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Purpose Dravet syndrome is an early-onset developmental and epileptic encephalopathy caused by pathogenic SCN1A variants in 80–90% of patients. EEG is initially normal, but abnormalities, both generalized and focal, may develop later. There is a limited understanding of typical EEG evolution in Dravet syndrome. Methods We searched Pubmed in July 2020 for studies including: ≥ 1 patient with Dravet syndrome clinical diagnosis and SCN1A pathogenic variant, and for each such patient, a description of ≥ 1 EEG and age at the time of the EEG. For each study, we evaluated for bias in patient selection. We also reviewed our research database for Dravet patients with available EEG reports. We extracted demographic data and EEG abnormalities reported (generalized/focal epileptiform abnormalities, focal/diffuse slowing). We determined the earliest ages at which different abnormalities were seen, as well as the percentage of reported abnormalities for different age ranges. Results We included 247 EEGs from 155 patients (from 31 studies and our research database). The earliest reported ages of generalized epileptiform discharges, focal epileptiform discharges, diffuse background slowing, and focal slowing, were six months, four months, four months, and four months, respectively. In patients 0–12 months, EEG was abnormal in 43%, but this rose to 90% for the 1–2 year-old group, and remained at approximately the same level for the remainder of the age groups. Conclusion Our results help clarify the relationship between age and EEG in Dravet syndrome; however, findings should be interpreted with caution given the inherent potential biases in the study design.

The aim of the present work was to evaluate changes in brain bioelectrical activity using electroencephalography (EEG) data in children with acute viral encephalitis. A total of 26 children were studied at the Pediatric Scientific Clinical Center for Infectious Diseases, Russian Federal Medical Biological Agency, with clinically confirmed diagnoses of “viral encephalitis.” Boys dominated the sex ratio of 18:8; mean age was 12 ± 2.1 years. All patients were in the acute period (first 14 days). The reference group for EEG analysis consisted of 10 healthy children. The groups were uniform in terms of sex and age. EEG recordings were made in all patients using a Neuron Spectrum 3 encephalograph (Ivanovo, Russia), with visual analysis of the EEG and spectral frequency analysis. Spectral power was evaluated in the α, θ, and δ frequency ranges, and the α/θ, α/δ ratios were also determined. Visual analysis of the EEG showed that 100% of children in the acute period of viral encephalitis showed diffuse slowing with recording of δ and θ frequencies. Focal changes in the form of sharp waves were recorded in 85% of cases (21 patients). Periodic activity was not recorded in even a single case in the study group of patients. Quantitative analysis of the results of statistical processing identified statistically significant decreases in the α/θ ratio (p = 0.035), maximum α (p = 0.046) and minimum θ (p = 0.044) in encephalitis patients as compared with the healthy children group. These data lead to the conclusion that pediatric patients during the acute period of viral encephalitis show significant impairments to the normal α/θ EEG power ratio. This impairment was apparent as a reduction in the power of the α and θ rhythms. It can be suggested that the cause of this reduction is suppression of the functional activity of the thalamus and thalamocortical pathways, as well as the reticular formation of the brain.

The objective of this study is to report EEG findings in both COVID-19 survivors and non-survivors who underwent EEG either due to seizure or encephalopathy. Out of total 1468 COVID-19-positive patients, 19 patients underwent EEG. Eight out of 19 patients had a history of seizure disorder and in the remaining 11 with no prior history of seizures, four had a clinical seizure during their hospital stay. Only one had new-onset complex focal status epilepticus on EEG. Amongst the survivors (13/19), the most common EEG findings were normal followed by mild diffuse slowing. Amongst the non-survivors (6/19), the most common EEG finding was moderate to severe slowing in 50% of the patients. It can be deduced that COVID-19 infection does not increase the propensity of epileptiform discharges on EEG. There is perhaps a trend towards increased risk of new-onset status epilepticus in patients with encephalopathy and focal lesions.

Background/ObjectivesWe aim to confirm the association between the high risk score on bispectral electroencephalogram (BSEEG) and mortality by comparing outcomes for those with “diffuse slowing” and normal findings on standard EEG.DesignThis is a retrospective study conducted with patient chart data from March 2015 to March 2017.SettingSingle center study at a tertiary care academic hospital in the Midwest region of the USA.Participants1069 subjects aged 55 years and older who were on an inpatient floor or intensive care unit and received a standard 24-hour EEG.MeasurementsPrimary outcome was all-cause mortality at 30-, 90-, 180-, and 365-days. Secondary outcomes were time-to-discharge, and discharge to home.ResultsPatients with “diffuse slowing” on standard EEG was significantly associated with 30-, 90-, 180-, and 365-day mortality (P < .001) compared to those with normal EEG findings when controlling for age, sex, and Carlson Comorbidity Index. Those with diffuse slowing also had a longer time to discharge (P < 0.001) and were less likely to discharge to home (P < 0.001) when controlling for the same factors. Findings were similar when limiting the study to only patients whose clinical status indicated “awake” at time of EEG, except for 30-day mortality.ConclusionOur findings show that a standard EEG finding of “diffuse slowing” for inpatients 55 year or older is associated with greater mortality. This study strengthens the importance of the association found between high BSEEG score and mortality.

