Proglonged epileptic twilight states: continuous recordings with nasopharyngeal electrodes and videotape analysis

Cyclic electrographic seizures in critically ill patients

PURPOSE

Prolonged electroencephalographic monitoring has facilitated the detection of nonconvulsive seizures. Compressed displays of EEG frequency spectra (such as compressed spectral array, CSA) can facilitate interpretation of continuous EEG by allowing the reader to observe on a single screen patterns evolving over many minutes or hours.

METHODS

Patients were identified retrospectively over a 4-year period as displaying a cycling pattern of seizures on CSA.

RESULTS

We describe a pattern of seizures recurring in a cyclic fashion in a series of 13 critically ill patients of all ages. Several patients had a gradual buildup of EEG power prior to each seizure.

CONCLUSION

We believe that while not rare, this pattern is difficult to recognize on standard EEG recording but it is readily apparent on CSA. The underlying pathophysiology of cyclic seizures is not known, but we speculate that cyclic seizures represent a form of status epilepticus in which the usual seizure terminating factors are present and transiently effective, but are inadequate to prevent resumption of the seizure activity. Studying these patients may provide insight into the pathophysiology of seizure initiation and cessation.

Rhythmic diffuse delta frequency activity presenting as an unusual EEG correlate of nonconvulsive status epilepticus: three case studies

We report three cases of nonconvulsive status epilepticus (NCSE) in which electroencephalograms (EEGs) were dominated by rhythmic or semirhythmic, high-voltage, diffuse, delta activity. These recordings initially contained little or no clear epileptiform activity. Two of these patients had prolonged episodes of NCSE, which were recorded with continuous long-term EEGs. These recordings revealed focal epileptiform discharges as well as persistent generalized epileptiform patterns. Rhythmic or semirhythmic, diffuse, delta activity with little or no clear epileptiform components has only rarely been reported with NCSE. Diffuse delta slowing is commonly seen in many toxic-metabolic encephalopathies, and this activity may occasionally appear rhythmic. EEG and clinical characteristics that may help distinguish these conditions are discussed.

Diagnosing Epilepsy in the Elderly

Elderly individuals represent the fastest-growing segment of the US population. Seizures are common among elderly persons, and the etiology, clinical presentation, and prognosis of seizure disorders can often differ between elderly patients and younger individuals. However, published information regarding the diagnosis and management of epilepsy in elderly patients is scarce. Because a number of conditions that are common in elderly patients may resemble epilepsy, diagnosis can be challenging. Cardiovascular conditions, migraines, drug effects, infections, metabolic disturbances, sleep disorders, and psychiatric disorders are all associated with signs and symptoms that may often mimic epilepsy. New paradigms must be put into practice to establish an accurate diagnosis in the elderly patient; besides an initial evaluation, the patient history and an electroencephalogram should be obtained. Proper diagnosis is essential for proper treatment in the elderly patient.

The clinical features, diagnosis, and prognosis of nonconvulsive status epilepticus

Nonconvulsive status epilepticus (NCSE) is a state of ongoing seizure activity for at least 30 minutes, with cognitive or behavioral changes, but without convulsive clinical manifestations. It requires EEG for confirmation. It has been categorized into groups having focal or generalized EEG epileptic activity; and by etiology and level of consciousness (which predict outcome). Points of contention include the evolving definition of what constitutes NCSE, various reasons for a delayed, missed, or misidentified diagnosis, and the optimal management of these conditions.

Nonconvulsive status epilepticus: clinical features and diagnostic challenges

NCSE, once thought to be a rare disorder, should be considered in any patient presenting with an alteration in mental status of indeterminate cause. The psychiatrist needs to be aware of the different clinical characteristics of this disorder as well as similarities and differences from psychiatric disorders. A history of seizure is not necessary for the diagnosis, nor is motor activity necessarily associated with NCSE. An EEG is required to confirm the diagnosis and should be performed when possible, because early recognition and treatment may improve outcome. There is usually a good response to an intravenous benzodiazepine; when response has been delayed, other anticonvulsants have been used as adjuncts. The EEG is necessary to distinguish AS from CPS so that, when indicated, the proper long-term antiepileptic drug therapy can be started. Although NCSE has been described in the literature for many years, there is still a great need for carefully designed prospective studies to help define clear guidelines to assist in clinical and management decision making and, ultimately, to improve outcomes.

