Novel popout with nonsense strings: effects of predictability of string length and spatial location

The implanted system was composed of four silver ball electrodes placed in the burr hole of the skull, a reference placed subcutaneously near the nose, two electrodes for EMG, and a ground. The dural attachment was 0.1 mm in diameter. A cassette connector was placed on the back. Implanted cables between the cassette connector and all electrodes consist of twisted fine wires placed in a silicone tube 0.5 mm in diameter. The implanted electrode system weighed 0.8 g. The outlet cables were of the same materials used for implanted cables and placed in a silicone tube 1.5 mm in diameter. The impedance matching between these cables was successful and assured the minimum contamination of artifacts in the EEG recording of freely moving mice. Long-term (4-5 weeks) recording, thus, became possible without damage to the implanted materials. Monopolar recordings demonstrated the localized paroxysmal discharges during general tonic clonic convulsion in El mice. Several artifacts are presented.     

"Cavernous sinus EEG": a new method for the preoperative evaluation of temporal lobe epilepsy

PURPOSE: In presurgical evaluation of temporal lobe epilepsy (TLE), invasive methods are necessary if results of various noninvasive methods are not sufficiently convergent enough to identify the epileptogenic area accurately. To detect the epileptiform discharges originating specifically from the mesial temporal lobe, we applied the cavernous sinus catheterization technique. METHODS: We placed Seeker Lite-10 guide wire electrodes into bilateral cavernous sinus through the internal jugular veins to record EEG (cavernous sinus EEG) in 6 patients with intractable TLE. Scalp EEG was simultaneously recorded in all 6 and electrocorticogram (ECoG) was also recorded in 4. RESULTS: The cavernous sinus EEG demonstrated clear epileptiform discharges, sometimes even when they were absent on the simultaneously recorded scalp EEG. The epileptiform discharges recorded from the cavernous sinus electrodes were specifically associated with those in the mesial temporal region on ECoG. Ictal EEG pattern originating from mesial temporal lobe was also clearly documented on the cavernous sinus EEG. CONCLUSIONS: This new, semi-invasive method of identifying epileptogenic areas can detect the epileptiform discharges specifically arising from the mesial temporal lobe; it is as useful as or complements the invasive techniques such as foramen ovale or depth recording.     

Histological change of keratinocyte in full-thickness skin autograft and its effect on hyperpigmentation of the graft

OBJECTIVES: To investigate the frequency of ECG abnormalities suggestive of myocardial ischaemia in patients with severe drug resistant epilepsy and without any indication of previous cardiac disease, assuming that these changes may be of significance for the group of epileptic patients with sudden unexpected death. MATERIAL AND METHODS: Twelve patients with medically intractable epilepsy were investigated with simultaneous long ECG and EEG recordings while attending either epilepsy surgery investigational procedures or the investigational programme for diagnostic purposes, and one while having an episode of status epilepticus. RESULTS: The ECG recording failed in 1 patient. This patient had chest pain and minor yet morphologically conspicuous changes in the ECG, suggestive of myocardial infarction. He died in heart arrest. Eight epilepsy patients had episodes of ST segment depression in the ECG, many of which coincided with video- and EEG documented epileptic seizures. Two patients experiencing simple partial seizures and 1 patient experiencing absence seizures had no ST segment depressions in the ECG. One patient had an episode of status epilepticus secondary to brain damage and no ST segment deviation was seen during the ECG recording which continued until 3 h before the patient died. CONCLUSION: Patients with severe drug resistant epilepsy have episodes of ST segment changes, some of which are closely related to epileptic seizures. Further studies are needed to confirm the present results and to investigate the nature of these changes and document the effect of prophylactic treatment with cardioactive drugs to reduce the risk of sudden death.     

