Etiology in complex partial epilepsy. II. Correlation between EEG topography and neuroimaging

Neuro-imaging studies (NI) in patients with complex partial seizures (CPC) demonstrate the epileptogenicity of a more or less localized underlying lesion. Correlation with the topography of the EEG focus permits affirmation of the origin. We analyze anomalies on NI and on the EEG of 151 patients with CPC. The EEG was abnormal in 128 and showed a unilateral epileptic focus in 117. NI was focal and unilateral in 72 of the 102 abnormal cases. Topographic correlation was 78.5%. This close correlation in our series makes us consider the localized lesions to be the probable aetiological factor.     

Ictal asomatognosia with hemiparesis

A 69-year-old woman presented with an ictal Anton-Babinski syndrome (asomatognosia with hemiparesis). Except for head and eye deviation to the side of the paralyzed limb, epileptic nystagmus, brief episodes of impaired consciousness, and automatisms, clinical symptomatology was identical to Anton-Babinski syndrome of vascular origin. Results of MRI imaging were normal. EEG showed a simple partial nonconvulsive status epilepticus of right parieto-temporal origin. Anton-Babinski syndrome may thus be a functional expression of focal status epilepticus.     

Multiple sclerosis as a cause of partial complex epilepsy

INTRODUCTION: Although the epileptic seizures (ES) have been described on patients with multiple sclerosis (MS), the causal relationship is not clear. Seizure's prevalence in this illness is low and their apparition concerning the MS course is variable, but more common after MS diagnosis. The predominant crises are generalized or partial with secondary generalization; the partial complex seizures have rarely referred. CLINICAL CASES AND CONCLUSIONS: We presented two patients with ES in the MS course. In the first case is arrived to MS diagnosis upon appearing the crisis, having presented two previous cerebral lesions in another level. In both cases demyelinating lesion was located in the temporal lobe, agreeing with EEG anomaly and seizures type.     

Significance of interictal temporal lobe delta activity for localization of the primary epileptogenic region

Because interictal temporal lobe delta activity (TLDA) has been described in 30 to 90% of patients with temporal lobe epilepsy (TLE) but has not been investigated in patients with extratemporal epilepsy, we sought to determine the localizing significance of TLDA. We compared the presurgical interictal scalp EEG results of 47 consecutive patients who received extratemporal resection (40 frontal and 7 parietal-occipital) for intractable epilepsy with 43 consecutive patients who received anterior temporal lobectomy. We defined lateralized TLDA as runs of lower than 4-Hz waveforms that were easily distinguished from the background rhythms and were maximal at electrodes T4, F8, and T6 or T3, F7, and T5. The lateralized TLDA was subcategorized as temporal intermittent rhythmic delta activity (TIRDA) or temporal intermittent polymorphic delta activity (TIPDA). A chi-square test was used to determine the association of the lobe of the epileptogenic zone with TIRDA and TIPDA. We found TIRDA in 12 (28%) and TIPDA in 8 (19%) patients in the temporal lobe group, and TIRDA in 2 (4%) and TIPDA in 9 (19%) patients in the extratemporal group. TIRDA was strongly associated with TLE (p < 0.003), whereas TIPDA occurred at an equal rate in both groups. Similar to anterior temporal epilepsy, lateralized TIPDA is present in up to 20% of patients with extratemporal epilepsy. The presence of TIRDA strongly suggests TLE but may infrequently occur in extratemporal epilepsy. Caution should be used when using lateralized TLDA as a presurgical localizing finding.     

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.     

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.     

EEG and clinical studies of the development of alumina cream epileptic focus in split-brain cats

Alumina cream epileptic focus was established in the right sensorimotor cortex in 20 split-brain cats (partial or complete). EEG and behavioral observations were made in a period ranging from 24 to 836 days. Four types of EEG changes after alumina cream injection were differentiated. These types could be related to the direct effects of brain damage and to development of epilepsy. Spikes and sharp waves and paroxysmal discharges (focal and multifocal) were observed in about 60% of the cats. Clinical seizures developed in about the same percentage of the animals. These values are below those reported for cats with intact interhemispheric commissures. Diphenylhydantoin (DPH) was given orally in a daily dose of up to 15 mg/kg body weight in 9 animals with developed epileptic EEG activity. Five of them had epileptic seizures. DPH was introduced not earlier than 1.5 months after intracortical alumina cream injection. The plasma level of DPH varied between 7-20 mug/ml. This dose produced chronic symptoms of intoxication. Neither EEG changes nor clinical seizures were entirely controlled by this drug. Additional doses of Relanium (diazepam), and phenobarbital were necessary to stop generalized seizures or status epilepticus.     

