Unusual presentation of poststreptococcal glomerulonephritis as posterior reversible encephalopathy syndrome.

Posterior reversible encephalopathy syndrome (PRES) is a rare clinicoradiologic condition manifesting with headache, seizures, altered sensorium, visual disturbances, and characteristic lesions on neuroimaging predominantly affecting the posterior regions of the brain. We report a case of an 8-year-old boy with poststreptococcal glomerulonephritis, presenting as PRES. A magnetic resonance imaging showed hyperintense lesions in bilateral frontal and parietooccipital parenchyma on fluid-attenuated inversion recovery and T2-weighted images, suggestive of "PRES." Patient made a complete neurological recovery without any deficit.

Introduction

Acute poststreptococcal glomerulonephritis (PSAGN) is a common glomerular cause of gross hematuria in children. It commonly presents as nephritic syndrome with sudden onset of gross hematuria, edema, hypertension, and renal insufficiency.[1] Varied presentations have been reported such as asymptomatic, mild syndrome, or with complications, such as myocardial dysfunction, acute renal failure, or encephalopathy.[1234] We herein report a case of an 8-year-old boy with PSAGN, presenting as posterior reversible encephalopathy syndrome (PRES).

Case Report

An 8-year-old boy presented with complaints of headache and vomiting since 3 days. He had one episode of generalized tonic clonic convulsion on the day of admission lasting for about 5 min. Following the convulsion, the child remained unconscious. He was passing cola-colored urine since 1 day. There was no history of oliguria, drug intake, head injury, or Koch's contact. On enquiry, there was history of skin infection 2 weeks back. His past, developmental, and family history were normal. On admission, the child was unconscious with a Pediatric Glasgow coma scale score of 8/15 (E2 V2 M4). His heart rate was 110/min, respiratory rate was 24/min, and blood pressure was 160/120 mm Hg in right upper arm (>95th percentile for age and sex). All his peripheral pulses were felt normally. There were no neurocutaneous markers on examination. There were multiple postpyoderma marks on the legs. His pupils were equal and reactive to light and fundoscopy was normal. There were no meningeal signs, focal neurological deficit, or cerebellar signs. Deep tendon jerks were depressed and plantars were extensors. Other systemic examination was normal. Laboratory studies revealed: Hemoglobin 9.7 g/dL, white blood count 17,200/cumm (neutrophils 70%, lymphocytes 30%), and platelet count 3.6 lac/cumm. Liver function tests, serum electrolytes and serum calcium were within normal limits. Blood urea nitrogen was 34 mg/dL and serum creatine was 1.2 mg/dL. Peripheral blood smear examination for malarial parasites was negative. Chest radiograph was normal. Urine microscopy showed 3-4 pus cells/hpf and 100-120 red blood cells/hpf. Urine culture and throat culture sent on the day of admission was negative. Ultrasound examination showed loss of corticomedullary differentiation with normal sized kidneys. Antistreptolysin titre was raised, that is, >200 IU/L. Serum complement C 3 level was 26 mg/dL (normal: 90-180 mg/dL). The child was started on nifedipine (0.3 mg/kg/dose, 6 hourly) and intravenous furosemide (1 mg/kg/dose, 8 hourly). Intravenous valproic acid (10 mg/kg/day) and anticerebral edema measures (i.e. intravenous mannitol and dexamethasone) were also started. In view of the convulsion, severe hypertension, and persistent altered sensorium a magnetic resonance (MR) imaging with fluid-attenuated inversion recovery (FLAIR) sequence was done. It showed hyperintense lesions in bilateral frontal and parietooccipital parenchyma on FLAIR images suggestive of “PRES” [Figure 1]. The blood pressure was controlled and he regained full consciousness within 48 h of admission. His repeat renal function tests done on 4th day of admission were normal. He was discharged on the 5th day of admission. Furosemide was omitted at the time of discharge and oral nifedipine was continued. On follow-up after 2 weeks, the child was asymptomatic with his blood pressure well-controlled. His nifedepine was also omitted and a repeat serum complement C3 done after 8 weeks was normal, that is, 110 mg/dL.

Figure 1

Magnetic resonance imaging brain with fluid-attenuated inversion recovery sequence shows bilateral symmetric hyperintense lesions in parieto-occipital parenchyma

Discussion

PRES was first reported in 1996 by Hinchey et al.[5] It is a rare clinico-radiologic condition manifesting with headache, vomiting, seizures, confusion, visual disturbances, and occasionally focal neurological deficit.[6] It is described mainly in conditions associated with an abrupt increase in blood pressure.[67] In children, it has been reported in association with Takayasu arteritis, ganglioneuroma, Henoch-Schönlein purpura, acute lymphoblastic leukaemia, steroids, hemolytic uremic syndrome, Addison's disease, hypertension, intraabdominal neurogenic tumours, porphyria, and bone marrow transplant.[78] PSAGN typically follows infection of the throat or skin by nephritogenic strains of group-A beta hemolytic streptococci. The pathogenesis of PSAGN is immune-complex-mediated and results in depression in the serum complement (C3) levels. Hypertension is found in up to 60% of patients with PSAGN and may be associated with hypertensive encephalopathy in 10% of the cases.[1] Encephalopathy may also result from the toxic effects of the streptococcal bacteria on the central nervous system. Very few cases of PSAGN with PRES have been reported in literature.[6] The pathophysiology of PRES in hypertensive encephalopathy has been explained by the “hyperperfusion injury" theory.[7910] A sudden rise of blood pressure overcomes the normal autoregulation of cerebral blood flow and causes dilatation of the cerebral arterioles, resulting in brain hyperperfusion. This increased perfusion pressure can overcome the blood-brain barrier, resulting in opening up of endothelial tight junctions, and leakage of plasma and red cells into the extracellular space, leading to cerebral edema (vasogenic edema). The relative paucity of sympathetic innervation in the posterior brain results in increased susceptibility to hyperperfusion and vasogenic edema during acute blood pressure elevations.[7] Computed tomography (CT) scan reveals nonenhancing hypodensities of cerebral white matter in bilateral parietooccipital lobes. Sparing of the calcarine fissure and paramedian occipital lobe structures helps differentiate PRES from bilateral infarction of the posterior cerebral artery territory. Involvement of brain stem, cerebellum, basal ganglion, and frontal lobes has also been reported.[7] MR helps to better identify lesions of affected lobes as compared with CT scan. The lesions are best visualized with MR imaging with FLAIR sequence. T2-weighted MR images, at the height of symptoms, characteristically show diffuse hyperintensity selectively involving the parietooccipital white matter. Occasionally, the lesions also involve the gray matter.[710] Children develop PRES at a lower absolute pressures than adults owing to the relative “left shift” of their range of cerebral blood flow autoregulation.[6] Early recognition of the condition, adequate control of hypertension, and appropriate anticonvulsant treatment are important in the management.[79] Anticonvulsant therapy is usually given for a short period due to the reversible nature of the condition.[7] However, irreversible cytotoxic edema, ischemia, and infarction in brain can occur due to delay in the diagnosis and treatment. This can result in long-term sequelae including neurodevelopmental delay, neurological deficits, epilepsy, persistent vision abnormalities, or even death.

In conclusion, we highlight this unusual presentation of PSAGN as posterior reversible encephalopathy syndrome. Also, physicians should maintain a high index of suspicion and consider PSAGN in their differential diagnosis when treating patients with posterior reversible encephalopathy syndrome.