Routine Electroencephalogram Research Articles

A rare cause of status epilepticus

Dear Editor, Status epilepticus (SE) has a long list of potential causes. In about 15% of cases, no cause is identified [1]. We report on a patient who presented with convulsive SE due to concomitant reversible cerebral vasoconstriction syndrome (RCVS) and posterior reversible encephalopathy syndrome (PRES) in the early postpartal period. A 44-year-old nulliparous pregnant woman was admitted for labor induction at gestational week 41. Intravaginal prostaglandin gel was applied but emergency caesarean section was then performed because of recurrent fetal bradycardia. Her initial blood pressure was 110/70 mmHg. Spinal anesthesia was associated with maternal hypotension and bradycardia, which responded to ephedrine 60 mg and atropine 0.75 mg boluses followed by intravenous administration of 500 mL of crystalloids. Her blood pressure then reached up to 162/82 mmHg. She also received oxytocin 10 IU intravenously during caesarean section followed by a continuous infusion of 10 IU over the next 6 h. During the cesarean section, she experienced a thunderclap headache. Immediately after delivery, her blood pressure increased to 160/85 mmHg requiring nicardipine infusion. She experienced a first tonic–clonic seizure less than 3 h after the caesarean section, when her blood pressure was 110/60 mmHg. A second seizure occurred rapidly and stopped only after an intravenous bolus of 2 mg of midazolam and 2 g of magnesium over 30 min. A continuous 2 g/day magnesium infusion was started. A third seizure during transportation to the radiology suite required an additional intravenous bolus of 1 mg of midazolam. Figure 1a, d shows results of the first cerebral magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). She was transferred to the ICU with a diagnosis of SE related to both RCVS and PRES. On ICU admission, blurred vision was the only abnormal clinical finding. Blood pressure was 120/62 mmHg. Routine electroencephalogram was normal. On day 2, her hemodynamic status was stable, her vision was normal, and her seizures were controlled. The continuous magnesium infusion was stopped. Intravenous administration of nimodipine (2 mg/h) was started to treat

Frontotemporal dementia: a case presentation

Frontotemporal dementia (FTD) is, next to Alzheimer disease, the most frequently encountered form of primary degenerative dementia among middle-aged subjects. It generally begins insidiously between the ages of 45 and 65 years, and is seen in both genders with equal frequency. It is characterized by changes in personality, behavior, and affect, in addition to loss of insight, perseverative and stereotypical behaviours, and changes in eating habits. These patients appear normal upon neurological examination and routine electroencephalography (EEG), but brain imaging reveals focal abnormalities in the frontotemporal lobes. There is significant deficiency in executive functions. This study describes a male patient with FTD that had began insidiously in his fifties, and in whom the changes in personality and impairment in behavior were the striking symptoms (loss of insight, hyperorality, and dietary changes; compulsive and stereotypical behaviours; blunted affect, decrease in the amount of speech and retardation in expressional behaviours; impairment in personal hygiene; urinary and fecal incontinence) along with a family history of dementia. The neurological examination and routine electroencephalogram (EEG) of the patient were normal. His cranial magnetic resonance imaging (MRI) revealed asymmetric atrophy, particularly in the right hemisphere at the dorsolateral and orbitofrontal regions. Tc-99 HMPAO single photon emission tomography (SPECT) detected asymmetric hypoperfusion within an extended region, including the right frontal and parietal lobes. There was deficiency in frontal executive functions. Partial improvement in behavioral symptoms was achieved by treating the patient with quetiapine 300 mg/day. The present case study showed that detailed history, as well as medical examination including physical and neurological examination and brain imaging, must be performed in the case of middle-aged patients with insidious onset of psychiatric symptoms.

P9-23 How common are the electroclinical seizures in the routine electroencephalogram?

P9-23 How common are the electroclinical seizures in the routine electroencephalogram?