Magnetoencephalography in partial epilepsy: clinical yield and localization accuracy

The goals of this study were to determine (1) the yield of magnetoencephalography (MEG) according to epilepsy type, (2) if MEG spike sources colocalize with focal epileptogenic pathology, and (3) if MEG can identify the epileptogenic zone when scalp ictal electroencephalogram (EEG) or magnetic resonance imaging (MRI) fail to localize it. Twenty-two patients with mesial temporal (10 patients), neocortical temporal (3 patients), and extratemporal lobe epilepsy (9 patients) were studied. A 37-channel biomagnetometer was used for simultaneously recording MEG with EEG. During the typical 2-3-hour MEG recording session, interictal epileptiform activity was observed in 16 of 22 patients. MEG localization yield was greater in patients with neocortical epilepsy (92%) than in those with mesial temporal lobe epilepsy (50%). In 5 of 6 patients with focal epileptogenic pathology, MEG spike sources were colocalized with the lesions. In 11 of 12 patients with nonlocalizing (ambiguous abnormalities or normal) MRI, MEG spike sources were localized in the region of the epileptogenic zone as ultimately defined by all clinical and EEG information (including intracranial EEG). In conclusion, MEG can reliably localize sources of spike discharges in patients with temporal and extratemporal lobe epilepsy. MEG sometimes provides noninvasive localization data that are not otherwise available with MRI or conventional scalp ictal EEG.     

Prolonged and monosymptomatic dysphasic status epilepticus

Dysphasic seizures are an infrequent form of epilepsy, and their serial appearance as a partial status epilepticus is quite exceptional. The young patient reported here had a partial dysphasic status epilepticus of 3 weeks' duration without other temporal lobe seizures. Simultaneous serial electroencephalograms, tape recordings of the seizures, and repeated neuropsychologic ictal examinations permitted studies of increased impairment of neuropsychologic function on testing and the appearance of new irritative discharges on encephalography.     

Simple partial frontal nonconvulsive status epilepticus

Non convulsive status epilepticus (NCSE) of frontal origin is a rare cause of mental confusion. The present case of possible frontal-onset NCSE proved to have a neuropsychological examination that was suggestive either of a disruption of attentional function or a left prefrontal dysfunction, exhibiting disturbances of immediate memory and logical programmation, perseverations and affective disinhibition. Vigilance was not impaired. This case was therefore, on a nosographic point of view, more consistent with a simple partial status epilepticus with cognitive and affective symptomatology rather than with a complex partial status epilepticus of extra-temporal origin.     

FDG-PET and volumetric MRI in the evaluation of patients with partial epilepsy

We performed interictal FDG-PET- and MRI-based hippocampal volumetric measurements on 18 adult patients with complex partial epilepsy of temporal lobe origin in whom we had identified their ictal focus by video-telemetry EEG. Sixteen patients (89%) had regional hypometabolism, 11 (61%) had focal 1.5-tesla T2-weighted MRI (two structural abnormalities, nine hippocampal formation [HF] increased T2 signal), and nine (50%) had absolute HF atrophy ipsilateral to the temporal ictal focus. Ten (55%) had abnormal L/R HF ratios, nine ipsilateral to the EEG focus. All patients with abnormal MRI volumetric studies had focal PET abnormalities. Only seven had both abnormal HF volume ratios and T2 MRI (all increased HF T2 signal). There was a significant correlation between hippocampal volume and inferior mesial and lateral temporal lobe cerebral metabolic rate of glucose asymmetry index (p < 0.01), suggesting that hypometabolism may reflect hippocampal atrophy. PET is more sensitive than MRI volumetry in identifying the ictal focus but does not provide additional information when HF atrophy is present.     

Frontal lobe epilepsy in infancy: is there a benign partial frontal lobe epilepsy?

