EEG abnormalities in nonepileptic patients

A total of 202 nonepileptic patients (120 males and 82 females) who exhibited spike abnormalities at least twice in their EEG examinations were studied. The incidence of spike abnormalities among nonepileptic patients was 8.1% (847/10,473). The majority (90%) were under age 19. Headache, dizziness and vomiting, and abdominal pain were more frequently observed compared with controls. Mild paroxysmal EEG abnormalities such as diffuse irregular slow wave bursts with spike (27%), positive spikes (25%) or small spike (8.4%) were commonly detected. In three patients who developed epileptic seizures during the follow-up period, more specific EEG abnormalities were often exhibited. Other factors like the age at onset before 9, characteristic clinical symptoms or a positive family history of seizures were confirmed to be necessary for the manifestation of clinical seizures.     

Spike EEG Abnormalities in Patients without Epileptic Seizures: A Clinical and Long-Term Follow-Up Study

Abstract: A study was conducted on a total of 850 patients who had not previously manifested any epileptic seizures but exhibited at least one spike EEG abnormality. They accounted for 7.2% of the total number of patients without epileptic seizures (850/11,773). Among the 850 patients, 564 were followed up for 1–24 years. Nine boys and one girl, 1.e. 1.8% of the 564 patients, had manifested epileptic seizures during the observation period. They expressed the following six characteristics: males, first EEG examination at 0–4 years of age, onset of initial chief complaints at 04 yeurs of age, mental retardation, spike and wave EEG abnormalities and past history of perinatal birth injuries. These factors are considered to be efficient in detecting patients liable to manifest epileptic seizures later.     

Nonepileptic Events in Childhood

The medical records of 27 children admitted to the MINCEP Epilepsy Program for evaluation of intractable epilepsy but later shown to have nonepileptic events by EEG with simultaneous video monitoring were reviewed. Four groups were identified: pure psychogenic events (5 patients), psychogenic events plus epileptic seizures (3 patients), pure nonepileptic physiologic events (5 patients), and nonepileptic physiologic events plus seizures (14 patients). Historical data, physical examinations, and neurodiagnostic evaluations (including previous EEGs, neuroradiologic evaluations, and neuropsychologic testing) were reviewed. Children in all groups, except for those with pure psychogenic seizures, had a history of multiple seizure types identified by parents or caretakers. A history of status epilepticus was obtained in 64% (of 22 patients), including 11 of 14 patients with physiologic events plus seizures. Abnormal findings on neurologic examination were common, especially in children with nonepileptic physiologic events. All but two patients had a history of interictal epileptiform abnormalities on previous routine EEGs. Based on identification of nonepileptic events, antiepileptic drugs (AEDs) were discontinued completely in eight patients (30%) and the total number of AEDs was reduced in nine others (33%). A diagnosis of nonepileptic events should be considered in all children with refractory seizures or multiple seizure types. Abnormal findings on routine (interictal) EEG may actually confound the diagnosis. Intensive neurodiagnostic EEG-video recording is the preferred method for distinguishing nonepileptic from epileptic seizures.     

Encephalopathy related to status epilepticus during slow sleep (ESES) as atypical evolution of Panayiotopoulos syndrome: an EEG and neuropsychological study

Aim: We report two patients with Panayiotopoulos syndrome (PS) who developed encephalopathy related to status epilepticus during slow sleep (ESES) at the peak of their clinical course. Methods: Clinical charts and EEG data were reviewed. Results: The patients exhibited nocturnal autonomic seizures and occipital EEG foci, the latter of which later evolved into multifocal EEG foci with synchronous frontopolar and occipital spikes (Fp‐O EEG foci), and finally into continuous spikes‐waves during sleep (CSWS; spike‐wave index >85% based on whole‐night sleep recording) at eight years and seven years of age, respectively. The occipital spikes always preceded frontopolar spikes by 30～50 mseconds based on the analysis of CSWS. Neuropsychological ability, including IQ, deteriorated during the CSWS period in both patients. The autonomic seizures and focal to bilateral tonic‐clonic seizures were initially resistant to antiepileptic drugs (AEDs), and occurred more than 10 times in both patients. However, the seizures and EEG findings gradually resolved, and AEDs were successfully terminated in both patients. Conclusion: PS can progress to ESES if the clinical course exhibits atypical evolution. The initial autonomic symptom of the seizures and interictal Fp‐O EEG foci should be carefully monitored in patients with CSWS or ESES.     

