Non-convulsive status epilepticus: mimics and chameleons.

Non-convulsive status epilepticus (NCSE) is an enigmatic condition with protean manifestations. It often goes unrecognised, leading to delays in its diagnosis and treatment. The principal reason for such delay is the failure to consider and request an electroencephalogram (EEG), although occasional presentations have no scalp or surface electroencephalographic correlate. In certain settings with limited EEG availability, particularly out-of-hours, clinicians should consider treating without an EEG. Patients need a careful risk-benefit analysis to assess the risks of neuronal damage and harm versus the risks of adverse effects from various intensities of therapeutic intervention. Specialists in EEG, intensive care or epilepsy are invaluable in the management of patients with possible NCSE.

Clinical utility of EEG in diagnosing and monitoring epilepsy in adults.

Electroencephalography (EEG) remains an essential diagnostic tool for people with epilepsy (PWE). The International Federation of Clinical Neurophysiology produces new guidelines as an educational service for clinicians to address gaps in knowledge in clinical neurophysiology. The current guideline was prepared in response to gaps present in epilepsy-related neurophysiological assessment and is not intended to replace sound clinical judgement in the care of PWE. Furthermore, addressing specific pathophysiological conditions of the brain that produce epilepsy is of primary importance though is beyond the scope of this guideline. Instead, our goal is to summarize the scientific evidence for the utility of EEG when diagnosing and monitoring PWE.

Hidden in plain sight: Non-convulsive status epilepticus-Recognition and management.

Non-convulsive status epilepticus (NCSE) is an electroclinical state associated with an altered level of consciousness but lacking convulsive motor activity. It can present in a multitude of ways, but classification based on the clinical presentation and electroencephalographic appearances assists in determining prognosis and planning treatment. The aggressiveness of treatment should be based on the likely prognosis and the underlying cause of the NCSE.

Early predictors of refractory status epilepticus: an international two-center study.

BACKGROUND AND PURPOSE: Status epilepticus (SE) refractory to first- and second-line antiepileptic drugs carries high mortality. Little is known on early prediction of refractory SE (RSE)­an essential tool for planning appropriate therapy. Our aim was to identify and validate independent early RSE predictors in adults. METHODS: Clinical and laboratory data on consecutive intensive care unit patients with SE from two academic care centers (a derivation data set from a Swiss center and a validation data set from a US center) were assessed. Multivariable analysis was performed with the derivation set to identify RSE predictors at SE onset. Their external validity was evaluated with an independent validation set. Measures of calibration and discrimination were assessed. RESULTS: In all, 302 patients were analyzed (138 with and 164 without RSE), 171 in the derivation data set and 131 in the validation data set. Acute SE etiology, coma/stupor and serum albumin <35 g/l at SE onset were independent predictors for RSE in the derivation data set [odds ratio (OR) 2.02, 95% confidence interval (CI) 1.01-4.07; OR 4.83, 95% CI 2.42-9.68; OR 2.45, 95% CI 1.16-5.16]. The prediction model showed good measures of calibration (Hosmer-Lemesow goodness-of-fit test P = 0.99) and discrimination (area under the receiver operating characteristic curve 0.8) on the derivation data set­results that were similar in the validation data set (Hosmer-Lemeshow P = 0.24; area under the receiver operating characteristic curve 0.73). CONCLUSIONS: This study confirms the independent prognostic value of readily available parameters for early RSE prediction. Prospective studies are needed to identify additional robust predictors, which could be added to the proposed model for further optimization towards a reliable prediction scoring system.

Electroencephalographic sleep elements and outcome in acute encephalopathic patients: a 4-year cohort study.