Status epilepticus: a review of different syndromes, their current evaluation, and treatment

BACKGROUND

Status epilepticus (SE) encompasses a wide range of seizure types with different clinical presentations, pathophysiologies, treatment imperatives, and outcomes. The most dramatic and life-threatening form, generalized convulsive status epilepticus, has been reviewed in all of these aspects, but other less common types of SE have been described less extensively.

REVIEW SUMMARY

Definitions of generalized convulsive SE and its pathophysiology are reviewed briefly. Defining SE by a specific duration of seizures is controversial and has implications for studies and for clinical management. Several types of SE are different in their causes, presentations, and outcomes. Many are underdiagnosed. This article focuses on the pharmacology and clinical studies of several anticonvulsant medications used to treat SE. A protocol approach is not detailed. Rather, the clinical evaluation begins with meticulous diagnosis of the type of SE. Establishing the SE syndrome diagnosis and use of anticonvulsants with demonstrated effectiveness facilitate an appropriate treatment plan for individual patients. Recent developments in the basic science of SE raise the possibility of better treatments in the future.

CONCLUSIONS

As there are many types of seizures, there are also many types of SE. Each has unique presentations and treatment considerations. Review of actual clinical data from SE treatment studies should be helpful in devising the best treatment for an individual patient.

De novo absence status of late onset following withdrawal of lorazepam: a case report

The aim of this report is to describe the clinical and electroencephalographic findings seen in an elderly woman without previous history of seizures who developed a nonconvulsive generalized status epilepticus following acute withdrawal of lorazepam. Scalp video-EEG monitoring was obtained using the standard 10/20 system of electrode placement. Cognitive and speech functions were specifically tested during the evaluation. Continuous irregular rhythmic generalized 2.0-2.5 Hz sharp-and-slow wave complexes intermixed with spikes and polyspikes more prominent over the frontocentral areas were seen on the EEG. This epileptic activity was continuous and unmodified by sensory stimulation and eyes opening and closing. Intravenous injection of diazepam caused a rapid normalization of the EEG with disappearance of the clinical manifestations. De novo absence status is a specific epileptic condition that should be suspected in all elderly subjects on chronic treatment with psychotropic drugs presenting in a confusional state. An urgent EEG is essential to confirm the diagnosis.

Presentation, evaluation, and treatment of nonconvulsive status epilepticus

Nonconvulsive status epilepticus (NCSE) is much more common than is generally appreciated. It is certainly underdiagnosed, but its presentation is protean. Diagnostic criteria and treatment are controversial. Absence status is characterized by confusion or diminished responsiveness, with occasional blinking or twitching, lasting hours to days, with generalized spike and slow wave discharges on the EEG. Complex partial status consists of prolonged or repetitive complex partial seizures (with a presumed focal onset) and produces an "epileptic twilight state" with fluctuating lack of responsiveness or confusion. There is a clear overlapping of syndromes. Other confused, stuporous, or comatose patients with rapid, rhythmic, epileptiform discharges on the EEG may have "electrographic" status and should be considered in the same diagnostic category. NCSE typically occurs following supposedly controlled convulsions or other seizures, but with persistent neurologic dysfunction despite apparently adequate treatment. Confusion in the elderly or among emergency room patients is also a typical setting. The diagnosis of NCSE usually involves an abnormal mental status with diminished responsiveness, a supportive EEG, and often a response to anticonvulsant medication. All patients have clinical neurologic deficits, but the EEG findings and response to seizure medication are variable and are more controversial criteria. The response to drugs can be delayed for up to days. Experimental models and pathologic studies showing neuronal damage from status epilepticus pertain primarily to generalized convulsive status. Most morbidity from NCSE appears due to the underlying illness rather than to the NCSE itself. Some cases of prolonged NCSE or those with concomitant systemic illness, focal lesions, or very rapid epileptiform discharges may suffer more long-lasting damage. Although clinical studies show little evidence of permanent neurologic injury, the prolonged memory dysfunction in several cases and the similarities to convulsive status suggest that NCSE should be treated expeditiously. The diagnosis is important to make because NCSE impairs the patient's health significantly, and it is often a treatable and completely reversible condition.

