What is the best course of action for a patient with a recent Human Rhinovirus/Enterovirus infection, presenting with worsening neurologic symptoms including speech difficulties, excessive sleepiness, reduced stamina, and staring spells?

Immediate Inpatient Neurologic Workup with Empiric IV Acyclovir

This patient requires urgent inpatient evaluation with immediate empiric IV acyclovir 10 mg/kg every 8 hours while awaiting comprehensive diagnostic workup, as the constellation of altered mental status, speech dysfunction, prolonged staring spells, and excessive somnolence following rhinovirus/enterovirus infection represents potential viral encephalitis until proven otherwise. 1

Why Empiric Acyclovir is Critical

• HSV encephalitis must be treated within 6 hours of admission if CSF/imaging results are unavailable or if the patient is severely ill or deteriorating, as delays beyond 48 hours significantly worsen outcomes 1
• The patient's progressive neurologic decline (worsening speech, prolonged unresponsiveness, persistent altered mental status) meets criteria for empiric treatment even though rhinovirus/enterovirus was detected 1
• CSF remains PCR-positive for several days after acyclovir initiation, so starting treatment does not compromise diagnostic accuracy 1
• For children aged 3 months to 12 years, the dose is 10-15 mg/kg three times daily 1

Diagnostic Priorities During Admission

Lumbar puncture with comprehensive CSF analysis is the single most important diagnostic test and should be performed immediately unless contraindicated by signs of increased intracranial pressure 1, 2

Essential CSF Testing:

• PCR for HSV-1, HSV-2, VZV, and enterovirus - this panel identifies 90% of known viral encephalitis cases 2
• CSF cell count, protein, glucose 3
• Results should be available within 24-48 hours 1

Additional Diagnostic Studies:

• MRI brain is preferred over CT for detecting encephalitis 1
• EEG monitoring is essential to identify non-convulsive seizures in patients with altered consciousness or confusion 1
• Repeat throat and rectal swabs for enterovirus (though positive results may represent prolonged shedding rather than active CNS infection) 3, 2

The Enterovirus Dilemma

While rhinovirus/enterovirus was detected on respiratory panel, this does not exclude concurrent HSV encephalitis or explain the severity of neurologic symptoms:

• Enterovirus encephalitis typically requires only supportive care, as no specific antiviral treatment is recommended for most cases 2
• However, enterovirus can cause severe neurologic complications including meningoencephalitis with seizures and altered consciousness, rhombencephalitis with ataxia and cranial nerve defects, and acute flaccid myelitis 2, 4
• The patient's prolonged staring spells (up to 10 minutes), speech dysfunction, and excessive somnolence are more severe than typical enterovirus presentations 2
• Positive respiratory enterovirus does not rule out HSV encephalitis - these can be coincidental findings rather than causal 3

Critical Care Considerations

The patient requires immediate access to pediatric ICU services given the falling level of consciousness and prolonged unresponsiveness 2

• Urgent assessment needed for airway protection, ventilatory support, and management of raised intracranial pressure 1, 2
• Multidisciplinary involvement should include neurology, infectious disease, virology, and intensive care 1
• Monitor for non-convulsive seizures with continuous EEG, as the prolonged staring spells may represent seizure activity 1

Duration of Acyclovir Therapy

If HSV encephalitis is confirmed:

• Continue IV acyclovir for 14-21 days 1
• Perform repeat lumbar puncture at completion to confirm CSF is HSV PCR-negative 1
• If CSF remains positive, continue acyclovir with weekly PCR monitoring until negative 1

If HSV is ruled out and enterovirus confirmed:

• Discontinue acyclovir and provide supportive care 2
• Consider pleconaril or intravenous immunoglobulin only in severe cases 2
• Most enterovirus infections are self-limiting and resolve within 1-3 weeks 5

Monitoring for Acyclovir Toxicity

• Reduce dose in renal impairment to prevent crystalluria and obstructive nephropathy, which affects up to 20% of patients after 4 days of IV therapy 1
• Monitor renal function closely throughout treatment 1

Common Pitfalls to Avoid

• Do not wait for PCR confirmation before starting acyclovir - the window for effective HSV treatment is narrow 1
• Do not assume respiratory enterovirus explains all neurologic symptoms - co-infection or alternative diagnoses must be excluded 3
• Do not use corticosteroids routinely while awaiting HSV results, as this may worsen outcomes in HSV encephalitis 1
• Do not discharge without definitive diagnosis - transfer to specialized neurology service within 24 hours if diagnosis unclear 1

Rehabilitation Planning

• All patients require rehabilitation assessment regardless of age 1
• Arrange outpatient follow-up with plans for ongoing therapy given the speech dysfunction and motor symptoms 1