Status Epilepticus

Prospective population-based study of intermittent and continuous convulsive status epilepticus in Richmond, Virginia

PURPOSE

Previous work suggested that there is a lower mortality for convulsive status epilepticus (SE) with intermittent seizures (intermittent SE) as opposed to SE with continuous seizure activity (continuous SE). A plausible hypothesis to explain this difference is that the shorter ictal time in intermittent SE is responsible for the lower mortality in this group. This study investigates the relative contributions of total ictal time and SE duration to the differing mortalities of intermittent and continuous SE.

METHODS

Six hundred forty-five cases of prospectively identified convulsive SE were examined. Nonparametric statistical methods were used to compare continuous SE and intermittent SE variables. Multivariate logistic regression analyses were used to determine which factors were most highly associated with mortality. Intermittent SE cases were analyzed to evaluate the relative contributions of ictal time versus SE duration to mortality.

RESULTS

Intermittent SE had a significantly lower mortality than continuous SE (19.6 vs. 31.4%; p < 0.001) in adults but not in children. Intermittent and continuous SE durations did not significantly differ in adult cases but did differ in pediatric cases. Ictal time was significantly shorter than SE duration for intermittent SE in both adults and children. After adjusting for age, etiology, and SE duration, SE type (continuous SE vs. intermittent SE) was shown to have an independent effect on mortality in adults. The relative risk of mortality for continuous SE was 1.79 times that of intermittent SE (p = 0.04). After controlling for SE duration, ictal time did not significantly affect mortality in adults.

CONCLUSIONS

Intermittent and continuous convulsive SE were common in both pediatric and adult populations. Intermittent SE had a significantly lower mortality than did continuous SE. This difference in mortality was not completely explained by differences in SE duration, total ictal time, etiology, or age. Further research is needed to identify the factor(s) contributing to the significant difference in mortality between intermittent SE and continuous SE.

Hemodynamic monitoring prior to and at the time of death in status epilepticus

Status epilepticus (SE) is a common neurological and medical emergency. Despite the significant mortality associated with SE, no human data have been available regarding cardiovascular changes prior to death in patients with this condition. This study was conducted to measure hemodynamic trends in the 24 h prior to death in a series of 24 prospectively evaluated SE patients. Two distinct cardiovascular patterns of mean arterial pressure (MAP) and heart rate (HR) were observed. Ten patients had a gradual decline in MAP and/or HR, and this group was designated as having gradual cardiac decompensation (GCD). The remaining 14 patients showed no significant changes in either MAP or HR up to the time of death. This group of patients was designated as having acute cardiac decompensation (ACD). The changes in MAP and HR over the last 24 h prior to death between the GCD and ACD groups were statistically significant. Ninety percent of the GCD patients had a history of multiple risk factors for arteriosclerotic cardiovascular disease (ASCVD), while only 30% of the ACD group had a history of multiple risk factors for ASCVD. The results provide the first human data of cardiovascular events immediately preceding death in SE patients. We propose that further investigation of the cardiovascular pathophysiology of SE may provide new therapeutic interventions which could decrease the significant mortality associated with SE.

[Emergency indications of EEG in the situation of a head injury in children and adults]

After initial loss of consciousness following brain injury, background EEG may show slowing and posterior slow waves are observed, consistent with the existence of commotio cerebri, particularly in children. However, discrepancies between cerebral electrogenesis and the clinical condition may also persist for several weeks. As EEG is correlated with the stage of posttraumatic coma, its reactivity to stimuli is of value. While important EEG impairment with paroxysmal abnormalities is frequent in children, the patients' outcome is poorly correlated with initial EEG record. In intensive care units, the use of continuous digitized EEG techniques has opened new avenues. Though in case of mild risks, EEG and clinical follow-up may be sufficient after brain injury, EEG recording is recommended when computerized tomography (CT-scan) is normal in case of severe risks. When consciousness impairment is unexplained by the importance of the brain injury, emergency CT-scan is recommended, searching for intracranial hematoma. If CT-scan proves to be normal EEG should then be recorded, searching for local injury. EEG may uncover non-convulsive status epilepticus, mainly in elderly patients. In case of early seizures, EEG recording should be done within the first 24 hours following brain injury. In the post-ictal period, EEG should be recorded in emergency in case of confusional state lasting more than 30 minutes, as potential non-convulsive status epilepticus should not be underestimated. EEG is not of good predictive value for posttraumatic epilepsy; however, the existence of paroxysmal, local abnormalities is a risk factor. Recording of abnormalities may be useful for the medico-legal expert.

