Periodic Lateralized Epileptiform Discharges Research Articles

Prolonged Deficits After Focal Inhibitory Seizures

Seizures are most commonly associated with positive phenomena such as tonic, clonic or myoclonic movements, automatisms, paresthesias and hallucinations. Negative phenomena, however, are not an uncommon manifestation of seizure activity. Examples of negative seizure phenomena include speech arrest, aphasia, amaurosis, amnesia, numbness, deafness, neglect and atonic seizures. Less commonly described in the literature are focal inhibitory motor seizures. Two patients presenting with rapidly progressive, prolonged hemiparesis, sensory neglect and hemi-visual field obscuration are described. Computed tomography (CT) and magnetic resonance imaging (MRI) of the brain did not reveal progression of known structural lesions or new lesions. The superficial cortex of the hemisphere contralateral to the hemiparesis and sensory neglect enhanced diffusely with gadolinium on T1-weighted MRI images. Electroencephalography demonstrated periodic lateralized epileptiform discharges (PLEDs) in one patient and lateralized suppression and slowing in the other patient. Single photon emission computed tomography (SPECT) revealed hyperperfusion in the hemisphere contralateral to the hemiparesis and sensory neglect. The changes seen on MRI and SPECT resolved with resolution of the symptoms. Taken together with the clinical history, the results from these investigations suggest focal inhibitory seizure as the underlying etiology. A review of the literature and investigations helpful in making this difficult diagnosis are provided.

Progression of P300 in a patient with bilateral hippocampal lesions

Objective To evaluate the effects of hippocampal damages on P300 of event-related potentials (ERPs). Methods ERPs were recorded over about 8 months using the auditory oddball paradigm in a patient with bilateral hippocampal lesions confirmed on brain magnetic resonance imaging. Findings were compared with those from clinical electroencephalography (periodic lateralized epileptiform discharges (PLEDs) or bilateral independent PLEDs (BIPLEDs)). The patient displayed no marked clinical symptoms aside from mild memory impairment during this time, and was able to fully perform the oddball task. Results Clearly identifiable P300 were present in all recordings. Furthermore, increases in the number of right PLEDs were significantly correlated with increases in P300 latency. Conclusions Two key results were apparent. First, the appearance of P300 in all ERP recordings supports the suggestion that the hippocampus is not indispensable for P300 generation. Second, the correlation between the number of PLEDs and P300 latency supports the suggestion that the hippocampus affect the components of P300 latency. Significance This case thus offers very suggestive evidence regarding the generation of P300.

Naturally Acquired West Nile Virus Encephalomyelitis in Transplant Recipients

In the 2003 West Nile virus (WNV) epidemic, Colorado reported more WNV cases than any other state, including an unprecedented number in organ transplant recipients. Physicians caring for transplant recipients hospitalized with naturally acquired WNV encephalitis provided data to characterize the clinical symptoms, results of diagnostic studies, and outcomes. Eleven transplant recipients were identified (4 kidney, 2 stem cell, 2 liver, 1 lung, and 2 kidney/pancreas). Seven were directly admitted to 1 of the 2 hospitals in the study, and 4 were referred to 1 of these centers from regional hospitals. All but 1 patient had a prodrome typical of WNV encephalitis in nonimmunosuppressed patients. Ten patients developed meningoencephalitis, which in 3 cases was associated with acute flaccid paralysis. One patient developed acute flaccid paralysis without encephalitis. Six patients had significant movement disorders including tremor, myoclonus, or parkinsonism. All patients had cerebrospinal fluid pleocytosis and WNV-specific IgM in the cerebrospinal fluid and/or serum. Cerebrospinal fluid cytologic studies (n = 5) showed atypical lymphocytes, some resembling plasma cells; however, flow cytometry (n = 3) showed that cells were almost exclusively of T-cell (not B-cell or plasma cell) lineage. Magnetic resonance images of the brain were abnormal in 7 of 8 tested patients, and electroencephalograms were abnormal in 7 of 7, with 2 showing periodic lateralized epileptiform discharges. Nine of 11 patients survived infection, but 3 had significant residual deficits. One patient died 17 days after admission, and autopsy findings revealed severe panencephalitic changes with multifocal areas of necrosis in the cerebral deep gray nuclei, brainstem, and spinal cord as well as diffuse macrophage influx in the periventricular white matter. A second patient died of complications of WNV encephalitis 6 months after hospital admission. Naturally acquired WNV encephalitis in transplant recipients shows diagnostic, clinical, and laboratory features similar to those reported in nonimmunocompromised individuals, but neuroimaging, electroencephalography, and autopsy results verify that these patients develop neurological damage at the severe end of the spectrum.