Long-term electroencephalographic monitoring for diagnosis and management of seizures

Long-term electroencephalographic (EEG) monitoring is the process of recording an EEG for a prolonged period in order to document epileptic seizures or other episodic disturbances of neurologic function. Indications for long-term EEG monitoring include diagnosis of a seizure disorder (epilepsy), classification of seizure types in patients with epilepsy, and localization of the epileptogenic region of the brain. Methods used for long-term EEG monitoring include prolonged analog or digital EEG, prolonged analog or digital ambulatory EEG, and prolonged analog or digital video-EEG monitoring with telemetry. Each of these methods has distinct advantages and disadvantages, particularly relative to storage, retrieval, and manipulation of data. Long-term EEG monitoring is useful in the management of patients with epilepsy and in the diagnosis of a seizure disorder. For most patients, inpatient long-term EEG monitoring is best performed in a specialized epilepsy-monitoring unit, which can provide a safe environment and both educational and psychosocial support. The choice of the most appropriate method of long-term monitoring for a specific clinical situation is best made by an epileptologist or a neurologist at an epilepsy center.     

The prognosis of epilepsy in children with generalized spikes and wave disc charges in electroencephalographic recording

INTRODUCTION: Epilepsy is a chronic disorder. The prognosis of one particular subtype, that of children with generalized spike and wave discharges (P-O) on the electroencephalogram (EEG), is unknown. OBJECTIVE: To determine the prognosis of children with epilepsy with P-O on EEG and the factors which affect this. PATIENTS AND METHODS: All EEGs done over ten years (39,322) were reviewed, and the epileptic patients under 14 years old identified. Absence and recurrence of crises were evaluated and the factors influencing them analyzed. Minimum significance was p < 0.05. The chi square test, Student's t test and Kaplan-Meier method were used. Logistic regression models were devised. RESULTS: Of the children studied, 78% became crisis-free. After monovariant and multivariant analysis the only conditions which fitted the regression models were: abnormal pregnancy; West syndrome or learning difficulties; having certain types of crises, myoclonic, clonic-tonic, partial simple or complex crises; a normal EEG with hypsarrhythmia, slow or fast P-O and requiring multiple medication. When medication ceased, 31.4% had recurrence of the episodes. On monovariant and multivariant analysis, protective factors were absence of attacks and risk factors were a family history of epilepsy or an EEG with rapid P-O. CONCLUSIONS: The overall prognosis for epileptic children with P-O is good. There are factors which improve or worsen the pronosis, but these cannot be modified.     

Partial simple vegetative crisis: importance of electroencephalographic findings

INTRODUCTION: 50% of the patients with cerebral tumours present with epileptic crises, which may be partial or generalized. The commonest partial crises have motor symptoms. These make up 30% of the simple partial crises. Partial simple crises with purely vegetative-type symptoms are very uncommon (less than 5%). They are considered to be caused by discharges in the internal regions of the temporal lobes, mainly in the limbic system. This means that it is very difficult to identify them using techniques of surface EEG. CLINICAL CASE: We describe the case of a patient with a cerebral tumour. The initial clinical features were short episodes of generalized coldness and sweating which had been present for the previous two weeks, without any other symptoms. During a routine EEG, focal critical paroxystic activity was recorded in the right temporal region. This coincided with a clinical episode similar to those described. CONCLUSIONS: The episodes were labelled partial simple vegetative crises. In this case the EEG was crucial for diagnosis and subsequently to recommend suitable treatment. However, difficulty in recording this type of crisis with a surface EEG makes correct diagnosis of these patients very difficult, since the epileptogenic focus is deeply situated.     