Prognostic value of EEG monitoring after status epilepticus: a prospective adult study

Despite the significant morbidity and mortality associated with status epilepticus (SE), little is known about changes in cortical function that occur after SE. We evaluated cortical function after clinical SE using continuous EEG monitoring lasting at least 24 h in 180 patients admitted to the Medical College of Virginia Hospitals (MCVH). The major EEG patterns observed after SE were a normal record, burst suppression, after SE ictal discharge (ASIDs), periodic lateralizing epileptiform discharges (PLEDs), attenuation, focal and generalized slowing, and epileptiform discharges. Normalization of the EEG after SE was highly correlated with good outcome. The presence of burst suppression and ASIDs was highly statistically significantly associated with mortality. PLEDs were also highly correlated with mortality, but not to the same degree as burst suppression and ASIDs. In addition, these EEG patterns were still significantly correlated with morbidity and mortality when we controlled for etiology using multivariate logistic statistical analysis. Persistent ictal activity was observed in many patients despite control of clinical seizure activity, indicating the importance of EEG monitoring to determine treatment patterns after clinical seizure activity in SE is controlled. The results indicate that certain EEG patterns (normalization of the EEG, ASIDs, burst suppression and PLEDs) are useful predictors of outcome in SE in addition to etiology. EEG monitoring after control of clinical SE is important to guide treatment of SE and is a useful technique for evaluating prognosis.

Operative strategies for patients with cortical dysplastic lesions and intractable epilepsy

Cortical dysplastic lesions (CDLs) are usually identified by magnetic resonance imaging (MRI). Clinical, electrographic and histologic findings suggest that focal CDLs (FCDLs) are highly epileptogenic, often involve the rolandic cortex, and can present variable degrees of histopathologic abnormalities. An ictal or "ictal-like" bursting pattern of electrographic activity was recorded over dysplastic cortex in 65% of our patients. Resective surgery can eliminate or significantly reduce seizure frequency in many medically intractable patients, depending on lesion location, degree, and extent of histopathologic abnormalities. Best results are achieved when complete or major excision of both the MRI-visible lesion and the cortical areas displaying ictal electrographic activity can be performed. This is more likely when the degree of histopathologic abnormality is mild to moderate or when the lesion is in a temporal lobe. More severe histopathologic abnormalities and central insular or multilobar lesions usually lead to less favorable results: either major excision of the visualized lesion is impractical or the lesion is microscopically more extensive than shown by MRI. Multilobar resection or hemispherectomy for patients with infantile spasms associated with CDLs and for patients with hemimegalencephaly are often associated with dramatic improvement in seizure control. Callosotomy can be performed in selected patients with diffuse CDLs who have intractable drop attacks.

Status Epilepticus

Status epilepticus is a medical emergency that requires prompt intervention with effective anticonvulsant drug therapy to minimize the risk of morbidity and mortality. Although status epilepticus can occur as the first presentation of seizures, it is more common in patients who have a history of epilepsy. Metabolic disturbances, stroke, infection, and head trauma can also precipitate repetitive or continuous seizures and, if possible, the underlying etiology should be corrected as the first step in effective management. Permanent neurological sequelae are more likely as the duration of status epilepticus exceeds 90 minutes. In this regard, it is essential that anticonvulsant drug therapy is initiated as soon as possible. Benzodiazepines (diazepam, Iorazepam) are commonly used as the agents of choice for early termination of status epilepticus. Phenytoin and phenobarbital are also useful because of their long-lasting anticonvulsant effects. Other agents that may be useful under special circumstances include midazolam, fosphenytoin (phenytoin prodrug), sodium valproate, paraldehyde, and high-dose barbiturates.

Refractory status epilepticus in adults

The management of status epilepticus has improved over the past 20 years, resulting in a substantial decrease in the associated morbidity and mortality. Patients who have seizures that are refractory to initial pharmacologic interventions tend to have significant underlying toxic, metabolic, structural, or infectious disorders, and therefore management of refractory status epilepticus must focus on stabilization and on identification and correction of seizure etiology. Regardless of etiology, the faster the seizures are brought under control, the better the prognosis. Risk of central nervous system injury increases after 30 minutes of seizure activity, and therefore efforts should focus on controlling the abnormal electrical discharges at the earliest time possible, preferably within one hour. Benzodiazepines, phenytoin, and phenobarbital remain the most commonly used first- and second-line anticonvulsants, have proven effective in cases of status epilepticus, and should be administered within the first 45 minutes of management. For refractory status epilepticus, pentobarbital anesthesia is evolving as an effective and recommended treatment modality and should be instituted immediately after phenytoin and phenobarbital loading. The role of other anticonvulsants remains to be investigated in controlled clinical trials.