Full neurologic recovery after fulminant thrombotic thrombocytopenic purpura with status epilepticus

Thrombotic thrombocytopenic purpura (TTP) is an ischemic vasculopathy frequently associated with neurological dysfunction including seizures. However, status epilepticus (SE) has rarely been reported in this condition. We report on a 70-year-old woman with fulminant TTP who developed convulsive SE despite high therapeutic serum levels of phenytoin and phenobarbital. Her electroencephalogram (EEG) was characterized by bilateral independent periodic lateralizing epileptiform discharges (BIPLEDs) propagating into clinical and electrographic seizures. She recovered completely after intensive plasmapheresis and treatment with pentobarbital induced coma for 5 days. This case illustrates that aggressive treatment with pentobarbital and plasmapheresis may prevent permanent neurologic deficits when TTP is complicated by SE and that periodic lateralizing epileptiform discharges (PLEDs) in this syndrome can be the manifestation of a reversible ischemic insult.

Focal nonconvulsive status epilepticus associated to PLEDs and intense focal hyperemia in an AIDS patient

Purpose: Periodic lateralised epileptiform discharges (PLEDs) can be seen associated to nonconvulsive status epilepticus (NCSE), although their pathophysiological meaning remains questionable. Functional neuroimaging has suggested that, in this setting, PLEDs may indeed be an ictal pattern. In this report we describe perfusional changes in a patient with AIDS, PLEDs and NCSE. Methods: A 37-year-old man with AIDS, cryptococcosis and recurrent epileptic seizures was admitted. After initial treatment, he remained comatose, and had MRI and serial EEG recordings performed. Technetium-99m-ethyl cysteinate dimer (99mTc-ECD) SPECT scans were also obtained, before and after continuous benzodiazepine infusion. Results: EEG disclosed PLEDs over the right fronto-polar region while MRI revealed meningeal thickening and scattered unspecific findings. SPECT revealed marked focal hyperperfusion overlapping the areas with PLEDs, both resolved after continuous midazolam infusion and clinical improvement. Conclusions: This report demonstrates association of PLEDs, NCSE, and focal hyperperfusion on SPECT, additionally supporting the concept of PLEDs as an ictal pattern. Considering that status epilepticus may eventually not be detected by conventional approaches alone, we advocate the use of functional neuroimaging to assess suspected patients with impaired consciousness.

A Glossary of Terms Used for PLEDs (Periodic Lateralized Epileptiform Discharges) and Related EEG Patterns

ABSTRACT.Since the term periodic lateralized epileptiform discharges (PLEDs) was first coined by Chatrian et dl. in 1964, there has been an evolution of terms used to describe variants of this EEG pattern. This article is an attempt to collect and define various terms used to describe these patterns.

Occurrence of nonconvulsive seizures, periodic epileptiform discharges, and intermittent rhythmic delta activity in rat focal ischemia

A significant proportion of neurologic patients suffer electroencephalographic (EEG) seizures in the acute phase following traumatic or ischemic brain injury, including many without overt behavioral manifestations. Although such nonconvulsive seizures may exacerbate neuropathological processes, they have received limited attention clinically and experimentally. Here we characterize seizure episodes following focal cerebral ischemia in the rat as a model for brain injury-induced seizures. Cortical EEG activity was recorded continuously from both hemispheres up to 72 h following middle cerebral artery occlusion (MCAo). Seizure discharges appeared in EEG recordings within 1 h of MCAo in 13/16 (81%) animals and consisted predominantly of generalized 1–3 Hz rhythmic spiking. During seizures animals engaged in quiet awake or normal motor behaviors, but exhibited no motor convulsant activity. Animals had a mean of 10.6 seizure episodes within 2 h, with a mean duration of 60 s per episode. On average, seizures ceased at 1 h 59 min post-MCAo in permanently occluded animals and did not occur following reperfusion at 2 h in transiently occluded animals. In addition to seizures, periodic lateralized epileptiform discharges (PLEDs) appeared over penumbral regions in the injured hemisphere while intermittent rhythmic delta activity (IRDA) recurred in the contralateral hemisphere with frontoparietal dominance. PLEDs and IRDA persisted up to 72 h in permanent MCAo animals, and early onset of the former was predictive of prolonged seizure activity. The presentation of these EEG waveforms, each with characteristic features replicating those in clinical neurologic populations, validates rat MCAo for study of acutely induced brain seizures and other neurophysiological aspects of brain injury.

