SUPER-refractory Status Epilepticus After Cardiac Arrest: a Multicenter, Retrospective, Cohort Study of Dual Anti-glutamate Therapy With Ketamine and Perampanel

Status epilepticus (SE) is found in 20-30% of patients in a coma after cardiac arrest, is frequently refractory to medical therapy and is usually considered a poor prognostic factor. The intensity and duration of treatment for post-anoxic refractory and super-refractory SE remains a highly controversial issue, posing the ethical dilemma between futility and premature discontinuation of care.

Although the TELSTAR randomized clinical trial demonstrated the futility of aggressive treatment in post-anoxic patients with generalized periodic pattern, the question remains open about the benefit of aggressive therapy in post-anoxic patients with SE properly defined according to the Salzburg criteria.

The latest guidelines of the European Resuscitation Council recommend the use of electroencephalogram (EEG) both for the neurological prognosis and for the diagnosis of post-cardiac arrest epileptic seizures, define the highly malignant EEG patterns (which do not include status epilepticus; while generalized periodic pattern and suppressed background are included) and recommend treatment of seizures with first-line antiepileptic therapy (levetiracetam or valproate), while there are no recommendations regarding second-line antiepileptic therapy. The same guidelines recommend a multi-modal approach, using different indicators (brainstem reflexes, somatosensory evoked potentials, EEG patterns, neuron-specific enolase [NSE] levels and neuroimaging) to arrive at the formulation of the neurological prognosis. A favorable neurological outcome is present in <15% of post-anoxic SE cases after moderate intensity treatment.

A recent study by the Epilepsy Center of the San Gerardo Hospital ASST Monza on a prospective cohort of 166 consecutive patients with cardiac arrest showed that patients with refractory post-anoxic SE and favorable prognostic indicators can achieve a good functional outcome (CPC 1-2) in > 40% of cases, if treated aggressively and prolonged with second-line anti-epileptic and anesthetic therapy.

However, there is profound uncertainty about the best combination of antiseizure medications and anesthetics to use in this condition. A pilot study of the Epilepsy Center of the San Gerardo ASST Monza hospital has shown an efficacy of 75% of anti-glutamatergic therapy with oral load of perampanel (anti-AMPA receptor), combined with different types of anesthetics (including ketamine, anti -NMDA receptor), in 8 patients with super-refractory post-anoxic SE. All patients included in this series presented the main favorable prognostic indicators (presence of brainstem reflexes, presence of N20 cortical evoked potentials, absence of generalized periodic pattern) and in 60% of cases (5 out of 8 cases) a neuroimaging with mild anoxic damage. The clinical outcome was favorable, with the achievement of functional independence in 50% of cases (4 cases out of 8) after 3 months.