Introduction: Hyponatremic hypertensive syndrome (HHS) is a rare sequelae of renal artery stenosis (RAS) that can lead to malignant hypertension and neurologic complications. To our knowledge, all reported pediatric cases are secondary to unilateral RAS. Here, we present a case of HHS that led to posterior reversible encephalopathy(PRES) in a 1-year-old child due to bilateral RAS. Description: A 1-year-old male presented with status epilepticus. CT head imaging had T2 symmetric hypodensity of the deep brain and cerebellar structures, concerning for PRES in the clinical context. He was hypertensive to 174/140. Presenting labs notable for polycythemia (Hgb 16.9 g/dL), hyponatremia (129 mmol/L), acidosis (HCO3 17 mmol/L), and acute kidney injury (BUN 30 mg/dL, Cr 0.8 mg/dL). The potassium was non-reportable. His malignant hyperthermia was refractory to management with five anti-hypertensives. CT angiogram showed focal stenosis of left renal artery and presence of two right-sided renal arteries. He underwent balloon angioplasty of his right-upper and left renal artery. Both arteries had severe stenosis. The second right-sided renal artery was of normal caliper. Bilateral renal vein sampling had increased renin levels. His blood pressure stabilized post-procedure, with continued anti-hypertensive need of two agents. The child demonstrated resultant functional decline that resolved with intensive rehabilitation. The child required repeat balloon angioplasty due to recurrent stenosis 4 months after diagnosis, notable for proximal narrowing of left renal artery and right upper renal artery. He weaned off anti-hypertensive therapy without recurrence at 2-year follow-up. Discussion: HHS is classically described in unilateral RAS due to the pressure natriuresis by the contralateral kidney in response to severe hypertension. Typically, bilateral RAS presents with RAAS-mediated fluid overload and ensuing complications. This case is a rare presentation of HHS in a patient with bilateral RAS. This is hypothesized to be due to the presence of a third renal artery, allowing for sodium wasting and volume contraction. This case highlights the therapeutic challenges of this diagnosis and the neurologic implications if unrecognized.
O’Neil et al. (Sun,) studied this question.