Evidence against permanent neurologic damage from nonconvulsive status epilepticus

Nonconvulsive status epilepticus (NCSE) is much more common than is generally appreciated and is certainly underdiagnosed, but its long-term effects are largely undetermined and remain controversial. There is increasing experimental evidence that generalized convulsive status epilepticus produces lasting neuropathologic damage in the hippocampus, but experimental models often include provocation of status epilepticus (SE) by physical (e.g., electrical stimulation) and chemical (including excitotoxic) agents that may induce damage independent of the epileptiform discharges. Also, damage appears to be related to the intensity and duration of electrical stimulation. Such models usually include high-frequency discharges sustained over long periods, somewhat different from the electrical activity of typical human NCSE. Pathologic studies in humans pertain primarily to patients who have had generalized convulsive status epilepticus. Clinical studies of the effects of NCSE are mandatory, but conclusions are difficult to come by, in part because of diverse definitions of NCSE. An altered mental status is obligatory, but the pertinent EEG and medication response criteria are controversial. Response to medication can be delayed by many hours or even days. Absence SE appears to cause no lasting effects. Complex partial SE is less uniform. Most reported cases have returned to baseline neurologic function, but several well-described patients have had prolonged memory deficits. The significance of other deficits is difficult to interpret in light of concomitant vascular and other diseases causing neurologic dysfunction. Clinical series usually lack premorbid neurologic and neuropsychologic assessment. The few exceptions are complicated by preexisting mental retardation and other deficits, by the coexistence of progressive illness, by the later effects of recurrent seizures, and almost always by the confounding influence of anticonvulsant medications. Most morbidity appears attributable to the underlying illnesses rather than to the NCSE itself. It is possible that relatively infrequent cases of prolonged NCSE or those with the synergistic effect of concomitant systemic illness, focal lesions, or very rapid excitatory epileptiform discharges may suffer more long-lasting damage, but these observations are still preliminary. NCSE should be treated expeditiously because of the acute neurologic impairment of the patients, because of the attendant morbidity including physical injury, and because it may go on to generalized convulsions. There is reasonable concern about possible long-term effects, but permanent neurologic damage from NCSE has not yet been established as a mandate for urgent treatment.

Clinical implications of generalized electrographic status epilepticus

We reviewed clinical features of 48 patients without prior epilepsy who had generalized electrographic status epilepticus (ESE) identified from EEG readings. Clinical status epilepticus (SE) had occurred in 40%, but most were thought to have stopped seizing. Overall, ESE was unsuspected in 81% of patients. Many types of seizures were present before the EEG, but clinical seizures recurred in only 17 patients after diagnosis, and 18 patients (38%) never had clinical evidence of seizures. Most patients (60%) were comatose. The cause of ESE often remained uncertain though many patients had serious medical illnesses. Eighty-eight percent died, and a poor outcome was predicted by coma at the time of diagnosis (29 of 29), anoxia (15 of 15), an invariantly discharging, low-voltage background EEG (15 of 16), and refractory electrographic or clinical seizures (29 of 31). Seizure type did not predict outcome, and mortality was as high for patients without clinical evidence of seizures (89%) as for the series as a whole. ESE is often unanticipated and signifies neurologic disease with a prognosis worse than convulsive SE or the typical nonconvulsive SE; the absence of clinical seizures confers no advantage.

