• Vol. 34 No. 7, 417–420
  • 15 August 2005

The NORSE (New-onset Refractory Status Epilepticus) Syndrome: Defining a Disease Entity



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Introduction: To characterise a homogeneous group of patients with new-onset refractory status epilepticus (NORSE syndrome). Materials and Methods: This is a descriptive, semiprospective review of all cases of NORSE syndrome seen between 2000 and 2004 at a tertiary care public hospital in Singapore. A review of the literature was performed to identify possible additional similar cases for comparison. Results: Seven patients with NORSE syndrome were identified. Characterising features were female gender, young age, previous good health, cerebrospinal fluid pleocytosis (in 4), antecedent febrile illness (in 5), extraordinarily prolonged status epilepticus (average 32 days), failure of extensive investigations to reveal an underlying cause, catastrophic outcome as well as temporal lobe and leptomeningeal abnormality on brain magnetic resonance imaging. A review of the literature identified 12 similar patients, comprising both adults and children. Conclusions: Based on our patients and those described in the literature, we characterise the NORSE syndrome. Increased recognition of this clinical entity is needed to help delineate the underlying aetiology of this unique severe illness.

Status epilepticus (SE) describes a clinical condition characterised by an epileptic seizure or a series of seizures that lasts for at least 30 minutes without consciousness being regained.1 Some authors have added a time line of 60 minutes. The incidence of generalised convulsive status epilepticus (GCSE) is between 40 and 80 per 100,000.2 The associated mortality rate has been estimated to be as high as 22%3 and may vary from 7.6% to 19% within the first 30 days.1,3,4 After 30 minutes to 60 minutes of continuous seizures, the physiologic compensatory mechanisms break down, resulting in an increased risk of neuronal damage as the seizures persist due to systemic and metabolic disturbances as well as a direct excitotoxic effect of neuronal discharges during the seizure.1 Refractory status epilepticus (RSE) is a life-threatening condition, which is characterised by the failure to respond to first- and second-line anticonvulsant therapy.5 Risk factors predisposing patients to RSE include delay in receiving treatment, infections of the central nervous system (CNS), metabolic encephalopathy and hypoxia.3,5 Most episodes of status are thought to develop without a prior history of epilepsy, and are almost always secondary to discernible underlying cerebral pathology.1 We describe a new clinical syndrome, consisting of cases with new-onset refractory status epilepticus (abbreviated to NORSE) seen in 7 patients over the last 3 years in our institution. The impressive clinical features of female gender, young age, previous good health, very long-lasting status epilepticus, extensive negative workup, including neuropathology in 2 patients and catastrophic outcome, caused us to review the literature in search of a possibly more widespread occurrence of this clinical syndrome.

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