When and how should the long-term anti-epileptic treatment be stopped

Although for some decades it has been customary to stop long-term treatment of epilepsy in patients who have been free of crises for several years, there is still no general agreement as to when, how and in which cases such treatment should be stopped. Several factors have to be taken into account when making such a decision: the known toxicity of anti-epileptic drugs; the fact that 10-20% of the patients on such treatment have recurrences of their epileptic crises and that around 25% of the children and 40% of the adults relapse when long-term treatment is stopped. On the other hand, factors which reduce the risk of relapse have recently been identified. When the psychological benefit of no longer having to take anti-epileptic drugs together with their high cost are also considered, it would seem advisable to stop treatment when the patient has had no epileptic crises for several years. Since there is no significant difference in the frequency of relapses when anti-epileptic drugs are suspended 2-5 years after the last crises, and these crises are more frequent when paroxystic activity is seen on the EEG before stopping the drugs, we recommend that treatment be stopped after 2 years free of crises in idiopathic epilepsy, after 3 years with no sign of abnormality in the EEG in patients with partial cryptogenic epilepsy and after at least 4 years without crises and 2 years of normal EEG in patients with partial symptomatic or generalized cryptogenic or symptomatic epilepsy. The criteria for suspending drug treatment should take account of the pharmacokinetic features and permit EEG control. Therefore we recommend that 40% of the total dose be stopped during the first 6 months at a rate of 20% every three months and then a further 20% every two months until medication has been stopped completely.     

A particular type of epilepsy in patients with congenital hemiparesis associated with polymicrogyria or unilateral pachygyria

INTRODUCTION: Magnetic resonance has permitted the recognition of cortical dysplasias in patients with congenital hemiparesia and epilepsy. OBJECTIVE: To study the clinic-EEG characteristics and course of epilepsy in patients with congenital hemiparesia and unilateral polymicrogyria. METHODS AND RESULTS: We analyzed the clinical histories of 11 patients seen between 1990 and 1996. We studied 6 girls and 5 boys aged between 5 and 13 years, with a follow-up period of from 1 to 6 years. The epilepsy began at between 1 and 6 years old with partial motor seizures. On EEG there were frontotemporal spikes in 9 cases, temporooccipital in 1 and parieto-occipital in another. All 11 patients had hemiparesia, with slight mental retardation in 9 patients and moderate mental retardation in 2. The CT/MR brain scan showed unilateral polymicrogyria. At between 2 and 8 years of age, all 11 patients developed subintrant atonic crises with a pseudo-ataxic gait, absences in 7 patients and myoclonia in 3. Awake EEG showed bilateral asymmetrical spikes. During sleep 7 patients had continuous spikewave discharges and 4 had frequent asymmetrical bilateral spikes. Four patients relapsed. Five patients are free of crises, five have sporadic crises and one continues to have daily crises. CONCLUSIONS: These patients had hemiparetic cerebral paralysis, slight mental retardation and epilepsy. At about the age of 6 a peculiar electro-clinical condition developed. Response to treatment was satisfactory, although the follow-up period is still not long.     

The effect of propofol on the electroencephalogram of patients with epilepsy

The effect of propofol on the electroencephalogram (EEG) in patients with epilepsy is still unclear. Case reports with electroencephalographic documentation highlight pro- and anticonvulsant effects and beta activation of the EEG. This prospective study sought to determine the effect of propofol in 17 patients undergoing cortical resection for intractable epilepsy. Each patient received 2 mg/kg of propofol intravenously and the EEG was recorded from chronically implanted subdural electrodes placed during a previous craniotomy. Frequency of interictal spikes, time to burst suppression, and appearance of beta activation were recorded. The median frequency of interictal spikes decreased significantly from 2 spikes/min before to 0 spikes/min after propofol (P = 0.001). Seizure activity did not increase after propofol. Profound burst suppression and an increase in beta activity were noted consistently. The use of propofol in patients with epilepsy seems to be safe but may interfere with the recording of EEG spikes.     

Electroencephalographic changes in patients with cardiopathies, subsequently operated under extracorporeal circulation. Significance and outcome. Evaluation of 679 cases

This study analysed the pre-operative electroencephalographic recordings of 679 patients with heart disease, later undergoing surgery under extra-corporeal circulation. The type and the severity of the abnormalities are listed for each heart disease. These results are compared to those already published in the literature on this subject and are discussed in terms of a number of possible aetiological factors: the age of the patients, data provided by the pre-operative cardio-pulmonary assessment. This analysis does not enable us to demonstrate, with any statistical significance, the aetiological factor(s) of these electroencephalographic alterations. Finally, comparison of the pre-, intra- and postoperative EEG in the same patients enables us to evaluate the prognostic value of these electrical abnormalities.     