Bilateral akinetic seizures: A clinical and electroencephalographic description

Purpose: The main feature of akinetic seizures is the inhibition of voluntary movements without impairment of awareness. Most clinical information about akinetic seizures has been obtained from cortical electrical stimulation studies, whereas clinical and video–electroen‐cephalography (EEG) features have not been described thoroughly. We aimed to analyze clinical and EEG characteristics of bilateral akinetic seizures (BAS). Methods: Patients with BAS were retrospectively identified from 1,858 consecutive video‐EEG studies. All patients had ictal video‐EEG, comprehensive clinical evaluation, neuropsychological testing, and brain magnetic resonance imaging (MRI). Results: Ten patients (nine men) were identified; mean age was 22.5 years (range 0.3–71 years) at the time of epilepsy onset and 34.9 years (range 5–73 years) at the time of evaluation. BAS was the only seizure type in four patients. BAS consisted of sudden speech and motor arrest in eight patients, whereas in two patients seizures were characterized by abrupt freezing precipitated by gait initiation. Startle precipitated BAS in four patients. Magnetic resonance imaging (MRI) showed mesial frontal lobe lesions in six patients. Epileptiform activity was restricted to the frontal midline electrodes in all patients, with variable extension to frontal regions. In five patients, BAS were initially misdiagnosed as generalized seizures or nonepileptic events. Discussion: BAS should be considered in the differential diagnosis of patients reporting paroxysmal inability to move with preservation of awareness, bearing in mind that these seizures can occur spontaneously or be precipitated by startle. The diagnosis can be achieved with video‐EEG monitoring, showing stereotyped semiology and distinctive EEG abnormalities, and is often supported by the presence of lesions involving the frontal lobes.     

Longitudinal study of epileptiform EEG patterns in normal children

EEG were recorded in 3,726 children, from 6 to 13 years of age who were neurologically normal and had no history of epileptic seizures. The records were taken during wakefulness, at rest, and during hyperventilation. In 131 cases (3.54%) epileptiform patterns were found. They consisted of 3 count/sec spike and slow waves discharges (4 cases), multiple spike and slow wave complexes (37 cases), midtemporal spikes (50 cases), rolandic or parietal spikes (27 cases), occipital spikes (2 cases), and multifocal spikes (11 cases). Half of the subjects with EEG abnormalities had behavior problems and/or slight psychomotor ability disturbances. Follow-up studies over an 8 to 9 year period were performed. These demonstrated the spontaneous disappearance of the EEG abnormalities, usually within school age or, at the latest, during adolesence. Only seven individuals developed epileptic seizures of the primary generalized type which responded well to anticonvulsant drug treatment. From this study we can deduce that the epileptiform EEG patterns that often are found in children during school age have no clinical relationship to epilepsy in the great majority of cases. The relationship with epilepsy exists probably on a genetic level for the generalized discharges. The spike foci are non-epileptic in nature in all probability, especially if they emerge from a fairly normal background activity and their duration is very similar to that of the constituents of the background activity, as found in the majority of these subjects. On the contrary, it is probable that these alterations express difficulties in affective or motor adaptation during childhood.     

Spike EEG abnormalities in patients without epileptic seizures: a clinical and long-term follow-up study

A study was conducted on a total of 850 patients who had not previously manifested any epileptic seizures but exhibited at least one spike EEG abnormality. They accounted for 7.2% of the total number of patients without epileptic seizures (850/11,773). Among the 850 patients, 564 were followed up for 1-24 years. Nine boys and one girl, i.e. 1.8% of the 564 patients, had manifested epileptic seizures during the observation period. They expressed the following six characteristics: males, first EEG examination at 0-4 years of age, onset of initial chief complaints at 0-6 years of age, mental retardation, spike and wave EEG abnormalities and past history of perinatal birth injuries. These factors are considered to be efficient in detecting patients liable to manifest epileptic seizures later.     

Comparison of epileptic and nonepileptic cases with centrotemporal spikes in view of clinical findings and electroencephalographic characteristics