Zusammenfassung Als breit verfugbares, kostengunstiges und wenig invasives Verfahren bietet sich die Elektroenzephalographie als Screening-Instrument bei akuten Verwirrtheitszustanden und deliranten Syndromen an. Trotz begrenzter Spezifitat lassen sich in der Regel fruhzeitig Hirnfunktionsstorungen erkennen und eine Eingrenzung moglicher organischer Ursachen vornehmen. Die Bewertung der Elektroenzephalographie steht im Kontext der klinischen Symptomatik und sollte komplementar zur bildgebenden Diagnostik erfolgen.

Cefepime is a fourth generation cephalosporin which is bactericidal for broad spectrum of organisms. This is a case-series of three patients who presented to our hospital with confusion secondary to cefepime use to treat urinary tract infection (UTI) and health care associated pneumonia (HCAP), after excluding other common etiologies of altered mental status (AMS). Of these three patients, one had progressive expressive aphasia and the other two demonstrated asynchronous myoclonic activity of the limbs. The symptoms were seen within four to five days of initiating the treatment and resolved within three days of discontinuation of cefepime. Acute structural abnormalities were excluded by computed tomography (CT) and magnetic resonance imaging (MRI) of the brain. Electroencephalogram (EEG) showed diffuse slowing activity with triphasic waves consistent with encephalopathy. In one patient, renal function was within normal limits, whereas it was abnormal in two patients. To our knowledge, this is the first report of cefepime induced asynchronous myoclonus and expressive aphasia in a patient with normal kidney function., Highlights • Recognizing cefepime neurotoxicity could be challenging in acute care settings. • Caution is recommended in patients with renal and hepatic impairments. • Patients may present with expressive aphasia and/or myoclonus even with normal kidney function. • Fortunately in most cases, neurotoxicity is reversible upon discontinuation of cefepime.

Zusammenfassung Die Bedeutung des Elektroenzephalogramms (EEG) fur Diagnostik und Therapie psychiatrischer Patienten wurde immer wieder kontrovers diskutiert. Routineempfehlungen legen den Einsatz der EEG-Diagnostik im Rahmen einer Psychopharmakotherapie nur noch bei Patienten mit epileptischen Anfallen in der Anamnese oder bei Vorliegen von Risikofaktoren fur epileptische Anfalle (Empfehlungen fur Antidepressiva) bzw. bei anfallsgefahrdeten Patienten und zur Diagnostik des Anfalls- und Toxizitatsrisikos (Empfehlungen fur Neuroleptika) nahe. Dennoch belegt die Literatur eindeutig, dass es auch weiterhin Psychopharmaka gibt, bei deren Einsatz eine EEG-Ableitung zum Standard gehoren sollte, so vor allem bei Lithium und Clozapin. Unter letzterem werden Inzidenzraten epileptischer Anfalle beschrieben, die je nach Untersuchung zwischen 3,5% bzw. 6% liegen. Unabhangig von der vergleichsweise hohen Inzidenzrate epileptischer Anfalle unter Clozapin liegt diese ganz allgemein bei Neuroleptika hoher als bei Antidepressiva. Bei diesen haben lediglich vier Praparate einen nennenswerten prokonvulsiven Effekt, namlich Maprotilin, Clomipramin, Bupropion und Amoxapin. Besondere Vorsicht fur Prokonvulsivitat gilt insbesondere bei Therapien im Hochdosisbereich und bei alteren oder multimorbid erkrankten Patienten. Fur den klinischen Alltag erscheint es auch weiterhin sinnvoll, haufige EEG-Veranderungen unter Psychopharmaka zu kennen und diese in ihrer Bedeutung adaquat einordnen zu konnen.

Hemiplegic migraine (HM) is an uncommon type of migraine which is classified into sporadic and familial subtype. The noticed electroencephalogram (EEG) findings during HM attack are diffuse slowing contralateral to the weakened limb, but are usually normal in asymptomatic states. A 52-year-old woman who suffered from headache accompanying right arm weakness and aphasic symptoms admitted to our hospital. She underwent total five times of EEG including 2 times before admission. Only the last EEG exam after 24 hours of sleep deprivation (SD) showed intermittent slowing and higher amplitude of positive occipital sharp transients (POSTs) on the left parieto-occipital area. Here, we report a case with HM who revealed abnormal EEG findings after SD, which was not observed in the routine EEG study without SD.

