What are the typical initial presentation symptoms of Posterior Reversible Encephalopathy Syndrome (PRES)?

Initial Presentation of Posterior Reversible Encephalopathy Syndrome (PRES)

PRES typically presents with four cardinal neurological symptoms: headache, altered mental status, visual disturbances, and seizures, occurring acutely in patients with specific risk factors such as hypertension, immunosuppression, or eclampsia. 1, 2

Core Clinical Features

Primary Neurological Symptoms

• Altered mental status is the most common presenting feature, occurring in 67% of emergency department presentations, ranging from confusion to decreased level of consciousness 3
• Headache presents in approximately 48% of patients and is a prominent early symptom 1, 3
• Seizures occur in 37% of patients at presentation, often as the initial manifestation that prompts medical evaluation 1, 3
• Visual disturbances affect 30-48% of patients and may include blurred vision, visual field defects, or cortical blindness 1, 4, 3

Secondary Clinical Features

• Focal neurologic deficits are present in 41% of cases, which can mimic stroke and complicate the diagnostic picture 3
• Nausea and vomiting occur in approximately 33% of patients as part of the acute presentation 3
• Gait instability may accompany other neurological symptoms due to posterior circulation involvement 1

Critical Risk Factors to Identify

High-Risk Patient Populations

• Hypertension is present in 82% of patients at time of presentation, with 78% having a documented history of chronic hypertension 3
• Immunosuppressive therapy or chemotherapy is active in 37% of patients at the time of PRES development, particularly cyclosporine and other immunosuppressants 1, 3
• Female gender represents 70% of cases, with eclampsia being a particularly important trigger in pregnant/postpartum women 4, 3
• Renal impairment is a common predisposing factor that contributes to blood pressure dysregulation 1, 5

Common Triggering Conditions

• Solid organ or bone marrow transplantation with associated immunosuppression 2
• Autoimmune diseases requiring immunomodulatory therapy 1, 2
• Eclampsia/pre-eclampsia in obstetric patients 4
• Cancer chemotherapy, particularly high-dose antineoplastic agents 1

Physical Examination Findings

• Markedly elevated blood pressure is typical, reflecting failure of cerebral autoregulation when blood pressure exceeds the brain's compensatory capacity 1, 6
• Asterixis may be present if metabolic encephalopathy coexists, though this is more suggestive of alternative diagnoses 7
• Decreased Glasgow Coma Scale scores reflect the severity of altered consciousness 5
• Bilateral reactive pupils are typically maintained unless severe complications develop 5

Key Diagnostic Pitfalls to Avoid

• Do not dismiss PRES in elderly patients despite its typical occurrence around age 45, as cases do occur in the geriatric population 5
• Consider PRES in patients with altered mental status and neurologic deficits when stroke has been ruled out, particularly in those with significant risk factors like active immunotherapy 3
• Recognize that symptoms are non-specific and overlap with many other neurological emergencies, requiring high clinical suspicion based on risk factor profile 1, 2
• Understand that delay in diagnosis leads to permanent neurological sequelae, making early recognition critical despite the challenging presentation 2

Clinical Context for Diagnosis

The combination of acute neurological symptoms (particularly the tetrad of headache, confusion, visual changes, and seizures) occurring in a patient with hypertension, immunosuppression, eclampsia, or renal failure should immediately raise suspicion for PRES and prompt urgent neuroimaging with MRI 1, 2, 3. The syndrome represents a medical emergency requiring immediate blood pressure management and withdrawal of offending agents to prevent irreversible brain injury 1, 2.