What are the clinical features and management of dengue encephalitis in patients with a history of travel to or residence in areas endemic for dengue (Dengue virus)?

Dengue Encephalitis: Clinical Features and Management

Dengue encephalitis presents with fever, headache, altered consciousness, and seizures in patients from endemic areas, requiring urgent ICU assessment for airway protection and aggressive supportive care, as no specific antiviral treatment exists and the condition carries a 20-30% case-fatality rate. 1

Clinical Features

Core Neurological Manifestations

• Altered mental status ranging from temporal-spatial disorientation to profound coma is the hallmark feature 2
• Seizures occur frequently, including generalized seizures and focal status epilepticus (epilepsia partialis continua) 3, 4
• Fever and severe headache with retro-orbital pain typically precede neurological symptoms 4, 5
• Behavioral changes including lethargy, restlessness, and acute cognitive dysfunction 6, 4

Spectrum of Neurological Complications

Dengue encephalitis represents one manifestation within a broader spectrum that includes encephalopathy (from metabolic derangements), myelitis, Guillain-Barré syndrome, myositis, and neuro-ophthalmic involvement 4, 5. The incidence of neurological complications ranges from 0.5-21% of hospitalized dengue patients, with dengue identified in 4-47% of encephalitis-like illness admissions in endemic areas 5.

Warning Signs Requiring Immediate Attention

• Persistent vomiting and severe abdominal pain/tenderness 6
• Progressive lethargy or restlessness 6
• Clinical fluid accumulation with hematocrit rise and concurrent thrombocytopenia 6
• Mucosal bleeding and hepatomegaly 6

These warning signs typically appear around days 3-7 of illness, coinciding with defervescence 6.

Diagnostic Evaluation

Cerebrospinal Fluid Analysis

• CSF may be normal in up to one-third of cases, making diagnosis challenging 2
• When abnormal, CSF typically shows increased protein concentration and pleocytosis 2
• CSF PCR for dengue virus is the definitive diagnostic test and should be obtained unless contraindicated by raised intracranial pressure or coagulopathy 1, 2
• Lumbar puncture should be performed with CSF PCR results available within 24-48 hours 1

Neuroimaging

• MRI is preferred over CT and should be performed as soon as possible, under general anesthesia if needed 1
• Neuroimaging findings are varied, nonspecific, and can be normal in 40-50% of cases 2
• Urgent imaging is essential to assess for cerebral edema, intracranial hemorrhage, and other structural complications 1

Additional Diagnostic Studies

• EEG should be obtained to assess for non-convulsive seizures and help distinguish organic encephalopathy from other causes 1
• Serum dengue testing with NS1 antigen (days 1-10) or IgM antibodies (after first week) supports diagnosis 7, 6
• PCR testing on serum is most effective in the first few days during viremia 7, 6

Management Approach

Immediate Critical Care

Patients require urgent ICU assessment for airway protection, ventilatory support, optimization of cerebral perfusion pressure, and correction of electrolyte imbalances 1. Dengue encephalopathy patients are at high risk for rapid deterioration, seizures, malignant raised intracranial pressure, and aspiration 1.

• Neurological specialist consultation within 24 hours involving infectious disease specialists, neurologists, and intensive care teams 1
• Manage in neurological wards, high dependency units, or ICUs depending on severity—not general medical wards 1

Supportive Treatment (No Specific Antiviral Exists)

• Early aggressive supportive care is critical given the 20-30% case-fatality ratio 1
• Maintain adequate hydration while avoiding fluid overload that could worsen cerebral edema 1
• Use acetaminophen for fever control—never aspirin or NSAIDs due to bleeding risk 1

Management of Raised Intracranial Pressure

• Elevate head of bed to 30 degrees if cerebral edema is present on imaging or clinically suspected 1
• Consider osmotic therapy with mannitol or hypertonic saline for acute management 1
• Maintain cerebral perfusion pressure and avoid hypotension 1

Seizure Management Algorithm

First-line: Benzodiazepines (lorazepam or diazepam) 1

Second-line options:

• IV valproate 20-30 mg/kg loading dose (88% efficacy) 1
• Levetiracetam 30-60 mg/kg/day (73% efficacy) 1
• Avoid phenytoin as first choice due to lower efficacy (56%) and hypotension risk 1

Discharge Planning and Follow-Up

Rehabilitation Assessment

All patients require comprehensive rehabilitation assessment before discharge, as neurological and psychiatric sequelae (anxiety, depression, obsessive behaviors, concentration difficulties) may not be immediately apparent 1. These complications are more frequently encountered after encephalitis than other causes of acute brain injury 8.

Multidisciplinary Follow-Up

• Arrange outpatient follow-up with specific plans for neuropsychology, neuropsychiatry, speech/language therapy, physiotherapy, and occupational therapy 1
• Access to specialist brain injury rehabilitation services is key to recovery 1

Monitoring Instructions

• Monitor temperature twice daily and return if fever ≥38°C on two consecutive readings 1
• Return immediately for persistent vomiting, severe headache, altered consciousness, or new neurological symptoms 1

Critical Pitfalls to Avoid

• Do not delay ICU assessment in patients with altered consciousness—rapid deterioration is common 1
• Do not assume normal CSF excludes dengue encephalitis—up to one-third have normal CSF 2
• Do not dismiss normal neuroimaging—40-50% of cases have normal imaging 2
• Do not use aspirin or NSAIDs for fever control due to hemorrhagic complications 1
• Do not discharge without rehabilitation assessment and follow-up plans—96% report ongoing complications 8