Benign neonatal sleep myoclonus

OBJECTIVE: To evaluate the clinical, electro-encephalographic and evolutionary characteristics of a series of patients diagnosed as having benign neonatal sleep myoclonus (BNSM). MATERIAL AND METHODS: The clinical histories of 21 patients with BNSM were analyzed. Criteria for inclusion in the study were: neonates who had had more than one episode of myoclonia during sleep and in whom neurological examination and psychomotor development were normal. CRITERIA FOR EXCLUSION: Patients with myoclonia while awake, a perinatal history which included significant pathology and/or the diagnosis of epilepsy. The period of evolution varied from 6 months to 5 years, and the following parameters were considered: clinical features of the myoclonia, neurological examination, psychomotor development and evolution. EEG were done between crises in all patients. In 5 cases we recorded EEG during crises and in 2 cases video-EEG were done. RESULTS: The study group was made up of 11 girls and 10 boys. The myoclonia started between the first and twenty third day of age (average = 7 days). Fifteen (71.4%) of the patients had generalized myoclonia, mainly in the distal part of the upper limbs in 13 and in the lower limbs in two. In 20 cases (95.2%) jerking was of short duration, lasting 10 to 20 seconds. In one case, the jerks were repeated in series lasting 30 minutes. Two patients later developed benign myoclonia of early infancy. The myoclonia disappeared before the age of 7 months in all cases. CONCLUSIONS: BNSM is seen in healthy newborns and disappear spontaneously during the first months of live. Differential diagnosis with epileptic seizures is imperative in order to avoid unnecessary medication.     

The normal neonatal EEG (author's transl)

Polygraphic examinations (EEG, EKG, electrooculogram and recording of respiration) were carried out on 120 full term healthy newborns. EEG recordings taken in wakefulness states showed a low-voltage background activity with a noticeable share of 8 c/sec. waves. The latter occurred in 12.5% of the examined newborn infants in more regular groups, lasting from 3--6 seconds, and reached an amplitude of up to 20--25 muV. The EEG sleep recordings differed from case to case. Certain identical EEG-patterns could be observed during active as well as during quiet sleep. Typical "tracés alternants" occurred in 63.4% of the recordings, as a rule in the quiet sleep phase. In nearly 1/3 of these cases they contained isolated fine spikes or sharp waves of variable localisation. In 70% of the sleep recordings bilateral fronto-central paroxysmal steeper transients and in 6.7% spindly about 14 c/sec. wave groups were observed, mainly during active sleep phases. In nearly 20% of the 52 newborns where the centro-temporal electrodes were connected transversally, single sharp and slow waves were recorded. They were localized resp. more pronounced in the right hemisphere. They did not appear in any of the 68 cases in which the electrodes were connected longitudinally only.     

Evaluation of an automatic seizure detection method for the newborn EEG

In another publication, we described a set of methods for automatic detection of EEG seizures in the newborn. We describe here the evaluation of these methods using a completely new set of data, which were not used in developing the method. This testing data set consisted of recording from 54 patients, lasting an average of 4.4 h. Recordings had 8-16 channels and were obtained, in approximately equal numbers, from 3 institutions in Canada, the USA and Australia. Recording conditions varied from short recordings fully attended by a technologist to overnight recordings largely unattended. The average seizure detection rate was 69% (77%, 53%, 84% in the 3 institutions). False detections occurred at the average rate of 2.3/h (4.1, 1.0, 2.7 in the 3 institutions), with fluctuations that reflected largely the technical quality and level of supervision of the recordings. The results are similar to those obtained in the commonly used method of epilepsy monitoring in adults and allow us to envisage clinical application.     