INTRODUCTION: Only the organic and cryptogenic forms of frontal lobe epilepsy have been admitted by the ILAE, but according to several reports in the literature, it probably exists also an idiopathic form, at present not well recognized. OBJECTIVE: To study the differences between the organic and the cryptogenic forms of frontal epilepsy in our patients, that might indicate the presence of idiopathic cases within the presumed cryptogenic group. MATERIAL AND METHODS: All patients diagnosed of frontal lobe epilepsy, EEG registered, at the neuropediatric clinic of our hospital during 1993-1996, were selected: 30 patients under 14 years of age that were classified as organic (10 cases) or cryptogenic (20 cases) according to CT or MRI findings. The Mann-Whitney test and the Fisher exact test were performed for statistical analysis. Five patients with peculiar neurocognitive symptoms, epilepsy-related, are described in detail. RESULTS: Significative differences between the organic and cryptogenic forms of frontal lobe epilepsy were not found except for the tendency of cryptogenic EEG foci to spread beyond the frontal lobe, to generalize and to be associated with foci of other localizations. Epileptic status, either convulsive or not convulsive, were a frequent complication in both groups. CONCLUSIONS: The identification of an idiopathic form of frontal lobe epilepsy is difficult by its low prevalence as compared to the cryptogenic and organic forms, by the tendency of frontal seizures to become epileptic status, which predicts an intractable epilepsy, and by the clinical characteristics essential to frontal discharges: heterogeneity, frequent impairment of consciousness and specially the neurocognitive semiology, including dementia, that occurs as a critic or paracritic phenomenon, and that sometimes may develop or be accentuated by antiepileptic medication.     

Case of simple partial status epilepticus in occipital lobe epilepsy misdiagnosed as migraine: clinical, electrophysiological, and magnetic resonance imaging characteristics

An 31-year-old man had a unique form of occipital lobe epilepsy. Since age 13 years, he has had episodes of simple partial status epilepticus (SE) occurring twice a month. These typically consisted of elementary visual hallucinations of flashing lights obscuring his left visual field for a period of 2 days, associated with a severe frontal headache initially diagnosed as migraine. These episodes of simple partial SE then evolved to a complex partial seizure (CPS) or secondarily generalized seizure. There were unique EEG features, including: (a) the perception of a flash of light in the left visual field with a single sharp/slow wave discharge over the right occipital lobe, (b) right occipital lobe epileptiform activity during the prolonged aura, and (c) an abnormal response to photic stimulation, with occipital lobe discharges during low rates of stimulation (3-5 Hz), time-locked to the stimulus. High-resolution magnetic resonance imaging (MRI) with quantitative morphometry demonstrated that the right hemisphere and right caudate nucleus were smaller than those on the left. An abnormal gyral pattern was also noted over the right parietal region. Occasionally, distinguishing occipital lobe epilepsy from migraine may be difficult.     

Rasmussen syndrome

INTRODUCTION: Rasmussen's encephalitis is a neurological disorder probably of immunological origin, characterized by intractable epilepsy, neurological deterioration and the presence of antibodies against R3 glutamate receptors. OBJECTIVE: To present the experience of an Argentinian Paediatric Neurology Service during the past 7 years. MATERIAL AND METHODS: We analyzed the clinical histories of 12 patients with RS as defined by the diagnostic criteria proposed by Hart et al. We evaluated the following parameters: neurological examination, neuropsychological assessment, types of crises, age of onset, frequency, distribution, electroencephalogram, video EEG, evoked potentials, neuro-radiological studies; CT and cerebral MR using gadolinium, SPECT, lumbar puncture and cerebral biopsy. RESULTS: The crises were of simple partial motor type in 12 cases, secondarily generalized partial crises in 7 cases, complex partial crises in 4 cases and partial and generalized motor states in 8 cases. RESULTS. The ictal EEGs during the continuous partial crises showed contralateral focal slow activity of the affected side of the body in 30% of cases. The neuro-radiological studies (CT and MR) showed signs of cerebral hemiatrophy in all 12 cases, hyper-intense images in the T2 sequences of the fronto-temporo-parietal regions in 5 cases, an asymmetric megacisterna magna in 1 case and hypoplasia of the cerebellar vermis in another case. CONCLUSIONS: The continuous partial crises showed little correlation with the electro-encephalography. Following administration of i.v. gammaglobulin there was a transient halt in progression of the neurological deterioration and control of the crises in 55% of the cases. Surgery continued to be the treatment recommended for control of the epileptic crises.     