Malformations of Cortical Development in Patients with Midline Facial Defects and Ocular Hypertelorism

We studied the neuroimaging and neurophysiological aspects of 17 patients with midline facial defects with ocular hypertelorism (MFDH). The investigation protocol included a previous semistructured questionnaire about family history; gestational, neonatal, and postnatal development; and dysmorphologic and neurologic evaluation. Recognized monogenic disorders and individuals with other well-known conditions were excluded. All patients had high resolution magnetic resonance imaging (MRI) with multiplanar reconstruction (MPR) and routine electroencephalograms (EEGs). We detected abnormalities in five patients whose MRIs had been previously reported as normal. MRI showed central nervous system (CNS) structural abnormalities in all patients, which included commissural alterations in 16/17 (94%), malformations of cortical development in 10/17 (58%), disturbances of neural tube closure in 7/17 (42%), and posterior fossa anomalies in 6/17 (35%). Some patients had more than one type of malformation occurring at different stages of the embryonary process. EEGs showed epileptiform activity in 4/17 (24%) and background abnormalities in 5/17 (29%) of patients. This study clearly demonstrated the presence of structural and functional neurologic alterations related to MFDH. Therefore, the CNS anomalies cannot be considered incidental findings but an intrinsic part of this condition, which could be related to environmental effects and/or genetic mutations. These findings would provide a basis for future investigations on MFDH and should also be considered when planning rehabilitation.

Duloxetine May Improve Tourette's Syndrome: A Case Report.

To the Editor: Patients affected by Tourette's syndrome (TS) suffer from sudden, involuntary, repetitive muscle movements (motor tics) and vocalizations (vocal tics). TS is also known as Gilles de la Tourette syndrome, named for the neurologist who first described the syndrome in 1885. The nature and complexity of the tics are usually variable over time, with natural waxing and waning in frequency and severity.1 Many patients also develop associated behavioral problems, such as obsessions and compulsions, inattention, hyperactivity, and impulsivity.2 Symptom onset typically occurs during childhood or early adolescence.3 The etiopathogenesis of Gilles de la Tourette syndrome has not been ascertained, but it seems that the frontal-subcortical neural pathways are involved.4 TS is frequently associated with attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, and behavior problems that impair daily life.2 Duloxetine is a monoamine agonist, mainly used to treat depressive patients. For that reason, my colleagues and I investigated its efficacy for a patient suffering from TS. Case report. I describe a 14-year-old girl 6 years after the onset of TS. Disease onset occurred in 2006 with involuntary, repetitive muscle movements and vocalizations. No triggering factors or accompanying symptoms could be identified. Family history was negative for sleep or other neurologic disorders. Comorbidities, especially attention-deficit/hyperactivity disorder, had been excluded by clinical interview and the Conners Rating Scales5; obsessive-compulsive spectrum disorders have been excluded by clinical interview. A routine electroencephalogram revealed no abnormalities and indicated the absence of epileptiform activities. We initiated duloxetine at 40 mg/d and continued treatment for 4 consecutive weeks. Six days after the start of treatment, improvement of both the involuntary muscle movements and the vocalizations was noticed (on the Yale Global Tic Severity Scale,6 the total motor score decreased from 17 to 10 and the total phonic score decreased from 18 to 12). The patient stated that she experienced a significant improvement of the symptoms. This is the first report to my knowledge illustrating the clinical efficacy of duloxetine in TS. If confirmed in controlled trials, this finding suggests efficacy of duloxetine in this disorder.

The Relationship of Interictal Epileptiform Discharges to Clinical Epilepsy Severity: A Study of Routine Electroencephalograms and Review of the Literature

Electroencephalograms are widely used to detect interictal epileptiform discharges (IEDs) in patients with a known history of seizures. However, previous studies have not found a consistent association between the presence or frequency of IEDs and clinical epilepsy severity, possibly because of differences in subject characteristics and recording techniques. We sought to investigate this relationship in a population and setting reflective of the most common clinical usage. We analyzed electroencephalograms and clinical records of all consenting patients with a history of at least two presumed focal-onset seizures who presented for routine electroencephalograms recording over 1-year time in an academic neurophysiology laboratory (n = 129). Despite adequate statistical power, we did not find an association between the presence or absence of IEDs or IED frequency and the most recently determined seizure frequency (median, 4 per year). A higher IED incidence was seen in subjects with longer epilepsy duration (P = 0.04). Neither IED incidence nor frequency (median, 10.0 per hour) correlated with age or antiepileptic drug use. Our results differ from those of some previous studies, most of which focused on more narrow subject populations, suggesting that the patient's clinical circumstances must be taken into account before assuming the utility of IEDs on routine electroencephalography in predicting epilepsy severity.

