Nonconvulsive Status Epilepticus in a Neurological Intensive Care Unit: Profile in a Developing Country

Abstract

Summary: Purpose: Nonconvulsive status epilepticus (NCSE)is an under-recognized cause of altered mental status. There are hardly any reported data on NCSE in developing countries.Material and Methods: Prospectively 210 consecutive patients with altered mental status admitted to neurological intensive care unit (NICU) of a tertiary care center in south India were studied for the frequency of NCSE. All patients were evaluated initially with 60-min emergent EEG (EmEEG) and subsequently by continuous EEG (cEEG) monitoring.Results: Of the 210 with altered mental status admitted to NICU, the diagnosis of NCSE was established in 22 (10.5%) patients, in 12 (55%) patients with 60-min EmEEG and in 10 (45%) after cEEG monitoring for 12 to 48 hours.Of the 22 patients with NCSE, 32% had subtle motor phenomena, these were not an initial presenting features, but were apparent during cEEG recording. Acute medical or neurologic etiology was the risk factor in 68% of patients. Central nervous system (CNS) infections and cortical sino-venous thrombosis (CSVT), respectively, accounted for 23% and 14% of the etiologies. Intravenous midazolam terminated NCSE in 19 patients and valproate in 2. Of the 15 patients with acute symptomatic NCSE, 4 (18%) had poor prognosis (3 deaths and one persistent vegetative state). The etiological risk factors in the 9 (41%) patients with excellent outcome included epilepsy (3), remote symptomatic (2), cryptogenic (1), and metabolic and drugs (3).Conclusions: The frequency of NCSE in the current study was comparable with those in prior reports from developed countries. CNS infections accounted for about a fifth of the etiology. Outcome was excellent in patients with nonacute symptomatic NCSE. Initial 60-min EmEEG may be performed in establishing the diagnosis of NCSE, but almost half of patients with NCSE will be missed with this approach.

Analysis of routine EEG usage in a general adult ICU

“…Three studies formally estimated the sensitivity of routine EEG (minimum 30 min to 1 h recording) compared with cEEG in the same patient group revealing that routine EEG detected electrographic seizures in approximately half of the patients, who manifested seizures on prolonged monitoring [4,5,6]. Nevertheless, the rates of electrographic seizure detection by routine EEG in these studies (5.7-11.4% of all patients studied) are still considerably higher than in ours (2%).…”

“…In a prospective study of patients with altered consciousness, Privitera et al [7] found NCSE in 37% of cases. More recently, Narayanan and Murthy [6] found NCSE in 10.5% of patients admitted to an NICU for altered mental status in southern India. Table 3 summarizes some of the published data on prevalence of NCSz and NCSE in different ICU environments.…”

“…Comparative studies show some utility for routine EEG in the ICU but demonstrate a lower pickup of NCSz and epileptiform abnormalities than with cEEG [4,5,6].…”

A Descriptive Analysis of Prognostic Indicators in Patients with Non-Convulsive Status Epilepticus in a Tertiary Hospital Population

“…This compares with numbers ranging from 1.2% to 37%, depending not only on the NCSE definition applied, but also on the population studied, rigour of screening, and intensity of EEG monitoring [23,[28][29][30][31][32][33]. This period prevalence is almost certainly an underestimate given this study's with unexplained alteration in mental state, and restricted use of CEEG monitoring.…”

“…Yet there have been no large controlled studies of NCSE, with most of the literature centering on small case series [10,11,21,24,28,31,32,35,48,49] and a case control study of 19 elderly [20]. Aside from a single paper assessing morbidity and mortality in 100 patients with NCSE [14], our series is the largest descriptive study of NCSE to date and the only one to systematically correlate NCSE clinical and electrographic variables with functional disability at discharge.…”