Subacute encephalopathy with seizures in alcoholism

Generalised seizures are a common manifestation of acute alcohol intoxication. Alcohol is known to precipitate generalised seizures in patients with focal brain pathology. A rare case of secondarily generalised seizures precipitated by alcohol in a patient without an underlying focal brain lesion is reported. Electroencephalopgraphy (EEG) showed periodic lateralised epileptiform discharges (PLEDs) on the side contralateral to the focal motor fits.

Periodic lateralized epileptiform discharges of pediatric patients in Taiwan

Periodic lateralized epileptiform discharges are special electroencephalographic abnormalities present in adults with stroke, brain tumor, intracranial hemorrhage, or other rare etiologies. Few reports focused on the etiologies in pediatric patients. We retrospectively reviewed 8002 of our pediatric electroencephalographic records for the past 12 years and listed all associated illness and their outcomes. Forty-four children with periodic lateralized epileptiform discharges were collected. We found that there was an obvious difference in etiologies of our pediatric patients from those reported in the literature. Nearly two thirds of our patients (28 children) were associated with central nervous system infections. The other etiologies included head injury, encephalopathy, epilepsy, and others. Herpes simplex virus was responsible for two thirds (12) of the 18 children with identified pathogens causing a central nervous system infection. Ten patients failed to have a defined pathogen. Periodic lateralized epileptiform discharges have a different clinical significance in pediatric patients than in adults. In Taiwan, central nervous system infection is the most common etiology of periodic lateralized epileptiform discharges in pediatric patients. Herpes simplex virus, although the most common pathogen, should not be considered to be the only cause of encephalitis in children with periodic lateralized epileptiform discharges.

Epilepsia partialis continua—a clinical and electroencephalography study

Epilepsia partialis continua (EPC) is a rare type of localization-related motor epilepsy. Clinical spectrum, electroencephalography (EEG) characteristics and various prognostic factors in EPC were studied in 20 patients. Patients who fulfilled the criteria for EPC between the years 1985 and 1999 were included in this retrospective and prospective study. The mean age was 18 years (range 5 months–70 years). Eleven patients (55%) had Type 1 EPC and in the remaining nine (45%) patients there were features of Type 2 EPC. Among children Rasmussen’s encephalitis and viral encephalitis were the commonest cause for EPC. Encephalitis and vascular aetiology were frequently observed in adults. Tuberculous meningitis and tuberculomas occurred evenly in both the groups. The cause was unknown in two cases. Focal EEG abnormalities commonly consisted of discrete spikes, sharp waves (or) slow wave activity and periodic lateralized epileptiform discharges. The mean duration of follow up was 9.6 months with a range between 1 month and 4 years. Cognitive decline, motor deficits and pharmacoresistance to drugs were significantly seen among children with Type 2 EPC. Patients with Type 1 EPC had mild impairment of functional status with good response to treatment. The long-term prognosis depends upon the underlying cause.

A Reexamination of PLEDs in the Setting of Status Epilepticus.

