EEG leading to the diagnosis of limbic encephalitis

Area of Science:

• Neurology
• Immunology

Background:

• Limbic encephalitis is an inflammatory neurological disorder often associated with voltage-gated potassium channel antibodies (VGKC-Abs).
• Typical presentations include memory loss, seizures, and psychiatric symptoms, with brain MRI often showing medial temporal lobe hyperintensities and CSF analysis revealing pleiocytosis.

Observation:

• This study details a 69-year-old male patient diagnosed with VGKC-Abs limbic encephalitis.
• The patient exhibited generalized tonic-clonic seizures, progressive memory deficits, visual hallucinations, depression, and severe insomnia.
• Notably, the patient's brain MRI and cerebrospinal fluid (CSF) analyses were normal.

Findings:

• Electroencephalogram (EEG) revealed bilateral frontal and temporal intermittent rhythmic delta activity, along with disorganized and slowed background activity.
• These EEG findings were crucial in diagnosing limbic encephalitis despite normal MRI and CSF results.
• The patient demonstrated significant clinical and electrophysiological improvement following immunosuppressive therapy.

Implications:

• This case highlights the diagnostic utility of EEG in limbic encephalitis, particularly when conventional imaging and CSF markers are unremarkable.
• Abnormalities on EEG may serve as an additional diagnostic criterion for limbic encephalitis, complementing MRI and CSF findings.
• Early diagnosis and initiation of immunosuppressive therapy are critical for favorable outcomes in VGKC-Abs limbic encephalitis.