Cortical blindness in a child with acute glomerulonephritis.

The association between hypertensive encephalopathy and cortical blindness in children with acute glomerulonephritis is extremely rare. We report the case of a 9-year old girl who presented with headache, seizures, altered sensorium, hematuria, and transient cortical blindness as a complication of hypertensive encephalopathy which showed complete reversal following normalization of blood pressure and an underlying post-infectious acute glomerulonephritis was revealed.

Introduction

Posterior reversible encephalopathy syndrome (PRES) refers to a clinico-radiological entity characterized by headache, confusion, visual disturbances, seizures, and posterior transient changes on neuroimaging. It represents a localized manifestation of hypertensive encephalopathy occurring secondary to hypertensive crisis.[1] We report a child with PRES revealing post-streptococcal acute glomerulonephritis (PSGN).

Case Report

A 9-year-old girl presented to the ER with history of low-grade fever for 7 days, sudden onset headache for 2 days, altered sensorium and three episodes of tonic clonic seizures since the previous day and loss of vision over the past 12 h. On examination, she was afebrile, irritable with altered sensorium, and mild puffiness of face. Her blood pressure (BP) was 136/100 mm Hg (>95th percentile for her age). Her other vital parameters and anthropometry were normal. Her pupils were bilaterally equal and reacting to light, with normal fundus examination. She had no other focal neurological deficits and had no signs of any meningeal irritation. Abdomen was mildly distended and there was no organomegaly. Other systemic examinations were normal. She was started on anti-hypertensive (sublingual nifedepine), fluid and salt restriction, anti-edema measures, anticonvulsants, and other supportive care. Her BP was carefully monitored.

Investigations revealed hemoglobin 10.6 gm/dl, total count 18 500 cells/mm3 (polymorphs 87%, lymphocytes 10%), platelets 404 000 cells/mm3; ESR 9 mm; C-reactive protein <0.6 mg/dl; raised blood urea nitrogen 40 mg/dl; and creatinine 0.65 mg/dl. Her serum electrolytes and liver function tests were normal. The urine collected after admission was cola-colored and urinalysis revealed plenty of RBCs with albuminuria 2+. Chest X-ray was normal and ultrasonogram of abdomen revealed mild ascites. Computed tomography (CT) of brain revealed symmetric occipital hypodense lesions with cerebral edema [Figure 1]. Anti-streptolysin-O titer was positive (571 IU/ml) and complement C3 level was low (40 mg/dl). Blood and throat swab culture were sterile. Anti-nuclear antibody and anti-double stranded DNA were negative.

Figure 1

Computed tomography of brain at admission showing areas of hypodensity in the bilateral occipital lobes white matter with mild edema

Her BP gradually returned to normal range, and she slowly regained vision and sensorium within 10 h of hospitalization. The anti-hypertensive was continued and adjusted with continuous BP monitoring. Her headache subsided and she had no fever spikes or seizures after hospitalization. Hematuria and proteinuria settled in about 5 days. With the above clinical presentation, imaging appearances and complete restoration of visual function following normalization of BP, a diagnosis of PRES with PSGN was made. Follow-up CT scan 2 weeks after the first study showed complete resolution of the previous abnormal lesions [Figure 2] On a 1-year periodic follow-up in our unit, the child had no further recurrence of symptoms.

Figure 2

Follow-up CT scan of brain 2 weeks after the first study revealed complete resolution of the white matter abnormality in the occipital lobes

Discussion

Posterior reversible encephalopathy syndrome, also known as reversible posterior leukoencephalopathy syndrome (RPLS) was initially described by Hinchey et al. in 1996.[2] It is a clinico-radiological entity characterized by neurological signs (headache, seizures, vomiting, altered mental status, visual disturbances especially cortical blindness, focal neurological deficits) and radiological abnormalities of occipital white matter, usually bilateral, characterized by cerebral edema with hypodense signals on CT scan; and hyperintense signals on T2 weighted images by MRI.[3] The most common presenting symptoms were headache, seizure, altered consciousness, and cortical blindness.

Hypertensive encephalopathy, pre-eclampsia, eclampsia, systemic lupus erythematosus, Wegener granulomatosis, minimal change nephrotic syndrome, chronic renal failure, post-transplantation, hemolytic uremic syndrome, acute intermittent porphyria, thrombotic thrombocytopenic purpura, vasculitis, malignancies, hypercalcemia, oxybutynin, intravenous immunoglobulins, organ transplantation, certain immunosuppressive, and cytotoxic drugs are among the known conditions associated with PRES.[24]

Hypertension has often been emphasized as a common feature of PRES-associated conditions. Two possible mechanisms proposed in the pathophysiology of PRES are: (i) vasospasm due to acutely increased BP and (ii) loss of autoregulation. In the first hypothesis, it has been suggested that vasospasm contributes to ischemia and cytotoxic edema at regions of the arterial border zone.[5] The second, more recent hypothesis is supported by diffusion images suggesting that dilation develops in cerebral arterioles due to autoregulatory failure. The objective of cerebral autoregulation is to keep blood flow constant, and to protect the brain during changes in BP; however, sudden and severe increases in BP can impair autoregulation, and lead to arteriolar vasodilatation and endothelial dysfunction (breakdown of blood brain barrier) leading to extravasations of plasma and red blood cells causing vasogenic edema.[6] The lesions of PRES have a predilection for the parieto-occipital region, because the posterior cerebral arterial circulation supplied by the vertibro-basilar system has a lower level of sympathetic innervation and, therefore, is frequently involved.[7]

The role of neuro-imaging is to establish the initial diagnosis and to exclude other causes of neurological symptoms and signs. In PRES, noncontrast CT (NCCT) is sufficient to make the diagnosis in a proper clinical setting, revealing areas of low attenuation in posterior white matter.[8] On MRI brain, bilateral symmetrical edema in the parieto-occipital region is hyperintense on T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences, and hypointense on T1-weighted sequences.[7] Diffusion-weighted imaging (DWI) can differentiate this condition from other major diseases such as infarction that are diffusion restricted.[9]

PRES occurs most commonly in the setting of known hypertension or use of immunosuppressive agents. Though the association between PSGN and PRES has been reported earlier,[10-12] PRES revealing acute glomerulonephritis is extremely rare in children.[213] In our case, the girl presented with neurological symptoms, was found to be hypertensive, later developed gross hematuria after admission, and subsequently diagnosed with acute glomerulonephritis. She had rapid resolution of neurological symptoms with adequate treatment of hypertension.

Our case highlights the possibility that cortical blindness may develop as a complication of acute glomerulonephritis in children. Prevention of the occurrence of neurological deficits in children with acute glomerulonephritis and hypertensive encephalopathy requires careful evaluation and appropriate management of hypertension.

In conclusion, the causes of the PRES may be multifactorial. It is important to consider this diagnosis in children presenting with encephalopathy and seizures in an appropriate clinical settings. PRES is a treatable and reversible cause of acute encephalopathy with blindness, as long as an early diagnosis and appropriate treatment is made. Without prompt treatment, the syndrome may lead to permanent brain injury or neurological sequelae such as chronic epilepsy.[7] We need to be aware of this unusual neurological complication, as early recognition may improve prognosis.