The clinical value of chloral hydrate in the routine electroencephalogram

To evaluate the diagnostic yield and clinical impact of chloral hydrate (CH) in the routine EEG. The EEG results and records of all patients receiving CH during routine EEG (CH-EEG) at Mayo Clinic Rochester between 4/1/07 and 9/30/07 (n=216 total; 148 adults) were reviewed for clinical indication, presence of epileptiform abnormalities and EEG duration. The results were compared to an equivalent number of consecutive EEGs performed without CH over the same time period (non-CH-EEGs). The clinical impact of the CH-EEG findings was evaluated by evaluating resulting clinical decisions made in the medical record. Chi-squared analysis was performed for discontinuous data, Student's t-test for continuous data. The proportion of EEGs with sleep-specific epileptiform abnormalities (SSEAs) was not statistically different (7.8% CH-EEG vs. 10.5% non-CH-EEG, p=0.34). CH was ordered more often by non-epileptologists than epileptologists (57% vs. 35%, p=0.0004). The mean acquisition time was greater for CH-EEGs (66.9min vs. 55.1min; p<<0.001). CH-EEGs resulted in a change in clinical management in 5/216 (2.3%). Compared to non-CH-EEGs, CH-EEGs were no more likely to show SSEAs, prolonged the acquisition time, and were associated with changes in clinical care in <3%. Routine use of CH in outpatient EEG is not strongly supported by these data.

Effects of Sleep Deprivation on the Pediatric Electroencephalogram

The routine electroencephalogram aids in epilepsy syndrome diagnosis. Unfortunately, routine outpatient electroencephalogram results are normal in roughly half of children with epilepsy. To increase the yield, practice guidelines recommend electroencephalograms with sleep and sleep deprivation. The purpose of this study was to rigorously evaluate this recommendation in children. We conducted a randomized, blinded comparison of routine electroencephalograms versus sleep-deprived electroencephalograms in 206 children aged 0 to 18 years. Electroencephalograms were ordered for standard indications after a neurologist's clinical assessment indicated > or =1 seizure (83%) or unclear spell (17%). The primary outcome was the proportion of normal routine electroencephalogram results versus sleep-deprived electroencephalogram results. Logistic regression modeling was used to assess the influence of sleep, as well as other clinical factors. Although children with sleep-deprived electroencephalograms had less sleep the night before (4.9 vs 7.9 hours) and more sleep during electroencephalograms (73% vs 55%), the increase in electroencephalogram yield was borderline significant (56% normal sleep-deprived electroencephalogram versus 68% normal routine electroencephalogram). Moreover, sleep during the electroencephalogram did not increase its diagnostic yield. Sleep-deprived electroencephalogram yield tended to be higher in children with preelectroencephalogram clinical diagnosis of seizure(s) and at older ages (>3 years). Sleep deprivation, but not sleep during the electroencephalogram, modestly increases the yield of the electroencephalogram in children diagnosed with seizures by neurologists. Compared with a routine electroencephalogram, the number needed to test with sleep-deprived electroencephalogram to identify 1 additional child with epileptiform discharges is approximately 11.

Quantitative evaluation of photic driving response for computer-aided diagnosis

The aim of our research is the quantification of the photic driving response, a routine electroencephalogram (EEG) examination, for computer-aided diagnosis. It is well known that the EEG responds not only to the fundamental frequency but also to all sub and higher harmonics of a stimulus. In this study, we propose a method for detecting and evaluating responses in screening data for individuals. This method consists of two comparisons based on statistical tests. One is an intraindividual comparison between the EEG at rest and the photic stimulation (PS) response reflecting enhancement and suppression by PS, and the other is a comparison between data from an individual and a distribution of normals reflecting the position of the individual's data in the distribution of normals in the normal database. These tests were evaluated using the Z-value based on the Mann–Whitney U-test. We measured EEGs from 130 normal subjects and 30 patients with any of schizophrenia, dementia and epilepsy. Normal data were divided into two groups, the first consisting of 100 data for database construction and the second of 30 data for test data. Using our method, a prominent statistical peak of the Z-value was recognized even if the harmonics and alpha band overlapped. Moreover, we found a statistical difference between patients and the normal database at diagnostically helpful frequencies such as subharmonics, the fundamental wave, higher harmonics and the alpha frequency band.

