Does leukoencephalopathy show on Electroencephalogram (EEG)?

Leukoencephalopathy Detection on EEG

Leukoencephalopathy is not directly detectable on EEG, as EEG primarily measures cortical electrical activity rather than white matter structural changes. 1

Diagnostic Approach for Leukoencephalopathy

Primary Diagnostic Modality

• MRI is the gold standard for diagnosing leukoencephalopathy, showing characteristic white matter hyperintensities on T2/FLAIR sequences
• MRI can reveal confluent subcortical white matter changes and sometimes restricted diffusion patterns 2

Role of EEG in Leukoencephalopathy

EEG findings in patients with leukoencephalopathy are:

• Non-specific and secondary to the white matter disease
• May show diffuse slowing of background activity 2
• Cannot directly visualize or diagnose white matter pathology
• May be completely normal despite significant white matter disease

In a case of cocaine-induced toxic leukoencephalopathy, EEG showed only mild diffuse slowing despite extensive white matter abnormalities on MRI 2.

Clinical Context

When evaluating patients with suspected leukoencephalopathy:

1. MRI is essential - T2/FLAIR sequences are most sensitive for white matter changes
2. EEG serves as an adjunctive test to:
   • Detect associated seizure activity
   • Assess overall brain function/encephalopathy
   • Rule out non-convulsive status epilepticus
   • Monitor treatment response if seizures are present 1

Specific EEG Patterns

While not diagnostic of leukoencephalopathy itself, EEG may show:

• Diffuse slowing (most common finding)
• Focal abnormalities corresponding to areas of severe white matter involvement
• Normal findings despite significant white matter disease 2

Important Distinctions

• Autoimmune encephalitis: May show specific EEG patterns like extreme delta brush in NMDAR encephalitis, but these reflect cortical dysfunction rather than white matter disease 1
• Hepatic encephalopathy: Shows characteristic triphasic waves on EEG, reflecting metabolic dysfunction rather than white matter pathology 1

Clinical Implications

For patients with suspected leukoencephalopathy:

1. Obtain MRI as the primary diagnostic test
2. Consider EEG to assess for:
   • Seizure activity that may complicate the clinical picture
   • Overall brain function
   • Response to treatment if seizures are present

Conclusion

For definitive diagnosis of leukoencephalopathy, MRI remains the essential imaging modality, while EEG provides complementary information about brain function but cannot directly detect white matter pathology.