Abstracts

Rationale:
Super refractory status epilepticus (SRSE) is continuous or recurrent seizures despite treatment with IV anesthesia. Evidence for treatment is limited. Interventions studied include medication, ketogenic diet, hypothermia, and surgical treatment with varying rates of success. We report a case of responsive neurostimulation (RNS) successfully treating an MRI normal patient with SRSE.
Method:
A 29-year-old man with autism spectrum disorder and epilepsy since age 5 presented in refractory status epilepticus. Semiology was bilateral arm tonic, occasionally with right asymmetry lasting up to 30 seconds. Baseline seizure frequency was nightly, with clusters occurring every 6 months. Neurological examination and remaining history were unremarkable. Brain MRI was unremarkable. EEG findings revealed a Cz seizure pattern of low amplitude fast activity followed by 1-2 seconds of rhythmic delta with up to 93 seizures daily. PET imaging showed left superior frontal gyrus hypometabolism; however ictal single photon emission tomography demonstrated right superior frontal gyrus increased uptake (Fig. 1). Seizures persisted despite six concurrent AEDs and subsequent elective intubation and IV anesthesia. He underwent stereoencephalography (SEEG) bilaterally to the superior, middle and inferior frontal gyri, as well as to the posterior cingulate. SEEG revealed an ictal pattern of rhythmic fast polyspike activity in the left > right SMA (Fig. 2). RNS implantation was discussed with family who elected to proceed. He underwent RNS implantation with two depth electrodes targeting bilateral SMA on day 17. He experienced seizure freedom post-operatively for 24 hours after which seizures recurred, although significantly improved and no longer in status epilepticus. Initial stimulation on hospital day 20 (POD #1) resulted in seizure frequency reduction greater than 50%, with settings at 1.0mA, 160µs pulse, 100ms burst duration and a charge density of 2.0µC/cm2. This also allowed decrease of his AED burden.  On day 36, the patient was discharged to inpatient rehabilitation. Current was increased to 2.0mA on Day 47 for further control. Upon 3 month follow up, the patient’s caregivers reported a > 90% seizure reduction, as well as no seizure clusters. They also reported improved language and psychomotor function.
Results:
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Conclusion:
To our knowledge, we present the second case of RNS treated SRSE and the first case without underlying MRI pathology. After a prolonged period of SRSE, RNS implantation immediately resolved the SRSE. At 3 months there was >90% seizure reduction without clusters. For patients in SRSE with a localizable epileptogenic region, RNS can be considered as a treatment strategy.
Funding:
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