Early Positive Brain 18F-FDG PET and Negative MRI in Rasmussen Encephalitis

Area of Science:

• Neurology
• Pediatric Neurology
• Neuroimaging

Background:

• Rasmussen encephalitis (RE) is a rare, chronic inflammatory neurological disease affecting one cerebral hemisphere.
• It typically presents in children and adolescents with intractable focal seizures, hemiparesis, and cognitive decline.
• Early and accurate diagnosis is challenging but critical for timely intervention.

Purpose of the Study:

• To highlight the utility of 18F-FDG PET in the early diagnosis of Rasmussen encephalitis.
• To present a case study illustrating the diagnostic process and treatment outcome.

Main Methods:

• A 15-year-old male with epilepsy and hemiparesis underwent electroencephalogram (EEG) and MRI.
• 18F-FDG PET imaging was performed to assess brain glucose metabolism.
• MRI and biopsy were used for confirmation, followed by surgical intervention.

Main Results:

• Initial MRI showed a lesion in the left putamen; EEG indicated right hemisphere abnormalities.
• 18F-FDG PET revealed focal hypermetabolism in the right paracentral lobule and hypometabolism in the right frontal/precentral gyri.
• A subsequent MRI showed a lesion in the paracentral lobule, confirmed by biopsy as Rasmussen encephalitis. The patient became seizure-free after hemispherotomy.

Conclusions:

• 18F-FDG PET is a valuable early diagnostic tool for Rasmussen encephalitis, detecting metabolic changes before structural MRI confirmation.
• This case underscores the importance of integrating advanced neuroimaging techniques for prompt RE diagnosis.
• Surgical intervention, such as hemispherotomy, can lead to seizure freedom in RE patients.