Serial EEG During Human Status Epilepticus: Evidence for PLED as an Ictal Pattern Garzon E, Fernandes RM, Sakamoto AC Neurology 2001;57:1175–1183 Objective To analyze the relationship between periodic lateralized epileptiform discharges (PLED) and status epilepticus (SE), to evaluate the relationship between mortality and periodic patterns, and to determine whether a stereotypic sequence of EEG patterns exists during human SE. Methods The authors performed a prospective clinical and electrographic study comprising 62 episodes of SE, 55 patients, and 254 ictal/postictal EEG recordings. Serial daily EEG were obtained in all cases. Results Partial SE was the predominant clinical type. Four distinct ictal EEG patterns were identified: intermittent EEG seizures (IES), merging EEG seizures (MES), continuous ictal discharges (CID), and periodic epileptiform discharges (PED) which could be lateralized (PLED) or bilateral (PBED). IES was the most common ictal pattern. In the same record, only one combination of ictal patterns was observed corresponding to an association of PLED or PBED and MES pattern. Serial EEG demonstrated that approximately one-third of SE resolved before the second EEG, another one-third persisted and maintained the same ictal pattern throughout the entire evolution, and the final one-third showed variable ictal EEG patterns. PLED were also unequivocally associated with epileptic seizures, and in some patients were the initial ictal pattern. Conclusion PLED can be an ictal pattern; and, in contrast to previous observations, no stereotyped sequence of ictal EEG patterns was found. PLED/PBED were not a terminal ictal pattern in every case, and outcome was more related to age and etiology than to specific ictal EEG patterns.

A Reexamination of PLEDs in the Setting of Status Epilepticus

ObjectiveTo analyze the relationship between periodic lateralized epileptiform discharges (PLED) and status epilepticus (SE), to evaluate the relationship between mortality and periodic patterns, and to determine whether a stereotypic sequence of EEG patterns exists during human SE. MethodsThe authors performed a prospective clinical and electrographic study comprising 62 episodes of SE, 55 patients, and 254 ictal/postictal EEG recordings. Serial daily EEG were obtained in all cases. ResultsPartial SE was the predominant clinical type. Four distinct ictal EEG patterns were identified: intermittent EEG seizures (IES), merging EEG seizures (MES), continuous ictal discharges (CID), and periodic epileptiform discharges (PED) which could be lateralized (PLED) or bilateral (PBED). IES was the most common ictal pattern. In the same record, only one combination of ictal patterns was observed corresponding to an association of PLED or PBED and MES pattern. Serial EEG demonstrated that approximately one-third of SE resolved before the second EEG, another one-third persisted and maintained the same ictal pattern throughout the entire evolution, and the final one-third showed variable ictal EEG patterns. PLED were also unequivocally associated with epileptic seizures, and in some patients were the initial ictal pattern. ConclusionPLED can be an ictal pattern; and, in contrast to previous observations, no stereotyped sequence of ictal EEG patterns was found. PLED/PBED were not a terminal ictal pattern in every case, and outcome was more related to age and etiology than to specific ictal EEG patterns.

Non-herpetic fulminant meningoencephalitis with periodic lateralised epileptiform discharges

This report concerns two patients with fulminant meningoencephalitis presenting in status epilepticus with periodic lateralised epileptiform discharges (PLEDs) observed on electroencephalogram. The titer of herpes simplex virus type 1 antibody was not elevated in either serum or cerebrospinal fluid, and acyclovir was not effective for either patient. Corticosteroid therapy was dramatically effective, however, suggesting that autoimmune inflammatory diseases were the underlying systemic disorders. PLEDs can thus be associated with steroid-responsive inflammatory meningoencephalitis.

Is It Status?

Nonconvulsive status epilepticus (NCSE) is difficult to diagnose in the obtunded/comatose patient. Such patients often have other serious medical conditions, and the diagnosis is frequently delayed. We review criteria for diagnosis, treatment, and prognosis of NCSE in this setting. Terms that have been used to describe SE in obtunded/comatose patients without tonic-clonic convulsions include subtle generalized SE, electrographic SE, SE in comatose patients, generalized electrographic SE, non-tonic-clonic SE, subclinical SE, and NCSE. Sometimes the same term has been used when describing different disorders, and different terms are often applied for the same entity. The incidence of NCSE in obtunded/comatose patients is uncertain. Clinically they may display subtle, intermittent focal or multifocal rhythmic movements suggestive of seizures; there may not be movements. NCSE can occur in a variety of disorders, including hypoxia, metabolic disturbances, and after convulsive seizures. A number of EEG patterns have been described in NCSE, and many of these are controversial, particularly as to whether they are ictal. These include periodic lateralized epileptiform discharges (PLEDS), bilateral independent PLEDS (BIPLEDS), periodic epileptiform discharges (PEDS), which can be either focal or generalized, and generalized triphasic waves (TWs). The diagnostic criteria for NCSE also are controversial, and there are no agreed-on criteria to diagnose NCSE in obtunded/comatose patients, nor is there consensus on how it should it be treated. Furthermore, outcome is poor, and several studies suggest that treatment may not be helpful.

