Initial EEG Research Articles

EEG comparisons in early Alzheimer's disease, dementia with Lewy bodies and Parkinson's disease with dementia patients with a 2-year follow-up

EEG abnormalities have been reported for both dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Although it has been suggested that variations in mean EEG frequency are greater in the former, the existence of meaningful differences remains controversial. No evidence is as yet available for Parkinson's disease with dementia (PDD). The aim of this study was to evaluate whether EEG abnormalities can discriminate between DLB, AD and PDD in the earliest stages of dementia and to do this 50 DLB, 50 AD and 40 PDD patients with slight cognitive impairment at first visit (MMSE > or = 20) were studied. To improve clinical diagnostic accuracy, special emphasis was placed on identifying cognitive fluctuations and REM-sleep behaviour disorder. EEG variability was assessed by mean frequency analysis and compressed spectral arrays (CSA) in order to detect changes over time from different scalp derivations. Patients' initial diagnoses were revised at a 2-year follow-up visit with neuroimaging evaluation. Initial diagnoses were confirmed in 36 DLB, 40 AD and 35 PDD patients. The most relevant group differences were observed between the AD and DLB patients in EEGs from posterior derivations (P<0.001). Dominant frequencies were 8.3 +/- 0.6 Hz for the AD group and 7.4 +/- 1.6 Hz for the DLB group, in which most of the patients (88%) exhibited a frequency band of 5.6-7.9 Hz. Dominant frequency variability also differed between the AD (1.1 +/- 0.4 Hz) and DLB groups (1.8 +/- 1.2 Hz, P<0.001). Of note, less than a half (46%) of the patients with PDD exhibited the EEG abnormalities seen in those with DLB. Graded according to the presence of alpha activity, five different patterns were identified on EEG CSA from posterior derivations. A pattern with dominant alpha bands was observed in patients with AD alone while, in those with DLB and PDD, the degree to which residual alpha and 5.6-7.9 bands appeared was related to the presence and severity of cognitive fluctuations. At follow-up, EEG abnormalities from posterior leads were seen in all subjects with DLB and in three-quarters of those with PDD. Of interest, in four patients initially labelled as having AD, in whom the occurrence of fluctuations and/or REM-sleep behaviour disorder during the 2-year follow-up had made the diagnosis of AD questionable, the initial EEG was characterized by the features observed in the DLB group. If revised consensus criteria for DLB diagnosis are properly applied (i.e. emphasizing the diagnostic weight of fluctuations and REM sleep behaviour disorder), EEG recording may act to support discrimination between AD and DLB at the earliest stages of dementia, since characteristic abnormalities may even precede the appearance of distinctive clinical features.

Effects of imipramine hydrochloride on the EEG of children with Attention-Deficit/Hyperactivity Disorder who are non-responsive to stimulants

Although stimulant medications are the most commonly-used treatments for Attention-Deficit/Hyperactivity Disorder (AD/HD), as many as 20% of treated children do not respond clinically to stimulants. One non-stimulant medication that has been widely used when the stimulants fail is a tricyclic antidepressant, imipramine hydrochloride. This study investigated the effects of imipramine on the EEG of children with AD/HD who were poor responders to dexamphetamine and ritalin, but who showed clinical improvement on a six month trial of imipramine. An initial pre-medication EEG was recorded during an eyes-closed resting condition, with data Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. A second EEG was recorded at the end of the imipramine trial. Compared to controls, the unmedicated AD/HD children had significant global increases in absolute and relative theta, with decreased global absolute and relative alpha, increased posterior relative delta, and decreased posterior absolute beta. No change in the EEG was found as a result of administering the medication. These results suggest that good responders to imipramine have an underlying EEG abnormality different from that in children who respond to the stimulants, and that an initial pre-treatment EEG may be useful in selecting a trial medication. However, as no change in the EEG was found with imipramine, it is unlikely that the EEG will be useful in evaluating responsivity to this medication.