Generalized convulsive status epilepticus: pathophysiology and treatment

The treatment of generalized convulsive status epilepticus according to a protocol, including a time schedule, prevents unnecessary delay and improves outcome. Based on a literature study and our own clinical experiences a treatment protocol is discussed with special emphasis on medical complications, choice of antiepileptic drugs, route of administration and a proper time schedule.

Status epilepticus in children. The acute management

Status epilepticus is a common pediatric emergency that may result in significant morbidity and mortality. This article provides a clinical update on generalized tonic-clonic status epilepticus in children and a practical approach to their initial stabilization and pharmacologic management. Only an organized approach to the initial stabilization and management of the child in status epilepticus will help prevent unnecessary complications and death.

Lidocaine in refractory status epilepticus: confirmation of efficacy with continuous EEG monitoring

Lidocaine was efficacious in 2 patients with refractory status epilepticus (RSE) unresponsive to several antiepileptic drugs (AEDs), including high-dose barbiturates. We confirmed the efficacy of lidocaine with, for the first time in adults, continuous EEG monitoring. Lidocaine, when properly used, may be a treatment option in RSE.

Focal neuronal migration disorders and intractable partial epilepsy: a study of 30 patients

We studied 30 patients with partial epilepsy and a radiological or pathological diagnosis of localized neuronal migration disorders, with a view to surgical treatment. Eight patients had identifiable prenatal etiological factors. The frequency of complex partial, partial motor, and secondarily generalized seizures was approximately 70% each. Drop attacks were present in 27%: Their presence usually correlated with a lesion involving the central region. Partial motor or generalized convulsive status epilepticus occurred in 30%, and was most frequently associated with extensive structural abnormalities involving two or more lobes. A full-scale intelligence quotient of less than 80 was found in 44%. Magnetic resonance imaging (MRI) was superior to computed tomography for identification of the dysplastic cortical lesions. In one third, MRI showed only subcortical abnormalities. It did not allow distinction between true pachygyria, focal cortical dysplasia, or the forme fruste of tuberous sclerosis. The epileptogenic area was usually more extensive than the lesion; it was multilobar in more than 70% of patients. Of 26 surgically treated patients, a histological diagnosis of the type of neuronal migration disorder was possible in 22: 12 had focal cortical dysplasia and 10 the forme fruste of tuberous sclerosis. In the remaining 4, no definite histological diagnosis was made, since the maximally abnormal tissue could not be examined. In the latter, and in the 4 nonoperated patients, the diagnosis of neuronal migration disorder was based on imaging findings. The presence of the forme fruste of tuberous sclerosis correlated with delayed psychomotor development and more extensive epileptogenic areas.

Retrospective inventory of EEG abnormalities in partial status epilepticus

In this retrospective study, EEG activity in partial status epilepticus (PSE) was classified into different patterns from analysis of both ictal and interictal discharges. In 64 patients with recorded PSE, continuous seizures and closely spaced seizures interrupted by only brief flat periods were uncommon. PLEDs, defined as classic periodic lateralized epileptiform discharges, and PLEDs Plus, defined as PLEDs associated with stereotyped low amplitude, were the most common abnormalities. PLEDs and PLEDs Plus can each occur alone or sequentially (sequential PLEDs) between consecutive seizures. The quantity of ictal activity was significantly lower with PLEDs, sporadic spikes and with the absence of epileptiform abnormalities than with PLEDs Plus and sequential PLEDs. EEG monitoring is important to gauge the effectiveness of treatment, particularly in patients with patterns associated with a high incidence of seizure activity, namely continuous seizures with or without flat periods, sequential PLEDs and PLEDs Plus. From serial recordings, a sequence was reconstructed which may be relied upon to further assess the need for additional energetic therapeutic measures. The reconstructed sequence differed in patients with chronic lesions since sequential PLEDs and PLEDs Plus were identified exclusively in patients with acute or subacute lesions.