Seizures associated with propofol anesthesia

Propofol is a new, fast-acting intravenous (i.v.) anesthetic. Involuntary movements or epileptic seizures have occurred during or after propofol-induced anesthesia in approximately 50 reported cases; a third of the patients have had epilepsy. We report 5 patients with seizures in association with propofol anesthesia. A female epileptic patient developed severe status epilepticus; the other patients with short-lasting seizures had no previous epilepsy. Although propofol has been used in treatment of patients of status epilepticus, the risk of precipitation of epileptic seizures warrants consideration especially when planning anesthesia for epileptic patients.     

EEG findings in frontal lobe epilepsies

As a group, epilepsies of frontal lobe origin are thought to be poorly localized using surface EEG recordings. This finding may depend on the specific areas of frontal lobe from which the seizures originate or the pathologic substrate. We reviewed the presurgical surface EEGs of patients with frontal lobe epilepsy who underwent epilepsy surgery. The specific area of the frontal lobe where seizures originated was determined by 1) intracranial ictal EEG recordings, or 2) the presence of a structural lesion, identified by imaging studies in patients who achieved complete seizure control following surgery. We differentiated patients whose seizures began in the dorsolateral frontal convexity from those whose seizures began in the medial frontal region, and we correlated EEG findings in the interictal, postictal, and ictal states with seizure semiology, pathologic substrate, and surgical outcome. Four of nine patients had seizures originating in the dorsolateral frontal convexity and five had medial frontal onset seizures. Patients whose seizures originated from the dorsolateral convexity had focal interictal epileptiform abnormalities that localized to the region of seizure onset. Patients whose seizures began in the medial frontal region had either no interictal epileptiform abnormality or had multifocal epileptiform discharges. Patients whose seizures began in the dorsolateral convexity showed focal electrographic seizure activity that was localizing. This rhythmic fast activity did not appear to be substrate-specific. Patients whose seizure onset localized to the medial frontal region did not show focal electrographic seizure at clinical onset. We conclude that the scalp EEG recordings of frontal lobe epilepsies contain features that enable differentiation of seizures originating from two different regions of the frontal lobe.     

Occurrence, causes and clinical characteristics of status epilepsy in adults

INTRODUCTION: Status epilepticus, particularly grand mal, is one of the gravest and most dramatic conditions in neurology requiring immediate attention. Status epilepticus can occur in epileptic patients, often with higher mortality rates in symptomatic than idiopathic, but also as an initial symptom of a number of neurological and systemic diseases. No data are available on the exact incidence rates of status epilepticus. According to some assessments, 10% of patients have at least one status epilepticus in their lifetime (3,6). The prognosis mostly depends on the main cause, time in which seizures are stopped and age of patients. Latest data available in literature suggest the mortality rate of 2-8%. MATERIALS AND METHODS: We analyzed frequency of hospital admissions, causes and clinical characteristics of status epilepticus in adults. The study was retrospective, based on case histories of epileptic patients from the Intensive Care Unit of the Neurology Clinic in Novi Sad in 1990, 1993 and 1995. Special emphasis was placed on differences in studied parameters between cases confirmed earlier and those with status epilepticus occurring as an initial symptom of some other illness or condition. RESULTS: Number of hospital admissions rose slightly in the interval observed in comparison with total admissions (0.68% in 1990, 1.24% in 1993, and 1.73% in 1995) (Tabs 1 and 2). During 1993, status epilepticus was more frequent in cases confirmed earlier (69%) compared with the years 1990 (56%) and 1995 (43%) (Graf.1). Epileptic patients were younger on the average than nonepileptic ones (Tab. 3). Status epilepticus occurred more often in male patients (Tab. 4). Irregular treatment was the prevailing cause in epileptic patients (Tab 5). Symptomatic status epilepticus was reported higher in 1990 and 1995, and stroke was definitely the predominant cause (Tab 6). Convulsive grand mal status prevailed in all patients (Graf 2). Focal status was a more frequent finding in nonepileptic patients (Graf 3). Every third in 16 patients died in 1993 and every fifth in 23 in 1995 probably due to the acute destructive brain damage rather than the status itself. No deaths occurred in 1990. DISCUSSION: According to research carried out by other authors, half of grand mal status cases occurred in confirmed epileptics (4). In our study the grand mal status was reported in 70.4% cases of epilepsy. Primary cause was abrupt withdrawal of antiepileptic treatment, infections, alcohol abuse and use of convulsive drugs. This is compatible with our results which confirm that grand mal status either primary or with secondary generalization prevail in both groups of patients (7,8,9). In terms of causes of status epilepticus in nonepileptic patients, literature data mainly suggest cerebral trauma, frontal brain tumors, cerebral arteriosclerosis or other vascular disorders and anaphylaxis (4). Our results point to stroke as the major cause of status epilepticus in nonepileptic patients, similar with data presented by Towne (10). There is no data in literature concerning the relation between sex of patients and occurrence of status. In our study status epilepticus occurred more frequently in male patients. CONCLUSION: The grand mal status was the major clinical type of status in all patients and was primarily caused by discontinued or irregular antiepileptic treatment in patients with confirmed epilepsy, and by stroke in nonepileptic patients.     