Early Detection of Periodic Sharp Wave Complexes on EEG by Independent Component Analysis in Patients With Creutzfeldt-Jakob Disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is the most common human prion disease. EEG is the method of choice to support the diagnosis of a human prion disease. Periodic sharp wave complexes (PSWCs) on the EEG usually indicate a progressive stage of CJD. However, PSWCs only become obvious at around 8 to 12 weeks after the onset of clinical symptoms, and in a few cases, even later. Independent component analysis (ICA) is a new technique to separate statistically independent components from a mixture of data. This study recruited seven patients who fit the criteria of CJD between 2002 and 2005 and 10 patients with Alzheimer's disease (AD) as control subjects. Using an ICA algorithm, we were able to split typical PSWCs into several independent temporal components in conjunction with spatial maps. The PSWCs were not observed in the initial EEG studies of patients with either AD or CJD. However, the ICA algorithm was able to extract periodic discharges and epileptiform discharges from raw EEG of patients with CJD at as early as 3 to 5 weeks after disease onset. Such discharges otherwise could hardly be discerned by visual inspection. In conclusion, ICA may increase the sensitivity of EEG and facilitate the early diagnosis of CJD.

Intensity and type of EEG reactions to a hyperventilation test and their relationship with changes in patients’ subjective state of health and some characteristics of the initial EEG pattern

Some EEG characteristics at rest and after a 3-min hyperventilation test (HVT) were studied in 100 adult patients along with the changes in their current subjective state of health, assessed with the help of a special three-stage survey and a questionnaire. Our findings demonstrated a clear correlation between the rate of changes in the current subjective state of health of a patient, the average number of observed symptoms, and the intensity of the EEG reaction. With regard to the methodological aspect, we recorded a difference in the assessment of subjective data obtained through the different types of survey. The frequency of two types of high-amplitude slow waves during the HVT (recorded in 21% of patients), as well as of paroxysmal epileptiform activity, was studied, and their correlation with the clinical manifestations of epilepsy was analyzed. Our study showed that the intensity of the general EEG reaction to the HVT is correlated with the presence of EEG disorders, such as minor bursts in the initial EEG pattern; the probability of high-amplitude slow activity during the HVT is especially high if these minor bursts are recorded at rest. We also noted a certain relationship between the intensity of hyperventilation-related EEG changes (and, therefore, the rate of changes in the current subjective state of health of a patient) and characteristics of the initial pattern, such as α-rhythm disorders and an increase in the intensity of slow or slow and frequent activity at rest.

Aborted and refractory status epilepticus in children: A comparative analysis

The aims of this retrospective study were: (1) to compare the demographics, clinical characteristics, etiology, and EEG findings of status epilepticus aborted with medication (ASE) and refractory status epilepticus (RSE), (2) to describe the treatment response of status epilepticus (SE), and (3) to determine predictors of long-term outcome in children with SE. Medical records and EEG lab logs with ICD-9 diagnostic codes related to SE were reviewed. Patients younger than 18 years of age, hospitalized in 1994-2004 at the Mayo Clinic, Rochester, were included. One hundred fifty-four children had SE; 94 (61%) had ASE, and 60 (39.0%) had RSE. Family history of seizures, higher seizure frequency score, higher number of maintenance antiepileptic drugs (AEDs), nonconvulsive SE, and focal or electrographic seizures on initial EEG were associated with RSE by univariate analysis. In-hospital mortality was significantly higher in RSE (13.3%) than in ASE (2.1%). In the long term, survivors with RSE developed more new neurological deficits (p < 0.001) and more epilepsy (p < 0.004) than children with ASE. Children treated in a more aggressive fashion appeared to have better treatment responses (p < 0.001) and outcomes (p = 0.03). Predictors of poor outcome were long seizure duration (p < 0.001), acute symptomatic etiology (p = 0.04), nonconvulsive SE (NCSE) (p = 0.01), and age at admission <5 years (p = 0.05). Several patient and clinical characteristics are associated with development of RSE and poor outcome. Prospective, randomized trials that assess different treatment protocols in children with SE are needed to determine the optimal sequence and timing of medications.

