Electroencephalographic patterns in unresponsive pediatric patients

Cephalosporin-related neurotoxicity: Metabolic encephalopathy or non-convulsive status epilepticus?

Nonconvulsive status epilepticus in adults: Electroclinical differences between proper and comatose forms

Advanced EEG analysis tools are needed for use on unconscious or comatose patients in hospital ICU and emergency departments. Their purpose is to monitor brain state and provide warnings, by analysis of EEG, that the patient's brain is in a dangerous state of ongoing epileptic seizure activity. In this study, our objective is limited to detection of Non-Convulsive Status Epilepticus (NCSE). The proposed NCSE detection techniques start with detection and classification of 1-sec EEG features (basic rhythms, paroxysmal events, sleep events, and artifacts). On the next step, 1-sec EEG features are accumulated over a period of 1-minute and 10-element EEG State Vector (ESV) is computed. ESV vectors are passed to a multi-layer perceptron that classifies 1-min EEG epochs as: NCSE, SLOW, FAST, BURST-SUPPRESSION, or ARTIFACT. One minute epochs from 9 training and 12 test records were expertly scored into one of the 5 EEG states listed above. The ANN correctly classified 71% epochs of NCSE and 99% epochs of non-NCSE. These findings suggest the potential for accurate detection of NCSE in the ICU and emergency departments.

OBJECTIVESTo report on five patients who developed, 2 to 4 days after an intracranial neurosurgical procedure, new, persistent, focal neurological deficits which were due to inhibitory simple partial (non-convulsive) status...

Determining the prognosis in nonconvulsive status epilepticus (NCSE) is complicated by several factors: under‐recognition of NCSE with its spontaneous resolution (thus decreasing the “denominator” of total cases that will have a poor outcome); incorrect diagnosis of NCSE based on misinterpretation of EEG “epileptiform” activity; mis‐classification of certain EEG patterns as NCSE ( e.g. PLEDs; triphasic waves); and grouping of different populations that have markedly different co‐morbidities (ambulatory patients with NCSE together with comatose patients with electrographic seizure activity on EEG). There are almost no prospective studies with premorbid neuropsychometric studies, and retrospective studies typically include isolated cases, or case series that include conditions in which the cause of NCSE itself causes cognitive morbidity. To summarize available data, absence status (ambulatory generalized non‐convulsive status epilepticus) would appear to carry no lasting morbidity. Complex partial status epilepticus in ambulatory patients rarely results in measurable permanent neurologic deficit, although rarely, short or longstanding deficits may clearly occur. Because intensive treatment with intravenous anticonvulsants ( e.g. benzodiazepines or phenytoin) can confer morbidity, the equation has not yet been made as to whether the morbidity of such intensive treatment for all cases of NCSE exceeds the morbidity of the disease itself. Larger, prospective studies will be needed to truly determine the prognosis in the different types of NCSE, stratified according to associated degrees of impairment (minimally impaired, moderately obtunded, comatose).

S176. A Mean field model to study the triphasic waves in acute hepatic encephalopathy

Generalized periodic patterns with triphasic wave morphology, long referred to as triphasic waves [TWs], had been associated with metabolic encephalopathies, although other neurologic and systemic causes have since been identified. In a recent classification of periodic patterns, TWs were formally grouped with the generalized periodic discharges, which are often associated with ictal activity. The interpretation of generalized periodic patterns with TWs as nonictal can have significant implications in the management of comatose patients in nonconvulsive status epilepticus. Electrographic characteristics that help distinguish nonictal periodic patterns with TWs from generalized periodic discharge ictal patterns include (1) TWs in long runs of periodic bilaterally synchronous and symmetric discharges, maximal in frontocentral or posterior head regions with and without a frontal-to-occipital lag or posterior-to-anterior lag, respectively; (2) recurrent spontaneous and/or low-dose benzodiazepine-induced attenuation and/or suppression of the periodic pattern and replacement with a diffuse slow wave activity throughout a prolonged EEG recording; and (3) stimulation-induced activation and/or increase in frequency and/or organization of TWs. We coined the term of status triphasicus to describe the electrographic periodic pattern of TWs with these three distinct characteristics. In this article, we discuss the advantages and limitations of keeping the status triphasicus pattern as a distinct electrographic entity different from periodic ictal generalized periodic discharge patterns. We discuss the circumstances in which a status triphasicus pattern can be associated with ictal activity and propose a simple pragmatic classification of status triphasicus that encompasses the different clinical scenarios it can be associated with.