Periodic lateralized epileptiform discharges: etiology, clinical aspects, seizures, and evolution in 130 patients.

The purpose of this study was to analyze the clinical aspects in 130 patients presenting periodic lateralized epileptiform discharges (PLEDs) in their EEG and to compare these results with those found in the literature. Etiology, neurologic deficit, seizure occurrence, and evolution were studied in each patient by historical review. The recordings were obtained on 8- or 16-channel EEGs with electrode placement according to the International 10-20 System. Recordings containing PLEDs were selected. PLEDs were defined as repetitive periodic, focal, or hemispheric epileptiform discharges (spikes, spike and waves, polyspikes, sharp waves) usually recurring every 1 to 2 seconds. The statistical study was carried out via the chi(2) test using the computer program SPSS. The main etiology found in this group of patients was stroke (61 of 130 patients). Other processes found were brain infections, tumors, hematomas, and several other entities grouped together as miscellaneous (anoxic encephalopathy, subarachnoid hemorrhage, craniocerebral trauma, Creutzfeldt-Jacob disease, migraine, multiple sclerosis, and aminophylline intoxication). Half of these patients (65 of 130) developed seizures, mostly partial motor seizures. No significant relation between etiology and seizures was found (chi(2) = 2.81, P = 0.4222). Seizures recurred in 14 of 130 patients during a follow-up of 14.5 months. PLEDs were not recorded in any EEG at the time of seizure recurrence. PLEDs constitute a distinctive but uncommon EEG phenomenon of repetitive, periodic, and stereotyped lateralized complexes. In agreement with the literature, PLEDs were associated with an acute process and occurred early during the course of the illness in all patients studied and were usually associated with structural lesions, with stroke being the main etiology. Traditionally, seizures occur with PLEDs but it is also accepted that they can exist in patients who never develop epileptic activity, either clinically or electrically, as demonstrated in 50% of the patients studied. No significant association between seizures and any etiology could be found. It was not demonstrated that the occurrence of seizures may influence the outcome in any way.

Descargas epileptiformes lateralizadas y periódicas como forma de presentación de neurosífilis

Neurosyphilis is a recognised cause of epileptic seizures, but its association with periodic lateralised epileptiform discharges (PLED) has been described only rarely, in spite of the fact that it gives rise to acute vascular lesions.We report the case of a male patient who was diagnosed as having meningovascular syphilis after the onset of tonic clonic epileptic seizures and PLED in the left frontotemporal region. The initial neurological exploration revealed a syndrome of confusion and mild mixed, but predominantly motor, dysphasia. In complementary tests, the most noteworthy features were positive luetic serology in the blood and in cerebrospinal fluid (CSF), which was confirmed by means of treponemic assays. The patient was treated with penicillin for two weeks. The study was completed with a magnetic resonance (MR) brain scan that showed a small left temporal infarction, which was the origin of the clinical and electrical convulsive activity. The patient s evolution was satisfactory, with an improvement in the language disorder, and the seizures were controlled after the administration of phenytoin. The control electroencephalogram (EEG) that was performed later only showed a slowing in the known injured area.PLED are an infrequent electroencephalographic pattern whose appearance has been linked with acute brain lesions, mainly with strokes, tumours and meningoencephalitis. When, exceptionally, they appear as a consequence of an ischemia secondary to meningovascular syphilis their significance, clinical features and prognosis do not differ from other causes of a cerebrovascular disease.

Les activités paroxystiques pseudo-périodiques en électroencéphalographie

Periodic and paroxysmal EEG patterns are frequent and easily recognized. They often correlate with particular neurological or systemic conditions. We propose a reclassification and critical examination of these periodic EEG patterns by reviewing the original work presented by J. Gaches in this journal some thirty years ago. Periodic EEG activity is still classified by its localisation – generalised or focal – and by its periodicity – long or short. Periodic long – interval diffuse paroxysmal patterns are reported with rare pathologies such as SSPE, trypanosomiasis or intoxication with phencyclidine. Suppression bursts (SB) may be found in two main situations post-anoxic encephalopathies and drug-induced comas. Ohtahara syndrome is a very rare childhood epileptic syndrome with SB. Periodic short – interval diffuse pattern have been reported in Creutzfeldt-Jakob disease but also in toxic encephalopathies, such as lithium intoxication or as recently reported in acute Cefepime intoxication as well as with metabolic encephalopathies and rarely during AIDS. Periodic lateralized epileptiform discharges (PLEDs) have been classified according to their morphology and the associated condition (epileptic seizures, subtle status, “vascular” seizure). The principal etiology is cerebro-vascular disease and herpes encephalitis but it has also been reported in several other neurological diseases.

