Case Report: Responsive Neurostimulation for Treatment of Super-Refractory Status Epilepticus
Key findings
- A 22-year-old woman without a history of injury or epilepsy was treated at another hospital for left arm myoclonic jerking, left eye deviation and left head version with intermittent impairment of awareness
- She did not respond to first- or second-line antiepileptic drugs or immunomodulatory therapy, and imaging failed to detect a malignancy; she was transferred to Massachusetts General Hospital on day 26
- The patient continued to demonstrate continuous clonic movements despite additional antiepileptic drugs, a ketogenic diet and 10 sessions of transcranial magnetic stimulation
- Responsive neurostimulation was initiated on day 75 after intracranial electrocorticography and stereo-EEG; by day 88 the patient had been discharged to rehabilitation and by day 94 she demonstrated a significant decrease in clinical seizures
- Events >40 seconds decreased 98% between days 81–90 (average number 549) and days 148–157 (average number 2; P<0.0002); the neurostimulation settings have not needed to be changed, suggesting neuromodulation of the underlying seizure network
There is no consensus about the best treatment of refractory status epilepticus (uncontrolled by first- and second-line antiepileptic drugs) or super-refractory status epilepticus (SRSE, persistent despite ≥24 hours of general anesthesia). In Annals of Clinical Translational Neurology, Massachusetts General Hospital physicians describe how regional therapy with responsive neurostimulation (RNS) controlled a months-long case of focal motor SRSE.
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Jimmy C. Yang, MD, neurosurgery resident, Mark Richardson, MD, PhD, director of the Functional Neurosurgery Program in the Department of Neurosurgery at Massachusetts General Hospital, and Sydney Cash, MD, PhD, co-director of the Center for Neurotechnology and Neurorecovery (CNTR) of the Department of Neurology at Mass General.
Initial Hospitalization
The 22-year-old female patient presented to another hospital with left visual field distortions and severe headache, which developed into left arm myoclonic jerking, left eye deviation and left head version with intermittent impairment of awareness. Scalp EEG demonstrated seizures in the right posterior region.
She continued to have electrographic and clinical seizures despite levetiracetam and lorazepam and then additional antiepileptic drugs. Initial imaging did not demonstrate a clear lesion, and laboratory test results were unremarkable. The patient eventually had a normal neurologic exam but seizures recurred on hospital day 15, requiring multiple sedatives. Empiric treatment with methylprednisolone and intravenous immunoglobulin did not result in improvement.
Initial Treatment at Mass General
The patient was transferred to Mass General on day 26. After anesthetics were discontinued, she opened her eyes to voice but could not follow commands. EEG showed right occipital periodic discharges. No malignancy was detected on positron emission tomography (PET) or MRI. Additional antiepileptic drugs and a ketogenic diet were initiated.
Repeat brain PET on day 47 suggested ongoing seizure activity in the right parietal and occipital lobes. Starting on day 52, the patient underwent 10 sessions of transcranial magnetic stimulation to those regions. She showed improvement but continued to demonstrate continuous clonic movements both while awake and asleep. This appeared consistent with epilepsia partialis continua, a type of focal motor status epilepticus.
Intracranial Recordings
Given the patient's inadequate response to multiple therapies, chronic neurostimulation was proposed. Intracranial EEG was considered necessary to understand whether a focal or diffuse approach was needed. The patient underwent a craniotomy on day 65 for placement of subdural strips, and stereo-EEG electrodes were placed on day 71, covering the deep structures around the right fronto-parieto-occipital regions and the centromedian thalamic nucleus.
Ultimately, the centromedian region did not appear to be involved in the primary organization of the patient's seizure network. In contrast, seizures were detected every two to five minutes in the right occipital posterior and right mesial parietal areas.
Chronic Neurostimulation
On day 74, the patient had a responsive neurostimulation (RNS) device implanted, and stimulation started the next day. Akin to a pacemaker, an RNS device is programmed to recognize a patient's unique pattern of seizures and automatically respond to prevent them. It also records and reports EEG data to allow tracking of treatment response.
The patient improved enough to be transferred to a rehabilitation hospital on day 88. Brain PET on day 87 showed reduced hypermetabolism, and by day 94 the patient demonstrated a significant decrease in clinical seizures.
Long events (>40 seconds) decreased 98% between days 81–90 (average number 549) and days 148–157 (average number 2; P<0.0002). Over this time, the patient resumed a normal diet and dosages of some of her antiepileptic drugs were decreased.
The patient's neurostimulation settings have not needed to be changed, suggesting neuromodulation of the underlying seizure network. RNS should be considered in other challenging cases of nonlesional SRSE.
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