Baclofen has been reported to cause both a metabolic encephalopathy and nonconvulsive status epilepticus. Baclofen is typically used in the management of muscle spasticity but is being increasingly used to manage alcohol withdrawal and opiate dependency. Given the increasing use of baclofen we describe the clinical and electrographical features of baclofen neurotoxicity seen at our institution. The clinical and EEG features of patients with an encephalopathy in the setting of baclofen therapy were analyzed. Patients were identified via our hospital EEG database. Fourteen patients were identified having presented with an acute confusional state without identifiable cause other than baclofen use. Five patients took a deliberate overdose, three of whom were baclofen naive, two patients presented after medication prescription error, and seven patients were on stable doses (30-140 mg daily). All patients presented with an encephalopathy, one patient was reported to have clinical seizures, and seven had multifocal myoclonus. EEGs were abnormal in all patients and showed moderate to severe generalized slowing. Generalized triphasic waves occurring at 1 to 2 Hz, sometimes with an anterior to posterior phase lag, were present in 10 patients (71%), and intermittent generalized suppression of the background was seen in three patients. Three patients received small doses of intravenous benzodiazepines, resulting in a marked depression of consciousness and respiration. All patients recovered within 48 hours of baclofen discontinuation. Baclofen toxicity can produce an acute encephalopathy even at modest doses, with the EEG showing generalized slowing and triphasic waves consistent with a toxic encephalopathy. Management consists of supportive care and cessation of baclofen. Patients with baclofen neurotoxicity exhibit a marked vulnerability to the depressant effects of benzodiazepines.

We investigated the repetitive manifestation of non-convulsive status epilepticus with an uncommon ictal electroencephalographic pattern observed in two patients suffering from epilepsy (aged 29 and 55 years). The patients had suffered from epilepsy since the age of 1 and 40 years, respectively. Interictal and ictal neurological, neuropsychological and electroencephalographic investigations were carried out. Non-convulsive status started and ended abruptly, clinically as well as electroencephalographically. The ictal electroencephalographic pattern was a monomorphic alpha activity with a generalized bilateral distribution. Altered responsiveness, sometimes eyelid myoclonia (in one patient) and amnesia were the most characteristic clinical findings during non-convulsive status. Intellectual development was delayed in the patient with early onset of epilepsy. However, this was not the case in the other patient, who developed memory impairment during the course of the disease. In both patients, lamotrigine added to valproate reduced the frequency of status epileptici significantly. Obviously, these patients suffer(ed) from a type of generalized non-convulsive status epilepticus with an uncommon electroencephalographic pattern.

Nonconvulsive status epilepticus (NCSE) is a type of status epilepticus (SE) lacking a predominant motor manifestation. The annual prevalence of NCSE is estimated to reach 10 to 20 cases in every 100,000 people. While almost half of all SE cases are nonconvulsive, there are several different types of NCSE: 1) epileptic absence SE, 2) epileptic focal seizure SE with consciousness disturbance (complex partial SE), 3) de novo NCSE of late onset, 4) NCSE due to acute brain injury or prolonged consciousness disturbance after convulsive SE. An electroencephalography (EEG) evaluation is necessary to diagnose NCSE. However, continuous EEG (cEEG) monitoring over at least 24 hours is preferable to detect NCSE, as cognitive disturbances due to this condition may fluctuate over time. In addition, neuroimaging techniques, such as MRI with arterial spin labeled sequences or single photon emission computed tomography (SPECT) can demonstrate hyperperfused areas in cases of focal onset. Thus, patients presenting with alternative cognitive disturbance with or without mild confusion should be evaluated using cEEG monitoring or blood flow imaging so as not to overlook treatable NCSE.

Nonconvulsive Status Epilepticus in the Elderly: A Case Series and a Review of the Literature

Utilidad del electroencefalograma en el manejo de la epilepsia en el Servicio de Urgencias

A recent assessment of the classification of nonconvulsive status epilepticus (NCSE) has incorporated the specific electroencephalographic (EEG) patterns on a syndromic basis. Such a clinical EEG syndromic approach may enable more accurate and expedited diagnosis of particular subtypes of NCSE so as to improve therapy. Herein, we review the characteristics of subacute encephalopathy with seizures in alcoholics syndrome, a subtype of focal NCSE occurring in chronic alcoholism with specific features, including encephalopathy, lateralized periodic discharges on the EEG, chronic microvascular ischemia on neuroimaging studies, and possible recurrence when chronic antiseizure treatment is stopped.

Electrolytes Disturbances and Seizures

Twenty-six (41%) of 63 consecutive patients with triphasic waves had various types of metabolic encephalopathies while 37 patients (59%) had non-metabolic encephalopathies, usually senile dementia. Triphasic waves were not found to be specific for any single type of metabolic encephalopathy. Etiology was more closely linked to conscious level at recording than any morphological or distributional feature of the triphasic waves themselves. Thus, all 31 alert patients had non-metabolic encephalopathies while all 13 comatose patients had metabolic encephalopathies. The second, positive, component (Wave II) most often had the highest voltage while equally maximal Waves I and II occurred next most commonly. Triphasic waves were most often maximally expressed anteriorly. Among patients with metabolic encephalopathies, a posterior-anterior delay or lag of the wave II peak occurred more commonly than did the better known anterior-posterior lag. Lags occurred with both metabolic and non-metabolic conditions, but were more common with the former. No difference in quantity or mode of appearance existed between the metabolic and non-metabolic groups when matched for conscious level. Prognosis for patients with either metabolic or non-metabolic encephalopathies was unfavourable. Only 4 of 24 metabolic and one of 35 non-metabolic patients were well at follow-up over 2 years later. Forty percent of EEGs with sharp and slow wave complexes (slow spike waves) had sporadically-appearing triphasic waves. The relative amplitudes of the 3 components differed from triphasic waves in other conditions: equally maximal Waves II and III were the most usual form.