Focal EEG Abnormalities Research Articles

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.

Prevalence of the Fuld profile in temporal lobe epilepsy

A pattern of performance on the WAIS-R presumably related to temporal lobe abnormalities associated with Alzheimer's Disease was examined in patients with focal temporal lobe EEG abnormalities to determine if the profile was related to other forms of temporal lobe disease. Among 120 patients with unilateral or bilateral temporal lobe EEG abnormalities, only 4(3%) demonstrated the profile. The presence of the profile was unrelated to laterality of EEG abnormality. These findings were discussed in regard to previous studies and the utility of the so-called Fuld profile.

Partial Epilepsies in Infancy: A Study of 40 Cases

Forty patients with partial epilepsy that began before they were aged 3 years were recorded at the Centre Saint-Paul between 1981 and 1986 with a follow-up ranging from 1 year 9 months to 20 years. We analyzed the following data: age at onset, clinical features of seizures at onset and during the follow-up period, ictal and interictal EEG features, etiologic circumstances, evolution of the epilepsy, and psychomotor development. The age of onset was mostly between 2 months and 2 years (more than two thirds of cases). Most had partial symptomatic epilepsy. In nine cases, epilepsy was preceded by febrile convulsions. Seizures at onset were of the following type (in order of decreasing occurrence): unilateral seizures, complex partial seizures, elementary partial seizures, and other seizures, often difficult to classify. A few patients with infantile spasms associated with focal or multifocal EEG abnormalities, differing from West's syndrome, were included in this study. We discuss the problem arising from the classification of infantile seizures and epilepsies.

Organic Disorders in Children with Epileptic Seizures

1) Brain C-T scan was done in 1,005 epileptic children as one of the diagnostic methods, and 32% showed abnormal findings. 2) Infantile spasm showed abnormal scan most frequently at 52.9%, persistent subtle seizure 46.7%, simple partial epilepsy 37.7%, and myoclonic epilepsy 37.5%, in order of frequency. 3) In partial epilepsy the positive scan detection rate was 35.2% of the total, with simple partial epilepsy 37.7%, complex partial epilepsy 36.1% and secondary generalized epilepsy 33.5%. These rates are higher than those of generalized epilepsy (27.1%). 4) In generalized epilepsy, generalized tonic clonic showed abnormal scan in 26.1%, generalized tonic in 23.6%, generalized clonic in 20.5%, atypical absence in 15% and typical absence in none. 5) Brain tumor was detected in 2.18%. 6) Positive scan is commonly detected in seizures starting in young age group, and in epileptic patients with focal neurologic signs as well as focal EEG abnormality. 7) The curable lesions were brain tumor, some granulomas, and arachnoid cyst. 8) Brain C-T scan is an effective diagnostic method in epileptic children to identify structural abnormalities of the brain and to make sure that the abnormality does not progress, but it would be better to perform C-T scan case by case rather than as a routine diagnostic procedure.

The relationship between EEG changes and cognitive functions in dementia: a study in a VA population.

This study explores the relationship between the results of tests of dementia and the EEG findings in 94 demented patients of different etiologies. Abnormal EEGs were found in 83% of all patients, usually diffuse slow wave abnormalities, the degree of which correlated very well with the Modified Hachinski test. Only a weak relationship was found between the EEG and the Mini-Mental Status Examination, while the Mattis and its subtests correlated better. Focal EEG abnormalities on the temporal areas were the characteristic pattern in patients with alcoholic dementia. The test scores in the 17% with normal EEGs were consistent with the above findings, in that patients with normal tracings scored well on the Modified Hachinski and Mattis tests, but not on the Mini-Mental Status Exam.

Genetics of the Partial Epilepsies: A Review

The research literature is consistent in reporting somewhat less familial aggregation in partial than in generalized epilepsy. However, relatives of patients with partial seizures do appear to have higher seizure risks than relatives of controls, suggesting that genetic factors are important in at least some partial epilepsies. Complex partial epilepsy appears to be only slightly less familial than other types of epilepsy. Relatives of patients with focal EEG abnormalities generally have been found to have lower risk of both EEG abnormalities and epilepsy than relatives of patients with generalized abnormalities. For focal temporocentral abnormalities, however, there is evidence of an important influence of genetic factors.