Assessment of digital EEG, quantitative EEG, and EEG brain mapping: report of the American Academy of Neurology and the American Clinical Neurophysiology Society

A. Digital EEG is an established substitute for recording, reviewing, and storing a paper EEG record. It is a clear technical advance over previous paper methods. It is highly recommended. (Class III evidence, Type C recommendation). B. EEG brain mapping and other advanced QEEG techniques should be used only by physicians highly skilled in clinical EEG, and only as an adjunct to and in conjunction with traditional EEG interpretation. These tests may be clinically useful only for patients who have been well selected on the basis of their clinical presentation. C. Certain quantitative EEG techniques are considered established as an addition to digital EEG in: C.1. Epilepsy: For screening for possible epileptic spikes or seizures in long-term EEG monitoring or ambulatory recording to facilitate subsequent expert visual EEG interpretation. (Class I and II evidence, Type A recommendation as a practice guideline). C.2. OR and ICU monitoring: For continuous EEG monitoring by frequency-trending to detect early, acute intracranial complications in the OR or ICU, and for screening for possible epileptic seizures in high-risk ICU patients. (Class II evidence, Type B recommendation as a practice option). D. Certain quantitative EEG techniques are considered possibly useful practice options as an addition to digital EEG in: D.1. Epilepsy: For topographic voltage and dipole analysis in presurgical evaluations. (Class II evidence, Type B recommendation). D.2. Cerebrovascular Disease: Based on Class II and III evidence, QEEG in expert hands may possibly be useful in evaluating certain patients with symptoms of cerebrovascular disease whose neuroimaging and routine EEG studies are not conclusive. (Type B recommendation). D.3. Dementia: Routine EEG has long been an established test used in evaluations of dementia and encephalopathy when the diagnosis remains unresolved after initial clinical evaluation. In occasional clinical evaluations, QEEG frequency analysis may be a useful adjunct to interpretation of the routine EEG when used in expert hands. (Class II and III evidence as a possibly useful test, Type B recommendation). E. On the basis of current clinical literature, opinions of most experts, and proposed rationales for their use, QEEG remains investigational for clinical use in postconcussion syndrome, mild or moderate head injury, learning disability, attention disorders, schizophrenia, depression, alcoholism, and drug abuse. (Class II and III evidence, Type D recommendation). F. On the basis of clinical and scientific evidence, opinions of most experts, and the technical and methodologic shortcomings, QEEG is not recommended for use in civil or criminal judicial proceedings. (Strong Class III evidence, Type E recommendation). G. Because of the very substantial risk of erroneous interpretations, it is unacceptable for any EEG brain mapping or other QEEG techniques to be used clinically by those who are not physicians highly skilled in clinical EEG interpretation. (Strong Class III evidence, Type E recommendation).     

Single unit recording capabilities of a 100 microelectrode array

We have developed a three-dimensional silicon electrode array which provides 100 separate channels for neural recording in cortex. The device is manufactured using silicon micromachining techniques, and we have conducted acute recording experiments in cat striate cortex to evaluate the recording capabilities of the array. In a series of five acute experiments, 58.6% of the electrodes in the array were found to be capable of recording visually evoked responses. In the most recent acute study, the average signal-to-noise ratio for recordings obtained from 56 of the electrodes in the array was calculated to be 5.5:1. Using standard window discrimination techniques, an average of 3.4 separable spikes were identified for each of these electrodes. In order to compare the two-dimensional mapping capabilities of the array with those derived from other technologies, orientation preference and ocular dominance maps were generated for each of the evoked responses. Histological evaluation of the implant site indicates some localized tissue insult, but this is likely due to the perfusion procedure since high signal-to-noise ratio neural responses were recorded. The recording capabilities of the Utah Intracortical Electrode Array in combination with the large number of electrodes available for recording make the array a tool well suited for investigations into the parallel processing mechanisms in cortex.     