Oxcarbazepine in Children With Nocturnal Frontal-Lobe Epilepsy

Nocturnal frontal-lobe epilepsy is characterized by paroxysmal arousals, motor seizures with dystonic or hyperkinetic features, and episodic nocturnal wanderings. Carbamazepine is effective for seizure control in some of these patients, but seizures may be refractory to multiple antiepileptic drugs. We report on eight children between ages 4-16 years with nocturnal frontal-lobe epilepsy who had a dramatic response to oxcarbazepine at standard recommended doses, some of whom were refractory to previous antiepileptic medications. Brain magnetic resonance imaging, routine electroencephalogram, and prolonged, continuous video-electroencephalogram telemetry were performed in all children. Nocturnal frontal-lobe epilepsy was diagnosed by demonstrating ictal electroencephalogram changes originating from the frontal lobes. The children were followed for response of seizures to oxcarbazepine, side effects, and routine blood tests, including serum 10-monohydroxide derivative levels. The mean oxcarbazepine dose was 30.4 mg/kg/day +/- 11.7 (mean +/- SD); the mean 10-monohydroxide level was 23.1 microg/mL +/- 8.6 (mean +/- SD). Seizures improved within 4 days of oxcarbazepine initiation in six children, whereas two children required higher doses. Their follow-up has ranged from 12 to 24 months, without seizure recurrence or serious side effects. Our patients demonstrate the efficacy of oxcarbazepine for nocturnal hyperkinetic seizures in children with nocturnal frontal-lobe epilepsy.

Value of long-term electroencephalogram in diagnosing epilepsy

Background Routine electroencephalogram (EEG) usually cannot accurately reflect the discharge of epileptic patients due to the short examination, and long-term EEG can make up the shortcoming. Objective To comparatively analyze the long-term EEG of epileptic and non-epileptic patients, and investigate the values of long-term EEG in the diagnosis and differential diagnosis of epilepsy. Design A case-controlled study. Setting Ningjin County People's Hospital. Participants Totally 122 patients with epilepsy (epilepsy group) were selected from the EEG room of Ningjin County People's Hospital from January 2000 to December 2006, including 76 males and 44 females, 7 months to 78 years of age, the disease course ranged from 7 days to 7.5 years, and they all according with the standards for epilepsy set by the International Association for Epilepsy in 1997. Meanwhile, 118 patients with non-epileptic paroxysmal diseases were selected as the control group, including 71 males and 47 females, 2.5–87 years of age, the disease course ranged from 3 days to 7.5 years. Informed contents were obtained from all the subjects. Methods OXFORD GATE WAY 2000 16-lead portable EEG recorder was used for 24-hour electroencephalographic procedure. The patients could move normally during the monitoring, their activities, sleeping conditions, time and manifestations of seizures were recorded in details. In the next day, EEG at wake was recorded for 10 minutes, followed by 3-minute hyperventilation and open/close eye induction test, the phases of non-rapid eye movement (I–IV) and rapid eye movement were performed using EEG at sleep according to the international EEG standard. The abnormal rates of EEG epileptic discharge at wake and sleep at different sites were calculated. Main outcome measures Abnormal rate of long-term EEG at wake and sleep in both groups; Epileptic discharge at different sleeping phases in both groups; Abnormal rates of EEG epileptic discharge at wake and sleep at different sites in the epilepsy group. Results All the 122 patients with epilepsy and 118 patients with paroxysmal diseases were involved in the final analysis of results. ▪ Comparison of abnormal rate of long-term EEG at wake and sleep: In the epilepsy group, the abnormal rate of EEG at wake was obviously lower than that at sleep (68%, 91%, P < 0.01). In the control group, the abnormal rate of EEG at wake and sleep had no obvious difference ( P > 0.05). ▪ Results of epileptic discharge at different sleeping phases: In the epilepsy group, the epileptic discharge occurred at I–II phases of sleep cycle in 88.1%, and at III–IV in 11.9%; In the control group, the epileptic discharge occurred at I–II phases of sleep cycle in 91.7%, and at III–IV phases in 8.3% (1/12). ▪ Comparison of the abnormal rates of EEG epileptic discharge at wake and sleep at different sites in the epilepsy group: The abnormal rates of epileptic discharge at frontal lobe and temporal lobe at sleep were obviously higher than those at wake (21.3%, 24.6%; 10.7%, 11.7%, P < 0.01), while there were no obvious differences at wake and sleep at occipital lobe, parietal lobe ( P > 0.05). Conclusion Long-term EEG has great importance in the diagnosis and differential diagnosis of epilepsy, especially that it increases the detective rate of discharge by several cycles of sleep derivation. This method also provides important reference for the allocation of epileptic focus.

