2024 American Academy of Neurology Abstract Website

Objective:

Encephalitis has various causes including infectious, paraneoplastic, and autoimmune. GAD65-encephalitis is an autoimmune disease that potentially presents with stiff-person syndrome, cerebellar ataxia, epilepsy, limbic encephalitis, myelopathy, or brainstem dysfunction. Here were discuss an unusual case of possible GAD-65 encephalitis characterized by intractable focal seizures.

Background:

59-year-old woman with history of metastatic squamous cell carcinoma (vulvar vs cervical), treated with chemotherapy, and current Pembrolizumab who presents with of stereotyped episodes of left sided paresthesias. EEG was initially surface negative, then showed corresponding right parietal onset seizures as they progressed. Despite treatment with two anti-epileptics and steroids, she developed decreased awareness and was found to be in non-convulsive status epileptics requiring escalation of treatment.

Design/Methods:

N/A

Results:

Routine EEG:

Right parietal, low amplitude fast activity, spread to the right temporal and occipital region. Increase in amplitude, became rhythmic theta at 3 to 4 Hz

MRI brain with/without contrast:

T2 FLAIR non-enhancing cortical hyperintensities in right parafalcine and frontoparietal lobes

Repeat MRI brain

Nodular enhancement at right hippocampus

CSF:

RBC <1, TNC 9 (95% lymph), Glucose 91, Protein 45, GAD65 12.1 nmol/L

Serum: GAD65 418 nmol/L

Conclusions:

Immunotherapy has been an emerging and effective treatment for malignancy, however has also been associated with autoimmune disease including encephalitis. This patient was diagnosed with SCC and received Pembrolizumab 5 months prior to diagnosis of encephalitis. Paraneoplastic etiology is also considered in this case, however unlikely given disease stability. The clinical features, and treatment are a new concept in the field of neuroimmunology, and further studies are needed to assess the association.