The morphological features of centrotemporal spike discharges (CTSD) and relationship of them with clinical diagnosis in cases with benign epilepsy of childhood with centrotemporal spikes (BECTS) and the other epileptic syndromes of childhood as well as some nonconvulsive neurological disorders were detected in the routine patient population who referred to the authors' EEG laboratory. Thirty-six cases (21 males, 15 females; 8 months-14 years old), in which awake and/or sleep EEGs revealed CTSD were included in this study. The cases were divided into two groups as epileptic and nonepileptic. The cases with seizure were divided into BECTS and the other epilepsies. Of the epileptic cases, 14 (38.8%) patients had typical rolandic seizures. In five cases, there were partial or secondary generalized seizures. Two cases had myoclonic seizures. In the nonepileptic group, there was mental retardation/behavioral disturbances in five cases; there were periodic syndromes of childhood such as migraine and equivalents of migraine in three cases; febrile convulsion in three cases, breath-holding spells in two cases, and primary enuresis nocturna in two cases. In the nonepileptic group, the discharges were significantly fewer than the other groups (p = .014). More frequent discharges occuring for shorter periods were more significantly observed in BECTS group (64%). Typically isolated spike and slow-waves in T3/T4 and C3/C4 location were significantly more common (86%) in rolandic epilepsy group (p = .01). The EEGs of cases with BECTS had more frequency in the cluster of discharges than the other groups (p = .018). Multifocal discharges were observed in 28.5% of cases with BECTS, in 20% of nonepileptic group, and in 71.4% of other epileptics in the trial. Although these epileptic and nonepileptic conditions have some differences in view of frequency and morphology and location, CTSDs could be manifested in the group without seizure. It was concluded that the similar focal abnormalities which could be seen in rolandic epilepsy may be observed in the other epileptic or nonepileptic disorders of childhood and this condition may be originated from the involvement of similar central structures.     

EEG in children with early-onset benign occipital seizure susceptibility syndrome: Panayiotopoulos syndrome

PURPOSE: We analyzed sequential changes in the localization of EEG foci along with age to identify a specific EEG pattern, and the relation between the clinical manifestations and the EEG pattern in patients with Panayiotopoulos syndrome (PS). METHODS: The subjects were 76 children, who had been followed up >2 years with repeated EEG examinations at 6-month intervals. Analysis of EEG findings included the determination of localization of spike foci, as a function of age, by using cross-sectional data, and the identification of subgroups with homogeneous EEG patterns. Then we compared certain clinical features among these subgroups. RESULTS: In the cross-sectional EEG study, the occipital EEG spike focus was most frequently seen between ages 2 and 5 years. Independent and synchronous frontopolar and occipital spikes (Fp-O spikes) and centroparietotemporal (CPT) EEG spike foci had increased incidences between ages 4 and 7 years, and between ages 6 and 10 years, respectively. We subclassified the 76 patients into the following five subgroups based on the evolutional changes in epileptic EEG foci, which frequently showed shifting, multiplications, and generalization: (a) persistent occipital focus group (O group), (b) Fp-O spikes group (Fp-O pattern group), (c) generalized EEG pattern group, (d) CPT foci group (CPT group), and (e) no epileptic EEG focus group. The Fp-O group showed the latest age at onset of epilepsy. The generalized EEG pattern group had the highest frequency of seizures as well as recurrences of status epilepticus (SE), as well as the longest active seizure period among the five groups. CONCLUSIONS: These results indicated that the EEG foci in most of patients with PS are frequently shifting location, multiplying, and propagating diffusely with age, rather than persistently localizing in the occipital region. In addition, the EEG patterns showed a certain trend and roughly corresponded to certain clinical characteristics. However, the prognosis of the seizures appeared to be favorable regardless of the EEG pattern.     

Clinical significance of EEG abnormalities during photic stimulation in patients with photosensitive epilepsy

PURPOSE: The continued presence of EEG abnormalities in patients with a history of photosensitive seizures is used to signify the persistence of photosensitive epilepsy. The extent to which this approach places patients at risk of seizures is unclear, however. We describe those EEG abnormalities that may be tolerated with low risk of further seizures, and those that are indicative of poor seizure control. METHODS: Fifty patients with EEG evidence of persistent photosensitive epilepsy underwent photosensitivity testing with diffuse and patterned light; 58% of patients continued to experience seizures, and 42% were seizure free. The incidence of EEG abnormalities to diffuse and patterned intermittent photic stimulation (IPS) was analysed as a function of recent seizures. RESULTS: All patients showed EEG abnormalities to patterned IPS; there was no significant association between patterned IPS and poor seizure control. EEG abnormalities to diffuse IPS occurred in 58% of patients, and 76% of these patients had experienced a seizure within the previous year. These patients were more than twice as likely to be poorly controlled than those who showed abnormalities only to patterned IPS. These results were consistent for both medicated and unmedicated patients. CONCLUSIONS: EEG abnormalities to patterned IPS can be used to signify the persistence of photosensitive epilepsy, but abnormalities to diffuse IPS are more likely to indicate the patient is poorly controlled and at risk of further seizures.