Electroencephalographic correlates of increased platelet membrane fluidity in Alzheimer's disease.

Increased platelet membrane fluidity is a stable, familial characteristic that describes a clinically distinct subgroup of patients with Alzheimer's disease. In the current study, electroencephalograms (EEGs) from 49 patients with probable Alzheimer's disease were subjected to visual and computerized spectral analysis. Only three (14.3%) of 21 patients in the subgroup with increased platelet membrane fluidity exhibited focal EEG abnormalities, while 12 (42.9%) of 28 of the residual subgroup exhibited focal EEG findings, a threefold difference. This difference in EEG profile provides further validation of these two subgroups and suggests that the subgroup with increased fluidity is less heterogeneous than the residual group.

Initial experience with 99m Tc-hexamethyl-propylene amine oxime (HM-PAO) single photon emission computedtomography (SPECT) in patients with focal epilepsy

Brain single photon emission computed tomography (SPECT) was performed in 16 patients with focal epilepsy, as well as EEG, using 99m Tc-HM-PAO SPECT and a rotating gamma camera system. Pathological Tc-HM-PAO SPECT findings were registered in 75%. CT was positive in 25%. MRI was positive in 76%. The results of Tc-HM-PAO SPECT findings were compared with those of CT and MRI. 61% of the MRI findings correlated with the pathological SPECT findings with respect to the side of the hemisphere, and in 75% of the patients the focal EEG abnormality and the pathological Tc-HM-PAO-SPECT findings were localized in the same hemisphere.

Psychomotor impairment and anticonvulsant therapy in adult epileptic patients.

Using a battery of simple tests, psychomotor performance was assessed in 11 healthy subjects, 14 untreated epileptic patients and 66 epileptics on chronic anticonvulsant medication. Significant differences were found between controls and untreated patients for choice reaction time, card sorting and Simple Simon memory game. Treated patients performed less well than both untreated epileptics and controls in choice reaction time (p less than 0.05; p less than 0.001), card sorting (p less than 0.01; p less than 0.001), Simple Simon (p less than 0.05; p less than 0.001) and finger tapping (p less than 0.05; p less than 0.001). Patients with centrencephalic epilepsy were slower than those with discrete focal EEG abnormalities in reaction time and card sorting. Patients receiving treatment with carbamazepine, phenytoin or sodium valproate alone all performed similarly to each other and to those patients taking anticonvulsant polypharmacy. Monotherapy patients with potentially "toxic" plasma anticonvulsant concentrations did no worse than those within or below the "therapeutic" range. Both the disease and its treatment reduce psychomotor performance. All major anticonvulsants appear to cause a similar degree of impairment across a wide range of concentrations. The effect of chronic anticonvulsant medication on "quality of life" should not be neglected in the pursuit of perfect seizure control.

Anomalies EEG de l'epilepsie tardive

Interictal EEG abnormalities were evaluated in 111 epileptic patients in which the first seizure occurred after the age of 18 years. Standard day-time EEG tracings performed prior to and after antiepileptic treatment, and all-night recordings were investigated. Before treatment, waking EEG was normal in 54% of patients. The percentage of normal sleep EEG recordings was only 28.6%. Focal EEG abnormalities were found in 39% of day-time recordings and in 48.6% of sleep recordings, while the percentage of generalized epileptic discharges observed was respectively 7 and 22.8. When considering the category of epilepsy and the etiology, it appears that the primary and secondary generalization of epileptic discharges is reduced with age.

Barbiturate-refractory epilepsy: safe schedule for therapeutic substitution.

