Despite the high prevalence of hypertension, its underlying causes are not fully understood. In infants and children, elevated BP is defined as systolic or diastolic BP at or above the 95th percentile for sex, age, and height on three separate occasions. Hypertension in this age group is most often secondary to another medical condition, such as renal abnormalities, congenital heart disease, endocrine disorders, cerebrovascular anomalies, or medication exposure. Although renovascular disease and congenital cardiac defects are more common causes, central nervous system–mediated mechanisms are less frequently recognized. We report the case of a 7-month-old infant who presented with hypertensive encephalopathy, highlighting the importance of close BP monitoring in infants. The exact mechanism of hypertension in this case remains unknown; however, dysregulation of the baroreceptor reflex or ischemic stimulation of central vasomotor pathways due to cerebral arterial hypoplasia may have contributed to persistent sympathetic overactivity and systemic hypertension.

A 7-month-old male infant presented to our emergency department on day 24 of illness with a history of fever for 3 days at illness onset, followed by rapid breathing and abnormal body movements for 20 days and altered sensorium for 15 days. On day 5 of illness, the child was admitted to another hospital, where he required mechanical ventilation for 1 day followed by high-flow oxygen support for 10 days. Initial investigations showed leukocytosis, with a white blood cell count of 22,460/mm³, elevated C-reactive protein (CRP), and electrolytes within normal limits. Cerebrospinal fluid (CSF) analysis was suggestive of meningitis, with 39 cells/mm³, glucose of 70 mg/dL, and protein of 90 mg/dL; chest radiography suggested right middle-zone consolidation. The child was treated for acute meningoencephalitis with pneumonia and was started on injectable antimicrobial therapy, including meropenem, levofloxacin, linezolid, fluconazole, and oseltamivir; multiple antiseizure medications, including levetiracetam and valproate; injectable dexamethasone; and nebulization. However, only marginal improvement was observed. The child was subsequently referred to our center on day 24 of illness. At presentation, he was encephalopathic, with a Glasgow Coma Scale score of E2V3M5=10, heart rate of 118 beats/min, respiratory rate of 40 breaths/min, oxygen saturation of 98% on room air measured in the right hand, and BP of 150/110 mm Hg measured in the right upper limb. No significant difference was observed between upper- and lower-limb BP readings. On central nervous system examination, tone was increased in all four limbs, with right-sided predominance; hypertonia was greater in the right lower limb than in the right upper limb. Hyperreflexia was present in all four limbs. Both pupils were sluggishly reactive. Fundus examination showed grade 2 papilledema, and the remaining systemic examination was unremarkable.

Investigations performed at our center showed a total leukocyte count of 8,900/mm³ with 17% neutrophils; CRP, 11.2 mg/dL; aspartate aminotransferase/alanine aminotransferase, 61/18 IU/L; serum urea, 19 mg/dL; serum creatinine, 0.2 mg/dL; serum sodium, 145 mmol/L; serum potassium, 4.4 mmol/L; and serum calcium, 9.8 mmol/L. Metabolic workup showed random blood glucose of 120 mg/dL, lactate of 1.2 mmol/L, ammonia of 42 µmol/L, negative blood ketones, and no acidosis on blood gas analysis. CSF analysis was not repeated. An evaluation was performed to rule out secondary causes of hypertension. Contrast-enhanced abdominal computed tomography and renal Doppler ultrasonography were normal. Echocardiography and carotid artery Doppler ultrasonography showed no abnormalities. Endocrine workup showed normal findings, including triiodothyronine, 9 pmol/L; thyroxine, 26 pmol/L; thyroid-stimulating hormone, 4.67 µIU/L; serum cortisol, 142.4 nmol/L; and urinary vanillylmandelic acid, 1.6 mg/24 hours. Autoimmune testing was unremarkable. Brain magnetic resonance imaging showed cortical laminar necrosis in the bilateral perirolandic areas, old intraventricular hemorrhage, and features suggestive of hypoxic brain injury. Magnetic resonance angiography of the brain and neck revealed hypoplasia of the right vertebral artery, the A1 segment of the right anterior cerebral artery, and the left posterior communicating artery. The P1 segment of the right posterior cerebral artery appeared hypoplastic, with a prominent right posterior communicating artery suggestive of a fetal right posterior cerebral artery (Figs. 1 and 2). The remaining arteries appeared normal in course, caliber, and outline. The differential diagnosis and associated evaluations are summarized in Table 1.