Single photon emission tomography in temporal epilepsy: interictal and ictal studies with visual and semi quantitative analysis

Single photon emission tomography (SPECT) was performed in 27 patients with refractory complex partial seizures from the temporal lobes due to mesial temporal sclerosis. Independent blinded observers assessed the 28 interictal studies and 9 ictal/postictal studies. Visual analysis of interictal studies detected hypoperfusion in 22, ipsilateral to the epileptogenic zone in 19 (67%) and contralateral in 3 (10.7%). Quantified temporal lobe asymmetry, greater than a previously derived normal range, correctly identified the epileptogenic zone in 16 (61.5%) with false lateralization in 4 (15.3%). In all 9 cases in which they were performed, ictal/postictal studies showed hyperperfusion at the region of epileptic focus. In 3 patients with complex partial seizures followed by symmetric generalized tonic-clonic seizures, hyperperfusion restricted to the temporal lobe was demonstrated. In 5 of these patients the interical studies were unable to demonstrate localized changes. There were no significant correlations between SPECT findings and clinical parameters or EEG slowing in the temporal lobes.     

Involvement of insulin-like growth factors-I and -II and their receptors in medroxyprogesterone acetate-induced growth of mouse mammary adenocarcinomas

Data about psychiatric disorders associated with epilepsy as well as their risk factors are heterogeneous. The overall prevalence of psychiatric disturbances in epileptic patients can be estimated between 20 and 30 per cent. It is the highest in pharmocoresistant cases seen in specialized centers. Psychotic disorders, depression, and suicide are the three most common among interictal disturbances. Psychoses affect 2 to 9 per cent of patients and are more frequent in cases with aura or altered consciousness, such as in complex partial seizures and absences. They correlate positively with the multiplicity of seizures but often inversely with their frequency. Temporal lobe epilepsy is associated with schizo phrenic-like and paranoid types of psychosis, but frontal lobe epilepsy is also common. A putative association with predominant left or bilateral EEG abnormalities in cases with partial epilepsy remains to be confirmed, as well as the frequency of underlying structural lesions. Depressive disorders affect 20 to 60 per cent of patients. While their occurrence with partial complex seizures and left hemisphere foci is common, the role of temporal lobe involvement still appears controversial. Depression prevails in cases with seizures that occasionally, albeit rarely, secondarily generalize and correlates with the duration of the disease, intractable seizures, and polypharmacy. A genetic factor is likely to play a role. Suicides rates are increased, encountered in 0.2-0.5 per cent of patients and causing deaths in 3-7 per cent of them. The overall risk might be the highest during the first years after diagnosis of epilepsy, as well as in patients with temporal lobe foci, depression, or psychosis. Great variability and discordance in results show the major difficulties encountered in epidemiologic studies. Most of these problems relate to the classification of epileptic disorders as well as that of psychiatric disorders, the variability in the methods and measures which are used, and frequent bias in the selection of patients. We review here data about the frequency of major psychiatric disorders in epileptic patients or the frequency of epileptic disorders in psychiatric patients, and also possible risk factors related to the epileptic disease and its evolution.     

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.