Phenytoin prodrug: preclinical and clinical studies

The currently available phenytoin (PHT) solution has many disadvantages stemming from poor aqueous solubility of PHT. A novel approach to solve the problem has been the synthesis of a phosphate ester of PHT (PHT prodrug ACC-9653). This water-soluble compound is metabolized rapidly into PO4 and PHT. A four center open-label, baseline-controlled study of 43 patients with epilepsy maintained on oral twice-daily PHT monotherapy was performed to evaluate the safety and pharmacokinetic profile of the prodrug. Patients received an i.v. or i.m. dose of ACC-9653 at a dose equivalent to the patients' morning dose of PHT. Intravenous dosages were infused at a rate of 75 mg/min, and i.m. dosages were given as one or two injections. After a period of 6 days, during which patients were again maintained with oral PHT, they were given a dose of ACC-9653 via whichever route they had not yet received. The Tmax of the prodrug averaged 5.7 and 36 min (0.095 and 0.606 h) after i.v. and i.m. administrations, respectively. The elimination half-life of ACC-9653 (conversion from prodrug to PHT) after i.v. and i.m. administration was 8.4 and 32.7 min (0.140 and 0.545 h), respectively, and both were independent of the dose. The plasma clearance of ACC-9653 was not dependent on dose or route of administration and averaged 19.8 +/- 1.16 and 17.8 +/- 0.83 L/h after i.v. and i.m. administrations, respectively. The area under curve ratio of PHT after i.m. and i.v. ACC-9653 was 1.17 +/- 0.13 which was not significantly different from 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Rectal diazepam in pediatric status epilepticus

Status epilepticus is a neurologic emergency with an 8% to 12% mortality. Rapid ablation of seizure activity is imperative. Although intravenous administration of diazepam is the preferred immediate treatment, vascular access is often difficult to achieve. Rectal administration of diazepam is easily accomplished during status epilepticus. Five cases in which diazepam administered in the rectal lumen stopped seizure activity are reported. Rectal diazepam appears to be safe and efficacious. It should be considered as an alternate to intravenous therapy when immediate vascular access is delayed. Rectal diazepam may have great benefit in the prehospital setting.

High-dose lorazepam therapy for status epilepticus in a pediatric patient

This report details the management of status epilepticus with high-dose lorazepam in a 14-year-old patient who was receiving oral clonazepam, ethosuximide, and phenobarbital for an intractable seizure disorder. Although respiratory depression is a frequently cited potential complication of therapy, it did not occur in this patient despite an extraordinarily high total dose of lorazepam, possibly because of tolerance associated with benzodiazepine-receptor down-regulation in this patient's chronic clonazepam therapy. Aggressive dosing of a benzodiazepine may be required for patients receiving chronic benzodiazepine therapy.

Anticonvulsant therapy in small animals

This article includes an overview of the pathophysiology of seizures and a discussion of the mechanism of action of anticonvulsants based on the targeted physiologic processes. The commonly used anticonvulsants are classified and reviewed by chemical group. The concept, indications, and benefits of therapeutic monitoring of serum anticonvulsant concentrations are presented. The use of anticonvulsant agents for treatment of status epilepticus is addressed.

Safety, tolerance and pharmacokinetics of intravenous doses of the phosphate ester of 3-hydroxymethyl-5,5-diphenylhydantoin: a new prodrug of phenytoin

A new prodrug of phenytoin, the disodium phosphate ester of 3-hydroxymethyl-5,5-diphenylhydantoin (ACC-9653), was administered intravenously over 30 minutes to four different groups of volunteers at doses of 150, 300, 600, and 1200 mg. The prodrug and phenytoin were measured in plasma samples, collected at specified times, by specific high performance liquid chromatography (HPLC) assays. The prodrug, after achieving a maximum concentration at the end of the 30-minute infusion (Cmax 20, 36, 75, 129 micrograms/mL) declined rapidly with a half-life (t1/2) of about 8 minutes. The area under the plasma concentration-time curve (10, 19, 43, 77 mg.hr/L) was proportional to dose whereas the total clearance, 14 L/hr, was independent of dose. The volume of distribution of the prodrug, a polar, water-soluble molecule was about 2.6 L, indicating that most of the dose remained in the plasma. The concentration of phenytoin reached 90% of its maximum about 12 minutes after the end of the infusion of ACC-9653. At the dose of 1200 mg of prodrug, the average peak concentration of phenytoin was about 17 micrograms/mL, near the upper limit of the therapeutic range. Adverse reactions (lightheadedness, nystagmus, incoordination) were minor and attributed to phenytoin. No significant abnormalities in ECG, Holter monitoring, or EEG were noted after the infusion of ACC-9653.