Four cases of GABAB receptor encephalitis

Area of Science:

• Neuroimmunology
• Oncology

Background:

• Gamma-aminobutyric acid type B receptor (GABABR) encephalitis is a rare autoimmune neurological disorder.
• This study presents four unique cases, including the first reported in Hungary.

Observation:

• One patient experienced memory loss without seizures, showing spontaneous recovery.
• Another presented with persistent hyponatremia.
• Three patients were diagnosed with small cell lung cancer (SCLC).

Findings:

• GABABR encephalitis can manifest without epilepsy and exhibit spontaneous memory improvement.
• Cerebrospinal fluid (CSF) was abnormal in fatal cases but normal in the spontaneously improving patient.
• Brain MRI revealed medial temporal lobe abnormalities in most cases.

Implications:

• These findings highlight the variable clinical presentation of GABABR encephalitis.
• Spontaneous recovery does not exclude underlying malignancy, necessitating ongoing cancer surveillance.
• The potential for encephalitis to precede SCLC by over a year underscores the importance of thorough oncological workup.