Epilepsia partialis continua and defects in the mitochondrial respiratory chain

Epilepsia partialis continua (EPC) is characterized by continuous myoclonic or clonic jerks repeated at short intervals followed by a slowly progressive neurological disorder. We report three patients with EPC and a defect in the mitochondrial respiratory chain. Clinical, neuroradiological, and biochemical data were reported. The patients presented continuous myoclonic jerks at age of 8 months, 11 months and 6 years, respectively. Two of the three patients had a previous developmental delay. Neurological examination at first admission revealed extrapyramidal symptoms in all patients. Initial biological investigations suggested mitochondrial dysfunction. Initial EEG showed a continuous discharge of periodic spikes (0.5-1Hz). MRI studies were initially normal then progressed to cerebral hemiatrophia. EEG revealed both correlation and absence of correlation between spikes or sharp waves and myoclonic jerks. The activity of one or several complexes of the mitochondrial respiratory chain was reduced in the muscle samples of the three patients. No mutation of mtDNA was found. Our report suggests that EPC can be due to mitochondrial respiratory chain disorders. Some clinical findings and initial investigations were indicative of a disorder of mitochondrial metabolism. Previous developmental delay, extrapyramidal symptoms and other organ involvement should suggest a possible mitochondrial etiology of EPC. In case of infant presenting EPC, mitochondrial respiratory chain disorder should be considered first.

Epilepsy in Children With Delayed Presentation of Perinatal Stroke

A subgroup of children with perinatal stroke do not present clinically until after the perinatal period. Detailed epilepsy outcomes in these children have not been well studied. A retrospective cohort study of 45 children with delayed presentation of perinatal stroke identified by review of pediatric stroke clinic records, physician referral, and International Classification of Diseases, Ninth edition, code searches of hospital records, was performed at a tertiary pediatric hospital in Indianapolis, Indiana. A modified version of the Engel scale was used to grade epilepsy outcomes. The chi(2) test, Fisher's exact test, and relative risks were calculated to examine the association of epilepsy at time of last follow-up with initial presentation with seizures, infantile spasms, radiographic findings, and initial abnormal electroencephalogram (EEG). These tests were also used to examine the association of epilepsy with cognitive or motor disability and the association of initial abnormal EEG with motor disability. Patients presented with hemiparesis (40; 89%), seizures (4; 9%), or headaches (1; 2%). All had unilateral infarcts on cranial imaging. Four children (9%) had infantile spasms, 2 at presentation and 2 later. Nineteen children received at least 1 EEG for suspicious spells or frank seizures; initial EEG was abnormal in 16 patients (84%). At last follow-up, 17 patients (38%) had epilepsy, which was severe in 4 (24% of those with epilepsy). Initial presentation with seizures (relative risk = 3.2; 95% confidence interval, 2.0-4.9) and infantile spasms (relative risk = 3.2; confidence interval, 2.0-4.9) were associated with epilepsy at last follow-up. Infantile spasms were also associated with moderate-to-severe epilepsy at last follow-up (relative risk = 10.3; confidence interval, 1.9-54.4). Epilepsy at last follow-up was associated with cognitive disability (P = .05). Initial abnormal EEG was not associated with cerebral palsy (P = .30). Epilepsy is frequent in children with delayed presentation of perinatal stroke and is associated with initial presentation with seizures and infantile spasms at any point in time. Cognitive disability often accompanies epilepsy in these children.

