Hypoglycemic activation of focal abnormalities in the EEG of patients considered for temporal lobectomy

EEGs were recorded in 22 patients with medically refractory complex partial epilepsy undergoing presurgical evaluation and 11 age-matched controls while subjected to moderate levels of hypoglycemia to determine if changes activated were predictive of underlying pathology. Five patients had fasting EEGs showing focal abnormalities not seen in the non-fasting state. With hypoglycemia, EEG tracings in normal individuals showed diffuse background slowing, whereas 7 of 22 patients developed focal temporal changes, including focal spike and focal slow wave activation. The development of focal changes correlated well with clinical data concerning underlying focal pathology; focal abnormalities were not evoked in patients with multifocal disease. Hypoglycemic activation of the EEG may be a useful technique for predicting the presence of pathology in patients considered for anterior temporal lobectomy.     

62例病毒性脑炎脑电图与临床及CT分析

为探讨病毒性脑炎（病脑）患者脑电图（EEG）与临床及CT之间的关系,将临床确诊的62例病脑患者进行EEG与CT检查,对其EEG异常的阳性率、异常程度与病程、临床表现、CT之间的关系进行比较分析,并作统计学处理。结果发现,发病10天以内EEG中、重度异常39倒（78%）,与10天以后比较有显著性差异（P＜0．001）。EET可表现为三种形式：以弥漫性异常为主（51.5％）;弥漫性异常伴局灶慢波（32．3%）;局灶性异常（16．2%）。EEG与CT之间无明显相关性（P＞0．05）。提示：EEG检查对病脑的诊断、鉴别诊断,以及动态观察病情、判断预后有重大意义。CT不能取代EEG。     

EEG and pathologic findings in patients undergoing brain biopsy for suspected encephalitis.

Previous studies have suggested that EEG may be helpful in the diagnosis of herpes encephalitis (HE). To further define the value of EEG in an acutely ill, febrile, encephalopathic patient suspected as having encephalitis, we reviewed initial preoperative EEGs with the results of cerebral biopsies in 24 consecutive patients suspected of having encephalitis. Statistical analysis demonstrated that EEG patterns have only limited association with biopsy results. Since diseases which mimic encephalitis may also generate identical EEG changes, this is not an unexpected finding. EEG is useful in the evaluation and management of patients with encephalitis. However, the absence of specific wave forms or focal EEG abnormalities in the proper clinical setting should not deter consideration of HE or delay treatment.     

EEG in neonatal herpes simplex encephalitis

The EEGs of 21 newborns with herpes simplex encephalitis were analysed. The diagnosis was based on the demonstration of herpes simplex infection in association with neurological symptoms, other etiological factors being excluded. Sixteen of 21 babies (76%) showed in their EEGs electrical seizures, either focal or unilateral. These paroxysms consisted of sharp waves or slow waves repeating at pseudo-periodic intervals, usually of 0.5-2 sec. Individual paroxysms had a duration of 10-20 sec in 6 babies and 1-2 min in 10 patients. During the same period, 20 other babies displayed the same EEG finding. Of these, 11 had encephalitis of unknown etiology. In our series there appeared to exist a correlation between both the duration of the electrical seizures and the degree of EEG background abnormality and the clinical outcome. Babies with markedly abnormal background and long-lasting paroxysms tended to have a poor prognosis. It is concluded that in newborns with clinical signs of encephalitis who show in their EEGs paroxysms of the type described, the possibility of herpes simplex encephalitis should be considered.     

Focal EEG findings in juvenile absence syndrome and the effect of antiepileptic drugs.

The presence of focal EEG abnormalities in juvenile absence syndrome (JAS) may cause it to be misdiagnosed as focal epilepsy. The purpose of our study was to determine the presence of focal EEG abnormalities in patients with JAS and to ascertain whether some clinical features or antiepileptic drugs (AEDs) have an effect on focality. Serial EEGs of 52 consecutive patients with JAS were retrospectively analyzed. The patients were divided into two groups according to whether they were treated with valproic acid and/or lamotrigine (VA-LTG) or not during the times of these EEG recordings. The relationship between the presence of EEG focality and the use of AEDs in addition to other risk factors was examined. Two or three consecutive EEGs (total 100) of the 52 patients were evaluated. Among these, the rates of focal EEG abnormalities were 18%, 36%, and 25% during the follow-up EEGs without AEDs (5/27) and first (16/45) and second EEGs (7/28) with AEDs, respectively. The last two EEGs showed a tendency towards a higher proportion of EEG focality in patients who received other AEDs (47%-45%) compared with those that received VA-LTG (13%-12%). The proportion of JAS patients with focal EEG findings in serial EEGs tended to decrease with an increasing rate of VA-LTG use. As a hypothetical explanation, changes in EEG focality may reflect the effect of AEDs other than VA and/or LTG, in addition to a developing hyperexcitable cortical area.     