To determine whether certain characteristic electroencephalography (EEG) features are indicative of a genetic cause in early-life epilepsy.We enrolled a total of 100 patients with infantile-onset (3 years) epilepsy due to known genetic cause (n = 50) and nongenetic cause (acquired, structural, or unknown, n = 50). The genetic group was classified into synaptopathies, channelopathies, mTOR (mammalian target of rapamycin)-opathies, and chromosomal abnormalities. The nongenetic group included epilepsy of unknown cause and structural abnormalities such as brain tumor, focal cortical dysplasia and encephalomalacia. The clinical features, magnetic resonance imaging, and video EEG obtained before 3 years of age and again at follow-up were reviewed. Specifically, the background rhythms and patterns of interictal epileptiform discharges were analyzed to define the EEG characteristics.The genetic group was more likely to have seizure recurrence beyond infancy and significant developmental delay (P .01). The genetic and nongenetic groups showed different EEG patterns in the initial EEGs that persisted in follow-up EEGs. Diffuse slowing with pleomorphic focal/multifocal epileptiform discharges were present more often in the genetic (86%) compared with the nongenetic group (20%) in the initial EEGs (P .01). The last available follow-up EEG features were similar (81% in genetic versus 17% in nongenetic) to the EEG performed prior to 3 years of age.Our findings suggest a simple guide for genetic screening in children with early-onset epilepsy. Genetic testing may be indicated and useful in infants with delayed development, no obvious cause, and significant EEG background slowing with pleomorphic focal or multifocal epileptiform discharges.

We hypothesized that the finding of diffuse slowing on bedside EEG in children with moderate to severe traumatic brain injury (TBI) is associated with prolonged hospital stay and worse functional outcomes.We reviewed the medical records of all patients admitted to a single level I pediatric trauma center with moderate or severe TBI from 1/10-12/12 (defined by GCS10 on admission). EEG monitoring results, patient demographics, clinical characteristics, length of stay and postinjury outcomes were recorded. We compared outcomes between patients with and without diffuse slowing on EEG. Data are presented as mean±SEM; p0.05 was considered statistically significant.219 children with TBI were identified; 81 had a bedside EEG performed within 48 hours of admission. Diffuse slowing was present in 50 (mean age 5.7+0.7 years) and absent in 31 (n=31, mean age 4.2+0.9 years). Patients with diffuse slowing had a significant increase in ventilator days, ICU LOS, need for rehabilitation, and rehabilitation length of stay.The presence of diffuse slowing on EEG in children with TBI is associated with prolonged patient recovery and poor functional outcomes. This finding should prompt early consideration for rehabilitation and the need for intensive therapy.

The burst-suppression (BS) pattern of the EEG occurs in a rather limited number of conditions. It has been observed in deep stages of general anesthesia and in conjunction with sedative overdoses. It is also known to occur in the wake of cardiorespiratory arrest. Undercutting of the cortex has been found to result in BS activity. Rare neonatal epileptic encephalopathies also give rise to BS. Our personal interest was prompted by the consistent finding of BS activity in rats following cerebral anoxia (nitrogen inhalation, airway obstruction): after periods of EEG flatness, BS activity developed, followed by periodic bursts and diffuse slowing. On the other hand, earlier literature (before 1960) showed virtually no observation of BS, neither in anoxic patients, nor in animal experiments. It is likely that the introduction of modern intensive care treatment has engineered episodes of BS activity, probably due to modifications of the anoxic cerebral pathology.

In an effort to aid the clinician in the differential diagnosis of catatonic states, we assessed the nature of electroencephalography (EEG) findings in both medical and psychiatric forms of catatonia. An exhaustive review of the literature on catatonia due to a general medical condition (CDGMC) was performed in addition to a prospective review of catatonic patients at The Ohio State University Neuwpsychiatric Facility.A total of 105 patients had documented, specific clinical and EEG information, with neurologic conditions accounting for 82.8% of case reports. Results from the case series of 31 episodes of catatonia indicate that there is an increased likelihood of diffuse slowing in patients with CDGMC versus psychiatric catatonia. Given the observed rate of abnormalities, EEG is an important but underutilized tool in the differential diagnosis of catatonic disorders.