Photoparoxysmal responses in children with chromosomal aberrations

Electroencephalographic (EEG) anomalies and epilepsy are commonly observed in the clinical picture of patients with chromosomal aberrations. However, no investigations have been performed on the relationship between chromosomal disorders and photoparoxysmal response (PPR). In this study, we evaluate the characteristics of PPRs elicited with intermittent photic stimulation during a routine electroencephalogram in children affected by chromosomal anomalies and correlated this with the clinical profile of the child. A review of the literature has also been performed. PPRs occurred in 14% (4/28) of patients. PPRs were brief (<less 5 s), self-limited, elicited by several series of flashes, with an onset latency between 2 and 9 s, and scarcely controlled by anticonvulsants. Although further studies are needed to confirm the present data, our observations and the review of the literature suggest that patients carrying chromosomal anomalies might have a higher risk for photosensitivity when compared to the normal population. In these patients, PPR might occur early in life, persist into adulthood, and is commonly inscribed in more polymorphic electroclinical patterns.

Lamotrigine Adjunctive Therapy Among Children and Adolescents With Primary Generalized Tonic-Clonic Seizures

Lamotrigine Adjunctive Therapy Among Children and Adolescents With Primary Generalized Tonic-Clonic Seizures

Interictal, Potentially Misleading, Epileptiform EEG Abnormalities in REM Sleep Behavior Disorder

To examine the implications of interictal epileptiform abnormalities (IEA) in idiopathic REM-sleep behavior disorder (RBD), particularly the risk of misdiagnosing RBD episodes as epileptic nocturnal seizures. Observational analysis and review. Tertiary sleep center. Thirty patients (28 men; mean age 66.3 +/- 7.5 years) referred to our sleep unit for a definite diagnosis of nocturnal sleep-related motor and behavioral paroxysmal episodes. N/A. All the patients were found to be affected by idiopathic RBD according to standard clinical and videopolysomnographic criteria. IEA(sporadic, fronto-temporal sharp-waves) were detected in 8 subjects (26.6%) during routine electroencephalogram and/or nocturnal in-lab videopolysomnography with extended EEG montages. In 2 of these 8 patients, IEA occurred during REM sleep. When only the clinical history is considered, RBD episodes may be confused with nocturnal epileptic focal seizures. The presence of IEA either on routine awake electroencephalograms, or during sleep electroencephalograms, may add support for a diagnosis of epileptic nocturnal seizures. Our data show that IEA may occur in wake and sleep (non rapid eye movement and rapid eye movement sleep) tracings of subjects with episodes of idiopathic RBD. However full-night extended electroencephalogram montages and polysomnography recording of an episode proved useful in establishing a definite diagnosis of RBD in these potentially misleading cases. Comparison of the patients' demographic data and RBD features revealed no differences between RBD with IEA and without IEA. On this basis-and given that these abnormalities have also been described in elderly people with wakefulness-related nonepileptic disorders-IEA in RBD could simply be interpreted as a nonspecific phenomenon, probably related to brain aging.

