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<< Seizures and Status Epilepticus: Diagnosis and Management in the Emergency Department
Nonconvulsive Status Epilepticus
Nonconvulsive status epilepticus (NCS), like convulsive status epilepticus, is a state of continuous or intermittent seizure activity lasting more than thirty minutes without a return to baseline function. Nonconvulsive status can be either a primary generalized process (absence status) or secondary generalized (complex partial status). The hallmark of NCS is altered mental status and, unless it is suspected, the diagnosis is easily missed. The literature is rife with patients who present with altered mental status and were initially labeled as having psychiatric problems. Only later was the NCS recognized, either by EEG or a subsequent convulsion.137, 138, 139, 140, 141 Though the distinction is not clear in the literature, NCS in general should be distinguished from subtle generalized convulsive status epilepticus, which is the end stage of GCSE, associated with anoxic brain injury, and has a very poor prognosis.4
Epidemiology of NCS: NCS has been reported in all age groups and can be the first manifestation of a seizure disorder. Absence status has been associated with benzodiazepine withdrawal,142 use of psychotropic drugs, metabolic disorders, and chronic alcoholism. A history of a seizure disorder, especially when the patient’s symptoms are temporally related to a convulsive event, is a red flag that needs to be pursued. Prolonged “postictal periods,” persisting aphasic, somatosensory, or psychic findings after ictus all suggest possible ongoing epileptogenic activity. Automatisms, abnormal eye movements, persistent twitches, or blinking provide clues to nonconvulsive status. When NCS is suspected, the definitive test is an EEG.143
Treatment: When presented with a patient thought to be in NCS, EEG confirmation is indicated. Benzodiazepines are generally effective in terminating the seizure, though they do not provide long term control. The literature is unclear as to the urgency of controlling NCS, although there is evidence that ongoing neuronal firing does result in neuronal injury.144 A neurology consultation should be obtained to determine long-term therapy.
Epidemiology of NCS: NCS has been reported in all age groups and can be the first manifestation of a seizure disorder. Absence status has been associated with benzodiazepine withdrawal,142 use of psychotropic drugs, metabolic disorders, and chronic alcoholism. A history of a seizure disorder, especially when the patient’s symptoms are temporally related to a convulsive event, is a red flag that needs to be pursued. Prolonged “postictal periods,” persisting aphasic, somatosensory, or psychic findings after ictus all suggest possible ongoing epileptogenic activity. Automatisms, abnormal eye movements, persistent twitches, or blinking provide clues to nonconvulsive status. When NCS is suspected, the definitive test is an EEG.143
Treatment: When presented with a patient thought to be in NCS, EEG confirmation is indicated. Benzodiazepines are generally effective in terminating the seizure, though they do not provide long term control. The literature is unclear as to the urgency of controlling NCS, although there is evidence that ongoing neuronal firing does result in neuronal injury.144 A neurology consultation should be obtained to determine long-term therapy.
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