The EEG is an accessible tool for detecting encephalopathy, which usually manifests as delirium and sometimes as coma. Several disturbances have been described in the EEG of patients with encephalopathy, including diffuse slowing and periodic discharges. The pathophysiology of these EEG alterations, however, is poorly understood. This article shows that simulating activity of large populations of neurons, using neural mass models and neural network analysis, may increase our understanding of EEG disturbances in encephalopathy. We provide a brief introduction on the concepts of neural mass modeling and graph theoretical network analysis, and insights from this approach in previous work on neurologic disease, with a focus on encephalopathy. Finally, we speculate how anatomically coupled neural mass modeling combined with network analysis could provide new insights in pathophysiology of encephalopathy.

Diffuse slowing constitutes 40 % of all electroencephalographic abnormalities in psychiatric patients and thus is the most common abnormality detected the EEGs obtained from psychiatric patients (Struve 1994). Correlations have been demonstrated between the degree of slowing of the EEG and impairment of functions such as awareness, attention, memory, and comprehension (Struve and Boutros 2005). As of the writing of this chapter, there are hardly any systematic and well-controlled studies examining the clinical correlates of diffuse EEG slowing in the various psychiatric populations.

In a retrospective study, 1863 EEG recordings made during clozapine treatment of 283 patients with normal pretreatment EEG evaluations were analyzed. Furthermore, they were compared to the EEGs of the same patients without clozapine (i.e., during other neuroleptic medication). Moreover, the data of all patients who had seizures during treatment with clozapine were evaluated in case reports. Classical clinical EEG evaluation criteria for normal versus abnormal were used (including diffuse slowing and grouped alterations according to Jung 1953 and Kugler 1983). Of the 283 patients investigated, 61.5% (174) showed at least one abnormal EEG under clozapine according to these criteria. Evaluating all recorded EEGs of these patients in order to get some longitudinal information, we found a rate of 53.4% abnormal EEG recordings during clozapine treatment. Most of the EEG changes were evaluated as slight (22.5%) to moderate (10.1%) diffuse slowing and some as groups of nonparoxysmal waves (39.8%) or sharp waves (16.2%) rendering the EEGs abnormal according to the above criteria. Potential signs of increased bioelectrical cerebral reagibility such as paroxysmal activity (4.3%) or severe diffuse slowing (0.2%) were rare. A nearly linear correlation with the daily dose was found in the range up to 300 mg clozapine/day for both diffuse and grouped alterations. Possibly due to selection, adaptive mechanisms/habituation, and/or other unknown factors, the rate of alterations decreased slightly at doses above 300 mg and rose again sharply for doses over 600 mg/d. Three of the clozapine-treated patients, equivalent to 1.1%, developed seizures.(ABSTRACT TRUNCATED AT 250 WORDS)

A 36-year-old woman was suffering from acute disseminated encephalomyelitis, which had been preceded by a febrile illness. Brain CT showed diffuse white matter hypo-attenuation. Electroencephalography initially revealed altered non-REM sleep followed by diffuse slowing. Brain stem auditory evoked potentials showed interwave delay, while pattern visual evoked potentials were normal. The patient made a full recovery and the CT scan arid EEC normalized. Serological evidence of Mycoplasma pneumoniae was present.

Eleven patients (six manic, five non-manic) were studied during administration of lithium carbonate. All patients manifested neutrophilia during administration and there was a tendency for elevation in the fasting blood sugar. Serial EEG examinations and lithium determinations were done throughout the study in nine patients. The records of all nine patients showed profound changes in the form of diffuse slowing, widening of the frequency spectrum, potentiation and disorganization of background rhythm. Sensitivity to hyperventilation and paroxysmal bilaterally synchronous delta activity were also noted. Potentiation of an epileptic focus was observed in the EEG of one patient. These findings indicate that the CNS effect of lithium is both cortical and subcortical.

Quantitative EEG (qEEG) findings in Parkinson disease (PD) have been reported in only five previous studies. In these studies, the sample size was small and the distribution of qEEG changes was not estimated. This is the first qEEG evaluation not only employing multiple logistic regression analysis but also estimating the distribution of qEEG changes. The subjects comprised 45 PD patients without remarkable dementia and 40 age-adjusted normal controls. The lack of ischemic lesions in all subjects was confirmed by MRI. Absolute power values were measured for four frequency bands from delta to beta. The electrodes were divided into six, viz. frontal pole, frontal, central, parietal, temporal, and occipital locations. We calculated the spectral ratio, i.e., the sum of the power values in the alpha and beta waves divided by the sum of the values in the slow waves. The dependent variable was either PD or normal control; the independent variables were the spectral ratios, age, sex, and Mini-Mental State Examination score. The significant predictive variables in PD were the spectral ratios at all electrode locations except for the frontal pole (frontal location: P = 0.025, other locations: P < 0.01). PD presented diffuse slowing in the qEEG when compared with age-adjusted normal controls.