Familial Temporal Lobe Epilepsy with Auditory Features

tial seizures with auditory features, which were described as a radio or a motorcycle running noise or “as if there were people talking on TV something she could not understand.” These symptoms could be followed or accompanied by distorted vision: “people’s face became disfigured.” She has good seizure control with carbamazepine. Her routine electroencephalogram (EEG) was normal. Magnetic resonance imaging (MRI) showed enlargement of left lateral temporal lobe and absence of first and second temporal sulci, and abnormal shape and axis of hippocampus (Fig. 2).

Adding Video Recording Increases the Diagnostic Yield of Routine Electroencephalograms in Children with Frequent Paroxysmal Events

To report on the usefulness of adding video recording to routine EEG studies of infants and children with frequent paroxysmal events. We analyzed the efficacy of this diagnostic means during a 4-year period. The decision whether to add video recording was made by the pediatric EEG interpreter at the time of the study. Studies were planned to last between 20 and 30 min, and, if needed, were extended by the EEG interpreter. For most studies, video recording was added from the beginning of EEG recording. In a minority of cases, the addition of video was implemented during the first part of the EEG test, as clinical events became obvious. In these cases, a new study (file) was begun. The success rate was analyzed according to the indications for the EEG study: paroxysmal eye movements, tremor, suspected seizures, myoclonus, staring episodes, suspected stereotypias and tics, absence epilepsy follow-up, cyanotic episodes, and suspected psychogenic nonepileptic events. Video recording was added to 137 of 666 routine studies. Mean patient age was 4.8 years. The nature of the event was determined in 61 (45%) of the EEG studies. Twenty-eight percent were hospitalized patients. The average study duration was 26 min. This diagnostic means was particularly useful for paroxysmal eye movements, staring spells, myoclonic jerks, stereotypias, and psychogenic nonepileptic events. About 46% of 116 patients for whom cognitive data were available were mentally retarded. EEG with added video recording was successfully performed in all 116 cases and provided useful information in 29 (55%) of these 53 patients. Adding video recording to routine EEG was helpful in 45% of cases referred for frequent paroxysmal events. This technique proved useful for hospitalized children as well as for outpatients. Moreover, it was successfully applied in cognitively impaired patients. Infants and children with paroxysmal eye movements, staring spells, myoclonic jerks, stereotypias, and pseudoseizures especially benefited from this diagnostic means. Because of its low cost and the little discomfort imposed on the patient and his or her family, this technique should be considered as a first diagnostic step in children with frequent paroxysmal events.

Surgical Treatment for Extratemporal Epilepsy.

Partial seizures of extratemporal origin may present unique challenges in the patient with medically refractory seizures. The efficacy of an extratemporal focal cortical resection may be less effective than an anterior temporal lobectomy for intractable epilepsy. The potential operative complications may be increased in individuals with extratemporal epilepsy because of functional cerebral cortex involvement and the need for a large cortical resection to significantly reduce seizure tendency. Partial seizures of extratemporal origin are predominantly associated with frontal lobe epilepsy. The most effective treatment for intractable partial epilepsy is a focal cortical resection with excision of the epileptogenic zone, that is, an area of ictal onset and initial seizure propagation. The preoperative evaluation and operative strategy in patients with partial epilepsy of extratemporal origin associated with pharmacoresistant seizures is determined by the anatomic localization of the epileptogenic zone and the presence of a substrate-directed disorder. The goals of surgical treatment in extratemporal epilepsy include rendering the patient seizure-free, avoiding operative morbidity, and allowing the individual to become a participating and productive member of society. Before surgical treatment, the individual with extratemporal epilepsy will require a comprehensive preoperative evaluation, including routine electroencephalogram (EEG), long-term EEG monitoring, neuropsychologic studies, and magnetic resonance imaging (MRI). Patients with a normal MRI study, conflicting preoperative evaluation, or involvement of suspected functional cerebral cortex would require chronic intracranial EEG monitoring. The rationale for intracranial EEG includes localization of the ictal onset zone or intraoperative functional mapping, or both. Two-fluorodeoxyglucose positron emission tomography studies are usually unremarkable in patients with extratemporal epilepsy and normal MRI scans. Subtraction ictal single photon emission computed tomography coregistered to MRI (SISCOM) study may be useful to demonstrate a localized cerebral perfusion alteration in patients with intractable partial epilepsy. The diagnostic yield of SISCOM has been confirmed in patients with extratemporal epilepsy undergoing surgical treatment. The results of the SISCOM study may tailor the placement of intracranial EEG electrodes and affect the operative strategy. Patients with extratemporal epilepsy overall are less favorable operative candidates than individuals with medial temporal lobe epilepsy. However, individuals with MRI-identified lesional pathology of SISCOM-identified perfusion alterations concordant with the epileptogenic zone may be considered for surgical treatment. Chronic intracranial EEG monitoring may be necessary to confirm the localization of the ictal onset zone before epilepsy surgery. Patients with normal neuroimaging studies and extratemporal epilepsy are unlikely to be rendered seizure-free with focal cortical resection and should be considered candidates for other alternative forms of treatment for intractable partial epilepsy. Patients with non-substrate-directed extratemporal epilepsy should undergo a preoperative evaluation and surgical treatment at a comprehensive epilepsy center with extensive experience in chronic intracranial EEG monitoring and contemporary neuroimaging procedures because of the inherently high acuity associated with the operative management clinical disorder.