Effects of stimulant medications on the EEG of girls with Attention-Deficit/Hyperactivity Disorder

Objective Stimulant medications are the most commonly used treatments for Attention-Deficit/Hyperactivity Disorder (AD/HD) in North America and Australia, although it is still not entirely known how these medications work. This study investigated the effects of stimulant medications on the EEG of girls with AD/HD. Methods An initial EEG was recorded during an eyes-closed resting condition. Data from 19 electrode sites were Fourier transformed to provide absolute and relative power estimates for the delta, theta, alpha and beta bands. The data were then averaged into 9 regions and an analysis of both global and regional differences was performed. Subjects were placed on a six-month trial of a stimulant and a second EEG was recorded at the end of the trial. Results The unmedicated girls had significantly greater total power, absolute delta and theta, more relative theta especially in the frontal regions, and reduced frontal relative delta and beta activity compared with controls. Medication resulted in normalisation of theta power, but after medication, increased relative beta was also apparent in the AD/HD group. Conclusions These results indicate that stimulant medications result in a normalisation of slow wave activity in the EEG. In line with published research on the effects of arousal on the EEG, these results suggest that stimulant medications may have their therapeutic effect by improving the EEG substrate of processing deficits in these children. However, this requires further testing during active processing tasks. Significance This is the first study to investigate the effect of stimulant medications on the EEG of girls with AD/HD.

Current Treatment of Myoclonic Astatic Epilepsy: Clinical Experience at the Children's Hospital of Philadelphia

Myoclonic astatic epilepsy (MAE) is a generalized epilepsy of early childhood. Little is known about the use of newer antiepileptic treatments (AET) in MAE. The purpose of this study was to describe the characteristics, treatment, and outcome of a contemporary MAE cohort exposed to the new generation AET. Charts of subjects with MAE treated between 1998 and 2005 were reviewed. Twenty-three subjects (19 boys), with a median (range) follow-up of 38 (2- 86) months were identified. Thirty-nine percent had a family history of epilepsy, and 39% had family history of febrile seizures. Age at seizure onset was a median of 36 (12-24) months. Initial EEG was normal in 30%. When seizures ceased, EEG background and epileptiform abnormalities persisted in 17 and 58%, respectively. On average, each subject was exposed to five AET. The most frequently used AET was valproate (83%). Seizure freedom occurred spontaneously in three subjects, with ethosuximide and levetiracetam in one each, valproate and lamotrigine in two each, topiramate in three and the ketogenic diet (KD) in five subjects. By 36 months after seizure onset, 67% achieved seizure freedom. At the last visit, 43% were developmentally normal, 52% had mild, and 5% had moderate cognitive disabilities. Time to seizure freedom did not correlate with cognitive outcome. The new generation of AET may offer significant benefit to children with MAE. The KD was the most effective AET in this series, and perhaps should be considered earlier in treatment.

Aggravation of Seizures and/or EEG Features in Children Treated with Oxcarbazepine Monotherapy

Exacerbation of epilepsy may occur following initiation of therapy with antiepileptic drugs (AEDs). The aim of this study is to analyze the clinical and EEG characteristics of a group of pediatric patients with worsening of seizures and/or EEG deterioration while on oxcarbazepine (OXC). A retrospective analysis of a clinical database was performed to identify patients with epilepsy treated with OXC over the past 3 years. History, neurological examination, and EEG findings were reviewed to identify any who had developed exacerbation of seizures or new abnormalities on EEG. Of 290 patients on OXC, we identified 12 patients with new onset seizures, all with initial normal neurological exam and normal EEG, who developed either worsening of preexisting seizures, new seizure types, and/or EEG deterioration following introduction of OXC monotherapy. EEG changes were primarily characterized by new onset of generalized epileptiform activity not reported on the initial baseline EEG. Following substitution of OXC with a broad spectrum AED, significant improvement of seizure control and improvement in the EEG was observed. These findings suggest that OXC can aggravate seizures and/or worsen EEG features in children. Following initiation of therapy with OXC, monitoring of patients with follow-up EEGs may be important, especially in patients who do not show adequate response to therapy.