Summary: Purpose: Because of the high incidence of nonconvulsive status epilepticus (NCSE), the attraction of a “quick and easy” screening electroencephalogram (EEG) is obvious. Previous studies have shown utility of hairline EEG in diagnosing epilepsy. However, this technique has not been evaluated as a screening tool for NCSE. We wanted to provide proof of principle that a screening hairline EEG has sufficient sensitivity to use as a screening tool for diagnosing NCSE. Methods: A total of 120, 2- to 3-min EEG samples of normal and various abnormal digital EEG studies were reformatted in three six-channel montages (A, longitudinal bipolar; B, referential to ipsilateral ear; C, referential to contralateral ear) that mimicked a hairline recording and were interpreted by five neurophysiologists. The test data interpretation was compared with the original EEG interpretation. Results: Performance was best with montages A and B; 71% and 70.5% of the samples were interpreted correctly by using these montages. Only 65% of the samples were correctly interpreted by using montage C. With the best montage (A), the sensitivities ranged from 91% for normal EEG to 54% for periodic lateralized epileptiform discharges (PLEDs). The sensitivity for seizures was only 72%. Seizures were frequently misinterpreted as more benign patterns such as normal and diffuse slowing. Conclusions: EEG data reformatted to resemble a hairline EEG had low sensitivity for detecting seizures. As a result, we do not recommend further pursuit of hairline EEG as a “quick and easy” screening tool for NCSE.

To report a case in which triphasic waves developed during pentobarbital treatment. Pentobarbital coma is indicated in status epilepticus, refractory to other anticonvulsants, and in certain neurologic conditions in order to decrease brain metabolism. At high doses of pentobarbital, the EEG shows a typical burst-suppression pattern, while at low doses, diffuse slowing. Triphasic waves have not been reported in association with pentobarbital. A 54-year-old female underwent surgery for giant ophthalmic aneurysm clipping. Due to tearing and bleeding of the carotid artery, a clamp was placed, an external-internal carotid artery bypass was done, and the patient was started on pentobarbital. The patient remained comatose, the EEG showed a burst-suppression pattern, and the pentobarbital level was 30.5 micrograms/dl. One week later, the patient was still comatose, the EEG showed generalized triphasic waves with anterior predominance, and the pentobarbital level was 11 micrograms/dl. One day later, the patient was awake, and the EEG was normalized. The patient made a complete recovery. Triphasic waves may be seen in patients on pentobarbital. It is important to recognize this finding in patients on pentobarbital due to status epilepticus. This pattern should not be misinterpreted as 'electrical' status epilepticus.

I read with interest the article by Capparelli et al.1 reporting the case of an elderly patient with normal renal function presenting with recurrent episodes of cephalosporin-induced encephalopathy. EEG showed a diffuse slowing without evidence of ongoing epileptiform activity. These authors hypothesized that this neurologic adverse effect could be secondary to the modification that these drugs may produce on the cerebral concentrations of gamma-aminobutyric acid (GABA). The existence of acute confusional states associated with the use of cephalosporins in subjects with variable degrees of renal failure …

Severe epilepsy with multiple independent spike foci is an electroclinical entity with the following characteristics: (1) EEG showing multiple independent spike foci (three or more foci in both hemisphere, i.e., at least one in each hemisphere) and diffuse slowing of the background activity, (2) very frequent multiple types of seizures but mainly generalized minor seizures, (3) frequent association with mental retardation and neurologic abnormalities, (4) underlying causes of various nonspecific prenatal, perinatal, and postnatal cerebral conditions, and (5) poor prognoses for seizures and psychomotor development. It represents a diffuse encephalopathy with mutual transition between other age-dependent epileptic encephalopathies. This electroclinical condition may be appropriately named Markand-Blume-Ohtahara syndrome, after Markand and Blume, who initially described in detail the EEG pattern of multifocal spike discharges with its major clinical correlates, and Ohtahara, who extensively studied the group of patients with both clinical and EEG characteristics and proposed the concept of severe epilepsy with multiple independent spike foci, classifying it as one type of generalized epilepsy.