Barbiturates are considered first line antiepileptic drugs in third world countries due to traditional and economic reasons. This prospective uncontrolled study of 52 patients aged 15 to 64 years (mean 24) demonstrates that patients who become refractory to barbiturates are mainly those with partial seizures with or without generalization or with a focal EEG abnormality (71%). Seizures tend to become refractory approximately 6 years after barbiturates were started. Progressive barbiturate withdrawal over a period of two to 8 months (mean 5) with institution of treatment with carbamazepine, phenytoin or sodium valproate allowed complete barbiturate withdrawal in 42 of the 52 patients (81%). Furthermore monthly seizure frequency in those in whom barbiturates were withdrawn decreased from 7.1 to 1.7 per patient. An improvement in mental status was observed but not measured. These results show that barbiturates should not be first-choice drugs in patients who have a chronic disease such as epilepsy, and indicate a schedule for barbiturate withdrawal which is safe and independent of hospitalization or monitoring of antiepileptic drug serum concentrations.

The Bear-Fedio personality inventory and temporal lobe epilepsy.

We administered the Bear-Fedio inventory to normal controls and to patients with epilepsy, chronic pain, and psychiatric disorders. The trait scores showed progressive increase with the severity of psychiatric symptoms. There were no statistically significant differences between epileptic patients with diffuse spike wave discharges and those with focal temporal EEG abnormalities. Also, there were no significant differences in patients with left versus right temporal foci. The inventory is markedly influenced by intellectual factors and, to some extent, by gender and anticonvulsant drug levels, especially those of carbamazepine. The test in its current form measures overall psychopathology rather than a specific syndrome.

The development of psychiatric disorder among schoolchildren with epilepsy.

Two groups of epileptic children, one newly diagnosed and one with chronic epilepsy, were compared with two comparable groups of diabetic children and with children in the general population in order to investigate the development of psychiatric disorder. The results confirm previous findings that children with chronic epilepsy are significantly more disturbed than children with chronic physical illness not involving the central nervous system, and than children in the general population. Children with newly diagnosed epilepsy were also significantly more disturbed than those with newly diagnosed diabetes, and than children in the general population. The rate of psychiatric disturbance was similar in the two groups of epileptic children. In both groups of epileptic children, those with focal EEG abnormalities and/or complex partial seizures were particularly vulnerable to psychiatric disturbance.

Somatosensorisch evozierte kortikale Reizantwortpotentiale bei Halbseitensymptomatik durch zerebrale Gefäßprozesse oder Hirntumoren

Comparative investigations of somatosensory evoked potentials in 23 patients with hemisyndromes following acute ischemia of the middle cerebral artery region and in 12 patients with similar hemisyndromes on the base of cerebral neoplasms revealed marked differences. Whereas in 87 % of the patients with ischemic lesions the primary cortical complex of the SEP was severely altered there were similar abnormalities in only one of the patients with neoplasm. The SEP changes were not dependent on the neurologic (sensory) symptoms nor on focal or diffuse EEG abnormalities.

Neuroradiological correlates of frontally predominant intermittent rhythmic delta activity (FIRDA)

A correlative, retrospective review of 80 consecutive cases of EEG FIRDA was performed with regard to the neuroradiological findings: 62 of the 80 patients had had CAT scan evaluations. Of the 61 patients with structural pathology, 53 had CAT scans which were abnormal in 40 (76%); of the 19 patients with ‘non-structural’ (mostly metabolic) brain lesions, 10 had normal CAT scans. In the structural group with normal CAT scans, the presence of pathology was demonstrated by arteriography (5 cases), radionuclide cysternography (1 case), brain scan (1 case), or pathological examination. Patients with ‘non-structural’ FIRDA had a significantly higher probability of being in an altered state of consciousness and of having abnormal background activity in their EEG. Focal EEG abnormalities are more frequently associated with structural lesions and FIRDA. If FIRDA is present on the EEG, further neuroradiological studies should be considered, especially when other electroclinical information suggests a non-metabolic substrate.

Partial epilepsy in childhood: clinical and EEG study of 261 cases.