Analysis of status epilepticus related presumed encephalitis in children

Objective Encephalitis is an acute infection of brain parenchyma characterized clinically by fever, headache, and an altered level of consciousness. There may also be focal or multifocal neurologic deficits, and focal or generalized seizure activity. Here we report an analysis of status epilepticus (SE) related presumed encephalitis in a series of children. Methods We retrospectively reviewed cases of SE related presumed encephalitis treated in the pediatric intensive care unit, between February 2002 and June 2006. Factors evaluated included age, sex, clinical symptoms, seizure type, presence of SE or refractory status epilepticus (RSE), initial electroencephalogram (EEG) finding, neuroimaging study, cerebrospinal fluid (CSF) and outcome. Results There were 46 patients (19 girls and 27 boys), aged 8 months to 16 years. Twenty (43.4%) of 46 children developed RSE. The major clinical symptoms included fever (100%), upper respiratory symptoms (56.5%) and altered level of consciousness (45.6%). The initial seizure type was categorized as focal (23.9%), generalized (34.8%), primary focal and secondary generalized (41.3%). Initial EEG revealed a focal (30.8%), or multifocal (19.2%) epileptiform discharge in the SE group and a focal (5%), or multifocal (70%) or generalized (25%) epileptiform discharge in the RSE group. The time of follow-up for this study was 6 months to 51 months. In the SE group, 4 died, 16 developed epilepsy and/or neurologic deficits, and 6 returned to baseline. In the RSE group, 6 died, 13 developed epilepsy and/or neurologic deficits, and none returned to baseline. All survivors were discharged on antiepileptic medications. Conclusions Our data indicated that children of SE related presumed encephalitis had a high mortality and morbidity. Outcome was related to multifocal or generalized abnormalities of the initial EEG and presence of RSE.

Is homeostatic sleep regulation under low sleep pressure modified by age?

We have previously shown that healthy older volunteers react with an attenuated frontal predominance of sleep electroen-cephalogram (EEG) delta activity in response to high sleep pressure. Here, we investigated age-related changes in homeostatic sleep regulation under low sleep pressure conditions, with respect to regional EEG differences and their dynamics. Analysis of the sleep EEG during an 8-hour baseline night, during a 40-hour multiple nap protocol (150 minutes of wakefulness and 75 minutes of sleep) and during the following 8-hour recovery night under constant posture conditions. Centre for Chronobiology, Psychiatric University Clinics, Basel, Switzerland Sixteen young (20-31 years) and 15 older (57-74 years) healthy volunteers N/A. All-night EEG spectra revealed an increase in spindle activity (13-15.25 Hz) for both age groups, but only in the young did we find a significant decrease of delta activity (0.5-1.25 Hz) in response to low sleep pressure conditions, predominantly in occipital brain regions. However, delta activity during the first non-rapid eye movement (NREM) sleep episode was equally reduced in both age groups. This response lasted significantly longer in the young (across the first 2 NREM sleep episodes) than in the older participants (only the first NREM sleep episode). The initial EEG delta response to low sleep pressure was similar in healthy older and young participants. Therefore, age-related sleep deteriorations cannot solely be attributed to alterations in the homeostatic sleep-regulatory system. It is, rather, the interplay of circadian and homeostatic factors of sleep regulation, which is changed with aging.

Corpus callosotomy: A palliative therapeutic technique may help identify resectable epileptogenic foci