Automatic EEG analysis during long-term monitoring in the ICU

To assist in the reviewing of prolonged EEGs, we have developed an automatic EEG analysis method that can be used to compress the prolonged EEG into two pages. The proposed approach of Automatic Analysis of Segmented-EEG (AAS-EEG) consists of 4 basic steps: (1) segmentation; (2) feature extraction; (3) classification; and (4) presentation. The idea is to break down the EEG into stationary segments and extract features that can be used to classify the segments into groups of like patterns. The final step involves the presentation of the processed data in a compressed form. This is done by providing the EEGer with a representative sample from each group of EEG patterns and a compressed time profile of the complete EEG. To verify the above approach, 41 6 h EEG records were assessed for normality via the AAS-EEG and conventional EEG approaches. The difference between the overall assessment via compressed and conventional EEG was within one abnormality level 100% of the time, and within one-half level for 73.6% of the records. We demonstrated the feasibility and reliability of automatically segmenting and clustering the EEG, thus allowing the reduction of a 6 h tracing to a few representative segments and their time sequence. This should facilitate review of long recordings during monitoring in the ICU.     

Circulating lymphocyte phenotypic surface markers in anxiety disorder patients and normal volunteers

Assessment of clinical utility involves a series of steps based primarily on published peer-reviewed medical literature. Relevant publications usually use the scientific method, appropriate control groups, blinded reading, prospective design, and other study elements. Assessments are more credible when conducted by those who do not have a conflict of interest in the technique. A detailed assessment of digital and quantitative EEG was conducted recently by the American Academy of Neurology. The American Clinical Neurophysiology Society was a joint sponsor. This assessment concluded that digital EEG is an excellent substitute for paper EEG. It also found quantitative techniques helpful in epilepsy monitoring, seizure detections, and in operating room/intensive care unit trend monitors. Several other applications were considered promising, whereas some applications were considered not ready for clinical use. Substantial problems still plague the field, predisposing to false-positive results.     

Benign myoclonic epilepsy in childhood. A case report]

INTRODUCTION: Benign myoclonic epilepsy of childhood is a rare syndrome which appears at between 4 months and 3 years of age. The prognosis is good if diagnosed and treated early. It is characterized by many short crises (usually of 3 seconds and not more than 5-10 seconds long), proximal and cephalic jerking movements without falling to the ground, and at no particular time of the day. In the EEG polygraph background activity continues and crises coincide with generalized spike and wave or multiple spike and wave discharges of 1 to 2 seconds, accompanied by isolated myoclonic movements in the neck and deltoid muscles, which persist during NREM sleep. Benign epilepsy of childhood usually responds to monotherapy with valproic acid. In our case photosensitivity appeared at 7 years of age with persistence of generalized spikes and waves during sleep. CONCLUSION: We suggest that photosensitivity may be used as an index of the clinical course, and that treatment should continue to be given until photosensitivity disappears.     

Ictal oroalimentary automatisms with preserved consciousness: implications for the pathophysiology of automatisms and relevance to the international classification of seizures

A patient showing seizures presenting ictal automatisms with preserved consciousness is reported. A 30-year-old, right-handed man with normal development and without family history of epilepsy was referred for surgical treatment of epilepsy. At 15 he began to have seizures, starting with an epigastric aura, occasionally developing automatisms (lip-smacking, chewing), sometimes followed by tonic-clonic convulsions. At the time of referral, he averaged six convulsive seizures per year and one nonconvulsive per week. His sleep EEG showed sharpened slow activity over the right anterior quadrant magnetic resonance imaging (MRI) showed a benign lesion in the mesial aspect of the right occipital lobe. Simultaneous video monitoring and intracranial EEG with subdural strips recording from the right temporal and occipital lobes was undertaken. During one seizure, he had pronounced oroalimentary automatisms while holding a conversation with a technician, answering her questions, and explaining details of his seizures. Memory of this event was preserved. At seizure onset, spike activity was seen at the mesial occipital strips. At midseizure, high-voltage sharpened delta was seen throughout the right hemisphere. Left-sided scalp electrodes remained relatively uninvolved. The lesion, a dysembryoplastic neuroepithelial tumour was removed. Surgery was followed by abolition of seizures described. Because it is agreed that complex partial seizures require impaired consciousness, a history of automatisms with retained consciousness usually suggests nonepileptic attacks. This case suggests that automatisms in epileptic seizures can take place with minimal loss of consciousness, particularly if there is widespread but unilateral involvement. The need for a revision of the International Classification is suggested.