Focal Electroencephalographic Abnormalities in Juvenile Myoclonic Epilepsy

Summary: A detailed study of EEGs of patients with an unequivocal diagnosis of juvenile myoclonic epilepsy (JME) showed a high prevalence of focal EEG abnormalities. Focal slow waves, spikes, and sharp waves and focal onset of the generalized discharge were present in 36.7% of EEGs in our patients with JME. In more than half of the patients, at least one EEG showed focal abnormalities. These features should not be misconstrued as indicative of partial epilepsy.     

Electroencephalographic changes in patients with herpes zoster

EEGs of 42 patients with herpes zoster and 6 with herpes zoster-associated encephalitis were studied to characterize the nature and prevalence of EEG abnormalities in apparently uncomplicated herpes zoster. Thirty-one percent of herpes zoster patients had EEG changes with reduced rhythm frequency ranging from 7 to 2 Hz activity. Frontotemporal localization was observed in 54% of the abnormal EEGs. When compared to EEG in herpes zoster associated encephalitis, the findings were qualitatively the same, but tended to be more severe in the encephalitis cases. No effect of acyclovir on the EEG could be demonstrated.     

Lateralization of interictal EEG findings.

Several reports indicate that interictal epileptiform discharges (IED) may be more likely to occur over the left cerebral hemisphere than over the right. The objective of our study was to determine the frequency and type of IED on routine and multihour EEGs in a tertiary epilepsy center to estimate the frequency of left-sided versus right-sided IED and to determine interictal spike distribution pattern differences between adult and pediatric epilepsy patients. The current study retrospectively reviewed 31,207 EEGs (25,793 routine EEGs and 5414 multihour EEGs) recorded on 24,003 patients during the period from 1993 to 2003. All EEGs were read according to a systematic EEG classification system. Every patient was considered only once by including the first abnormal EEG. Regional unilateral or bilateral IEDs were recorded in 1707 patients (7%). Regional unilateral or bilateral slow was recorded in 2297 patients (9.6%). Left-sided regional IED were seen in 828 patients and accounted for 58% of all unilateral IED. Left-sided slow was seen in 1389 patients and accounted for 65% of all unilateral slow. Lateralization of slow was due to intermittent slow, whereas continuous slow involved both hemispheres equally. There was no lateralization difference in benign focal epileptiform discharges of childhood. Lateralization shows a tendency toward greater left-sided lateralization of interictal findings with aging. Benign focal epileptiform discharges were only seen under the age of 20 years old. Regional IEDs were seen in approximately 7% of patients and slowing occurs in 10% of patients. Both abnormalities were seen more frequently in the left hemisphere. Age adjusted analysis of the data revealed that this left-sided predominance was mildly increased in adults as compared with pediatric patients.     

EEG and seizures in autistic children and adolescents: further findings with therapeutic implications.

The goal of this study was to investigate the incidence of epilepsy and also the EEG findings among children with autism (A), a devastating disorder, and to compare these data to an EEG control group. EEGs were quantified as to the degree of epileptiform activity and also slow wave abnormalities. Abnormal EEGs were found in 75% of the 59 A children and 82% of their 151 EEGs; 46% had clinical seizures. Nearly all children with seizures had epileptiform activity, but almost 20% of those with spike discharges did not have clinical attacks. Slow wave abnormalities were more frequent and of a greater degree of severity in the A group, compared to controls. One new finding was that a greater variability of EEG abnormalities was found in the A group. Therapeutic implications, based on these latter findings, are discussed.     

Electroencephalography in herpes simplex encephalitis

The EEG in the acute stage of herpes simplex encephalitis (HSE) can show a variety of abnormalities, including uni- or bilateral periodic sharp waves or attenuation of amplitude, focal or generalized slow waves or epileptiform discharges, or electrical seizures. No specific EEG patterns are pathognomonic for HSE, but a focal or lateralized EEG abnormality in the presence of encephalitis is highly suspicious of HSE. In the acute stage, EEG appears to be more sensitive than computerized tomography or radioisotope brain scanning. The EEG findings tend to differ in the course of illness, and the periodic discharges occur only during the acute stage. The EEG findings in either the acute stage or long-term follow-up do not predict the chance of survival or severity of disability, and EEG changes appear to lag behind the clinical changes. EEG results can become normal in both adults and neonates when the acute stage is over.     