Non-convulsive status epilepticus in the adult mentally retarded. Classification and role of benzodiazepines

Non-convulsive status epilepticus (NCS) is rarely encountered and may appear with a psychiatric mask. As clouding of consciousness is the major ictal manifestation, the condition may easily be overlooked in the mentally retarded. We have studied 11 mentally retarded patients with NCS. Since NCS with a focal onset may have a generalized ictal EEG pattern, a classification of NCS solely based on the seizure classification may be misleading. In some patients, it is impossible, both clinically and on the basis of EEG recordings, to distinguish between continuous complex partial seizures and atypical absences. We therefore propose a revised classification of NCS based on the ictal EEG pattern and the epilepsy syndrome diagnosis (I) NCS in generalized epilepsy syndromes, (II) NCS in localization-related epilepsy, (a) with localized EEG features, (b) with generalized EEG features, and (c) with transitional EEG features, and (III) undetermined NCS. Four of our patients were classified as Group I, two as Group IIa, one as Group IIb, one as Group IIc, and three as Group III. Benzodiazepines at small or standard doses may be ineffective in terminating NCS, particularly in the Lennox-Gastaut Syndrome. The identification of trigger factors is essential. Drugs seemed to be the most important precipitants in our patients; in three, NCS was induced by recurrent rectal diazepam over-administration. This complication of rectal diazepam treatment in epilepsy has not been addressed previously.

Absence status epilepticus with computed tomographic brain changes following metrizamide myelography

Absence status epilepticus following metrizamide myelography was associated with computed tomographic scan evidence of a high concentration of the dye in brain gray matter. We suggest that absence status epilepticus is due to the direct effect of metrizamide on the cortex and that this clinically treatable condition may have escaped diagnosis in previous reports.

Confusional states and seizures. When are they related?

Although less often due to seizures than to other conditions, confusional states may be associated with complex partial seizures in adults or absence (petit mal) seizures in younger persons and children. Absence of a metabolic disorder, intoxication, or risk factors for cerebral ischemia increases the probability that seizure caused the confusional state. A computed tomographic scan or magnetic resonance imaging of the brain is essential when the patient is acutely ill or has had several recent confusional episodes. Once a seizure disorder is diagnosed, appropriate drug therapy can be started.

Complex partial status epilepticus

Clinical features, ictal manifestations, EEG and CT findings of two patients with CPS are presented. Status consisted of confusion associated with continuous focal EEG findings in both cases.

Confusional states with periodic lateralized epileptiform discharges (PLEDs): a peculiar epileptic syndrome in the elderly

The histories of seven patients over the age of 60 years are reported. They all suffered from recurrent and prolonged episodes of confusional state associated with psychic and neurologic manifestations. All episodes were accompanied by the occurrence of periodic lateralized epileptiform discharges (PLEDs) on the EEG, which became normal when the ictal episodes subsided either spontaneously or after administration of diazepam i.v. Although PLEDs may correspond to severe hemispheric lesions, serial computed tomography (CT) scan and laboratory investigations detected significant abnormalities in only one case, that of a patient with a progressive dementing outcome. In the other six patients, follow-up neuropsychological controls indicated moderate impairment of higher cortical functions according to the hemisphere involved by PLEDs. Administration of carbamazepine (CBZ) proved rather effective in preventing the recurrence of the ictal episodes. For its clinical, EEG, and prognostic features, this condition may represent a peculiar nonconvulsive status epilepticus in the elderly.

Complex partial status epilepticus: a depth-electrode study

Of 87 patients with complex partial epilepsy who were evaluated with depth electrodes, 8 developed complex partial status epilepticus (CPSE). Seizures originated extratemporally in all 8 patients. Frontal lobe onset was established in 4 patients and was probable in 1 more. Medial parietal onset was documented in 1 patient. Medial occipitoparietal onset occurred in another, and 1 patient had multifocal onsets. Even when seizures did not begin frontrally, the frontal lobes were prominently involved during CPSE. CPSE did not occur in 60 patients with seizures originating in the temporal lobe. Both recurrent clinical seizures and continuous altered behavior were observed. Some patients exhibited both clinical patterns at different times during the same episode. Depth recording consistently demonstrated recurrent isolated seizure discharges throughout episodes. The clinical patterns were related, in part, to electroencephalographic seizure frequency, duration, and intensity. Episodes of CPSE were not associated with intellectual deterioration.

