Case Presentation: A 60 year-old female with no significant past medical history was brought in as a level 2 trauma after being involved in a motor vehicle accident. The non-contrast head CT demonstrated bilateral frontal brain lesions, prompting a brain MRI which revealed a non-enhancing T2/FLAIR hyperintense lesion in the anterior frontal lobes and crossing the genu of the corpus callosum. The patient was noted to have persistent episodes of right upper and lower extremity shaking with right gaze deviation with an awake though impaired sensorium. She was transferred to the medicine service and placed on video EEG which showed focal seizures originating in the right and left temporal lobes. The patient was noted to have focal seizures every 3-20 minutes while on 5 anti-epileptic drugs (AED). Further history from the patient’s husband indicated that the patient had developed irritability with poor impulse control and hyperphagia with associated weight gain. Workup included a lumbar puncture (LP) and brain biopsy, both unremarkable. The patient continued to have refractory seizures during this period with worsening mental status despite continual AED. Given concern for an inflammatory etiology the patient was started on dexamethasone and IVIG and a repeat LP was obtained which was positive for oligoclonal bands and anti-GAD65 antibodies. This made for a presumed diagnosis of autoimmune encephalitis. The patient was seizure free after 5 days of treatment with IVIG, dexamethasone and up-titration of AED.
Discussion: The International League Against Epilepsy published in 2017 a revised classification of seizure types. Seizures are first divided into onset: generalized, focal or unknown; subcategories for motor or non-motor and then for focal onset, retained or impaired awareness 1. With the new nomenclature, our patient was experiencing focal impaired awareness seizures with motor onset, previously known as complex partial seizures. Since the patient was having multiple unprovoked seizures while on 5 AED, she was also experiencing refractory epilepsy (RE). RE is defined as disabling seizures that continue despite appropriate trials of two AED, either alone or in combination 2. Most seizures in autoimmune encephalitis are AED resistant 3. Immunotherapy (steroids, IVIG, plasma exchange) and tumor treatment are causal treatments in autoimmune encephalitis, while AED are only for symptomatic treatment 3. Autoimmune encephalitis is being increasingly recognized as an etiology for acute onset and chronic epilepsy, accounting for more than 20% of adult epilepsy of unknown etiology 4,5. Autoimmune encephalitis should be considered early as a cause of refractory epilepsy to avoid an unnecessary brain biopsy.
Conclusions: It is imperative that autoimmune encephalitis be considered when a patient presents with RE. Early identification of autoimmune encephalitis can prevent the patient from undergoing unnecessary procedures. If the diagnosis of autoimmune encephalitis is made and a primary malignancy is not identified, the patient should be started immediately on immunotherapy. The hospitalist should be aware of the revised seizure nomenclature.