Electroencephalograms (EEG) in 250 patients with epilepsy in a cysticercosis endemic area in Burundi]

OBJECTIVES: This work aimed at describing EEG abnormalities in epileptic patients living in areas endemic for cysticercosis, underlining the electroclinical correlations and discussing the interest of EEG examination in this context. METHODS: During a case-control study, 250 EEGs from patients with epilepsy were recorded with a portable system. Types of seizures were assessed clinically and from information obtained through a standardised questionnaire, and along with EEG were related to the results of cysticercosis serological tests. RESULTS: Among the 249 EEGs, 48% were normal, 5.2% had epileptic abnormalities, 6.8% showed an association between epileptic abnormalities and slow alterations. Slow theta and delta abnormalities were found in 21.8% of cases, and isolated deterioration of basic rhythms was observed in 17.3% of cases. Most seizures were generalized, and 61% of the patients had positive serology. One EEG was uninterpretable and another showed isolated spikes. Electroclinical agreement was considered to be satisfactory in 33 patients, and was better with the epileptic than with slow abnormalities. The existence of epileptiform EEG abnormalities confirmed clinically diagnosed epilepsy, but did not allow etiological diagnosis. Electroserological agreement was good in 24 patients. A significant association (Chi2, p = 0.03) existed between slow focal abnormalities and positive cysticercosis serology. Conversely, no significant association was detected between epileptic patterns and serology results. CONCLUSION: While the EEG alone clearly does not allow aetiological diagnosis, its joint use with clinical and biological results was a key element of the etiological and therapeutic discussion. When it shows focal abnormalities in a patient with epilepsy living in a high prevalence cysticercosis area, it confirms the clinical suspicion of neurocysticercosis. Morphological imagery alone can provide etiological information on the seizures by showing the nature and localization of the parenchymal lesions.     

Comparative pre- and postoperative interictal scalp electroencephalographic examinations in patients with selective amygdalohippocampectomy

The conventional interictal scalp EEGs of 93 patients who underwent selective amygdalohippocampectomy were analyzed over a period of 4 pre- and postoperative years. In each EEG, the following parameters were visually assessed and quantitatively rated: background activity, ipsi- and contralateral focal slowing, ipsi- and contralateral epileptogenic foci, and generalized epileptiform abnormalities. EEG findings were rated by calculating an abnormality index for each EEG parameter correlated with (a) patient's postoperative seizure outcome and (b) presence or absence of morphological lesions. This way the degree of abnormality and the course of each EEG parameter over 8 years became apparent. Comparing the EEGs of patients with a structural lesion to patients without a structural lesion we found that, in patients without a structural lesion, all analyzed parameters—except for the ipsilateral focal slowing—were preoperatively more pathological. Furthermore, in both groups the EEG parameters improved following the operation. The amount of the improvement, however, differed. Comparing the EEGs of patients with good and bad postoperative seizure outcomes, preoperatively there was no significant difference in the abnormality of the EEG parameters. There was a strong correlation between the amount of the improvement of the parameters and the clinical seizure outcome.     

Periodic EEG complexes in infectious mononucleosis encephalitis.

The presence of periodic EEG complexes in patients with an acute viral encephalitis is generally held to suggest that infection is due to herpes simplex. We now report a patient with clinical and laboratory findings of infectious mononucleosis, and neurologic involvement manifested by lymphocyte meningitis, coma, seizures, aphasia, hemiparesis and hemianopsia. Serial EEGs showed periodic, predominantly left-sided slow wave complexes occurring every 4 to 5 seconds, which disappeared with clinical resolution of the illness. In view of our findings and the similar findings reported previously by others in another case of infectious mononucleosis encephalitis, an EEG showing periodic complexes in the clinical setting of acute viral encephalitis should not be considered pathognomonic of herpes encephalitis, and infectious mononucleosis should be included in the differential diagnosis.     