This chapter discusses electroencephalographic (EEG) findings in boxers. Many EEG recordings of boxers have been obtained either as a part of neurological examinations or in an attempt to measure acute traumatic injuries of the central nervous system. In the latter case, they were recorded immediately before and after boxing bouts. Compulsory EEG examinations were made on 24 professional boxers with the cooperation of the State Athletic Commission of Colorado. A statistically significant, increased incidence of dysrhythmic electroencephalograms was found in nine boxers. There were four records showing severe disturbances: three of these showed a temporal slow-wave focus and one revealed diffuse slowing and paroxysms. Five records showing moderate disturbance were also noted. Three of these were diffusely slow, and two were indicative of temporal slow-wave foci. In totaling the severely and moderately disturbed records, five were found to be focal and four showed diffuse findings.

EEG has been used widely in diagnosing encephalitis, as it demonstrates rather typical abnormalities, especially in herpes simplex virus encephalitis (HSVE). We analysed 204 EEG recordings from 98 consecutive acyclovir-treated patients with acute encephalitis between 1984 and 1994. Periodic complexes (PC) in the acute phase predicted poor outcome (Kendall tau 0.40, P < 0.001). However, unlike in many other diseases, e.g. stroke and intracerebral haemorrhage, the diffuse slowing of the background activity at acute phase did not predict outcome (Kendall tau -0.6, P = 0.35). At follow-up, the emergence of diffuse slow background activity was significantly associated with a less favourable outcome (Kendall tau 0.33, P = 0.0016). Among clinical variables, only epileptic seizures early during the course of the disease correlated significantly with outcome. EEG does have value as a prognostic indicator in acute encephalitides, but it seems that diffuse slowing of background activity or irritative features acutely are not as important as previously thought, based on the experiences of the pre-acyclovir era.

A 49-year-old woman attended the headache outpatient clinic for a tension-type headache. Her clinical examination was normal but EEG showed diffuse slowing over the left hemisphere. …

Aim To describe the clinical presentation of ‘Kleine-Levin (sleeping beauty) syndrome’ in a child, who presented with recurrent episodes consistent with encephalopathy, associated with excessive sleepiness, cognitive and behavioural disturbance and hyper sexuality. Method We report a previously well 14 years old boy who following a viral throat infection presented acutely with excessive tiredness, sleeping excessively, abnormal behaviour and hypersexuality. On examination he was sleepy but easily arousable. His GCS (15/15) and rest of the neurological examination including fundoscopy and other systemic examination was completely unremarkable. All his initial investigation including electrolytes, LFTs, CSF, virology screen and MRI brain scan were normal. Detailed autoimmune screening including anti-NMDAR, potassium channel and anti-GAD antibodies were also negative. EEG showed non-specific diffuse slowing consistent with encephalopathy. His excessive sleepiness gradually improved together with his altered behaviour in about two weeks after presentation. Hyper sexuality became more overt during this phase manifesting as fiddling with his genitalia, putting his pant down in front of parents and even inappropriate behaviour towards female staff. All these symptoms completely disappeared three weeks after his presentation and he attended school as before. He was readmitted six weeks later with exactly similar presentation and again only positive result being diffuse non-specific slowing of EEG. His recovery was also similar and he was completely back to his normal self in three weeks time. Result His recurrent symptoms are consistent with ‘Kleine-Levin syndrome (KLS)’ or ‘sleeping beauty syndrome’. KLS is a rare disorder which mainly affects adolescent men. Common symptoms include hypersomnia (100%), cognitive changes (96%), eating disturbances (80%), hypersexuality, compulsions, and depressed mood. The syndrome usually lasts for 8 years, with on an average seven episode of 10 days each recurring every 3.5 months. It is most frequently precipitated by infections and somnolence decreases using stimulants in nearly 40% of cases. Conclusion We believe neurologist and paediatricians should be aware of this (KLS) rare but distinct syndrome as early diagnosis will help us in reassuring patients and their families and will prevent unnecessary investigations.

A previous study using the quantitative EEG technique confirmed that diffuse slowing of the EEG is present in Parkinson disease. The present study was the first to assess the relationship between cognitive impairment and quantitative EEG in Parkinson disease. A total of 100 patients with Parkinson disease with a mean Hoehn-Yahr stage of 2.68 were serially enrolled. Cognitive impairment was assessed using the Mini-Mental State Examination. Lack of ischemic lesions was confirmed in all the patients by MRI. Absolute power values were measured for four frequency bands from δ to β. The electrodes were divided among six locations as follows: frontal pole and frontal, central, parietal, temporal, and occipital locations. Spectral ratio was calculated as the sum of power values for the α- and β-waves divided by the sum of values for slow waves. The relationship between Mini-Mental State Examination score and spectral ratio was assessed by the Jonckheere-Terpstra trend test. At all electrode locations, spectral ratio significantly decreased with a decline in Mini-Mental State Examination score (frontal pole, P = 0.017; frontal, P = 0.028; central, P = 0.019; parietal, P = 0.004; temporal, P = 0.002; occipital, P = 0.006). The rate of patients with Parkinson disease with slowing of the EEG was more frequent with serious cognitive impairment.

