What is the role of neurosurgical intervention in acute necrotizing encephalopathy of childhood?

Neurosurgical Intervention in Acute Necrotizing Encephalopathy of Childhood

Neurosurgical intervention is rarely indicated as primary treatment for acute necrotizing encephalopathy of childhood (ANEC), but may be necessary in cases of acute hydrocephalus requiring external ventricular drainage.

Overview of ANEC

Acute necrotizing encephalopathy of childhood is a rare, rapidly progressing encephalopathy characterized by:

• Fever and preceding viral illness (often influenza)
• Altered level of consciousness and seizures
• Symmetrical multifocal brain lesions affecting primarily the bilateral thalami
• Additional involvement may include brainstem tegmentum, cerebral periventricular white matter, and cerebellar medulla 1

ANEC predominantly affects infants and young children, with most cases reported in East Asian populations, particularly Japan and Taiwan, suggesting possible genetic predisposition 2, 1.

Clinical Presentation and Diagnosis

The typical presentation includes:

• Preceding febrile illness (usually 2-4 days before neurological symptoms)
• Rapid deterioration of consciousness
• Convulsions
• Hyperpyrexia

Diagnosis is based on:

• Clinical presentation
• Characteristic neuroimaging findings showing symmetrical lesions in bilateral thalami
• Additional involvement may include brainstem, periventricular white matter, or cerebellum 3, 4

Neurosurgical Indications

Neurosurgical intervention in ANEC is primarily limited to:

1. Management of acute hydrocephalus:

   • Patients with new onset acute hydrocephalus should be referred for urgent neurosurgical consultation 2
   • External ventricular drainage (EVD) may be required in cases of persistent elevated intracranial pressure 2

2. Monitoring and management of intracranial pressure (ICP):

   • In cases with signs of increased ICP, monitoring may be warranted 5
   • First-line measures include head elevation at 20-30°, adequate sedation and analgesia, maintaining euvolemia, and treating fever and seizures 5

3. Decompressive surgery:

   • May be considered in rare cases of severe cerebral edema with refractory intracranial hypertension 5
   • Decision should be made on a case-by-case basis after multidisciplinary discussion

Primary Treatment Approach

The primary management of ANEC is medical rather than surgical:

1. Initial empirical treatment:

   • Antibiotics and antiviral agents (particularly against influenza) 6

2. Immunomodulatory therapy:

   • Intravenous immunoglobulin (IVIG)
   • IV Methylprednisolone 6

3. Supportive care:

   • Seizure control
   • Respiratory support
   • Maintenance of cerebral perfusion pressure (≥60 mmHg) 5
   • Prevention of secondary brain injury

Outcomes and Prognosis

ANEC has historically had poor outcomes:

• Mortality rates of up to 25% have been reported in recent series 6
• Less than 10% of patients recover completely 3
• Survivors often have neurological sequelae
• Early intervention with IVIG and IV Methylprednisolone may improve outcomes 6

Key Considerations for Neurosurgical Decision-Making

When evaluating the need for neurosurgical intervention:

1. Assess for hydrocephalus:

   • CT or MRI evidence of ventricular enlargement
   • Signs of increased ICP (altered mental status, pupillary changes)

2. Monitor for cerebral edema:

   • Serial neurological examinations
   • Repeat neuroimaging if clinical deterioration occurs

3. Consider neurosurgical consultation when:

   • Evidence of acute hydrocephalus requiring CSF diversion 2
   • Refractory intracranial hypertension despite medical management
   • Progressive neurological deterioration with mass effect on imaging

Pitfalls and Caveats

• ANEC can be confused with other encephalopathies including Reye's syndrome, Leigh syndrome, and Wernicke encephalopathy 1
• Spinal cord involvement has been reported in rare cases and requires special attention 4
• Avoid aspirin in children with suspected viral illnesses due to risk of Reye's syndrome 2
• The decision for neurosurgical intervention must be weighed against the overall poor prognosis of the disease in many cases

In conclusion, while neurosurgical intervention is not the primary treatment modality for ANEC, prompt neurosurgical consultation is warranted in cases complicated by hydrocephalus or refractory increased intracranial pressure. The mainstay of treatment remains medical management with immunomodulatory therapy and supportive care.