Corpus callosotomy has a long history as a palliative treatment for intractable epilepsy. Identification of a single epileptogenic zone is critical to performing successful resective surgery. We describe three patients in which corpus callosotomy allowed recognition of unapparent seizure foci, leading to subsequent successful resection. We retrospectively reviewed our epilepsy surgery database from 2003 to 2005 for children who had a prior callosotomy and were candidates for focal resection. All underwent magnetic resonance imaging and scalp video electroencephalograph monitoring, and two had magnetoencephalography, electrocorticography and/or intracranial video electroencephalograph monitoring. The children were 8 and 9 years old, and seizure onset varied from early infancy to early childhood. One child had a history of head trauma preceding seizure onset, one had a large intracerebral infarct and dysplastic cortex in the contralateral frontal lobe, and the other had an anterior temporal lobe resection without improvement in seizure frequency. After medical management failed, callosotomy was performed with the expectation of decreasing the seizure types affecting both hemispheres. Following transection of the callosal fibers, a single focus was recognized and resected, with resultant dramatic improvement in seizure control. In medically refractory epilepsy, where rapid secondary bisynchrony is suspected but the electroencephalograph is non-localizing, callosotomy should be considered as a means of treating generalized seizure types, but may also assist in identifying potentially operable seizure foci. Study limitations include its retrospective nature and cohort size. The findings, however, suggest the need for prospective, systematic, well-controlled studies of the use of corpus callostomy in this intractable patient population.

Images in Neurology: Periodic Sharp Wave Complexes in patient with Creutzfeldt- Jakob Disease

Creutzfeldt- Jakob disease (CJD) is included under the umbrella of prior related neurodegenerative diseases. Other prior related diseases include Gerstmann-Str‰usslerScheinker (GSS), fatal familial insomnia (FFI), Kuru and new variant CJD (BSE) in humans, chronic wasting disease (CWD) in deer and scrapie in sheep. Sporadic CJD presents with rapidly progressive dementia and myoclonus. Diagnosis is typically clinical and supplemented by electroencephalography (EEG) and analysis of cerebrospinal fluid. During the course of sporadic CJD, most patients develop a characteristic picture on EEG with one second periodic or pseudoperiodic sharp waves complexes (PSWC) or spikes superimposed on a slow background (Fig 1). The sensitivity and specificity of PSWC varies from 60% to 80 % on a single EEG recorded from a suspected patient of CJD. They may not be present on the initial EEG but as the disease progresses more than 90% of the patients show the characteristic periodic EEG abnormalities. No PSWC occur in EEG recordings of patients with new variant CJD 1. Figure 1 EEG showing periodic sharp wave complexes (PSWC) in a patient with CJD.

The Clinical Characterizations of Benign Partial Epilepsy in Infancy

The aim of this study is to clarify the detailed clinical features of benign partial epilepsy in infancy. The subject of the study was 33 patients with benign partial epilepsy in infancy confirmed by a long-term follow-up beyond 8 years of age. The data were obtained from medical records of the patients in combination with the data obtained from telephone interview. The median age at the first and last seizure was 5 and 8 months, respectively. In 26 patients, seizures disappeared within 3 months after the onset. Family history of benign partial epilepsy in infancy was seen in 17 patients. The median number of seizures was 7. A cluster of seizures was observed in 26 patients. The type of seizures was complex partial seizures alone in 6 patients, secondarily generalized seizures alone in 9, and both types in 18. Decreased responsiveness, lateral eye deviation, and cyanosis were commonly observed. Initial interictal electroencephalograms were normal in all patients. However, paroxysmal discharges were recognized in 2 patients in the second EEG during the first year of life. The main features of benign partial epilepsy in infancy were a high incidence of a cluster of seizures, short persistence of seizures, and normal initial interictal EEGs.

Hypothalamic Hamartoma and Infantile Spasms

A small number of patients with hypothalamic hamartoma (HH) present with infantile spasms (IS) as an initial or early seizure type. We describe the clinical features of IS associated with HH. Our series of patients with HH and epilepsy was reviewed to identify cases with a history of IS. The clinical features and neuroradiological findings in this study group were compared to a control group of patients with HH and refractory epilepsy, but without a history of IS. We identified six patients with HH and a history of IS in this series (n = 122, 4.9%). Five of the six are male. Four of the six patients (67%) developed IS as their first seizure type. The mean age for onset of IS was 6.2 months (range 4-9 months). Results of electroencephalographic (EEG) study at the time of IS diagnosis showed hypsarrhythmia in two (33%). Five patients were treated with adrenocorticotropic hormone (ACTH), and four of the five (80%) responded with control of IS. However, these patients developed other seizure types, and were ultimately refractory to medical management. Aside from the IS, no significant differences in clinical and imaging features were determined between the study group and the control group. HH should be included in the differential diagnosis for infants presenting with IS. These patients may have hypsarrhythmia on initial EEG, and may respond to ACTH treatment with improvement of IS. However, all became refractory with other seizure types, more commonly seen in HH patients. Focal pathologies associated with IS may be subcortical, as well as cortical, in nature. We have not identified any predictive features for the occurrence of IS in the HH population.

