Abstracts

Rationale: Nonconvulsive status epilepticus (NCSE) is a common cause of altered state of consciousness (ASC) and worsening of prognosis in critical care comatose or confused patients. It is reported that 8% of comatose without evidence of clinical seizures had nonconvulsive seizures (NCS) detected by a 30-minute routine electroencephalogram (rEEG)1. The gold-standard for diagnosis is continuous EEG (cEEG) that increase the percentage to 21%2.. The aim of this study was to analyze the percentage of NCSE in patients with ASC evaluated by rEEG in patients with no diagnosis of or evidence of clinical seizures. Methods: The digital database of Neurology Departments Electroencephalography Laboratory of Clinical Hospital - University of Sao Paulo (Brazil) was retrospectively analyzed, searching for rEEG requested for investigation of ASC during 2015. Exclusion criteria were patients whose rEEG were ordered because of seizures and only one seizure recorded during EEG (they should have at least 3 seizures), since the objective was looking for NCSE. Etiologies as cause of ASC were toxic-metabolic encephalopathy, infectious encephalopathy, acute or chronic structural lesions, miscellaneous (when more than one cause was possible) and unknown cause. Results: A total of 2215 inpatient rEEG were performed in 2015. Among them, 396 (17,9%) rEEG were ordered in 310 patients (some patients had more than one rEEG) for ASC investigation. Out of 310, 146 patients (47,1%) were female, with an average age of 54,9 years. The most common clinical hypothesis for ASC, before rEEG, was miscellaneous (98 patients, 31,6%), as shown in Figure 1. NCSE was detected in 18 (5,8%) patients, 10 female (55,6%), with an average age of 59,3 years. Out of them, the most common etiology associated to NCSE was toxic-metabolic encephalopathy (6 cases, 33,3%), as shown in Figure 2. Conclusions: The incidence of NCSE in our study is lower than other literature studies. Some conditions could explain this difference, such as the exclusion of patients with only one seizure recorded and exclusion of rEEG recorded because of clinical seizures. The main objective was to determine how often rEEG could help identify NCSE, when no clinical evidence of seizure was witnessed. The incidence found is not negligible, especially considering that seizures are treatable. Although the gold-standard is cEEG, it is not available in many intensive care-units. It is possible that patients with only one NCS recorded in rEEG could be in NCSE, as well patients with no seizure recorded could be having some seizures. The advantage of cEEG is obvious, but rEEG is a very important tool that that cannot be ruled out. References 1- Towne AR, Waterhouse EJ, Boggs JG et al. Prevalence of nonconvulsive status epilepticus in comatose patients. Neurology. 2000 Jan; 54(2): 340-5. 2- Laccheo I, Sonmezturk H, Bhatt AB et al. Non-convulsive Status Epilepticus and Non-convulsive Seizures in Neurological ICU Patients. Neurocrit Care. 2015; 22: 202-11. Funding: No funding