Posterior reversible encephalopathy syndrome (PRES) is a clinical-radiographic condition with diverse aetiologies characterised by diffuse but reversible subcortical vasogenic oedema seen on neuroimaging. Common triggers include hypertension, autoimmune disorders, drugs, and chemotherapy, which disrupt the brain’s autoregulatory mechanisms, leading to blood component leakage into brain tissue and subsequent local inflammation [1].
Clinical presentation typically includes headaches, altered consciousness, visual disturbances, and seizures [2]. Classic MRI findings show bilateral symmetrical hyperintensities in the posterior brain on FLAIR sequences. Still, we describe a rare variant primarily affecting the deep and subcortical anterior circulation, involving the basal ganglia and frontal lobes [1,2].
Differential diagnoses can be challenging and include conditions like reversible cerebral vasoconstriction syndrome, eclampsia, CNS vasculitis, and deep venous thrombosis (DVT) [2]. DVT is a particularly important differential diagnosis in this case, given the patient’s history of chronic kidney disease and haemodialysis, which are associated with hypercoagulability and an increased risk of venous thrombosis. DVT can cause venous congestion and secondary brain oedema, mimicking the imaging findings of PRES. Ruling out DVT is essential as its management, involving anticoagulation, differs significantly from that of PRES. A comprehensive clinical evaluation and the use of appropriate imaging modalities, such as Doppler ultrasonography or CT/MR venography, are crucial to exclude this differential and guide treatment appropriately.
Key diagnostic features include subcortical white matter oedema that resolves significantly on follow-up imaging after the triggering stimulus is addressed. The lentiform fork sign—bilateral basal ganglia hyperintensities surrounded by a hyperintense rim—is a hallmark of this anterior variant and has also been reported in acute metabolic acidosis [3].
Optimal management involves correcting the precipitating factors and controlling blood pressure. The prognosis is generally favourable with early intervention, leading to full recovery. However, severe cases can lead to persistent neurological deficits, complications such as seizures or strokes, and a small risk of mortality, emphasising the need for prompt diagnosis, targeted treatment, and careful follow-up to prevent recurrence [2,3].
Take Home Message / Teaching Points
Posterior reversible encephalopathy syndrome (PRES) is triggered by hypertension, autoimmune disorders, drugs, or chemotherapy, disrupting cerebral autoregulation. Symptoms include headache, seizures, altered consciousness, and visual disturbances. Neuroimaging typically shows posterior hyperintensities, with rare variants affecting the basal ganglia. Diagnosis relies on identifying subcortical vasogenic oedema, which resolves after treating the trigger. Early intervention, especially blood pressure control, usually leads to a good prognosis, though severe cases can result in lasting neurological deficits and seizures.
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