Early evolution and incidence of electroencephalographic abnormalities in Creutzfeldt-Jakob disease

The clinical and EEG findings in patients in the literature with Creutzfeldt-Jakob disease (CJD) were reviewed and compared with findings in 36 patients with CJD at the Massachusetts General Hospital (MGH). Twenty-one of the 36 MGH cases had histopathology, all with findings consistent with CJD. EEGs in 18 patients studied pathologically and in 10 without pathological investigation (28 of the 36) had periodic sharp wave complexes (PSWC) at some time during the clinical course. Of the other eight patients, two had only a single EEG early in the course of the illness, four experienced unusually long clinical courses, and two never showed PSWC despite numerous EEGs. PSWC made their appearance within 12 weeks of onset of clinical symptoms in 25 of 27 in whom EEGs were done during that period. In the early stages, EEGs in 14 of 28 showed focal PSWC or amplitude asymmetries of PSWC that corresponded well with focal myoclonus or other focal neurological abnormalities. In the literature, PSWC occurred within 12 weeks of the onset of the illness in 66 of 75 patients (88%) with CJD who had comparable clinical and neuropathological findings and adequate EEG data during the first 3 months of the illness. In the approximately 10% of patients who experienced unusually long courses, PSWC occurred in only about 55%. The presence of PSWC in association with the appropriate clinical, biochemical, cerebrospinal fluid, and neuroradiological findings is diagnostic of CJD. Brain biopsy is, therefore, unnecessary even when clinical therapeutic trials are undertaken and certainty of diagnosis is required. The absence of PSWC in the EEG after 12 weeks' duration of illness is a point strongly against the diagnosis of CJD unless it is a rare subtype of long duration. Only those patients without PSWC need to be biopsied.     

Concomitant administration of sodium dichloroacetate and thiamine in west syndrome caused by thiamine-responsive pyruvate dehydrogenase complex deficiency

IRDA (intermittent rhythmic delta activity) is an abnormal generalized EEG pattern that is not specific to any single etiology and can occur with diffuse or focal cerebral disturbances. To determine whether different electrographic features of IRDA and associated EEG findings can differentiate underlying focal from diffuse brain disturbances, we performed a blind analysis of 58 consecutive EEGs with an IRDA pattern, recorded from 1993 until 1996, in which we evaluated posterior background activity, focal slowing and IRDA characteristics (frequency, distribution, duration, symmetry and abundance). The clinical diagnosis, state of consciousness and CT brain findings were retrieved from the patients' hospital records. There were 58 patients (33 females; mean age, 58+/-21 years). Twelve (21%) had only focal brain lesions, while 46 (79%) had diffuse brain abnormalities, (15 diffuse structural, 19 metabolic abnormalities, 12 postictal). Normal consciousness and focal EEG slowing were more frequent in patients with focal abnormalities, however, this was not statistically significant. Of the patients with focal abnormality, 11 (92%) had normal posterior background activity either bilaterally (n=4) or contralateral to the focal lesion (n=7). Bilaterally normal posterior background activity was observed in about 30% in both groups. Bilaterally abnormal posterior background activity was apparent in one patient (8%) with focal brain lesion and in 31 patients (67%) with diffuse brain abnormalities (P<0.0001). There were no significant differences in IRDA electrographic features between the focal group and the group with diffuse brain disturbances. We conclude that IRDA morphology cannot distinguish between focal and diffuse brain abnormalities.     

Neurologic, neuropsychologic, and electroencephalographic findings after European tick-borne encephalitis in children

Tick-borne European early summer meningoencephalitis is believed to be a benign disease in childhood. The causative RNA virus is from the same family as the West Nile virus, and the respective clinical presentations have many similarities. We studied 19 German children who had suffered from tick-borne encephalitis virus meningitis or meningoencephalitis in an endemic area and compared them with 19 matched controls. Epidemiologic data were consistent with known features of tick-borne encephalitis infection in southern Germany. None of the children studied had severe neurologic or neuropsychologic sequelae. One child developed significant clinical depression shortly after the illness. Electroencephalograms (EEGs) from children with tick-borne encephalitis were significantly slower on follow-up than control EEGs. After tick-borne encephalitis, children had a higher likelihood of having an impairment of attention and psychomotor speed. Using the Touwen neurologic examination, after tick-borne encephalitis, children had lower scores than control children on 4 of the 10 subsystems. Owing to the small sample size, it was difficult to identify risk factors for and predictors of adverse outcomes.     