Protracted epileptiform encephalopathy: an unusual form of partial complex status epilepticus

An 11-year-old previously healthy boy had an abrupt onset of partial complex, focal, multifocal, and generalized seizures, with interictal expressive aphasia, extreme emotional lability, agitation, and complex visual and auditory hallucinations. EEGs showed frequent runs of rhythmic high-voltage delta over the right and subsequently over the right and left temporal and frontal regions. All other studies were negative (repeated computed tomography, spinal fluids, viral titers, and cultures). Nadir during the second month showed virtual unresponsiveness, prolonged rhythmic motor and apneic seizures, total anorexia, and sleeplessness. Remission of the electrical and clinical seizure activity and a gradual improvement through a state of agitation and emotional lability occurred during the third and fourth months. One year later he was entirely normal. Compared with the other previously documented cases of prolonged partial complex status, this case is notable for its florid and severe symptomatology, long duration, and final benign outcome.

Case report: psychomotor status-like episodes under haloperidol treatment

Generalized and partial seizures induced by antipsychotic agents are well documented in the medical literature, but these patients generally do not present a management problem. The incidence of this phenomenon is less than 1% in both psychiatric and general medical population (Malcolm, 1972); we came upon only one report of a psychomotor status-like episode due to iatrogenic drug effect in the relevant literature (Kuschke, 1972). According to Gastaut's (1970) classification of epileptic seizures, the general term for psychomotor status is partial seizures with complex symptoms.

Ictal confusion--an electroclinical syndrome report of three adult cases with unusual features

Ictal confusion--an electro-clinical syndrome consisting of varying degrees of confusion with an EEG correlate of seizure activity, abolished by intravenous diazepam, is reported in three adult patients. The unusual features were 'de novo' occurrence in adults, a chronic course, focal neurological deficits and a poor response to anticonvulsants.

Complex partial status epilepticus in young children

Complex partial status epilepticus (CPSE) has rarely been described in children. We have recently studied four girls, aged 1 to 4 years, who presented with CPSE. Their seizures were characterized by decreased level of consciousness, lack of response to familiar persons, diminished response to pain, starting, slow visual tracking, eye deviation, picking at nearby objects, and lip smacking. Three patients developed focal clonic activity during their seizures and one progressed to a generalized motor seizure after 4 hours of CPSE. Two patients had ictal electroencephalograms demonstrating temporooccipital polyspikes and slow waves.

Epilepsy in adults

The past decade has seen advances in the management of patients with epilepsy. The development of practical long-term electroencephalographic techniques, with or without simultaneous video recording, has increased the accuracy of diagnosis of seizure types. The technique also provides clinicians and investigators with a method for establishing the clinical efficacy of antiepileptic drugs and determining their therapeutic serum concentrations. Computerized tomography has enhanced the identification of structural brain lesions. Most of the reported CT abnormalities consist of diffuse and focal atrophies, mild ventricular dilatations, and porencephalies. CT has detected tumors in 8 to 10% of the patients regardless of age or type of seizure involved. New concepts of antiepileptic drug therapy have developed from the recognition of pharmacological properties peculiar to each agent. Determination of serum antiepileptic drug levels has to be utilized to reduce the problem of pharmacokinetic variability from one patient to another and in the same patient at different times, so that dosage can be individualized to achieve maximum therapeutic effects with least toxicity. Review of the literature on pregnancy in epileptic women shows that a third to half experienced more seizures during gestation. Reduced serum levels of most antiepileptic drugs have recently been observed during gestation. Infants of epileptic women taking antiepileptic drugs have a two to three times greater risk for congenital anomalies than infants of nonepileptic women. However, with the exception of oxazolidinediones, evidence to date has not proved the teratogenicity of antiepileptic drugs. The role of genetic factors and the effect of seizures during pregnancy have not been determined. Modest progress has been made in epilepsy rehabilitation, but serious problems still remain. The unemployment rate of persons with epilepsy is twice the national average. Half of those who are successfully employed did not disclose their disorder at the time of employment. Several prognostic indicators have been reported, but the validity of many of these indicators is questionable. For example, does shorter life expectancy apply to all subgroups, or does it vary according to seizure type and cause? The life expectancy, treatment response, and probability of remission in epileptic persons must be reevaluated after consistent applications of current methods of epilepsy management.