The EEG is a useful and, at times, an essential test in the evaluation of delirium. In most patients with delirium, the EEG will show diffuse slowing and thus is helpful in differentiating organic etiologies from functional, psychiatric disorders. The degree of the EEG changes correlates with the severity of the encephalopathy so that the EEG may be used to help monitor therapy. In some delirious patients, the EEG may indicate whether the patient is suffering from focal, rather than global, impairment. Furthermore, the EEG is the only test that can identify an ongoing epileptic state (e.g., nonconvulsive status epilepticus) as being responsible for the clinical picture of confusion. Other electrophysiological tests that may prove helpful in the evaluation of delirium, such as computerized EEG spectral analysis, topographic brain mapping, and sleep studies, are briefly reviewed.

In an attempt to clearly identify the different HMSN subgroups, we prospectively evaluated 128 subjects (46 index cases, 39 affected and 43 unaffected relatives) on clinical, genetic and electrophysiological grounds. The diagnosis of HMNS I or II was made in 77 patients. Differential diagnosis between type I and II patients was impossible on clinical grounds alone, but nerve conduction study showed a clear-cut subdivision into two populations. MCV behavior was consistent within families. Inheritance, autosomal dominant in almost all cases, was probably recessive in three HMSN I subjects and pedigree analysis pointed to X-linked transmission in one HMSN I family. We found no evidence for linkage to Duffy locus. We think that similar HMSN phenotypes can be determined by different gene defects. Ulnar nerve F-conduction velocity did not significantly differ from distal MCV in HMSN I: the evidence of a diffuse slowing of nerve conduction supports the hypothesis of a primary myelin defect.

Permanent injury to a cranial nerve during carotid endarterectomy is uncommon and most often attributed to iatrogenic causes. Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant generalized demyelinating neuropathy. Sporadic cases of HNPP also exist. HNPP is usually associated with a 1.5 megabase deletion of locus 17p11.2, which includes the gene for peripheral myelin protein-22 ( PMP22 ). PMP22 is located in the myelin of all myelinated peripheral nerves.1 The HNPP phenotype is one of recurrent focal painless neuropathies usually at common sites of entrapment often preceded by trivial or even obscure trauma. Electrodiagnostic studies may reveal diffuse slowing of sensory conduction velocities and accentuated distal slowing in affected nerves.2,3⇓ We report the case of a 74-year-old man with HNPP, revealed after bilateral carotid endarterectomy resulted in bilateral hypoglossal nerve injuries. A 74-year-old man had 90 …

To the Editor: A 72-year-old man with recurrent dizziness, confusion, and syncope told an internist that cold, carbonated beverages caused him to feel strange, dizzy, and confused and might have triggered several episodes over a one-year study period. A carotid Doppler study, 24-hour Holter monitor, cranial magnetic resonance imaging scan, computed tomographic scan, and echocardiogram were unremarkable. An electroencephalogram showed diffuse slowing. Phenytoin was given but provided no improvement. Another internist evaluated the patient's condition and ordered a treadmill exercise test and another magnetic resonance imaging scan, which were negative. A cardiologist was consulted, and the results of a tilt-table . . .

We retrospectively evaluated the clinical and EEG features of status epilepticus (SE) in 47 comatose adult patients in whom SE was suspected clinically or because the EEG revealed repetitive electrographic seizures or continuous spike-and-wave activity. Three groups of patients were identified. Group-1 patients (n = 33) had SE both clinically and on EEG. They usually had subtle, clonic movements restricted to the eyes, face, and upper extremities, and the EEG most commonly showed repetitive electrographic seizures or continuous spike-and-wave activity. Group-2 patients (n = 9) also had subtle motor manifestations of seizures, but the EEG was not that of SE, consisting of either irregular slowing with frequent spikes and sharp waves, an irregular mixed-frequency background with episodic accentuation, or diffuse slowing; one patient also had an intermittent burst-suppression pattern. The five patients in Group 3 lacked any clinical signs of seizures, but the EEG showed repetitive electrographic seizures or continuous spike-and-wave activity. There were no significant differences between groups in etiology of SE, response to therapy, or outcome, and there was no obvious relationship between the EEG findings and duration of SE. We conclude that recognition of SE in comatose patients may require both clinical and EEG evaluation since either approach by itself may fail to establish the diagnosis. Furthermore, the EEG findings in established SE do not necessarily progress through the series of defined stages suggested by some authors.