The patient was diagnosed with hypertension, possibly associated with hypoplastic cerebrovascular arteries. The child initially presented with features consistent with acute meningoencephalitis and subsequently developed persistent hypertension. Despite treatment directed at suspected infection and elevated intracranial pressure (ICP), BP remained markedly elevated and improved substantially only after antihypertensive therapy was initiated. The child was started on an infusion of labetalol, an α- and β-adrenergic blocker, at 1 mg/kg/hr; the dose was gradually increased to 2 mg/kg/hr with continuous monitoring until the target BP was achieved. Levetiracetam was continued. Over the next 3 days, the infant’s sensorium improved, after which he was gradually transitioned to oral antihypertensives: labetalol, 9 mg/kg/day; amlodipine, a calcium channel blocker, 5 mg daily; and enalapril, an angiotensin-converting enzyme inhibitor, 0.5 mg/kg/day. Hypertonia persisted, and the child had lost previously attained milestones; therefore, baclofen and supportive therapies, including occupational therapy and physiotherapy, were initiated. The infant was discharged after 15 days on oral antihypertensives, baclofen, and levetiracetam. At the 6-month follow-up, BP remained between the 50th and 90th percentiles, and no further clinical deterioration was noted. Medication adherence was good, and the medications and supportive therapies were well tolerated. Although the child did not regain previously attained milestones, hypertonia decreased, and he had no recurrent seizures or episodes of altered sensorium. No evidence of nephropathy, cardiomyopathy, or retinopathy was observed during follow-up.

Hypertension in infants is rare and often missed. It warrants extensive evaluation because it is frequently secondary to an underlying chronic condition. In our case, the child presented with acute encephalopathy, seizures, and hypertension. He had been developmentally normal before the illness and was exclusively breastfed. There was no family history of genetic disease or seizures, and there was no history of maternal use of medications such as corticosteroids, antiseizure medications, or non-steroidal anti-inflammatory drugs. The antenatal history was uneventful, and the patient had no history of neonatal intensive care unit stay or previous hospital admission. No known prior risk factor for hypertension was identified; therefore, the child was investigated to determine the underlying cause. Common renal, adrenal, endocrine, cardiovascular, and infectious causes were ruled out, creating a diagnostic challenge. The only notable finding was hypoplastic cerebrovascular arteries, which may have been associated with hypertension. We propose that these vascular variants may have contributed to hypertension through a Cushing response, also known as the selfish brain hypothesis, in which diminished cerebral perfusion elicits sympathetic overactivity and activation of the renin–angiotensin–aldosterone system, with subsequent elevation of BP to preserve cerebral blood flow [3-5]. However, the absence of functional perfusion studies limits the ability to establish a direct causal relationship. Therefore, the vascular findings should be interpreted cautiously and presented as a potential association rather than definitive evidence of causation.

The precise etiology of vertebral artery hypoplasia and incomplete posterior circle of Willis in humans is not fully understood. However, emerging evidence suggests an association between gestational age and cerebral vessel tortuosity [6,7]. A recent retrospective study from the United Kingdom also found that vertebral artery hypoplasia combined with an incomplete posterior circle of Willis independently predicted hypertension in young adults, suggesting that this variant is not acquired with aging into midlife [8]. In utero exposures and gestational age may contribute to hypoplastic vessel development. Further research is needed to clarify the long-term consequences of hypoplastic cerebral vessels.

As shown in this case, hypertensive encephalopathy was followed by neurodevelopmental sequelae, underscoring the risks of delayed BP measurement in infants and children. Key barriers may include the lack of appropriately sized BP cuffs, particularly in developing countries such as India, and limited awareness among health care workers regarding the importance of BP measurement in pediatric patients. We therefore recommend BP measurement in pediatric patients who present to the emergency department with neurological signs or symptoms, regardless of age. Distinguishing hypertension as a primary cause of encephalopathy from hypertension secondary to elevated ICP remains a clinical challenge; therefore, a detailed history and examination are central to diagnosis. The use of appropriately sized BP cuffs and comparison of measured BP with age-, sex-, and height-specific percentiles are essential to avoid misinterpretation. At our center, we follow the American Academy of Pediatrics guidelines on pediatric hypertension [9].

Based on this case, hypoplastic cerebrovascular arteries may be considered a rare potential contributor to otherwise unexplained hypertension after common secondary causes have been excluded. Additional studies and case reports are needed to delineate the manifestations and clinical course of this condition in infants and children. BP measurement is essential in acutely ill children who present to the emergency department. Appropriately sized cuffs should be available in every emergency department to detect hypertension early and guide detailed evaluation and timely management. To select an appropriately sized cuff, the bladder length should be 80% to 100% of the arm circumference, and the bladder width should be at least 40% of the arm circumference [9]. Prompt, detailed evaluation is necessary to determine the etiology of hypertension. In addition to a detailed history and examination, a stepwise workup should be planned for every pediatric patient with high BP readings. Whether elevated ICP led to hypertension or vice versa remains a diagnostic dilemma. In our case, ICP was not directly measured but was inferred from clinical features, highlighting the need for detailed evaluation to delineate the chronological sequence.

Written informed consent for publication was obtained from the parents before submission to this journal. All efforts were made to conceal the child’s identity.