PRES

PRES
Name	PRES
Field	Neurology
Symptoms	Headache, seizures, visual disturbance, altered consciousness
Complications	Ischaemic infarction, intracerebral haemorrhage
Onset	Acute to subacute
Duration	Reversible with treatment
Causes	Hypertensive emergency, eclampsia, immunosuppressive therapy
Risks	Preeclampsia, renal failure, cytotoxic agents
Diagnosis	Clinical assessment, MRI
Differential	Cerebral infarction, encephalitis, posterior circulation stroke
Treatment	Blood pressure control, seizure management, withdrawal of offending agents

PRES

Posterior reversible encephalopathy syndrome (PRES) is an acute neurotoxic state characterised by headache, seizures, visual disturbance and altered consciousness occurring in association with variable blood pressure elevation, systemic illness, or exposure to specific medications. It is typically reversible with prompt recognition and treatment but can progress to infarction or haemorrhage if unaddressed. Clinical recognition relies on correlating presentation with imaging patterns and antecedent conditions such as hypertensive emergency, eclampsia, or exposure to cytotoxic agents.

Signs and symptoms

Patients commonly present with sudden onset headache, focal or generalised seizures, visual symptoms (including cortical blindness and visual field deficits), and varying levels of encephalopathy. Associated features include nausea, vomiting, focal neurological deficits and status epilepticus. Presentations often overlap with acute hypertensive crises seen in settings such as preeclampsia/eclampsia and renal transplantation, and may mimic acute presentations in stroke units, intensive care units and obstetric wards.

Causes and risk factors

PRES occurs in association with hypertensive emergency and rapid blood pressure fluctuations, severe preeclampsia and eclampsia in obstetrics, renal failure and uremia in nephrology, and following exposure to immunosuppressive and cytotoxic agents such as tacrolimus, cyclosporine, bevacizumab and cisplatin. Additional associations include systemic autoimmune diseases such as systemic lupus erythematosus, sepsis and multiorgan failure in critical care, organ transplantation in transplant surgery, and hematologic malignancies treated with cytotoxic chemotherapy in oncology. Other reported precipitants include severe pancreatitis, electrolyte disturbances, and contrast agents used in interventional radiology and cardiology.

Pathophysiology

Pathophysiology is incompletely understood but centres on endothelial dysfunction with blood–brain barrier disruption leading to vasogenic oedema, particularly in the posterior circulation territories supplied by the vertebrobasilar system. Hypertensive surges can exceed autoregulatory capacity causing hyperperfusion and capillary leakage, whereas cytotoxic agents and inflammatory states produce direct endothelial injury resulting in increased permeability. Predilection for parieto-occipital lobes has been attributed to relative paucity of sympathetic innervation in posterior cerebral autoregulatory pathways, with potential contributions from microvascular ischemia and impaired cerebral autoregulation described in critical care, nephrology and obstetric literature.

Diagnosis

Diagnosis is clinical and radiological, integrating acute neurologic symptoms with risk factors from obstetrics, oncology, nephrology, or transplantation, and supportive laboratory findings such as elevated creatinine or evidence of systemic inflammation in rheumatology or infectious disease contexts. Electroencephalography is useful to detect non-convulsive seizures in neurology consults. Exclusion of differential entities like posterior circulation stroke, herpes encephalitis, central nervous system vasculitis, and osmotic demyelination requires collaboration with stroke teams, infectious disease specialists, and neuroradiology. Ancillary tests include blood pressure monitoring, renal function panels in nephrology, coagulation profiles in haematology, and drug level assessments in transplant medicine.

Imaging findings

Magnetic resonance imaging with T2-weighted and fluid-attenuated inversion recovery sequences classically shows symmetric subcortical vasogenic oedema in parieto-occipital regions; involvement of frontal lobes, temporal lobes, cerebellum and brainstem is common. Diffusion-weighted imaging typically demonstrates vasogenic rather than cytotoxic oedema, with increased apparent diffusion coefficient values distinguishing PRES from acute infarction identified in stroke imaging protocols. Contrast-enhanced studies and susceptibility-weighted imaging can reveal focal enhancement or haemorrhagic conversion. Computed tomography may show hypodensities in posterior regions when MRI is unavailable; perfusion imaging and angiography may demonstrate vasoconstriction or posterior reversible vasoconstriction syndrome overlaps encountered in neuroradiology and vascular neurology.

Differential diagnosis

Key differentials include acute posterior circulation ischaemic stroke managed by stroke services, herpes simplex encephalitis assessed by virology and infectious diseases, acute hypertensive encephalopathy seen in cardiology and emergency medicine, autoimmune encephalitis evaluated by neurology and rheumatology, central pontine and extrapontine myelinolysis managed in hepatology and critical care, and cerebral venous sinus thrombosis encountered in obstetrics and hematology. Other considerations are toxic leukoencephalopathy from chemotherapeutic agents in oncology, metabolic encephalopathies in nephrology and intensive care, and intracerebral haemorrhage requiring neurosurgical consultation.

Management and prognosis

Management focuses on removal or reversal of triggers: aggressive but controlled blood pressure reduction as advised by hypertension guidelines and critical care protocols, withdrawal or dose adjustment of offending immunosuppressive or cytotoxic drugs under transplant or oncology guidance, seizure control with antiepileptic drugs per neurology recommendations, and supportive care in intensive care units for respiratory or hemodynamic instability. Obstetric cases require coordination with maternal–fetal medicine and may necessitate delivery in eclampsia. Prognosis is favourable for most patients with clinical and radiological reversal over days to weeks, but complications such as cortical blindness, persistent seizures, ischaemic infarction or intracerebral haemorrhage can result in permanent deficits or increased mortality, necessitating follow-up by neurology, rehabilitation medicine and specialty clinics.

Category:Neurological disorders