Utility of Neurodiagnostic Studies in the Diagnosis of Autoimmune Encephalitis in Children

BackgroundAutoimmune encephalitis is currently a clinical diagnosis without widely accepted diagnostic criteria, often leading to a delay in diagnosis. The utility of magnetic resonance imaging (MRI) and electroencephalography (EEG) in this disease is unknown. The objective of this study was to identify disease-specific patterns of neurodiagnostic studies (MRI and EEG) for autoimmune encephalitis in children.MethodsWe completed a retrospective chart review of encephalopathic patients seen at a large pediatric hospital over a four year interval. Clinical presentation, autoantibody status, and MRI and EEG findings were identified and compared. Individuals with autoantibodies were considered “definite” cases, whereas those without antibodies or those with only thyroperoxidase antibodies were characterized as “suspected.”ResultsEighteen patients met the inclusion criteria and autoantibodies were identified in nine of these. The patients with definite autoimmune encephalitis had MRI abnormalities within limbic structures, most notably the anteromedial temporal lobes (56%). Only individuals with suspected disease had nontemporal lobe cortical lesions. Sixteen patients had an EEG and 13 (81%) of these were abnormal. The most common findings were abnormal background rhythm (63%), generalized slowing (50%), focal slowing (43%), and focal epileptiform discharges (31%). Sleep spindle abnormalities occurred in 38% of patients. There were no specific differences in the EEG findings between the definite and suspected cases. Focal EEG findings only correlated with a focal lesion on MRI in a single definite case.ConclusionsPediatric patients with definite autoimmune encephalitis have a narrow spectrum of MRI abnormalities. Conversely, EEG abnormalities are mostly nonspecific. All patients in our cohort had abnormalities on one or both of these neurodiagnostic studies.     

Electroencephalographic findings in children with primary duodenal ulcer

The authors compared the EEG records of 18 children with radiologically confirmed primary duodenal ulcers to those of 15 controls. Ten patients had abnormal EEGs in contradistinction to six of the controls' EEGs and the group of patients had more marked EEG abnormalities. The findings appear to support the notion that neurophysiological factors are related to the pathogenesis of primary duodenal ulcer in childhood. However, the small sample and the fact that the two groups were not clearly differentiated with respect to the severity of EEG abnormalities call for caution in the interpretation of the findings.     

EEG findings in steroid-responsive encephalopathy associated with autoimmune thyroiditis.

OBJECTIVE: To analyze the electroencephalogram (EEG) findings of patients with steroid-responsive encephalopathy associated with autoimmune (Hashimoto) thyroiditis. METHODS: We reviewed 51 EEGs and the clinical records of 17 patients (5 men and 12 women, 27-84 years old). RESULTS: All patients had mild to severe generalized slowing on the EEG which corresponded to the clinical severity of the underlying encephalopathy. Other findings included triphasic waves, epileptiform abnormalities, photomyogenic response, and photoparoxysmal response. Follow-up EEGs of 13 patients showed slowing in 7 and a return to normal in 6. Myoclonic jerks were recorded during the EEG study of 8 patients but did not have an EEG correlate. The EEG and clinical condition improved after treatment with corticosteroids. When encephalopathy recurred, the EEG showed corresponding abnormalities. CONCLUSIONS: EEG findings in steroid-responsive encephalopathy associated with autoimmune thyroiditis consist mainly of slow wave abnormalities that reflect the degree of severity of the underlying encephalopathy. The EEG findings often paralleled the course of the disease, showing improvement with improvement in the clinical condition and worsening with recurrence of symptoms. SIGNIFICANCE: The EEG is helpful in evaluating and following patients with steroid-responsive encephalopathy associated with autoimmune thyroiditis in reflecting the degree of central nervous system (CNS) involvement, in determining whether their condition is better or worse, and in ruling out other causes of encephalopathy.     

Electroencephalography in tetanus

ABSTRACT To assess the brain involvement caused by tetanus, we examined the EEGs of 39 patients recovered from tetanus and those of 39 sex- and age-matched controls. The patients had significantly more frequent and more severe EEG abnormalities than their controls. The most marked difference was in the occurrence of diffuse EEG abnormalities (P < 0.05). Twenty patients had normal EEGs. EEGs of 14 patients (5 of whom in this follow-up) during acute tetanus showed abnormalities in 10 patients, marked in degree in 3 of those. EEG abnormalities started to improve after the acute phase of tetanus. It is concluded that EEGs of patients with tetanus are often abnormal and that EEG is helpful in revealing brain involvement in patients after tetanus.