Pitfalls of Diagnosing Epilepsy: A Case Report

A 36-year-old right-handed woman had her first seizure at the age of 15 months. This generalized tonic–clonic (GTC) seizure occurred with a high fever and a Roseola infection. She subsequently had developmental delays and experienced both complex partial and secondarily GTC seizures, increasing in frequency after puberty. The seizures now are described as: head deviation to the left (and sometimes right) associated with behavioral arrest, staring, drooling, confusion, lip smacking, with automatisms of either hand, followed by bilateral upper extremity flexion, and then generalization. She has 4–6 seizures per month. Medical history is significant for Type II Diabetes, Bartter's syndrome, Gitelman's syndrome (both of which produce low vascular tone due to dysregulation of angiotensin II). Surgical history is significant for a vagal nerve stimulator that was implanted in 2004. Family history was negative. At the time of her video-EEG study, her medications included zonisamide, felbamate, buspirone, amiloride, and glucophage. She was previously treated with six other antiepileptic drugs. General examination was normal. Neurological examination was remarkable for mild psychomotor slowing and disorientation to situation. She had poor eye contact and was irritable and not fully cooperative. There were mild bilaterally symmetric sustention and intention tremors in the upper extremities. Spontaneous gait was cautious and tandem gait was unsteady. MRI revealed left mesial temporal sclerosis. Video-EEG monitoring captured four of her typical spells as confirmed by her mother. EEG's for three of these are included in 1, 2, and 3. During these events the most prominent finding was a cardiac brady-arrhythmia that quickly evolved into asystole and sinus arrest. With one of these (Fig. 2), a subtle rhythmic change with sharp waves was observed in the right temporal derivations. Seizure. Thirty seconds of EEG shown. Note EKG strip and asystole with accompanying attenuation of the EEG. A: Seizure, with EEG spread out. Note the onset of rhythmic theta in the right temporal derivations, particularly in T2-T4 prior to the brady-arrhythmia, suggesting epileptic asystole. B: Seizure continued with EEG spread out. Note the continuation of a right temporal rhythm as asystole occurs. Seizure. 30 seconds of EEG are shown. Note EKG strip with sinus Arrest and asystole with attendant attenuation of EEG. This case illustrates the difficulties of definitive diagnosis in epilepsy. She had spells nearly her entire life that appear to be epileptic in nature by her clinical semiology. When she was monitored with scalp electrodes the diagnosis became less clear. Indeed, during her inpatient video-EEG admission, the day after her four events were captured, she had a cardiac pacemaker placed. The question of whether she had a primary epilepsy that led to asystole, or primary cardiac dysrhythmia that led to an epileptic spell was not fully answered, though the initial EEG changes seen with one of the spells suggest that an epileptogenic focus was the primary pathology of her illness.