BACKGROUND AND PURPOSE: Acute encephalopathy in hospitalized patients is common and associated with high mortality. Preservation of physiological sleep has been associated with favorable outcomes in acute brain injury. It is hypothesized that electroencephalographic presence of sleep elements is associated with good outcome in encephalopathic adults. METHODS: This observational study was performed at an academic tertiary medical care center. Clinical data, electroencephalogram (EEG) characteristics and outcome of critically ill patients with acute encephalopathy were assessed. EEGs were interpreted regarding the presence of sleep elements (K-complexes, vertex sharp-waves and sleep spindles). Associations between sleep elements and outcome (graded by the Glasgow Outcome Scale, GOS) were analyzed. RESULTS: One hundred and forty-two consecutive patients with a median age of 64.5 years (range 18-98) and mean Glasgow Coma Scale 10.4 (± 3.8) were included. Leading etiologies were infections (47.2%), intracranial hemorrhages (14.1%) and ischaemic strokes (10.6%). All EEGs demonstrated encephalopathy patterns and 38% had ≥ 1 sleep element (27.5% K-complexes, 31.7% vertex sharp-waves and 33.8% sleep spindles). Patients without sleep elements were older (P = 0.010) and septic shock was more common (P = 0.014). Amongst sleep elements, K-complexes were significantly associated with good outcome, even after adjusting for possible confounders (odds ratio for GOS 5 = 2.79, 95% confidence interval 1.16-6.69) and without significant effect modification across subgroups. CONCLUSIONS: Whilst EEG sleep elements were detected more frequently in patients with favorable outcome, only K-complexes were significantly and independently associated with good outcome in intensive care unit patients with acute encephalopathy, findings that need to be confirmed in larger prospective studies.

Uncovering clinical and radiological associations of triphasic waves in acute encephalopathy: a case-control study.

BACKGROUND AND PURPOSE: Triphasic waves (TWs) are archetypal waveforms seen on electroencephalography (EEG) in some forms of encephalopathy. Their particular underlying pathological substrates are largely unexplored. This case-control study was designed to identify and quantify specific clinical and neuroradiological associations underlying TWs and to determine if TWs predicate outcome. METHODS: From 2004 to 2012, adult encephalopathic patients with TWs (cases) were matched 1:1 with encephalopathic patients without TWs (controls) by Glasgow Coma Scale (GCS) and the frequency range of EEG background activity. Clinical characteristics, neuroimaging and outcomes were assessed. RESULTS: The mean age of 190 patients (95 with and 95 without TWs) was 66.6 years (±15.6). In multivariable analyses, patients with TWs had significantly higher odds for liver insufficiency [odds ratio (OR) = 8.10, 95% confidence interval (CI) 1.98-33.08], alcohol abuse (OR = 3.65, 95% CI 1.25-10.63), subcortical brain atrophy (OR = 2.82, 95% CI 1.39-5.71) and respiratory tract infections (OR = 1.28, 95% CI 1.01-4.71). With each additional independent predictor, the odds increased for the occurrence of TWs (1 predictor, OR = 2.40, 95% CI 1.16-5.13; ≥2 predictors, OR = 9.20, 95% CI 3.27-25.62). Mortality was 15% and tended to be higher in patients with TWs (19% with vs. 11% without TWs). CONCLUSIONS: Alcohol abuse, liver insufficiency, infections and subcortical brain atrophy were independently associated with TWs in patients matched for clinical and EEG features of encephalopathy. These associations strengthen the hypothesis that TWs evolve from an interplay of pathological neurostructural, metabolic and toxic conditions. When matched for EEG background activity and GCS, TWs were not associated with death.

Slow pseudoperiodic lateralized epileptiform discharges in nonconvulsive status epilepticus in a patient with cerebral palsy and a large central meningioma.

The presence of cerebral palsy and that of slow growing brain tumors are risk factors for convulsive and nonconvulsive status epilepticus. Nonconvulsive status epilepticus (NCSE) needs electroencephalographic (EEG) monitoring to be confirmed as it may be clinically subtle. Furthermore, it may present with a variety of ictal EEG morphologies. We report a case of a patient with cerebral palsy and a large central meningioma. Electroencephalogram showed a slow pattern of periodic lateralized epileptiform discharges (PLEDs) (a pattern considered as being situated in the ictal-interictal continuum) on an alpha background. The patient was treated for NCSE successfully with benzodiazepines followed by up-titration of his antiepileptic drug doses.