm

BP at Presentation BP at 6 hours after start of treatment BP at 12 hours after start of treatment BP at 24 hours after start of treatment BP at 48 hours after start of treatment
Case 1 170/100 160/90 150/90 140/80 140/80
Case 2 210/120 180/100 160/90 150/90 140/90
Case 3 150/100 140/90 140/90 130/80 130/80
Case 4 170/110 170/100 150/90 140/90 140/90
Case 5 180/100 160/90 150/80 150/80 140/80

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