To the Editor .—Carmel 1 has described a series of pernicious anemia cases defined by a low serum cobalamin level and either an abnormal Schilling test result, absence of intrinsic factor, or presence of anti—intrinsic factor antibodies. A number of these cases displayed only neurologic or neuropsychiatric symptoms, with normal hematologic parameters. In another recent study, Lindenbaum et al 2 described similar observations. We agree with these authors and feel that the neuropsychiatric aspects of cobalamin deficiency need to be emphasized. Cobalamin deficiency may present as organic psychosis with neither spinal cord nor hematologic abnormalities. 3,4 We have studied two patients who presented with organic psychosis and low vitamin B 12 levels in the absence of any neurologic or hematologic abnormalities. One patient showed diffuse slowing on electroencephalographic examination and mild cerebral dysfunction on neuropsychologic testing; both the electroencephalographic and the neuropsychiatric test results became normal after vitamin B 12

17 patients suffering from the presenile dementia characterised by polycystic lipomenbranous osteodysplasia and sclerosing leukoencephalopathy were studied neurophysiologically. Noteworthy findings were diffuse slowing, the accentuation of 6-8 Hz parasagittal activity, slowing of the dominant occipital rhythm and, in the late phase when 13 of patients got epileptic seizures, there was paroxysmal activity in the EEG.

A clinical and electrophysiological investigation on 33 rabbits with experimental herpetic encephalitis revealed changes in brain electrical activity correlating with the clinical picture of the disease. In the acute period of encephalitis diffuse slowing of the brain potentials was accompanied by paroxysmal activity of two types: paroxysmal periodic complexes and “spike+slow wave” complexes at the rate of three per second.

Se estudian dos casos de enfermedad de Creutzfeldt-Jakob comprobados por examen necrópsico. Uno de ellos presentaba típicas descargas hipersincrónicas, periódicas en el electroencefalograma; el otro caso no mostraba estas descargas epileptiformes y evolucionó con una lentitud difusa progresiva. La espongiosis, gliosis y pérdida neuronal fué intensa en la corteza del caso con espigas y muy moderada en el caso sin espigas. El compromiso subcortical era similar en ambos casos. Se postula que la diferente expresión topográfica de su histopatología explicaria tambien la diferencia en el comportamiento de los potenciales evocados somatosensoriales y el diferente modelo electroencefalográfico del sueno penthotálico. La independencia de las descargas epileptiformes en cada hemisferio se prueba con el test de Wada. Se discute el origen de las espigas y su periodicidad. Se postula teóricamente que el predominio de las lesiones de las capas II a IV privaria a las células piramidales remanentes, de influencias inhibitorias, lo que explicaria la génesis de las espigas. Two syndromatic forms of Creutzfeldt-Jakob disease are illustrated with data from two cases confirmed by necropsy and studied by means of electroencephalogram, evoked potential recording and neuropathological techniques. One of the cases presented the typical hypersynchronous periodic discharges thougth to be characteristic of this disease. The other did not exhibit epileptiform diischarges, showing an evolution in which progressive diffuse slowing was the prominent feature. Cortical spongyosis, gliosis, and neuronal lose were intense in the case showing spikes, and moderate in the one without spikes. Subcortical involvement was similar in both cases. This different topography of pathological involvement might explain, in addition to electroencephalographic findings, the different behavior of somatosensory evoked potentials, which were of larger amplitude in the case showing epileptiform discharges, although in both cases deterioration of clinical state was accompanied by a progressive amplitude decrement in the evoked potential. Sleep induced by barbiturates was disrupted in the case with spikes, its pattern being closer to normal in the case with less severe cortical involvement. A Wada test demostrated that discharges in the hemispheres were independent. Spike periodicity is discussed. It is postulated that the heavier involvement of cortical layers II to IV deprive the remaining pyramidal cells of inhibitory influences, a condition which might explain the generation of periodic spike discharges.

Electroencephalographic aspects of coma in 201 children are presented. The ages of the subjects ranged between 1 month and 14 years. The EEG picture was not specific. Diffuse slowing and convulsive activity were present in meningoencephalitis and postconvulsive coma. Diffuse slowing was also present in coma of metabolic origin. Mixed slow and fast activity was typical of coma due to benzodiazepines, barbiturates and alcohol. In patients with intracerebral hemorrhages, there was marked focal slowing associated with generalized delta and theta waves. In 12 patients with craniocerebral trauma, the EEG showed generalized slowing which was associated with focal reduction of voltage in 6 cases and with convulsive activity in 2. Extreme slowing or an isoelectric recording had a bad prognosis. The reappearance of sleep spindles was a favorable sign.