A prospective clinical and EEG study is presented based on 261 children affected by partial seizures with or without focal EEG abnormalities, or by generalized seizures with focal EEG disturbances. From the clinical point of view, the partial seizures were most frequently elementary and motor, quite often associated with generalized seizures (64.36%), appearing in the majority of the cases during the first year of life, with rare frequency (less than 1 seizure/6 months). Perinatal disturbances appear to be the most important etiological factor. Partial epilepsy is often included within a previous neurological syndrome (secondary epilepsy). The clinical outcome is most frequently favorable (71.72%) with therapeutic treatment, especially with respect to the cases of primary epilepsy, characterized by rare seizures, which appear after the first year of life. From the EEG point of view, we noted specific monofocal abnormalities (72.79%), most frequently with temporal and rolandic localisation; during the follow-up the EEG abnormalities presented modifications in 58.89% of the cases, with normalisation in 22.98%.

Neurological and electroencephalographic abnormalities after febrile seizures. Possible association with cytomegalovirus.

In order to assess the possible association of cytomegalovirus (CMV) with cerebral damage, 65 children aged between 2 and 10 years were tested for CMV isolation and antibody status. All of them had previously presented one or more episodes of febrile convulsions. At the time of our study, they were grouped according to their clinical features and electroencephalogram (EEG). 21 had typical and/or atypical absence attacks with 3 c/s spike-wave EEG (primary generalized epilepsy), 21 presented febrile seizures and spontaneous fits with focal EEG abnormalities, 23 had no seizures and a normal EEG. We performed the same investigation in 41 healthy children. The study showed a similar isolation rate of CMV in healthy subjects and in patients without neurological and EEG alterations, while a significantly higher isolation rate was observed in the groups with neurological and EEG abnormalities. As for serology, no significant difference was observed between the four groups, although the positivity rate of the healthy children was lower than in the other three groups. The study suggests a possible association of CMV with neurological and EEG abnormalities after febrile seizures.

Time course and development of electro-clinical features in relation to pentylenetetrazol thresholds in monkeys with focal seizures

Seizure manifestations occurred concurrently with significantly increased focal EEG abnormalities and significantly lowered pentylenetetrazol thresholds in monkeys, 69 ± 2 days following standardized aluminium hydeoxide injections into motor cortical sites in both hemispheres. Seizure occurence, chemical threshold and EEG changes tended to stabilize after 145 ± 5 days. Onset of epileptic changes occured significantly faster in monkeys with motor cortical foci in both hemispheres rather than in those with unilateral foci. Focal EEG changes, viz. spike density, was inversely correlated with pentylenetetrazol thresholds to a highly significant extent.

Epileptic seizures and abnormal electroencephalographic findings in hydrocephalus and their relation to the shunting procedures

A total of 92 patients with hydrocephalus were studied. The incidence of seizures was significantly greater in the “shunted” group (18.2% in the “non-shunted” and 65.4% in the “shunted” group). All of the shunted patients who had seizures developed them after the placement of the shunt. Left sided focal motor seizures were the commonest focal seizures in the patients with right sided shunts. There was a higher incidence of abnormal EEG tracings in the “shunt” group (47% of the “non-shunt” patients and 95% of the “shunt” group). All types of focal EEG abnormalities, but particularly the slow wave foci, were seen more frequently over the hemisphere which had the shunt, and in more than half these localized to the neighborhood of the shunt itself. It is suggested that the shunt, which may act as a foreign body, may be responsible, at least in part, for these findings.

Epilepsia Partialis Continua

Clinical, EEG, and autopsy findings were studied in 32 patients with epilepsia partialis continua. The seizures occurred at different ages and with diverse diseases of the brain. Facial and distal limb muscles were preferentially involved. Often, seizures suggested multifocal origin within a limited cerebral region, with low-amplitude, irregular, asynchronous contractions that could resemble other movement disorders. Twitching varied in rate, rhythm, intensity, and territorial extent continued sometimes for decades and was poorly responsive to therapy. Focal EEG abnormalities commonly consisted of discrete spikes, sharp waves, or slow-wave activity. Autopsy findings in eight patients showed consistent involvement of the motor cortex or closely adjacent areas. Clinical, EEG, and pathologic data favor a cortical origin of epilepsia partialis continua.