Photoparoxysmal responses in children: their characteristics and clinical correlates

This study evaluates the characteristics of photoparoxysmal responses elicited with intermittent photic stimulation during a routine electroencephalogram in childhood and correlated this with the clinical profile of the child. Photoparoxysmal responses occurred in 8% (21/263) of children where activation was undertaken. Photoparoxysmal responses were often brief and had a variable onset latency. This study suggests increasing the duration of the stimulus train to 10 seconds or more will increase the diagnostic yield. Photoparoxysmal responses very rarely outlasted the stimulus, and self-limited photoparoxysmal responses probably have greater significance than previously attributed to them. They are highly correlated with epilepsy.

Frontal Theta Rhythm: Evaluation of its Clinical Electrophysiological Significance with a View Point of Aging

Background: Frontal theta rhythms can be observed in routine electroencephalogram (EEG) examinations. Their significance has been interpreted from pathological or physiological viewpoints by many previous studies. We evaluated the clinical electrophysiological significance including aging of the frontal theta rhythms to differentiate pathological theta activities. Methods: Since 23 EEGs, out of 2,424 patients routinely taken in our hospital and 87 healthy volunteers, showed frontal theta rhythms during drowsiness, those subjects were re‐examined at rest and during a mental task. The morphological features of theta rhythms were compared between the two conditions and analyzed in terms of clinical conditions. Results: In 16 subjects theta rhythms either disappeared or were suppressed during the mental task (“suppressed” group). In the seven subjects theta rhythms recorded during drowsiness were equivalent or were activated by the mental task (“activated” group). The subjects of the suppressed group were found to have clinical findings suggesting cerebral organic changes, while those of the activated group did not have such findings. In the morphological comparison between these groups, the frequency, amplitude, and duration were significantly different. Conclusion: The differentiation of these two types of frontal theta rhythms may be possible by clinical information, morphological features of theta rhythms and their changes during a mental task. In the case of pathological theta rhythms appearing in middle and advanced age, they can sometimes be based on aging due to arteriosclerotic changes and others.

Electrophysiological assessment of neuropsychiatric disorders.

In this article the clinical usefulness and limitations of the routine electroencephalogram (EEG) are discussed. Emphasis is placed on 3 specific clinical situations where EEG can be most useful: the differential diagnosis of dementia versus pseudodementia, the evaluation of episodic behavior disorders including aggressive episodes, and acute confusional states. An atypical clinical presentation is emphasized as the most important indiction for obtaining an EEG evaluation. The issue of controversial EEG waveforms is discussed in some detail. The need for well-designed, controlled studies to further examine these EEG patterns is emphasized. Finally, the limitations of the routine EEG are discussed. The article concludes with a brief mention of the future promise of other electrophysiological testing modalities such as quantified EEG, evoked potentials, and sleep studies.