LaCrosse viral encephalitis mimics herpes simplex viral encephalitis

Temporal lobe abnormalities, findings commonly associated with herpes simplex virus encephalitis, were observed in a male 10 years of age found to have LaCrosse virus encephalitis. Diagnostic features included magnetic resonance imaging revealing abnormal signal intensity in the bilateral frontotemporal regions, and left-sided periodic lateralizing epileptiform discharges. LaCrosse virus encephalitis should be included in the differential diagnosis of viral encephalitis associated with structural and electrographic temporal lobe lesions, represented by periodic lateralizing epileptiform discharges. The recently developed LaCrosse RNA polymerase chain reaction for cerebrospinal fluid may enable rapid diagnosis, prevent the need for treatment with acyclovir, and give parents an encouraging prognosis.

Significance of epileptiform discharges in patients without epilepsy in the community.

To determine the frequency of recording epileptiform discharges (EDs) in patients without epilepsy in the community and to assess their risk of seizure disorders subsequently developing. We identified all outpatient and inpatient EEGs that were recorded in persons residing in Rochester, Minnesota, from 1979 to 1988. Patients with a history of unprovoked seizure disorders before the index EEG were excluded. Periodic lateralized EDs (PLEDs) were not evaluated, because of their well-established association with seizure disorders. Five hundred twenty-one patients in the community had no history of unprovoked seizure disorders before their EEG. Sixty-four (12.3%) patients had EDs; neither isolated unprovoked seizure nor epilepsy developed during 230.8 person-years of follow-up. Forty-seven (73.4%) of the 64 patients had acute or progressive cerebral disorders when EEG detected EDs. Seizures that were acutely provoked by the underlying disorder (enlarging brain tumor, cerebral infarct, or bilateral subdural hematoma, in one patient each) subsequently developed in three (6.3%) of the 64 patients. Seizures of any type did not develop in the 17 patients without acute or progressive cerebral disorders. In a community setting, EDs are sometimes observed in patients without epilepsy. However, nearly three fourths have underlying acute or progressive cerebral disorders. Acutely provoked seizures may develop in a small proportion of patients. Although none of our patients developed isolated unprovoked seizures or epilepsy, a longer period of follow-up is needed to determine their risks relative to the general population.

Serial EEG during human status epilepticus: evidence for PLED as an ictal pattern.

To analyze the relationship between periodic lateralized epileptiform discharges (PLED) and status epilepticus (SE), to evaluate the relationship between mortality and periodic patterns, and to determine whether a stereotypic sequence of EEG patterns exists during human SE. The authors performed a prospective clinical and electrographic study comprising 62 episodes of SE, 55 patients, and 254 ictal/postictal EEG recordings. Serial daily EEG were obtained in all cases. Partial SE was the predominant clinical type. Four distinct ictal EEG patterns were identified: intermittent EEG seizures (IES), merging EEG seizures (MES), continuous ictal discharges (CID), and periodic epileptiform discharges (PED) which could be lateralized (PLED) or bilateral (PBED). IES was the most common ictal pattern. In the same record, only one combination of ictal patterns was observed corresponding to an association of PLED or PBED and MES pattern. Serial EEG demonstrated that approximately one-third of SE resolved before the second EEG, another one-third persisted and maintained the same ictal pattern throughout the entire evolution, and the final one-third showed variable ictal EEG patterns. PLED were also unequivocally associated with epileptic seizures, and in some patients were the initial ictal pattern. PLED can be an ictal pattern; and, in contrast to previous observations, no stereotyped sequence of ictal EEG patterns was found. PLED/PBED were not a terminal ictal pattern in every case, and outcome was more related to age and etiology than to specific ictal EEG patterns.