EEG Features in Idiopathic Generalized Epilepsy: Clues to Diagnosis

To the Editor: We read with interest the article by Betting et al., 2006 entitled “EEG Features in Idiopathic Generalized Epilepsy: Clues to Diagnosis (1).” The authors investigated the contribution of EEG recordings for diagnosis and management of 180 patients with a clinical diagnosis of idiopathic generalized epilepsy (IGE). They found that the first EEGs yielded 45% with normal activity, 55% with abnormal activity, and only 33% indicated typical abnormalities. Patients with absence epilepsy were most likely to exhibit specific EEG abnormalities. At the time of EEG evaluation 92% of the patients were taking an AED and 80% of the patients had remained seizure free for ≥ 1 year. From this information the authors concluded that clinical history contributes more to the diagnosis of IGE and that treatment may be inappropriately delayed while “waiting” for a typical abnormal pattern on EEG. Significant studies on the predictive value of EEG after the first unprovoked seizure have revealed contradictory results. Some studies have shown EEG abnormalities in up to 70% of patients after an initial unprovoked seizure (2). Others have shown that obtaining an EEG provides little additional information in further treatment of the patients (3). In fact, our group has previously shown that extended EEG monitoring is important in establishing the diagnosis of the type of epilepsy and making an appropriate choice of antiepileptic drug (AED) therapy in the future care of patients (4, 5). Indeed, the accurate diagnosis of idiopathic generalized epilepsy was confirmed after prolonged EEG monitoring in only 29% of patients (5). Further controversy exists on whether risk for seizure recurrence is increased by the presence of an abnormal EEG on first examination. Several studies have demonstrated that the risk of recurrence doubles with an abnormal EEG (6, 7). We recommend caution when interpreting the results of this study. Our main reservation is that EEG interpretations were performed independent of whether the patient was receiving AED treatment or not. Studies have demonstrated normalization of EEGs while on AED therapy (8). Moreover, the EEG data was not assessed in patients with new onset seizures only. Initial EEGs were performed in some patients up to 44 years after seizure onset. We understand that in situations where resources are limited, there may be delays before performing an EEG. In this situation, we agree with the authors that AED treatment should not be withheld from a patient with seizures while “waiting” for an EEG. However, EEG is and will continue to be an important investigation in the diagnosis, treatment, and prognosis of patients with epilepsy.

EEG Changes in a Patient With Steroid-Responsive Encephalopathy Associated With Antibodies to Thyroperoxidase (SREAT, Hashimoto's Encephalopathy)

A 56-year-old woman presented with an acute confusional state and moderate global aphasia. Thyroperoxidase antibody level was elevated (3,890 IU/mL) and SREAT was diagnosed. MRI findings were normal. Cerebrospinal fluid examination revealed only a mildly increased protein. The initial electroencephalogram EEG showed slowing and markedly decreased amplitude over the left hemisphere and left temporal sharp waves. An EEG performed after treatment with intravenous steroids showed a significant improvement of the background slowing, which correlated with clinical improvement. One week later, the patient had an episode of forced head-turning and fencing posture to the right. The EEG shortly afterward showed slowing and a decreased amplitude over the right hemisphere. Continuous EEG monitoring was performed at the time of steroid treatment. Again, there was a significant improvement of the EEG after this treatment that correlated with the clinical condition. SREAT is characterized by fluctuations in mental status and variable EEG findings. These patients often show an excellent clinical improvement to immunosuppressive therapy, including corticosteroids. This case report documents the dramatic clinical and EEG improvement with steroid therapy.

Cerebral malaria owing toPlasmodium vivax: case report

Cerebral malaria is a diffuse encephalopathy associated with seizures and status epilepticus which can occur in up to one-third of children with severe malaria, particularly that caused by Plasmodium falciparum. We report a unique case of P. vivax infection complicated by status epilepticus. A 4-year-old boy was admitted to the emergency outpatient clinic with intractable seizures for the previous hour. During resuscitation, two episodes of left-focal tonic convulsions occurred and he received phenytoin. Because of a history of P. vivax infection in the family 3 months previously, a blood slide for malaria was undertaken. Thin blood smears demonstrated P. vivax. He was treated with chloroquine and primaquine. An initial EEG was normal but after 3 months of follow-up a second EEG showed generalised epileptic activity. Rarely, cerebral malaria is a presenting complication or occurs during the course of P. vivax infection. In endemic areas such as Turkey, the possibility of cerebral malaria should be considered.